Astrophysics
New submissions
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New submissions for Wed, 5 Feb 20
- [1] arXiv:2002.00947 [pdf, ps, other]
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Title: Rigorous "Rich Argument" in Microlensing ParallaxAuthors: Andrew GouldComments: 4 pages, submitted to JKASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)
I show that when the observables $(\vec \pi_{{\rm E}},t_{{\rm E}},\theta_{{\rm E}},\pi_s,\vec \mu_s)$ are well measured up to a discrete degeneracy in the microlensing parallax vector $\vec \pi_{{\rm E}}$, the relative likelihood of the different solutions can be written in closed form $P_i = K H_i B_i$, where $H_i$ is the number of stars (potential lenses) having the mass and kinematics of the inferred parameters of solution $i$ and $B_i$ is an additional factor that is formally derived from the Jacobian of the transformation from Galactic to microlensing parameters. The Jacobian term $B_i$ constitutes an explicit evaluation of the ``Rich Argument'', i.e., that there is an extra geometric factor disfavoring large-parallax solutions in addition to the reduced frequency of lenses given by $H_i$. Here $t_{{\rm E}}$ is the Einstein timescale, $\theta_{{\rm E}}$ is the angular Einstein radius, and $(\pi_s,\vec \mu_s)$ are the (parallax, proper motion) of the microlensed source. I also discuss how this analytic expression degrades in the presence of finite errors in the measured observables.
- [2] arXiv:2002.00954 [pdf, other]
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Title: Polarization Imaging of M87 Jets by General Relativistic Radiative Transfer Calculation based on GRMHD SimulationsComments: 18 pages, 14 figures, 1 table. Accepted by PASJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
The spectacular images of the M87 black hole taken by the Event Horizon Telescope (EHT) have opened a new era of black hole research. One of the next issues is to take polarization images around the central black hole (BH). Since radio emission is produced by synchrotron process, polarization properties should vividly reflect the magnetic field structure at the jet base and thus provide good information regarding the magnetic mechanism of jet formation. With this kept in mind we perform general relativistic (GR) radiative transfer calculations of polarized light based on the GR magnetohydrodynamic (MHD) simulation data of accretion flow and outflow in M87, to obtain their linear and circular polarization images in the horizon-scale. We found that the linear polarization components from the jet base and inner accretion flow should experience Faraday rotation when passing through magnetized plasmas around the BH, thus sensitively depending on the BH spin. Through the comparison with intensity image at 1.3mm by EHT and the polarized degree and the rotation measure (RM) at 1.3mm with the Submillimeter Array, the model with the spin parameter of a=0.9M_BH (with M_BH being the BH mass) is favored over other models with a=0.5M_BH or 0.99M_BH, though we need further systematic studies for confirmation. We also find in low-temperature models clear ring-like image in the circular polarization map, which arises because of Faraday conversion of the linearly polarized synchrotron emission and is thus indicative of magnetic field. This occurs only when the emission region is threaded with well-ordered magnetic fields and hence no clear images are expected in high-temperature disk models, in which disk emission is appreciable. We will be able to elucidate the field configuration through the comparison between the simulated polarization images and future polarimetry with EHT and other VLBI observations.
- [3] arXiv:2002.00955 [pdf, other]
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Title: A Large Population of Obscured AGN in Disguise as Low Luminosity AGN in Chandra Deep Field SouthComments: 23 pages, 16 figures, submitted to the Astrophysical Journal, first round of revision completedSubjects: Astrophysics of Galaxies (astro-ph.GA)
Population synthesis models of actively accreting super-massive black holes (or active galactic nuclei -- AGN) predict a large fraction that must grow behind dense, obscuring screens of gas and dust. Deep X-ray surveys are thought to have provided the most complete and unbiased samples of AGN, but there is strong observational evidence that a portion of the population of obscured AGN is being missed. In this paper we use a sample of AGN derived from the deepest X-ray survey to date, the Chandra 7Ms GOODS-South Survey, to investigate the nature of low flux X-ray sources. We make full use of the extensive multi-wavelength coverage of the GOODS-South field, and cross-match our objects with wavelengths from the Radio to the IR. We find the low X-ray flux AGN in our sample have X-ray luminosities that indicate low-luminosity AGN classification, while their radio, infrared and optical counterparts indicate moderate to powerful AGN classification. We find the predicted column densities is on average an order of magnitude higher than the calculated column densities via X-ray detections for X-ray faint sources. We interpret our results as evidence of obscured AGN disguising as low-luminosity AGN via their X-ray luminosities. When we compare the estimation of the obscured AGN space density with and without these objects, we find a difference of 40% in the lowest X-ray luminosity regime probed by our sample.
- [4] arXiv:2002.00956 [pdf, other]
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Title: Updated Parameter Estimates for GW190425 Using Astrophysical Arguments and Implications for the Electromagnetic CounterpartAuthors: Ryan J. Foley, David A. Coulter, Charles D. Kilpatrick, Anthony L. Piro, Enrico Ramirez-Ruiz, Josiah SchwabComments: 11 pages, 6 figures, submittedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The progenitor system of the compact binary merger GW190425 had a total mass of $3.4^{+0.3}_{-0.1}$ M$_\odot$ (90th-percentile confidence region) as measured from its gravitational wave signal. This mass is significantly different from the Milky Way (MW) population of binary neutron stars (BNSs) that are expected to merge in a Hubble time and from that of the first BNS merger, GW170817. Here we explore the expected electromagnetic signatures of such a system. We make several astrophysically motivated assumptions to further constrain the parameters of GW190425. By simply assuming that both components were NSs, we reduce the possible component masses significantly, finding $m_1 = 1.85^{+0.27}_{-0.19}$ M$_\odot$ and $m_2 = 1.47^{+0.16}_{-0.18}$ M$_\odot$. However if the GW190425 progenitor system was a NS-black hole merger, we find best-fitting parameters $m_1 = 2.19^{+0.21}_{-0.17}$ M$_\odot$ and $m_2 = 1.26^{+0.10}_{-0.08}$ M$_\odot$. For a well-motivated BNS system where the lighter NS has a mass similar to the mass of non-recycled NSs in MW BNS systems, we find $m_1 = 2.03^{+0.15}_{-0.14}$ M$_\odot$ and $m_2 = 1.35 \pm 0.09$ M$_\odot$, corresponding to only 7% mass uncertainties. For all scenarios, we expect a prompt collapse of the resulting remnant to a black hole. Examining detailed models with component masses similar to our best-fitting results, we find the electromagnetic counterpart to GW190425 is expected to be significantly redder and fainter than that of GW170817. We find that almost all reported observations used to search for an electromagnetic counterpart for GW190425 were too shallow to detect the expected counterpart. If the LIGO-Virgo Collaboration promptly provides the chirp mass, the astronomical community can adapt their observations to improve the likelihood of detecting a counterpart for similarly "high-mass" BNS systems. (abridged)
- [5] arXiv:2002.00957 [pdf, ps, other]
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Title: The WISSH quasars project VIII. The impact of extreme radiative field in the accretion disk -- X-ray corona interplayAuthors: L. Zappacosta, E. Piconcelli, M. Giustini, G. Vietri, F. Duras, G. Miniutti, M. Bischetti, A. Bongiorno, M. Brusa, M. Chiaberge, A. Comastri, C. Feruglio, A. Luminari, A. Marconi, C. Ricci, C. Vignali, F. FioreComments: 10 pages (including Appendix), 4 figures. Accepted for publication in A&A LetterSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
Hyperluminous quasars ($L_{\rm bol}\gtrsim 10^{47}$ erg s$^{-1}$) are ideal laboratories to study the interaction and impact of extreme radiative field and the most powerful winds in the AGN nuclear regions. They typically exhibit low coronal X-ray luminosity ($L_{\rm X}$) compared to the UV and MIR radiative outputs ($L_{\rm UV}$ and $L_{\rm MIR}$) with a non-negligible fraction of them reporting even $\sim$1 dex weaker $L_{\rm X}$ compared to the prediction of the well established $L_{\rm X}$-$L_{\rm UV}$ and $L_{\rm X}$-$L_{\rm MIR}$ relations followed by the bulk of the AGN population. We report in our WISE/SDSS-selected Hyperluminous (WISSH) $z=2-4$ broad-line quasar sample, the discovery of a dependence between the intrinsic 2-10 keV luminosity ($L_{\rm 2-10}$) and the blueshifted velocity of the CIV emission line ($v_{\rm CIV}$) indicative of accretion disc winds. In particular, sources with fastest winds ($v_{\rm CIV}\gtrsim 3000~\rm km s^{-1}$) possess $\sim$0.5-1 dex lower $L_{\rm 2-10}$ than sources with negligible $v_{\rm CIV}$. No similar dependence is found on $L_{\rm UV}$, $L_{\rm MIR}$, $L_{\rm bol}$, photon index and absorption column density. We interpret these findings in the context of accretion disc wind models. Both magnetohydrodynamic and line-driven models can qualitatively explain the reported relations as a consequence of X-ray shielding from the inner wind regions. In case of line-driven winds, the launch of fast winds is favoured by a reduced X-ray emission, and we speculate that these winds may play a role in directly limiting the coronal hard X-ray production.
- [6] arXiv:2002.00958 [pdf, other]
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Title: The ALMA view of the high redshift relation between supermassive black holes and their host galaxiesComments: 31 pages, 31 figures, accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
This work aims at studying the $M_{BH}-M_{dyn}$ relation of a sample of $2<z<7$ quasars by constraining their host galaxy masses through a full kinematical modelling of the cold gas kinematics thus avoiding all possible biases and effects introduced by the rough virial estimates usually adopted so far. For this purpose we retrieved public observations of $72$ quasar host galaxies observed in ${\rm [CII]_{158\mu m}}$ or ${\rm CO}$ transitions with the Atacama Large Millimeter Array (ALMA). We then selected those quasars whose line emission is spatially resolved and performed a kinematic analysis on ALMA observations. We estimated the dynamical mass of the systems by modelling the gas kinematics with a rotating disc taking into account geometrical and instrumental effects. Our dynamical mass estimates, combined with $M_{BH}$ obtained from literature and our own new ${\rm CIV}\lambda1550$ observations have allowed us to investigate the $ M_{BH}/M_{dyn}$ in the early Universe. Overall we obtained a sample of $10$ quasars at $z\sim2-7$ in which line emission is detected with high SNR ($> 5-10$) and the gas kinematics is spatially resolved and dominated by ordered rotation. The estimated dynamical masses place $6$ out of $10$ quasars above the local relation yielding to a $M_{BH}/M_{dyn}$ ratios $\sim10\times$ higher than those estimated in low-$z$ galaxies. On the other hand we found that $4$ quasars at $z\sim 4-6$ have dynamical-to-BH mass ratios consistent with what is observed in early type galaxies in the local Universe.
- [7] arXiv:2002.00959 [pdf, other]
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Title: Galaxy mergers in EAGLE do not induce a significant amount of black hole growth yet do increase the rate of luminous AGNAuthors: Stuart McAlpine (1), Chris M. Harrison (2), David J. Rosario (3), David M. Alexander (3), Sara L. Ellison (4), Peter H. Johansson (1), David R. Patton (5) ((1) University of Helsinki, (2) Newcastle University (3) CEA, Durham University, (4) University of Victoria, (5) Trent University)Comments: 21 pages, 17 figures, submitted to MNRAS (comments welcome)Subjects: Astrophysics of Galaxies (astro-ph.GA)
We investigate the connection between galaxy--galaxy mergers and enhanced black hole (BH) growth using the cosmological hydrodynamical \eagle simulation. We do this via three methods of analysis, investigating: the merger fraction of AGN, the AGN fraction of merging systems and the AGN fraction of galaxies with close companions. In each case, we find an increased abundance of AGN within merging systems relative to control samples of inactive or isolated galaxies (by up to a factor of $\approx 4$ depending on the analysis method used), confirming that mergers are enhancing BH accretion rates for at least a subset of the galaxy population. The greatest excess of AGN triggered via a merger are found in lower mass ($M_* \sim 10^{10}$~\Msol) gas rich ($f_{\mathrm{gas}} > 0.1$) central galaxies with lower mass BHs ($M_{\mathrm{BH}} \sim 10^{7}$~\Msol) at lower redshifts ($z<1$). We find no enhancement of AGN triggered via mergers in more massive galaxies ($M_* \gtrsim 10^{11}$~\Msol). The enhancement of AGN is not uniform throughout the phases of a merger, and instead peaks within the early \emph{remnants} of merging systems (typically lagging $\approx 300$~Myr post-coalescence of the two galaxies at $z=0.5$). We argue that neither major ($M_{\mathrm{*,1}} / M_{\mathrm{*,2}} \geq \frac{1}{4}$) nor minor mergers ($\frac{1}{10} < M_{\mathrm{*,1}} / M_{\mathrm{*,2}} < \frac{1}{4}$) are statistically relevant for enhancing BH masses globally. Whilst at all redshifts the galaxies experiencing a merger have accretion rates that are on average 2--3 times that of isolated galaxies, the majority of mass that is accreted onto BHs occurs outside the periods of a merger. We compute that on average no more than 15\% of a BHs final day mass comes from the enhanced accretion rates triggered via a merger.
- [8] arXiv:2002.00960 [pdf, other]
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Title: Cosmic structures from a mathematical perspective 1. Dark matter halo mass density profilesAuthors: Jenny WagnerComments: 25 pages, 1 figure, submitted to General Relativity and Gravitation, comments very welcomeSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The shapes of individual self-gravitating structures of an ensemble of identical, collisionless particles have remained elusive for decades. In particular, a reason why mass density profiles like the Navarro-Frenk-White or the Einasto profile are good fits to simulation- and observation-based dark matter halos has not been found. Given the class of three dimensional, spherically symmetric power-law probability density distributions to locate individual particles in the ensemble mentioned above, we derive the constraining equation for the power-law index for the most and least likely joint ensemble configurations. Interpreting the scaling radius as the mean free path length of the particles, a dark matter halo can be constructed as a core of free moving particles, transitioning into a homogeneous dark matter fluid. The mean radius of the specific particle distribution fixes the power-law index in the core. The fluid region becomes isothermal in the limit of infinitely many particles. The slope of the mass density profile far from the centre is determined by the definition of the halo boundary, such that two typical limiting cases arise that explain the $r^{-3}$-slope for galaxy-cluster outskirts and the $r^{-4}$-slope for galactic outskirts. Hence, the different power-law slopes of the individual regions allow to put limits on the properties of the dark matter particles like their number density and mean free path length. These results also allow to find a simple explanation for the cusp-core-problem and to separate the halo description from its dynamics.
- [9] arXiv:2002.00961 [pdf, other]
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Title: The ALPINE-ALMA [CII] Survey: On the nature of an extremely obscured serendipitous galaxyAuthors: Michael Romano, P. Cassata, L. Morselli, B. C. Lemaux, M. Bethermin, P. Capak, A. Faisst, O. Le Fevre, D. Schaerer, J. Silverman, L. Yan, S. Bardelli, M. Boquien, A. Cimatti, M. Dessauges-Zavadsky, A. Enia, Y. Fudamoto, S. Fujimoto, M. Ginolfi, C. Gruppioni, N. P. Hathi, E. Ibar, G. C. Jones, A. M. Koekemoer, F. Loiacono, C. Mancini, D. A. Riechers, G. Rodighiero, L. Rodriguez-Munoz, M. Talia, L. Vallini, D. Vergani, G. Zamorani, E. ZuccaComments: 13 pages, 6 figures. Submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
We report the serendipitous discovery of a bright galaxy (Gal-A) observed as part of the ALMA Large Program to INvestigate [CII] at Early times (ALPINE). While this galaxy is detected both in line and continuum emission in ALMA Band 7, it is completely dark in UV/optical filters and only presents a marginal detection in the UltraVISTA Ks band. We discuss the nature of the observed ALMA line, i.e. whether the emission comes from [CII] at z~4.6, or from high-J CO transitions at z~2.2. In the first case we find a [CII]-to-FIR luminosity ratio of log(L_[CII]/L_FIR)=-2.5, consistent with the average value for local star-forming galaxies (SFGs); in the second case, instead, the source would lie outside of the empirical relations between L_CO and L_FIR found in the literature. At both redshifts, we derive the star-formation rate (SFR) from the ALMA continuum, and the stellar mass (M*) by using stellar population synthesis models as input for LePHARE spectral energy distribution (SED) fitting. Exploiting our results, we believe that Gal-A is a Main-Sequence (MS), dusty SFG at z=4.6 (i.e. [CII] emitter) with log(SFR/[M/yr])~1.4 and log(M*/M)~9.7. This work underlines the crucial role of the ALPINE survey in making a census of this class of objects, in order to unveil their contribution to the global star-formation rate density (SFRD) of the Universe at the end of the Reionisation epoch.
- [10] arXiv:2002.00962 [pdf, other]
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Title: The ALPINE-ALMA [CII] Survey: data processing, catalogs, and statistical source propertiesAuthors: M. Bethermin, Y. Fudamoto, M. Ginolfi, F. Loiacono, Y. Khusanova, P. L. Capak, P. Cassata, A. Faisst, O. Le Fevre, D. Schaerer, J. D. Silverman, L. Yan, R. Amorin, S. Bardelli, M. Boquien, A. Cimatti, I. Davidzon, M. Dessauges-Zavadsky, S. Fujimoto, C. Gruppioni, N. P. Hathi, E. Ibar, G. C. Jones, A. M. Koekemoer, G. Lagache, B. C. Lemaux, P. A. Oesch, F. Pozzi, D. A. Riechers, M. Talia, S. Toft, L. Vallini, D. Vergani, G. Zamorani, E. ZuccaComments: 41 pages, 29 figures, 14 tables, submitted to A&A, the catalog tables will be released when the paper will be accepted to avoid spreading several versionsSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The ALPINE-ALMA large program targets the [CII] 158 $\mu$m line and the far-infrared continuum in 118 spectroscopically confirmed star-forming galaxies between z=4.4 and z=5.9. It represents the first large [CII] statistical sample built in this redshift range. We present details of the data processing and the construction of the catalogs. We detected 23 of our targets in the continuum. To derive accurate infrared luminosities and obscured star formation rates, we measured the conversion factor from the ALMA 158 $\mu$m rest-frame dust continuum luminosity to the total infrared luminosity (L$_{\rm IR}$) after constraining the dust spectral energy distribution by stacking a photometric sample similar to ALPINE in ancillary single-dish far-infrared data. We found that our continuum detections have a median L$_{\rm IR}$ of 4.4$\times 10^{11}$ L$_\odot$. We also detected 57 additional continuum sources in our ALMA pointings. They are at lower redshift than the ALPINE targets, with a mean photometric redshift of 2.5$\pm$0.2. We measured the 850 $\mu$m number counts between 0.35 and 3.5 mJy, improving the current interferometric constraints in this flux density range. We found a slope break in the number counts around 3 mJy with a shallower slope below this value. More than 40 % of the cosmic infrared background is emitted by sources brighter than 0.35 mJy. Finally, we detected the [CII] line in 75 of our targets. Their median [CII] luminosity is 4.8$\times$10$^8$ L$_\odot$ and their median full width at half maximum is 252 km/s. After measuring the mean obscured SFR in various [CII] luminosity bins by stacking ALPINE continuum data, we find a good agreement between our data and the local and predicted SFR-L$_{\rm [CII]}$ relations of De Looze et al. (2014) and Lagache et al. (2018).
- [11] arXiv:2002.00964 [pdf, other]
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Title: Closing in on the origin of cosmic rays using multimessenger informationComments: Invited review article, 133 pages, 45 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
In cosmic ray physics extensive progress has been made in recent years, both concerning theory and observation. The vast details in direct, indirect and secondary detections on the one hand provide the basis for a detailed modeling of the signatures via cosmic-ray transport and interaction, paving the way for the identification of Galactic cosmic-ray sources. On the other hand, the large number of constraints from different channels of cosmic-ray observables challenges these models frequently.
In this review, we will summarize the state-of-the art of the detection of cosmic rays and their secondaries, followed by a discussion what we can learn from coupling our knowledge of the cosmic-ray observables to the theory of cosmic-ray transport in the Galactic magnetic field. Finally, information from neutral secondaries will be added to draw a multimessenger-picture of the non-thermal sky, in which the hypothesis of supernova remnants as the dominant sources survives best. While this has been known since the 1930s, evidence for this scenario is steadily growing, with the first detection of hadronic signatures at GeV energies detected for three SNRs with Fermi. The existence of SNRs as PeVatrons, however, is not validated yet. The discussion of this and other open questions concerning the level of anisotropy, composition and spectral shape of the cosmic-ray energy spectrum is reviewed. Future perspectives of how to find the smoking cosmic-ray source gun concludes this review. - [12] arXiv:2002.00965 [pdf, other]
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Title: Bayesian delensing delight: sampling-based inference of the primordial CMB and gravitational lensingComments: 23 pages, 10 figures. An accompanying software package is available at this https URLSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The search for primordial gravitational waves in the Cosmic Microwave Background (CMB) will soon be limited by our ability to remove the lensing contamination to $B$-mode polarization. The often-used quadratic estimator for lensing is known to be suboptimal for surveys that are currently operating and will continue to become less and less efficient as instrumental noise decreases. While foregrounds can in principle be mitigated by observing in more frequency bands, progress in delensing hinges entirely on algorithmic advances. We demonstrate here a new inference method that solves this problem by sampling the exact Bayesian posterior of any desired cosmological parameters, of the gravitational lensing potential, and of the delensed CMB maps, given lensed temperature and polarization data. We validate the method using simulated CMB data with non-white noise and masking on up to 650\,deg$^2$ patches of sky. A unique strength of this approach is the ability to jointly estimate cosmological parameters which control both the primordial CMB and the lensing potential, which we demonstrate here for the first time by sampling both the tensor-to-scalar ratio, $r$, and the amplitude of the lensing potential, $A_\phi$. The method allows us to perform the most precise check to-date of several important approximations underlying CMB-S4 $r$ forecasting, and we confirm these yield the correct expected uncertainty on $r$ to better than 10%.
- [13] arXiv:2002.00967 [pdf, other]
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Title: The ALPINE-ALMA [CII] survey: Small Lyα-[CII] velocity offsets in main-sequence galaxies at 4.4 < z < 6Authors: P. Cassata, L. Morselli, A. Faisst, M. Ginolfi, M. Bethermin, P. Capak, O. Le Fevre, D. Schaerer, J. Silverman, L. Yan, B. C. Lemaux, M. Romano, M. Talia, S. Bardelli, M. Boquien, A. Cimatti, M. Dessauges-Zavadsky, Y. Fudamoto, S. Fujimoto, M. Giavalisco, N. Hathi, E. Ibar, G. Jones, A. M. Koekemoer, H. Mendez-Hernandez, C. Mancini, P. Oesch, F. Pozzi, D. A. Riechers, G. Rodighiero, D. Vergani, G. Zamorani, E. ZuccaComments: 20 pages, 6 figures, submitted to A&ASubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The Lya line in the UV and the [CII] line in the FIR are widely used tools to identify galaxies and to get insights about their ISM properties in the Early Universe. Combining data obtained with ALMA in band 7 as part of the ALMA Large Program to INvestigate [CII] at EarlyTimes (ALPINE) with spectroscopic data from DEIMOS/Keck, VIMOS/VLT and FORS2/VLT we assembled an unique sample of 53 main sequence galaxies at 4.4<z<6 in which we detect both the Lya line and the [CII]. We use [CII], observed with ALMA, as a tracer of the systemic velocity, and we exploit the available optical spectroscopy to obtain the Lya-[CII] and the ISM-[CII] velocity offsets. We find that 90% of the objects have Lya-[CII] offsets in the range 0<Dv_Lya-[CII]<400 km/s, in line with the few measurements available so far in the Early Universe, and much smaller than those observed at lower redshifts. At the same time, we observe ISM-[CII] offsets in the range -500<Dv_ISM-[CII]<0 km/s, in line with values at all redshifts, that we interpret as evidence for outflows in these galaxies. We find significant anti-correlations between Dv_Lya-[CII] and the Lya equivalent width EW0(Lya)(or equivalently f_esc(Lya)), with galaxies that show smaller Dv_Lya-[CII] having larger EW0(Lya) and f_esc(Lya). We interpret these results in the framework of the uniform expanding shell model: the escape of Lya photons is determined by the neutral hydrogen column density NHI. In galaxies with slow outflows (0 <v_out<300km/s) when NHI is high, Dv_Lya-[CII] is high and f_esc(Lya) is low, and vice-versa. In galaxies with fast outflows (v_out>300km/s), the probability of Lya photons to escape is high and Dv_Lya-[CII]is always small. We suggest that the observed increase of the Lya escape observed in the literature between z~2 and ~6 is not due to a higher incidence of fast outflows at high redshift, but rather to a decrease of NHI in the ISM.
- [14] arXiv:2002.00970 [pdf, ps, other]
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Title: GSN 069 -- A Tidal Disruption Near-MissAuthors: Andrew KingComments: MNRAS, acceptedSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
I suggest that the quasiperiodic ultrasoft X-ray eruptions recently observed from the galaxy GSN 069 may result from accretion from a low-mass white dwarf in a highly eccentric orbit about its central black hole. At 0.21M_sun, this star was probably the core of a captured red giant. Such events should occur in significant numbers as less extreme outcomes of whatever process leads to tidal disruption events. I show that gravitational radiation losses can drive the observed mass transfer rate, and that the precession of the white dwarf orbit may be detectable in X-rays as a superorbital quasiperiod P_super ~ 2 d. The very short lifetime of the current event, and the likelihood that similar ones involving more massive stars would be less observable, together suggest that stars may transfer mass to the low-mass SMBH in this and similar galaxies at a total rate potentially making a significant contribution to their masses. A similar or even much greater inflow rate would be unobservable in most galaxies. I discuss the implications for SMBH mass growth.
- [15] arXiv:2002.00971 [pdf, ps, other]
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Title: Deprojecting galaxy-cluster cold fronts: evidence for bulk, magnetised spiral flowsComments: 29 pages, 20 figures, 6 tablesSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Tangential discontinuities known as cold fronts (CFs) are abundant in groups and clusters of galaxies (GCs). The relaxed, spiral-type CFs were initially thought to be isobaric, but a significant, $10\%$--$20\%$ jump in the thermal pressure $P_t$ was reported when deprojected CFs were stacked, interpreted as missing $P_t$ below the CFs (i.e. at smaller radii $r$) due to a locally-enhanced nonthermal pressure $P_{nt}$. We report a significant ($\sim4.3\sigma$) deprojected jump in $P_t$ across a single sharp CF in the Centaurus cluster. Additional seven CFs are deprojected in the GCs A2029, A2142, A2204, and Centaurus, all found to be consistent (stacked: $\sim1.9\sigma$) with similar pressure jumps. Combining our sample with high quality deprojected CFs from the literature indicates pressure jumps at significance levels ranging between $2.7\sigma$ and $5.0\sigma$, depending on assumptions. Our nominal results are consistent with $P_{nt}\simeq (0.1\mbox{--}0.3)P_t$ just below the CF. We test different deprojection and analysis methods to confirm that our results are robust, and show that without careful deprojection, an opposite pressure trend may incorrectly be inferred. Analysing all available deprojected data, we also find: (i) a nearly constant CF contrast $q$ of density and temperature within each GC, monotonically increasing with the GC mass $M_{200}$ as $q\propto M_{200}^{0.23\pm0.04}$; (ii) hydrostatic mass discontinuities indicating fast bulk tangential flows below all deprojected CFs, with a mean Mach number $\sim0.76$; and (iii) the newly deprojected CFs are consistent (stacked: $\sim2.9\sigma$) with a $1.25^{+0.09}_{-0.08}$ metallicity drop across the CF. These findings suggest that GCs quite generally harbor extended spiral flows.
- [16] arXiv:2002.00972 [pdf, other]
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Title: What do observations tell us about the highest-redshift supermassive black holes?Authors: Benny TrakhtenbrotComments: 13 pages of text, 6 figures. Invited review talk at IAU Symposium 356, "Nuclear Activity in Galaxies across Cosmic Time", Oct 2019Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
I review the current understanding of some key properties of the first generation of growing supermassive black holes (SMBHs), as determined from the most up-to-date observations. This includes their accretion rates and growth history, their host galaxies, and the large-scale environments that enabled their emergence less than a billion years after the Big Bang. The available multi-wavelength data show that these SMBHs are consistent with Eddington-limited, radiatively efficient accretion that had to proceed almost continuously since very early epochs. ALMA observations of the hosts' ISM reveal gas-rich, well developed galaxies, with a wide range of SFRs that may exceed ~1000 M_sol/yr. Moreover, ALMA uncovers a high fraction of companion, interacting galaxies, on scales of <100 kpc. This supports the idea that the first generation of high-mass, luminous SMBHs grew in over-dense environments, and that major mergers may be important drivers for rapid SMBH and host galaxy growth. Current X-ray surveys cannot access the lower-mass, supposedly more abundant counterparts of these rare z>5 massive quasars, which should be able to elucidate the earliest stages of BH formation and growth. Such lower-mass nuclear BHs will be the prime targets of the deepest surveys foreseen for the next generation of facilities and surveys, such as the upcoming Athena mission and the Lynx mission concept.
- [17] arXiv:2002.00974 [pdf, other]
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Title: Supernova Siblings: Assessing the Consistency of Properties of Type Ia Supernovae that Share the Same Parent GalaxiesAuthors: D. Scolnic, M. Smith, A. Massiah, P. Wiseman, D. Brout, R. Kessler, T. M. Davis, R. J. Foley, L. Galbany, S. R. Hinton, R. Hounsell, L. Kelsey, C. Lidman, R. Morgan, R. C. Nichol, A. Möller, M. Sako, M. Sullivan, B. P. Thomas, T. M. C. Abbott, M. Aguena, S. Allam, J. Annis, S. Avila, K. Bechtol, E. Bertin, D. Brooks, D. L. Burke, A. Carnero Rosell, D. Carollo, M. Carrasco Kind, J. Carretero, M. Costanzi, L. N. da Costa, J. De Vicente, S. Desai, H. T. Diehl, P. Doel, A. Drlica-Wagner, K. Eckert, T. F. Eifler, S. Everett, B. Flaugher, P. Fosalba, J. Frieman, J. García-Bellido, E. Gaztanaga, D. W. Gerdes, K. Glazebrook, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, W. G. Hartley, D. L. Hollowood, K. Honscheid, D. J. James, K. Kuehn, N. Kuropatkin, G. F. Lewis, T. S. Li, M. Lima, et al. (22 additional authors not shown)Comments: Submitted to ApJL. Comments welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
While many studies have shown a correlation between properties of the light curves of Type Ia SN (SNe Ia) and properties of their host galaxies, it remains unclear what is driving these correlations. We introduce a new direct method to study these correlations by analyzing `parent' galaxies that host multiple SNe Ia 'siblings'. Here, we search the Dark Energy Survey SN sample, one of the largest samples of discovered SNe, and find 8 galaxies that hosted two likely Type Ia SNe. Comparing the light-curve properties of these SNe and recovered distances from the light curves, we find no better agreement between properties of SNe in the same galaxy as any random pair of galaxies, with the exception of the SN light-curve stretch. We show at $2.8\sigma$ significance that at least 1/2 of the intrinsic scatter of SNe Ia distance modulus residuals is not from common host properties. We also discuss the robustness with which we could make this evaluation with LSST, which will find $100\times$ more pairs of galaxies, and pave a new line of study on the consistency of Type Ia supernovae in the same parent galaxies. Finally, we argue that it is unlikely some of these SNe are actually single, lensed SN with multiple images.
- [18] arXiv:2002.00976 [pdf, other]
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Title: Calibration Method and Uncertainty for the Primordial Inflation Explorer (PIXIE)Comments: 18 pages including 8 figuresSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The Primordial Inflation Explorer (PIXIE) is an Explorer-class mission concept to measure cosmological signals from both linear polarization of the cosmic microwave background and spectral distortions from a perfect blackbody. The targeted measurement sensitivity is 2--4 orders of magnitude below competing astrophysical foregrounds, placing stringent requirements on instrument calibration. An on-board blackbody calibrator presents a polarizing Fourier transform spectrometer with a known signal to enable conversion of the sampled interference fringe patterns from telemetry units to physical units. We describe the instrumentation and operations needed to calibrate PIXIE, derive the expected uncertainty for the intensity, polarization, and frequency scales, and show the effect of calibration uncertainty in the derived cosmological signals. In-flight calibration is expected to be accurate to a few parts in $10^6$ at frequencies dominated by the CMB, and a few parts in $10^4$ at higher frequencies dominated by the diffuse dust foreground.
- [19] arXiv:2002.00978 [pdf, other]
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Title: X-ray study of high-and-low luminosity modes and peculiar low-soft-and-hard activity in the transitional pulsar XSS J12270-4859Comments: accepted for publication in A&ASubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
XSS J12270-4859 (henceforth J12270) is the first low-mass X-ray binary to exhibit a transition, taking place at the end of 2012, from an X-ray active state to a radio pulsar state. The X-ray emission based on archival XMM-Newton observations is highly variable, showing rapid variations (10 s) from a high X-ray luminosity mode to a low mode and back. A flaring mode has also been observed. X-ray pulsations have been detected during the high mode only. In this work we present two possible interpretations for the rapid swings between the high and low modes. In the first scenario, this phenomenon can be explained by a rapid oscillation between a propeller state and a radio-ejection pulsar state, during which the pulsar wind prevents matter from falling onto the neutron star surface. In the second scenario, a radio pulsar is always active, the intra-binary shock is located just outside the light cylinder in the high mode, while it expands during the low mode. At variance with other transitional pulsars, J12270 shows two instances of the low mode: a low-soft and low-hard mode. Performing an X-ray spectral analysis, we show that the harder component, present in the low-hard spectra, is probably related to the tail of the flare emission. This supports the understanding that the flare mechanism is independent of the high-to-low mode transitions.
- [20] arXiv:2002.00979 [pdf, other]
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Title: The ALPINE-ALMA [CII] survey. No or weak evolution in the [CII]-SFR relation over the last 13 GyrAuthors: D. Schaerer, M. Ginolfi, M. Bethermin, Y. Fudamoto, P.A. Oesch, O. Le Fevre, A. Faisst, P. Capak, P. Cassata, J.D. Silverman, Lin Yan, G.C. Jones, R. Amorin, S. Bardelli, M. Boquien, A. Cimatti, M. Dessauges-Zavadsky, M. Giavalisco, N.P. Hathi, S. Fujimoto, E. Ibar, A. Koekemoer, G. Lagache, B.C. Lemaux, F. Loiacono, R. Maiolino, D. Narayanan, L. Morselli, Hugo Mendez-Hernandez, F. Pozzi, D. Riechers, M. Talia, S. Toft, L. Vallini, D. Vergani, G. Zamorani, E. ZuccaComments: 11 pages, 7 figures. Submitted to Astronomy & AstrophysicsSubjects: Astrophysics of Galaxies (astro-ph.GA)
The [CII] 158 micron line is one of the strongest IR emission lines, which has been shown to trace the star-formation rate (SFR) of galaxies in the nearby Universe and up to $z \sim 2$. Whether this is also the case at higher redshift and in the early Universe remains debated. The ALPINE survey, which targeted 118 star-forming galaxies at $4.4 < z< 5.9$, provides a new opportunity to examine this question with the first statistical dataset. Using the ALPINE data and earlier measurements from the literature we examine the relation between the [CII] luminosity and the SFR over the entire redshift range from $z \sim 4-8$. ALPINE galaxies, which are both detected in [CII] and dust continuum, show a good agreement with the local L([CII])-SFR relation. Galaxies undetected in the continuum with ALMA are found to be over-luminous in [CII], when the UV SFR is used. After accounting for dust-obscured star formation, by an amount SFR(IR)$\approx$SFR(UV) on average, which results from two different stacking methods and SED fitting, the ALPINE galaxies show an L([CII])-SFR relation comparable to the local one. When [CII] non-detections are taken into account, the slope may be marginally steeper at high-z, although this is still somewhat uncertain. When compared in a homogeneous manner, the $z>6 $ [CII] measurements (detections and upper limits) do not behave very differently from the $z \sim 4-6$ data. We find a weak dependence of L([CII])/SFR on the Lyman-alpha equivalent width. Finally, we find that the ratio L([CII])/LIR $\sim (1-3) \times 10^{-3}$ for the ALPINE sources, comparable to that of ``normal" galaxies at lower redshift. Our analysis, which includes the largest sample ($\sim 150$ galaxies) of [CII] measurements at $z>4$ available so far, suggests no or little evolution of the L([CII])-SFR relation over the last 13 Gyr of cosmic time.
- [21] arXiv:2002.00981 [pdf, other]
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Title: SNe Ia from double detonations: Impact of core-shell mixing on the carbon ignition mechanismAuthors: Sabrina Gronow (1, 2), Christine Collins (3), Sebastian T. Ohlmann (4, 1), Ruediger Pakmor (5), Markus Kromer (1, 6), Ivo R. Seitenzahl (7), Stuart A. Sim (3), Friedrich K. Roepke (1, 6) ((1) Heidelberger Institut für Theoretische Studien, (2) Zentrum für Astronomie der Universität Heidelberg, Astronomisches Rechen-Institut, (3) Astrophysics Research Center, School of Mathematics and Physics, Queen`s University Belfast, (4) Max Planck Computing and Data Facility, (5) Max Planck Institute for Astrophysics, (6) Zentrum für Astronomie der Universität Heidelberg, Institut für Theoretische Astrophysik, (7) School of Science, University of New South Wales, Australian Defence Force Academy)Comments: Accepted for publication in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Sub-Chandrasekhar mass white dwarfs accreting a helium shell on a carbon-oxygen core are potential progenitors of normal Type Ia supernovae. This work focuses on the details of the onset of the carbon detonation in the double detonation sub-Chandrasekhar model. In order to simulate the influence of core-shell mixing on the carbon ignition mechanism, the helium shell and its detonation are followed with an increased resolution compared to the rest of the star treating the propagation of the detonation wave more accurately. This significantly improves the predictions of the nucleosynthetic yields from the helium burning. The simulations were carried out with the AREPO code. A carbon-oxygen core with a helium shell was set up in one dimension and mapped to three dimensions. We ensured the stability of the white dwarf with a relaxation step before the hydrodynamic detonation simulation started. Synthetic observables were calculated with the radiative transfer code ARTIS. An ignition mechanism of the carbon detonation was observed, which received little attention before. In this "scissors mechanism", the impact the helium detonation wave has on unburnt material when converging opposite to its ignition spot is strong enough to ignite a carbon detonation. This is possible in a carbon enriched transition region between the core and shell. The detonation mechanism is found to be sensitive to details of the core-shell transition and our models illustrate the need to consider core-shell mixing taking place during the accretion process. Even though the detonation ignition mechanism differs form the converging shock mechanism, the differences in the synthetic observables are not significant. Though they do not fit observations better than previous simulations, they illustrate the need for multi-dimensional simulations.
- [22] arXiv:2002.00982 [pdf, other]
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Title: On the global alignments of parsec-scale AGN radio jets and their polarization planesComments: 8 pages, 9 figures, accepted by Astronomy and AstrophysicsSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Astrophysical Phenomena (astro-ph.HE)
A number of works reported on the existence of a large scale alignment of the polarization plane of extragalactic sources as well as the alignment of radio-sources structural axes. However, both claims and their interpretation remain controversial. For the first time we explore the parsec-scale jets alignments. Additionally, we use archival polarimetric data at different wavelengths in order to compare relative orientations of the jets and the polarization planes of their emission. Using the flux density distribution in Very-Long-Baseline Interferometry (VLBI) radio maps from the Astrogeo database we find the parsec-scale jet orientation for the largest to date sample of active galactic nuclei (AGN). Employing the method of parallel transport and statistics proposed by Jain et al. (2004) we test whether the identified jets are significantly aligned. We show that the parsec-scale jets in our sample do not demonstrate any significant global alignments. Moreover, the jet direction is found to be weakly correlated with the polarization plane direction at different frequencies.
- [23] arXiv:2002.00983 [pdf, other]
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Title: The Birth of Binary Direct-Collapse Black HolesComments: Submitted to ApJL , comments are welcomeSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
Supermassive primordial stars forming during catastrophic baryon collapse in atomically-cooling halos at $z \sim$ 15 - 20 may be the origin of the first quasars in the universe. However, no simulation to date has followed the evolution of these halos at resolutions that are high enough or for times that are long enough to determine if collapse actually produces SMSs. Here we report new cosmological simulations of baryon collapse in atomically-cooled halos for times that are long enough for SMSs to form and die as direct-collapse black holes (DCBHs). We find that the high infall rates required to build up such stars do persist until the end of their lives and could fuel the rapid growth of their BHs thereafter. Our simulations also demonstrate that binary and even small multiples of SMSs can form in low-spin and high-spin halos, respectively. This discovery raises the exciting prospect of detecting gravitational waves from DCBH mergers with LISA and tidal disruption events in the near infrared with the {\em James Webb Space Telescope} and ground-based telescopes in the coming decade.
- [24] arXiv:2002.00984 [pdf]
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Title: The Design of a Space-based Observation and Tracking System for Interstellar ObjectsComments: 19 pages, 17 figures, AAS GNC Conferences 2020/Advances in Astronautical SciencesSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Neural and Evolutionary Computing (cs.NE); Systems and Control (eess.SY)
The recent observation of interstellar objects, 1I/Oumuamua and 2I/Borisov cross the solar system opened new opportunities for planetary science and planetary defense. As the first confirmed objects originating outside of the solar system, there are myriads of origin questions to explore and discuss, including where they came from, how did they get here and what are they composed of. Besides, there is a need to be cognizant especially if such interstellar objects pass by the Earth of potential dangers of impact. Specifically, in the case of Oumuamua, which was detected after its perihelion, passed by the Earth at around 0.2 AU, with an estimated excess speed of 60 km/s relative to the Earth. Without enough forewarning time, a collision with such high-speed objects can pose a catastrophic danger to all life Earth. Such challenges underscore the importance of detection and exploration systems to study these interstellar visitors. The detection system can include a spacecraft constellation with zenith-pointing telescope spacecraft. After an event is detected, a spacecraft swarm can be deployed from Earth to flyby past the visitor. The flyby can then be designed to perform a proximity operation of interest. This work aims to develop algorithms to design these swarm missions through the IDEAS (Integrated Design Engineering & Automation of Swarms) architecture. Specifically, we develop automated algorithms to design an Earth-based detection constellation and a spacecraft swarm that generates detailed surface maps of the visitor during the rendezvous, along with their heliocentric cruise trajectories.
- [25] arXiv:2002.00988 [pdf, other]
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Title: VIRGO Newtonian-noise reassessmentSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
The LIGO and Virgo scientific collaborations have cataloged ten confident detections from binary black holes and one from binary neutron stars in their first two observing runs, which has already brought up an immense desire among the scientists to study the universe and to extend the knowledge of astrophysics from these compact objects. One of the fundamental noise sources limiting the achievable detector bandwidth is given by Newtonian noise arising from terrestrial gravity fluctuations. It is important to model Newtonian noise spectra very accurately as it cannot be monitored directly using current technology. In this article, we show the reduction in the Newtonian noise curve obtained by more accurately modelling the current configuration of the Virgo observatory. In Virgo, there are clean rooms or recess like structures underneath each test mirror forming the main two Fabry-Perot arm cavities of the detector. We compute the displacements originating from an isotropic Rayleigh field including the recess structure. We find an overall strain noise reduction factor of 2 in the frequency band from 12 to about 15 Hz relative to previous models. The reduction factor depends on frequency and also varies between individual test masses.
- [26] arXiv:2002.00994 [pdf, other]
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Title: Scalable End-to-end Recurrent Neural Network for Variable star classificationAuthors: Ignacio Becker, Karim Pichara, Márcio Catelan, Pavlos Protopapas, Carlos Aguirre, Fatemeh NikzatComments: 15 pages, 17 figures. To be published in MNRASSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Machine Learning (cs.LG)
During the last decade, considerable effort has been made to perform automatic classification of variable stars using machine learning techniques. Traditionally, light curves are represented as a vector of descriptors or features used as input for many algorithms. Some features are computationally expensive, cannot be updated quickly and hence for large datasets such as the LSST cannot be applied. Previous work has been done to develop alternative unsupervised feature extraction algorithms for light curves, but the cost of doing so still remains high. In this work, we propose an end-to-end algorithm that automatically learns the representation of light curves that allows an accurate automatic classification. We study a series of deep learning architectures based on Recurrent Neural Networks and test them in automated classification scenarios. Our method uses minimal data preprocessing, can be updated with a low computational cost for new observations and light curves, and can scale up to massive datasets. We transform each light curve into an input matrix representation whose elements are the differences in time and magnitude, and the outputs are classification probabilities. We test our method in three surveys: OGLE-III, Gaia and WISE. We obtain accuracies of about $95\%$ in the main classes and $75\%$ in the majority of subclasses. We compare our results with the Random Forest classifier and obtain competitive accuracies while being faster and scalable. The analysis shows that the computational complexity of our approach grows up linearly with the light curve size, while the traditional approach cost grows as $N\log{(N)}$.
- [27] arXiv:2002.00998 [pdf, other]
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Title: Silicate Melting and Vaporization during Rocky Planet FormationAuthors: Erik J. Davies, Phil J. Carter, Seth Root, Richard G. Kraus, Dylan K. Spaulding, Sarah T. Stewart, Stein B. Jacobsen$^{4}$Comments: 15 pages, 8 figures, Accepted for publication in JGR: PlanetsSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Geophysics (physics.geo-ph)
Collisions that induce melting and vaporization can have a substantial effect on the thermal and geochemical evolution of planets. However, the thermodynamics of major minerals are not well known at the extreme conditions attained during planet formation. We obtained new data at the Sandia Z Machine and use published thermodynamic data for the major mineral forsterite (Mg$_2$SiO$_4$) to calculate the specific entropy in the liquid region of the principal Hugoniot. We use our calculated specific entropy of shocked forsterite, and revised entropies for shocked silica, to determine the critical impact velocities for melting or vaporization upon decompression from the shocked state to 1 bar and the triple points, which are near the pressures of the solar nebula. We also demonstrate the importance of the initial temperature on the criteria for vaporization. Applying these results to $N$-body simulations of terrestrial planet formation, we find that up to 20 to 40% of the total system mass is processed through collisions with velocities that exceed the criteria for incipient vaporization at the triple point. Vaporizing collisions between small bodies are an important component of terrestrial planet formation.
- [28] arXiv:2002.01009 [pdf, other]
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Title: Shapiro delay in PSR~J1811$-$2405Authors: C. Ng, L. Guillemot, P. C. C. Freire, M. Kramer, D. J. Champion, I. Cognard, G. Theureau, E. D. BarrComments: 7 pages, 5 figures, accepted by MNRASSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)
This paper presents the first detection of Shapiro delay from the binary millisecond pulsar PSR J1811-2405. We report a 11-${\sigma}$ measurement of the orthometric amplitude, h$_3$=6.8(6)x10$^{-7}$, and a 16-${\sigma}$ measurement of the orthometric ratio, ${\varsigma}$= 0.81(5). Given the relatively high orbital inclination, i= 79(2) deg, of this binary system, we obtain constraints on the companion mass of m$_c$= 0.31$\substack{+0.08 \\ -0.06}M_\odot$. The pulsar mass is currently less well constrained, with a value of 2.0$\substack{+0.8 \\ -0.5}M_\odot$. The companion mass and the orbital period are in agreement with the prediction made by previous numerical calculations of the evolution of compact binary systems. From a study of the polarization, we find that the orbital inclination angle is ~100 deg and that PSR J1811-2405 is an orthogonal rotator. In addition, the ${\mu}$s-level timing precision together with its narrow profile make PSR J1811-2405 a good candidate for inclusion in the pulsar timing arrays being used to detect nHz Gravitational waves.
- [29] arXiv:2002.01011 [pdf, other]
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Title: Bridging between the integrated and resolved main sequence of star formationAuthors: Shoubaneh Hemmati, Bahram Mobasher, Hooshang Nayyeri, Abtin Shahidi, Peter Capak, Behnam Darvish, Nima Chartab, Marzyeh Jafariyazani, Zahra SattariComments: 5 pages, 3 figures, Accepted for publication by ApJLSubjects: Astrophysics of Galaxies (astro-ph.GA)
The position of galaxies on the stellar mass, star formation rate plane with respect to the star-forming main sequence at each redshift is a convenient way to infer where the galaxy is in its evolution compared to the rest of the population. We use Hubble Space Telescope high resolution images in the GOODS-S field from the CANDELS survey and fit multi wavelength lights in resolution elements of galaxies with stellar population synthesis models. We then construct resolved kpc-scale stellar mass, star formation rate surface density curves for galaxies at z~1. Fitting these resolved main sequence curves with Schechter functions, we parameterize and explain the multi-wavelength structure of galaxies with three variables: phi*, alpha, and M*. For quenched galaxies below the main sequence, we find an average high mass slope (alpha) of the resolved main sequence curves to be ~ -0.4. The scatter of this slope is higher among the lower mass star forming galaxies and those above the main sequence compared to quenched galaxies, due to lack of an evolved bulge. Our findings agree well with an inside-out quenching of star-formation. We find that the knee of the Schechter fits (M*) for galaxies below the main sequence occurs at lower stellar mass surface densities compared to star forming galaxies, which hints at how far quenching has proceeded outwards.
- [30] arXiv:2002.01015 [pdf, other]
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Title: Stripped-envelope core-collapse supernova $^{56}$Ni masses: Persistently larger values than supernovae type IIComments: Resubmitted to A&A after minor suggestions from the refereeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
The mass of synthesised radioactive material is an important power source for all supernova (SN) types. Anderson 2019 recently compiled literature values and obtained $^{56}$Ni distributions for different core-collapse supernovae (CC-SNe), showing that the $^{56}$Ni distribution of stripped envelope CC-SNe (SE-SNe: types IIb, Ib, and Ic) is highly incompatible with that of hydrogen rich type II SNe (SNe-II). This motivates questions on differences in progenitors, explosion mechanisms, and $^{56}$Ni estimation methods. Here, we re-estimate the nucleosynthetic yields of $^{56}$Ni for a well-observed and well-defined sample of SE-SNe in a uniform manner. This allows us to investigate whether the observed SN-II--SE-SN $^{56}$Ni separation is due to real differences between these SN types, or because of systematic errors in the estimation methods. We compiled a sample of well observed SE-SNe and measured $^{56}$Ni masses through three different methods proposed in the literature. Arnett's rule -as previously shown - gives $^{56}$Ni masses for SE-SNe that are considerably higher than SNe-II. While for the distributions calculated using both the Khatami&Kasen prescription and Tail $^{56}$Ni masses are offset to lower values than `Arnett values', their $^{56}$Ni distributions are still statistically higher than that of SNe II. Our results are strongly driven by a lack of SE-SN with low $^{56}$Ni masses (that are in addition strictly lower limits). The lowest SE-SN $^{56}$Ni mass in our sample is of 0.015M$_\odot$, below which are more than 25$\%$ of SNe II. We conclude that there exists real, intrinsic differences in the mass of synthesised radioactive material between SNe II and SE-SNe . Any proposed current or future CCSN progenitor scenario and explosion mechanism must be able to explain why and how such differences arise, or outline a yet to be fully explored bias in current SN samples.
- [31] arXiv:2002.01021 [pdf, ps, other]
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Title: A Word to the WISE: Confusion is Unavoidable for WISE-selected Infrared ExcessesComments: 13 pages, 4 Figures; Accepted for publication in ApJSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)
Stars with excess infrared radiation from circumstellar dust are invaluable for studies of exoplanetary systems, informing our understanding on processes of planet formation and destruction alike. All-sky photometric surveys have made the identification of dusty infrared excess candidates trivial, however, samples that rely on data from WISE are plagued with source confusion, leading to high false positive rates. Techniques to limit its contribution to WISE-selected samples have been developed, and their effectiveness is even more important as we near the end-of-life of Spitzer, the only facility capable of confirming the excess. Here, we present a Spitzer follow-up of a sample of 22 WISE-selected infrared excess candidates near the faint-end of the WISE detection limits. Eight of the 22 excesses are deemed the result of source confusion, with the remaining candidates all confirmed by the Spitzer data. We consider the efficacy of ground-based near-infrared imaging and astrometric filtering of samples to limit confusion among the sample. We find that both techniques are worthwhile for vetting candidates, but fail to identify all of the confused excesses, indicating that they cannot be used to confirm WISE-selected infrared excess candidates, but only to rule them out. This result confirms the expectation that WISE-selected infrared excess samples will always suffer from appreciable levels of contamination, and that care should be taken in their interpretation regardless of the filters applied.
- [32] arXiv:2002.01033 [pdf, other]
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Title: A Second Look at 12 Candidate Dual AGNs using ${\tt BAYMAX}$Authors: Adi Foord, Kayhan Gültekin, Rebecca Nevin, Julia M. Comerford, Edmund Hodges-Kluck, R. Scott Barrows, Andrew D. Goulding, Jenny E. GreeneComments: 26 pages, 9 figures, accepted to ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)
We present an analysis of 12 optically selected dual AGN candidates at $z < 0.34$. Each candidate was originally identified via double-peaked [O III] $\lambda$5007 emission lines, and have received follow-up $Chandra$ and $HST$ observations. Because the X-ray data are low-count ($<100$ counts) with small separations ($<1$"), a robust analysis is necessary for classifying each source. Pairing long-slit [O III] observations with existing $Chandra$ observations, we re-analyze the X-ray observations with ${\tt BAYMAX}$ to determine whether the X-ray emission from each system is more likely a single or dual point source. We find that 4 of the 12 sources are likely dual X-ray point source systems. We examine each point source's spectra via a Monte Carlo method that probabilistically identifies the likely origin of each photon. When doing so, we find that (i) the secondary X-ray point sources in 2 of the systems have $L_{\mathrm{X}}<10^{40}$ erg s$^{-1}$, such that we cannot rule out a non-AGN origin, (ii) one source has a secondary with $L_{\mathrm{X}}>10^{40}$ erg s$^{-1}$ but a spectrum that is too soft to definitively preclude being X-ray emitting diffuse gas that was photoionized by the primary AGN, and (iii) one system (SDSS J1126+2944) is a dual AGN. Additionally, using complementary $HST$ observations, we analyze a sub-sample of systems that are visually identified as merging. Our results suggest that dual AGNs may preferentially reside in mergers with small separations, consistent with both simulations and observations.
- [33] arXiv:2002.01063 [pdf, other]
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Title: A comparison of exoplanet spectroscopic retrieval toolsAuthors: Joanna K. Barstow, Quentin Changeat, Ryan Garland, Michael R. Line, Marco Rocchetto, Ingo P. WaldmannComments: 25 pages, 21 figures. Submitted to MNRASSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)
Over the last several years, spectroscopic observations of transiting exoplanets have begun to uncover information about their atmospheres, including atmospheric composition and indications of the presence of clouds and hazes. Spectral retrieval is the leading technique for interpretation of transmission spectra and is employed by several teams using a variety of forward models and parameter estimation algorithms. However, different model suites have mostly been used in isolation and so it is unknown whether the results from each are comparable. As we approach the launch of the James Webb Space Telescope we anticipate advances in wavelength coverage, precision, and resolution of transit spectroscopic data, so it is important that the tools that will be used to interpret these information rich spectra are validated. To this end, we present an inter-model comparison of three retrieval suites: TauREx, NEMESIS and CHIMERA. We demonstrate that the forward model spectra are in good agreement (residual deviations on the order of 20 - 40 ppm), and discuss the results of cross retrievals between the three tools. Generally, the constraints from the cross retrievals are consistent with each other and with input values to within 1 sigma However, for high precision scenarios with error envelopes of order 30 ppm, subtle differences in the simulated spectra result in discrepancies between the different retrieval suites, and inaccuracies in retrieved values of several sigma. This can be considered analogous to substantial systematic/astrophysical noise in a real observation, or errors/omissions in a forward model such as molecular linelist incompleteness or missing absorbers.
- [34] arXiv:2002.01079 [pdf, ps, other]
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Title: Full analytical approximation to the stochastic gravitational wave background generated by cosmic string networksComments: 13 pages, 6 figures, submitted to PRDSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We derive a full analytical approximation to the stochastic gravitational wave background generated by the loops that are produced throughout the cosmological evolution of cosmic string networks. We show that this approximation not only predicts the amplitude of the radiation-era plateau exactly, but also provides a good fit to the high-frequency cut-off and to the low-frequency peak generated by the loops that decay during the matter era, irrespective of cosmic string tension and of the length of loops created. We then find that it provides a good quantitative description of the full stochastic gravitational wave background across the relevant frequency range.
- [35] arXiv:2002.01086 [pdf, other]
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Title: Temporal Evolution of Spatially-Resolved Individual Star Spots on a Planet-Hosting Solar-type Star: Kepler 17Authors: Kosuke Namekata, James R. A. Davenport, Brett M. Morris, Suzanne L. Hawley, Hiroyuki Maehara, Yuta Notsu, Shin Toriumi, Kai Ikuta, Shota Notsu, Satoshi Honda, Daisaku Nogami, Kazunari ShibataComments: 37 pages, 12 figures, 1 table. Accepted for publication in The Astrophysical JournalSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP)
Star spot evolution is visible evidence of the emergence/decay of the magnetic field on stellar surface, and it is therefore important for the understanding of the underlying stellar dynamo and consequential stellar flares. In this paper, we report the temporal evolution of individual star spot area on the hot-Jupiter-hosting active solar-type star Kepler 17 whose transits occur every 1.5 days. The spot longitude and area evolution are estimated (1) from the stellar rotational modulations of Kepler data and (2) from the brightness enhancements during the exoplanet transits caused by existence of large star spots. As a result of the comparison, number of spots, spot locations, and the temporal evolution derived from the rotational modulations is largely different from those of in-transit spots. We confirm that although only two light curve minima appear per rotation, there are clearly many spots present on the star. We find that the observed differential intensity changes are sometimes consistent with the spot pattern detected by transits, but they sometimes do not match with each other. Although the temporal evolution derived from the rotational modulation differs from those of in-transit spots to a certain degree, the emergence/decay rates of in-transit spots are within an order of magnitude of those derived for sunspots as well as our previous research based only on rotational modulations. This supports a hypothesis that the emergence/decay of sunspots and extremely-large star spots on solar-type stars occur through the same underlying processes.
- [36] arXiv:2002.01097 [pdf, other]
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Title: In-orbit Calibration to the Point-Spread Function of Insight-HXMTAuthors: Yi Nang, Jin-Yuan Liao, Na Sai, Chen Wang, Ju Guan, Cheng-Kui Li, Cheng-Cheng Guo, Yuan Liu, Jing Jin, Xiao-Bo Li, Shu Zhang, Shuang-Nan ZhangComments: 15 pages, 27 figures, accepted for publication in JHEAPSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
We make the in-orbit calibration to the point-spread functions (PSFs) of the collimators of the Hard X-ray Modulation Telescope with the scanning observation of the Crab. We construct the empirical adjustments to the theoretically calculated geometrical PSFs. The adjustments contain two parts: a rotating matrix to adjust the directional deviation of the collimators and a paraboloidal function to correct the inhomogeneity of the real PSFs. The parameters of the adjusting matrices and paraboloidal functions are determined by fitting the scanning data with lower scanning speed and smaller intervals during the calibration observations. After the PSF calibration, the systematic errors in source localization in the Galactic plane scanning survey are 0.010 deg, 0.015 deg, 0.113 deg for the Low-Energy Telescope (LE), the Medium-Energy telescope (ME) and the High-Energy telescope (HE), respectively; meanwhile, the systematic errors in source flux estimation are 1.8%, 1.6%, 2.7% for LE, ME and HE, respectively.
- [37] arXiv:2002.01109 [pdf, other]
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Title: Baryon acoustic oscillations signature in the three-point angular correlation function from the SDSS-DR12 quasar surveyComments: 9 pages, 8 figuresJournal-ref: MNRAS 492, 2020, 4469-4476Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The clustering properties of the Universe at large-scales are currently being probed at various redshifts through several cosmological tracers and with diverse statistical estimators. Here we use the three-point angular correlation function (3PACF) to probe the baryon acoustic oscillation (BAO) features in the quasars catalogue from the twelfth data release of the Sloan Digital Sky Survey, with mean redshift z = 2.225, detecting the BAO imprint with a statistical significance of 2.9{\sigma}, obtained using lognormal mocks. Following a quasi model-independent approach for the 3PACF, we find the BAO transversal signature for triangles with sides $\theta_1 = 1.0^\circ$ and $\theta_2 = 1.5^\circ$ and the angle between them of $\alpha = 1.59 \pm 0.17$ rad, a value that corresponds to the angular BAO scale ${\theta}_{BAO} = 1.82^\circ \pm 0.21^\circ$ , in excellent agreement with the value found in a recent work (${\theta}_{BAO} = 1.77^\circ \pm 0.31^\circ$ ) applying the 2PACF to similar data. Moreover, we performed two type of tests: one to confirm the robustness of the BAO signal in the 3PACF through random displacements in the dataset, and the other to verify the suitability of our random samples, a null test that in fact does not show any signature that could bias our results.
- [38] arXiv:2002.01118 [pdf, other]
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Title: Study of the Cosmic Rays and Interstellar Medium in Local HI Clouds using Fermi-LAT Gamma-Ray ObservationsAuthors: T. Mizuno, S. Abdollahi, Y. Fukui, K. Hayashi, T. Koyama, A. Okumura, H. Tajima, H. YamamotoComments: accepted for publication in ApJSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
An accurate estimate of the interstellar gas density distribution is crucial to understanding the interstellar medium (ISM) and Galactic cosmic rays (CRs). To comprehend the ISM and CRs in a local environment, a study of the diffuse $\gamma$-ray emission in a mid-latitude region of the third quadrant was performed. The $\gamma$-ray data in the 0.1--25.6~GeV energy range of the Fermi Large Area Telescope (LAT) and other interstellar gas tracers such as the HI4PI survey data and the Planck dust thermal emission model were used, and the northern and southern regions were analyzed separately. The variation of the dust emission Dem with the total neutral gas column density NH was studied in high dust-temperature areas, and the NH/Dem ratio was calibrated using $\gamma$-ray data under the assumption of a uniform CR intensity in the studied regions. The measured integrated $\gamma$-ray emissivities above 100~MeV are $(1.58\pm0.04)\times10^{-26}~\mathrm{photons~s^{-1}~sr^{-1}~H\mbox{-}atom^{-1}}$ and $(1.59\pm0.02)\times10^{-26}~\mathrm{photons~s^{-1}~sr^{-1}~H\mbox{-}atom^{-1}}$ in the northern and southern regions, respectively, supporting the existence of a uniform CR intensity in the vicinity of the solar system. While most of the gas can be interpreted to be HI with a spin temperature of $T_\mathrm{S} = 125~\mathrm{K}$ or higher, an area dominated by optically thick HI with $T_\mathrm{S} \sim 40~\mathrm{K}$ was identified.
- [39] arXiv:2002.01141 [pdf, other]
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Title: Physics and phenomenology of weakly magnetized, relativistic astrophysical shock wavesAuthors: A. Vanthieghem (SLAC), M. Lemoine (IAP), I. Plotnikov (IRAP), A. Grassi (SLAC), M. Grech (LULI), L. Gremillet (CEA), G. Pelletier (IPAG)Comments: to be published in: Galaxies, Special issue on "Particle Acceleration Processes in Astrophysical Jets''Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
Weakly magnetized, relativistic collisionless shock waves are not only the natural offsprings of relativistic jets in high-energy astrophysical sources, they are also associated with some of the most outstanding displays of energy dissipation through particle acceleration and radiation. Perhaps their most peculiar and exciting feature is that the magnetized turbulence that sustains the acceleration process, and (possibly) the secondary radiation itself, is self-excited by the accelerated particles themselves, so that the phenomenology of these shock waves hinges strongly on the microphysics of the shock. In this review, we draw a status report of this microphysics, benchmarking analytical arguments with particle-in-cell simulations, and extract consequences of direct interest to the phenomenology, regarding in particular the so-called microphysical parameters used in phenomenological studies.
- [40] arXiv:2002.01150 [pdf, other]
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Title: Locating the Source Field Lines of Jovian Decametric Radio EmissionsComments: accepted by Earth and Planetary Physics, 10 pages, 9 figures and 1 tableSubjects: Earth and Planetary Astrophysics (astro-ph.EP); Space Physics (physics.space-ph)
Decametric (DAM) radio emissions are one of the main windows through which one can reveal and understand the Jovian magnetospheric dynamics and its interaction with the moons. DAMs are generated by energetic electrons through cyclotron-maser instability. For Io (the most active moon) related DAMs, the energetic electrons are sourced from Io volcanic activities, and quickly trapped by neighboring Jovian magnetic field. To properly interpret the physical processes behind DAMs, it is important to precisely locate the source field lines from which DAMs are emitted. Following the work by Hess et al. [2008, 2010], we develop a method to locate the source region as well as the associated field lines for any given DAM emission recorded in a radio dynamic spectrum by, e.g., Wind/WAVES or STEREO/WAVES. The field lines are calculated by the state-of-art analytical model, called JRM09 [Connerney et al., 2018]. By using this method, we may also derive the emission cone angle and the energy of associated electrons. If multiple radio instruments at different perspectives saw the same DAM event, the evolution of its source region and associated field lines is able to be revealed. We apply the method to an Io-DAM event, and find that the method is valid and reliable. Some physical processes behind the DAM event are also discussed.
- [41] arXiv:2002.01159 [pdf, other]
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Title: Additional Calibration of the Ultra-Violet Imaging Telescope on board AstroSatAuthors: S.N. Tandon, J. Postma, P. Joseph, A. Devaraj, A Subramaniam, I. V. Barve, K. George, S. K. Ghosh, V. Girish, J. B. Hutchings, P. U. Kamath, S. Kathiravan, A. Kumar, J. P. Lancelot, D. Leahy, P.K. Mahesh, R. Mohan, S. Nagabhushana, A. K. Pati, N. Kameswara Rao, K. Sankarasubramanian, S. Sriram, C. S. StalinComments: 15 pages, 8 figures, Accepted for publication in Astronomical JournalSubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
Results of the initial calibration of the Ultra-Violet Imaging Telescope (UVIT) were reported earlier by Tandon et al. (2017). The results reported earlier were based on the ground calibration as well as the first observations in orbit. Some additional data from the ground calibration and data from more in-orbit observations have been used to improve the results. In particular, extensive new data from in-orbit observations have been used to obtain (a) new photometric calibration which includes (i) zero-points (ii) flat fields (iii) saturation, (b) sensitivity variations (c) spectral calibration for the near Ultra Violet (NUV; 2000 - 3000 Angstroms) and far Ultra-Violet (FUV; 1300 - 1800 Angstroms) gratings, (d) point spread function and (e) astrometric calibration which included distortion. Data acquired over the last three years show continued good performance of UVIT with no reduction in sensitivity in both the UV channels.
- [42] arXiv:2002.01188 [pdf, ps, other]
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Title: Probing the galactic halo with RR Lyrae stars I: The catalogAuthors: G.-C. Liu, Y. Huang, H.-W. Zhang, M.-S. Xiang, J.-J., Ren, B.-Q. Chen, H.-B. Yuan, C. Wang, Y. Yang, Z.-J. Tian, F. Wang, X.-W. LiuComments: 14 pages, 10 figures, Accepted by ApJSSubjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)
We present a catalog of 5,290 RR Lyrae stars (RRLs) with metallicities estimated from spectra of the LAMOST Experiment for Galactic Understanding and Exploration (LEGUE) and the Sloan Extension for Galactic Understanding and Exploration (SEGUE) surveys. Nearly 70 per cent of them (3,642 objects) also have systemic radial velocities measured. Given the pulsating nature of RRLs, metallicity estimates are based on spectra of individual exposures, by matching them with the synthetic templates. The systemic radial velocities are measured by fitting the observed velocity as a function of phase assuming an empirical pulsating velocity template curve. Various tests show that our analyses yield metallicities with a typical precision of 0.20\,dex and systemic radial velocities with uncertainties ranging from 5 to 21\,km\,s$^{-1}$ (depending on the number of radial velocity measurements available for a given star). Based on the well calibrated near-infrared $PM_{W1}Z$ or $PM_{K_{\rm s}}Z$, and $M_{V}$-[Fe/H] relations, precise distances are derived for these RRLs. Finally, we include Gaia DR2 proper motions in our catalog. The catalog should be very useful for various Galactic studies, especially of the Galactic halo.
- [43] arXiv:2002.01194 [pdf, other]
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Title: Solar Rossby waves observed in GONG++ ring-diagram flow mapsComments: 6 pages, 4 figures, 1 table, Accepted in A&ASubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Context: Solar sectoral Rossby waves have only recently been unambiguously identified in Helioseimsic and Magnetic Imager (HMI) and Michelson Doppler Imager (MDI) maps of flows near the solar surface. So far this has not been done with the Global Oscillation Network Group (GONG) ground-based observations, which have different noise properties.
Aims: We utilize 17 years of GONG++ data, to identify and characterize solar Rossby waves using ring-diagram helioseismology. We compare directly with HMI ring-diagram analysis.
Methods: Maps of the radial vorticity are obtained for flows within the top 2 Mm of the surface for 17 years of GONG++. The data is corrected for systematic effects including the annual periodicity related to the $B_0$ angle. We then compute the Fourier components of the radial vorticity of the flows in the co-rotating frame. We perform the same analysis on the HMI data that overlap in time.
Results: We find that the solar Rossby waves have measurable amplitudes in the GONG++ sectoral power spectra for azimuthal orders between $m=3$ and $m=15$. The measured mode characteristics (frequencies, lifetimes and amplitudes) from GONG++ are consistent with the HMI measurements in the overlap period from 2010 to 2018 for $m\le9$. For higher-$m$ modes the amplitudes and frequencies agree within two sigmas. The signal-to-noise ratio of modes in GONG++ power spectra is comparable to HMI for $8\le m\le11$, but is lower by a factor of two for other modes.
Conclusions: The GONG++ data provide a long and uniform data set to study solar global-scale Rossby waves from 2001. - [44] arXiv:2002.01198 [pdf]
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Title: Three-dimensional modelling of absorption by various species for hot Jupiter HD 209458bAuthors: I F Shaikhislamov, M L Khodachenko, H Lammer, A G Berezutsky, I B Miroshnichenko, M S RumenskikhJournal-ref: Shaikhislamov, I. F., et al. "3D Modeling of absorption by various species for hot jupiter HD209458b." Monthly Notices of the Royal Astronomical Society (2019)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)
The absorption of stellar radiation observed by the HD209458b in resonant lines of OI and CII has not yet been satisfactorily modeled. In our previous 2D simulations we have shown that the hydrogen-dominated upper atmosphere of HD209458b, heated by XUV radiation, expands supersonically beyond the Roche lobe and drags the heavier species along with it. Assuming solar abundances, OI and CII particles accelerated by tidal forces to velocities up to 50 km/s should produce the absorption due to Doppler resonance mechanism at the level of 6-10%, consistent with the observations. Since the 2D geometry does not take into account the Coriolis force in the planet reference frame, the question remained to which extent the spiraling of the escaping planetary material and its actually achieved velocity may influence the conclusions made on the basis of 2D modeling. In the present paper we apply for the first time in the study of HD209458b a global 3D hydrodynamic multi-fluid model that self-consistently describes the formation and expansion of the escaping planetary wind, affected by the tidal and Coriolis forces, as well as by the surrounding stellar wind. The modeling results confirm our previous findings that the velocity and density of the planetary flow are sufficiently high to produce the absorption in HI, OI, and CII resonant lines at the level close to the in-transit observed values. The novel finding is that the matching of the absorption measured in MgII and SiIII lines requires at least 10 times lower abundances of these elements than the Solar system values.
- [45] arXiv:2002.01229 [pdf, other]
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Title: Dark matter constraints from dwarf galaxies with data-driven J-factorsAuthors: Alexandre Alvarez, Francesca Calore, Anna Genina, Justin I. Read, Pasquale D. Serpico, Bryan ZaldivarComments: 14 pages, 6 figures, 2 tables. Comments are welcome!Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We present an updated analysis of the gamma-ray flux from the directions of classical dwarf spheroidal galaxies, deriving new constraints on WIMP dark matter (DM) annihilation using a decade of Fermi-LAT data. Among the major novelties, we infer the dwarfs' J-factors by including new observations without imposing any a priori parametric profile for the DM distribution. While statistically compatible with results obtained from more conventional parameterisations, this procedure reduces the theoretical bias imposed on the data. Furthermore, we retain the full data-driven shape of the J-factors' empirical probability distributions when setting limits on DM, without imposing log-normality as is typically done. In conjunction with the data-driven J-factors, we use a new method for estimating the probability distribution function of the astrophysical background at the dwarf position, fully profiling over background uncertainties. We show that, for most classical dwarfs, the background systematic uncertainty dominates over the uncertainty on their J-factors.
- [46] arXiv:2002.01238 [pdf, other]
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Title: Determination of the relative inclination and the viewing angle of an interacting pair of galaxies using convolutional neural networksSubjects: Astrophysics of Galaxies (astro-ph.GA); Computer Vision and Pattern Recognition (cs.CV); Machine Learning (cs.LG)
Constructing dynamical models for interacting pair of galaxies as constrained by their observed structure and kinematics crucially depends on the correct choice of the values of the relative inclination ($i$) between their galactic planes as well as the viewing angle ($\theta$), the angle between the line of sight and the normal to the plane of their orbital motion. We construct Deep Convolutional Neural Network (DCNN) models to determine the relative inclination ($i$) and the viewing angle ($\theta$) of interacting galaxy pairs, using N-body $+$ Smoothed Particle Hydrodynamics (SPH) simulation data from the GALMER database for training the same. In order to classify galaxy pairs based on their $i$ values only, we first construct DCNN models for a (a) 2-class ( $i$ = 0 $^{\circ}$, 45$^{\circ}$ ) and (b) 3-class ($i = 0^{\circ}, 45^{\circ} \text{ and } 90^{\circ}$) classification, obtaining $F_1$ scores of 99% and 98% respectively. Further, for a classification based on both $i$ and $\theta$ values, we develop a DCNN model for a 9-class classification ($(i,\theta) \sim (0^{\circ},15^{\circ}) ,(0^{\circ},45^{\circ}), (0^{\circ},90^{\circ}), (45^{\circ},15^{\circ}), (45^{\circ}, 45^{\circ}), (45^{\circ}, 90^{\circ}), (90^{\circ}, 15^{\circ}), (90^{\circ}, 45^{\circ}), (90^{\circ},90^{\circ})$), and the $F_1$ score was 97$\%$. Finally, we tested our 2-class model on real data of interacting galaxy pairs from the Sloan Digital Sky Survey (SDSS) DR15, and achieve an $F_1$ score of 78%. Our DCNN models could be further extended to determine additional parameters needed to model dynamics of interacting galaxy pairs, which is currently accomplished by trial and error method.
- [47] arXiv:2002.01250 [pdf, ps, other]
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Title: Scattering, absorption, and thermal emission by large cometary dust particles: Synoptic numerical solutionComments: 7 pages, 8 figuresJournal-ref: A&A 631, A164 (2019)Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Computational Physics (physics.comp-ph)
Context: Remote light scattering and thermal infrared observations provide clues about the physical properties of cometary and interplanetary dust particles. Identifying these properties will lead to a better understanding of the formation and evolution of the Solar System. Aims: We present a numerical solution for the radiative and conductive heat transport in a random particulate medium enclosed by an arbitrarily shaped surface. The method will be applied to study thermal properties of cometary dust particles. Methods: The recently introduced incoherent Monte Carlo radiative transfer method developed for scattering, absorption, and propagation of electromagnetic waves in dense discrete random media is extended for radiative heat transfer and thermal emission. The solution is coupled with the conductive Fourier transport equation that is solved with the finite-element method. Results: The proposed method allows the synoptic analysis of light scattering and thermal emission by large cometary dust particles consisting of submicrometer-sized grains. In particular, we show that these particles can sustain significant temperature gradients resulting in the superheating factor phase function observed for the coma of comet 67P/Churyumov-Gerasimenko.
- [48] arXiv:2002.01271 [pdf, other]
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Title: Apsidal motion in the massive binary HD152248Comments: 22 pages, A&A acceptedSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
The eccentric massive binary HD152248 (also known as V1007 Sco), which hosts two O7.5 III-II(f) stars, is the most emblematic eclipsing O-star binary in the very young and rich open cluster NGC6231. Its properties render the system an interesting target for studying tidally induced apsidal motion. Measuring the rate of apsidal motion in such a binary system gives insight into the internal structure and evolutionary state of the stars composing it. A large set of optical spectra was used to reconstruct the spectra of the individual binary components and establish their radial velocities using a disentangling code. Radial velocities measured over seven decades were used to establish the rate of apsidal motion. We furthermore analysed the reconstructed spectra with the CMFGEN model atmosphere code to determine stellar and wind properties of the system. Optical photometry was analysed with the Nightfall binary star code. A complete photometric and radial velocity model was constructed in PHOEBE 2 to determine robust uncertainties. We find a rate of apsidal motion of $(1.843^{+0.064}_{-0.083})\deg$ yr$^{-1}$. The photometric data indicate an orbital inclination of $(67.6^{+0.2}_{-0.1})\deg$ and Roche-lobe filling factors of both stars of about 0.86. Absolute masses of $29.5^{+0.5}_{-0.4}$M$_\odot$ and mean stellar radii of $15.07^{+0.08}_{-0.12}$R$_\odot$ are derived for both stars. We infer an observational value for the internal structure constant of both stars of $0.0010\pm0.0001$. Our in-depth analysis of the massive binary HD152248 and the redetermination of its fundamental parameters can serve as a basis for the construction of stellar evolution models to determine theoretical rates of apsidal motion to be compared with the observational one. In addition, the system hosts two twin stars, which offers a unique opportunity to obtain direct insight into the internal structure of the stars.
- [49] arXiv:2002.01272 [pdf, other]
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Title: Detectability of nGauss primordial magnetic fields in the B-mode polarization of CMBComments: 15 pages, 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
The origin of large-scale magnetic fields in the Universe is still unknown. Observations suggest the presence of nGauss primordial magnetic fields at the last scattering surface. The presence of such fields will affect the evolution of cosmological perturbations and potentially leave an imprint on the CMB anisotropies. Here, we show that the B-mode power spectrum carries a clear signature of the stochastic primordial magnetic fields up to a few nGauss. Specifically, the presence of nGauss primordial magnetic fields changes the BB power spectrum at all scales. At large scales, the tensor modes contribute to the B-mode spectrum, while non-vanishing vector modes contribute at small scales. We show that the B-mode of CMB carry a distinct signature of the primordial magnetic fields. To validate our prediction, we use BICEP2 and POLARBEAR data and find that B-mode observations from the experiments are consistent with non-zero primordial fields. We also use the BICEP2 observations to constrain the primordial magnetic field. We provide a detailed analysis of the B-mode polarization of the CMB with primordial magnetic fields and investigate the implications for the upcoming CMB missions.
- [50] arXiv:2002.01283 [pdf, ps, other]
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Title: CHIPP: INAF pilot project for HTC, HPC and HPDAAuthors: Giuliano Taffoni, Ugo Becciani, Bianca Garilli, Gianmarco Maggio, Fabio Pasian, Grazia Umana, Riccardo Smareglia, Fabio VitelloComments: 4 pages, conference, ADASS 2019Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Distributed, Parallel, and Cluster Computing (cs.DC)
CHIPP (Computing HTC in INAF Pilot Project) is an Italian project funded by the Italian Institute for Astrophysics (INAF) and promoted by the ICT office of INAF. The main purpose of the CHIPP project is to coordinate the use of, and access to, already existing high throughput computing and high-performance computing and data processing resources (for small/medium size programs) for the INAF community. Today, Tier2/Tier3 systems (1,200 CPU/core) are provided at the INAF institutes at Trieste and Catania, but in the future, the project will evolve including also other computing infrastructures. During the last two years, more than 30 programs have been approved for a total request of 30 Million CPU-h. Most of the programs are HPC, data reduction and analysis, machine learning. In this paper, we describe in details the CHIPP infrastructures and the results of the first two years of activity.
- [51] arXiv:2002.01286 [pdf, other]
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Title: Limits on primordial magnetic fields from primordial black hole abundanceComments: 17 pages, 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
Primordial magnetic field (PMF) is one of the feasible candidates to explain observed large-scale magnetic fields, for example, intergalactic magnetic fields. We present a new mechanism that brings us information about PMFs on small scales based on the abundance of primordial black holes (PBHs). The anisotropic stress of the PMFs can act as a source of the super-horizon curvature perturbation in the early universe. If the amplitude of PMFs is sufficiently large, the resultant density perturbation also has a large amplitude, and thereby, the PBH abundance is enhanced. Since the anisotropic stress of the PMFs is consist of the square of the magnetic fields, the statistics of the density perturbation follows the non-Gaussian distribution. We use a Monte-Carlo method to obtain an exact probability density function of the density perturbation induced by PMFs. Finally, we place the strongest constraint on the amplitude of PMFs as a few hundred nano-Gauss on $10^{2}\;{\rm Mpc}^{-1} \leq k\leq 10^{18}\;{\rm Mpc}^{-1}$ where the typical cosmological observations never reach.
- [52] arXiv:2002.01291 [pdf, other]
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Title: Discovery of a giant radio fossil in the Ophiuchus galaxy clusterComments: 18 pages, 12 figures, accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
The Ophiuchus galaxy cluster exhibits a curious concave gas density discontinuity at the edge of its cool core. It was discovered in the Chandra X-ray image by Werner and collaborators, who considered a possibility of it being a boundary of an AGN-inflated bubble located outside the core, but discounted this possibility because it required much too powerful an AGN outburst. Using low-frequency (72-240 MHz) radio data from MWA GLEAM and GMRT, we found that the X-ray structure is, in fact, a giant cavity in the X-ray gas filled with diffuse radio emission with an extraordinarily steep radio spectrum. It thus appears to be a very aged fossil of the most powerful AGN outburst seen in any galaxy cluster ($pV\sim 5\times 10^{61}$ erg for this cavity). There is no apparent diametrically opposite counterpart either in X-ray or in the radio. It may have aged out of the observable radio band because of the cluster asymmetry. At present, the central AGN exhibits only a weak radio source, so it should have been much more powerful in the past to have produced such a bubble. The AGN is currently starved of accreting cool gas because the gas density peak is displaced by core sloshing. The sloshing itself could have been set off by this extraordinary explosion if it had occurred in an asymmetric gas core. This dinosaur may be an early example of a new class of sources to be uncovered by low-frequency surveys of galaxy clusters.
- [53] arXiv:2002.01296 [pdf]
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Title: A model of the 3-μm hydration band with Exponentially Modified Gaussian (EMG) profiles: application to hydrated chondrites and asteroidsComments: Accepted in IcarusSubjects: Earth and Planetary Astrophysics (astro-ph.EP)
We present here a new method to model the shape of the 3-{\mu}m absorption band in the reflectance spectra of meteorites and small bodies. The band is decomposed into several OH/H2O components using Exponentially Modified Gaussian (EMG) profiles, as well as possible organic components using Gaussian profiles when present. We compare this model to polynomial and multiple Gaussian profile fits and show that the EMGs model returns the best rendering of the shape of the band, with significantly lower residuals. We also propose as an example an algorithm to estimate the error on the band parameters using a bootstrap method. We then present an application of the model to two spectral analyses of smectites subjected to different H2O vapor pressures, and present the variations of the components with decreasing humidity. This example emphasizes the ability of this model to coherently retrieve weak bands that are hidden within much stronger ones.
- [54] arXiv:2002.01346 [pdf, other]
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Title: Physical and chemical modeling of a starless core: L1512Comments: 22 pages, 18 figures, accepted for publication in A&ASubjects: Astrophysics of Galaxies (astro-ph.GA)
The deuterium fractionation in starless cores gives us a clue to estimate their lifetime scales, thus allowing us to distinguish between different dynamical theories of core formation. Cores also seem to be subject to a differential N2 and CO depletion which was not expected from models. We aim to make a survey of 10 cores to estimate their lifetime scales and depletion profiles in detail. After L183, in Serpens, we present the second cloud of the series, L1512 in Auriga. To constrain the lifetime scale, we perform chemical modeling of the deuteration profiles across L1512 based on dust extinction measurements from near-infrared observations and non-local thermal equilibrium radiative transfer with multiple line observations of N2H+, N2D+, DCO+, C18O, and 13CO, plus H2D+ (1$_{10}$--1$_{11}$). We find a peak density of 1.1$\times$10$^5$ cm$^{-3}$ and a central temperature of 7.5$\pm$1 K, which are respectively higher and lower compared with previous dust emission studies. The depletion factors of N2H+ and N2D+ are 27$^{+17}_{-13}$ and 4$^{+2}_{-1}$ in L1512, intermediate between the two other more advanced and denser starless core cases, L183 and L1544. These factors also indicate a similar freeze-out of N2 in L1512, compared to the two others despite a peak density one to two orders of magnitude lower. Retrieving CO and N2 abundance profiles with the chemical model, we find that CO has a depletion factor of $\sim$430-870 and the N2 profile is similar to that of CO unlike towards L183. Therefore, L1512 has probably been living long enough so that N2 chemistry has reached steady state. N2H+ modeling remains compulsory to assess the precise physical conditions in the center of cold starless cores, rather than dust emission. L1512 is presumably older than 1.4 Myr. Therefore, the dominating core formation mechanism should be ambipolar diffusion for this source.
- [55] arXiv:2002.01367 [pdf, other]
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Title: The observed velocity distribution of young pulsars II: analysis of complete PSR$π$Authors: Andrei P. IgoshevComments: Submitted to the MNRAS. 11 pages, 9 figuresSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We use maximum likelihood methods as published in Verbunt et al. to analyse a new large dataset of parallaxes and proper motions measured by Deller et al. This sample is roughly three times larger than number of measurements available before. For both the complete sample and its younger part ($\tau < 3$ Myr), we find that a velocity distribution containing two Maxwellians describes the measured parallaxes and proper motion better than a single Maxwellian. The sum of two Maxwelians has the following parameters: fraction of low-velocity pulsars and average velocities $\sigma\sqrt{8/\pi}$ of low and high-velocity pulsars. For a complete sample these parameters are as following: 42 per cent, $205$ km s$^{-1}$ and 476 km s$^{-1}$. For younger pulsars which are used as a proxy for the natal kick, these parameters are as following: 20 per cent, $90$ km s$^{-1}$ and 540 km s$^{-1}$. 5 per cent of pulsars has natal kicks less than 60 km s$^{-1}$. We analyse parameters of the Galactic distribution of pulsars and found that the vertical scale-height strongly depends on the spin-down age and is 320 pc for complete sample and 180~pc for pulsars with $\tau < 3$ Myr. The radial scale-length is not as sensitive to age and is $\approx 0.8$ kpc. Results of the velocity analysis are weakly sensitive to the exact values of scale-lengths. As in the original research, our main result is that the velocity distribution is wider than a single Maxwellian.
- [56] arXiv:2002.01385 [pdf, ps, other]
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Title: Distorted surfaces of magnetic helium-peculiar stars: An application to a CenComments: 9 pages, accepted for publication in MNRASSubjects: Solar and Stellar Astrophysics (astro-ph.SR)
Helium-peculiar magnetic chemically peculiar stars show variations of helium abundance across their surfaces. As a result of associated atmospheric scale height variations, the stellar surface becomes distorted, with helium-rich regions dented inwards. Effectively, on top of flux variations due to opacity effects, the depressed helium-rich surface regions become less bright in the optical regions and brighter in the ultraviolet. We study the observational effects of the aspherical surface on the light curves of a Cen. We simulate the light curves of this star adopting surface distributions of He, N, O, Si, and Fe derived from Doppler mapping and introducing the effect of distortion proportional to helium abundance. We show that while most of the optical and UV variations of this star result from flux redistribution due to the non-uniform surface distributions of helium and iron, the reduction of light variations due to the helium-related surface distortion leads to a better agreement between simulated optical light curves and the light curves observed with the BRITE satellites.
- [57] arXiv:2002.01390 [pdf, ps, other]
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Title: Magnetic effect on the rotational frequency of a neutron starSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
A neutron star contains regions with particles which exhibit magnetic moments, which, in turn, generate respective magnetizations. By magnetoelastic interactions between the magnetization and the matter there arises a magnetostriction. The magnetostriction changes the mass density of the neutron star and hence its inertia tensor, and as a result it changes the rotation frequency of the star. We also sketch how the calculation of the magnetostriction in the different inner regions of the neutron star has to proceed, and which parameter inputs are needed.
- [58] arXiv:2002.01399 [pdf, other]
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Title: A bright, high rotation-measure FRB that skewers the M33 haloAuthors: Liam Connor, Joeri van Leeuwen, L. C. Oostrum, E. Petroff, Yogesh Maan, E. A. K. Adams, J. J. Attema, J. E. Bast, O. M. Boersma, H. Dénes, D. W. Gardenier, J. E. Hargreaves, E. Kooistra, I. Pastor-Marazuela, R. Schulz, A. Sclocco, R. Smits, S. M. Straal, D. van der Schuur, Dany Vohl, B. Adebahr, W. J. G. de Blok, W. A. van Cappellen, A. H. W. M. Coolen, S. Damstra, G. N. J. van Diepen, B. S. Frank, K. M. Hess, B. Hut, G. Marcel Loose, D. M. Lucero, Á. Mika, V. A. Moss, H. Mulder, T. A. Oosterloo, M. Ruiter, H. Vedantham, N. J. Vermaas, S. J. Wijnholds, J. ZiemkeSubjects: High Energy Astrophysical Phenomena (astro-ph.HE)
We report the detection of a bright fast radio burst, FRB\,191108, with Apertif on the Westerbork Synthesis Radio Telescope (WSRT). The interferometer allows us to localise the FRB to a narrow $5\arcsec\times7\arcmin$ ellipse by employing both multibeam information within the Apertif phased-array feed (PAF) beam pattern, and across different tied-array beams. The resulting sight line passes close to Local Group galaxy M33, with an impact parameter of only 18\,kpc with respect to the core. It also traverses the much larger circumgalactic medium of M31, the Andromeda Galaxy. We find that the shared plasma of the Local Group galaxies could contribute $\sim$10\% of its dispersion measure of 588\,pc\,cm$^{-3}$, but not detectable scintillation, temporal scattering, or significant Faraday rotation in this case. FRB\,191108 has a Faraday rotation measure of +474\,$\pm\,3$\,rad\,m$^{-2}$, which is too large to be explained by either the Milky Way or the intergalactic medium. This indicates a dense local magneto-ionic environment in the source host galaxy---as has been argued for other FRBs. We found no accompanying persistent radio sources in the Apertif imaging survey data.
- [59] arXiv:2002.01421 [pdf, other]
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Title: Can magnetized turbulence set the mass scale of stars?Authors: David Guszejnov, Michael Y. Grudić, Philip F. Hopkins, Stella S. R. Offner, Claude-André Faucher-GiguèreComments: 16 pages, 15 figures, submitted to MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
Understanding the evolution of self-gravitating, isothermal, magnetized gas is crucial for star formation, as these physical processes have been postulated to set the initial mass function (IMF). We present a suite of isothermal magnetohydrodynamic (MHD) simulations using the GIZMO code, that resolve the formation of individual stars in giant molecular clouds (GMCs), spanning a range of Mach numbers found in observed GMCs. As in past works, the mean and median stellar masses are sensitive to numerical resolution, because they are sensitive to low-mass stars that contribute a vanishing fraction of the overall stellar mass. The {\em mass-weighted} median stellar mass $M_\mathrm{50}$ becomes insensitive to resolution once turbulent fragmentation is well-resolved. Without imposing Larson-like scaling laws, our simulations find $M_\mathrm{50} \propto M_\mathrm{0} \mathcal{M}^{-3} \alpha_\mathrm{turb} \mathrm{SFE}^{1/3}$ for GMC mass $M_\mathrm{0}$, sonic Mach number $\mathcal{M}$, virial parameter $\alpha_\mathrm{turb}$, and star formation efficiency $\mathrm{SFE}=M_\mathrm{\star}/M_\mathrm{0}$. This fit agrees well with previous IMF results from the RAMSES, ORION2, and SphNG codes. Although $M_\mathrm{50}$ has no significant dependence on the magnetic field strength at the cloud scale, MHD is necessary to prevent a fragmentation cascade that results in non-convergent stellar masses. For initial conditions and SFE similar to star-forming GMCs in our Galaxy, we predict $M_\mathrm{50}$ to be $>20 M_{\odot}$, an order of magnitude larger than observed ($\sim 2 M_\odot$), together with an excess of brown dwarfs. Moreover, $M_\mathrm{50}$ is sensitive to initial cloud properties and evolves strongly in time within a given cloud, predicting much larger IMF variations than are observationally allowed. We conclude that physics beyond MHD turbulence and gravity are necessary ingredients for the IMF.
- [60] arXiv:2002.01468 [pdf, other]
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Title: Ricochets on AsteroidsAuthors: Esteban Wright, Alice Quillen, Juiliana South, Randal C. Nelson, Paul Sanchez, John Siu, Hesam Askari, Miki Nakajima, Stephen R. SchwartzComments: Link to the high speed videos for the 3 experiments tracked and discussed: this https URL Preliminary results presented at American Geophysical Union (AGU) 2019 Fall Meeting (P43D-3497). Submitted to the journal Icarus on February 3, 2020Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
Spin off events and impacts can eject boulders from an asteroid surface and rubble pile asteroids can accumulate from debris following a collision between large asteroids. These processes produce a population of gravitational bound objects in orbit that can impact an asteroid surface at low velocity and with a distribution of impact angles. We present laboratory experiments of low velocity spherical projectiles into a fine granular medium, sand. We delineate velocity and impact angles giving ricochets, those giving projectiles that roll-out from the impact crater and those that stop within their impact crater. With high speed camera images and fluorescent markers on the projectiles we track spin and projectile trajectories during impact. We find that the projectile only reaches a rolling without slipping condition well after the marble has reached peak penetration depth. The required friction coefficient during the penetration phase of impact is 4-5 times lower than that of the sand suggesting that the sand is fluidized near the projectile surface during penetration. We find that the critical grazing impact critical angle dividing ricochets from roll-outs, increases with increasing impact velocity. The critical angles for ricochet and for roll-out as a function of velocity can be matched by an empirical model during the rebound phase that balances a lift force against gravity. We estimate constraints on projectile radius, velocity and impact angle that would allow projectiles on asteroids to ricochet or roll away from impact, finally coming to rest distant from their initial impact sites.
Cross-lists for Wed, 5 Feb 20
- [61] arXiv:2002.01064 (cross-list from hep-th) [pdf, ps, other]
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Title: Quantum nature of Wigner function for inflationary tensor perturbationsComments: 24 pagesSubjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Quantum Physics (quant-ph)
We study the Winger function for the inflationary tensor perturbation defined in the real phase space. We compute explicitly the Wigner function including the contributions from the cubic self-interaction Hamintonian of tensor perturbations. Then we argue that it is no longer an appropriate description for the probability distribution in the sense that quantum nature allows negativity around vanishing phase variables. This comes from the non-Gaussian wavefunction in the mixed state as a result of the non-linear interaction between super- and sub-horizon modes. We also show that this is related to the explicit infrared divergence in the Wigner function, in contrast to the trace of the density matrix.
- [62] arXiv:2002.01131 (cross-list from hep-ph) [pdf, other]
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Title: Cosmological Signatures of Superheavy Dark MatterComments: 26 pages, 5 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)
We discuss two possible scenarios, namely the curvaton mechanism and the dark matter density modulation, where non-Gaussianity signals of superheavy dark matter produced by gravity can be enhanced and observed. In both scenarios, superheavy dark matter couples to an additional light field as a mediator. In the case of derivative coupling, the resulting non-Gaussianities induced by the light field can be large, which can provide inflationary evidences for these superheavy dark matter scenarios.
- [63] arXiv:2002.01185 (cross-list from hep-ph) [pdf, other]
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Title: Combined search for anisotropic birefringence in the gravitational-wave transient catalog GWTC-1Authors: Lijing ShaoComments: 13 pages, 6 figures, 6 tablesSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
The discovery of gravitational waves (GWs) provides an unprecedented arena to test general relativity, including the gravitational Lorentz invariance violation (gLIV). In the propagation of GWs, a generic gLIV leads to anisotropy, dispersion, and birefringence. GW events constrain the anisotropic birefringence particularly well. Kosteleck\'y and Mewes (2016) performed a preliminary analysis for GW150914. We improve their method and extend the analysis systematically to the whole GW transient catalog, GWTC-1. This is the first global analysis of the spacetime anisotropic Lorentzian structure with a catalog of GWs, where multiple events are crucial in breaking the degeneracy among gLIV parameters. With the absence of abnormal propagation, we obtain new limits on 34 coefficients for gLIV in the nonminimal gravity that surpass previous limits by $\sim 10^2$-$10^5$.
- [64] arXiv:2002.01217 (cross-list from hep-ph) [pdf, other]
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Title: QCD equation of state at vanishing and high baryon density: Chiral Mean Field modelComments: 4 pages, 2 figures, Proceedings of the XXVIIIth International Conference on Ultrarelativistic Nucleus-Nucleus Collisions (Quark Matter 2019), Wuhan, China, November 3-9 2019Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
The thermodynamic properties of high temperature and high density QCD-matter are studied using the Chiral SU(3)-flavor parity-doublet Polyakov-loop quark-hadron mean-field model, CMF. The CMF model provides a proper description of lattice QCD data, heavy-ions physics, and static neutron stars. The behavior of lines of constant pressure with increase of baryon density is discussed. The rapid change of pressure behavior at $\mu_B/T\approx3$ suggests a strong contribution of baryons to thermodynamic properties at this region. The position of this region is very close to the radius of convergence for a Taylor expansion of the QCD pressure. The role of mesons and unstable hadrons in the hydrodynamic expansion of strongly interacting matter is also discussed.
- [65] arXiv:2002.01431 (cross-list from stat.CO) [pdf, other]
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Title: Mean shift cluster recognition method implementation in the nested sampling algorithmSubjects: Computation (stat.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM); Computational Physics (physics.comp-ph); Machine Learning (stat.ML)
Nested sampling is an efficient algorithm for the calculation of the Bayesian evidence and posterior parameter probability distributions. It is based on the step-by-step exploration of the parameter space by Monte Carlo sampling with a series of values sets called live points that evolve towards the region of interest, i.e. where the likelihood function is maximal. In presence of several local likelihood maxima, the algorithm converges with difficulty. Some systematic errors can also be introduced by unexplored parameter volume regions. In order to avoid this, different methods are proposed in the literature for an efficient search of new live points, even in presence of local maxima. Here we present a new solution based on the mean shift cluster recognition method implemented in a random walk search algorithm. The clustering recognition is integrated within the Bayesian analysis program NestedFit. It is tested with the analysis of some difficult cases. Compared to the analysis results without cluster recognition, the computation time is considerably reduced. At the same time, the entire parameter space is efficiently explored, which translates into a smaller uncertainty of the extracted value of the Bayesian evidence.
- [66] arXiv:2002.01451 (cross-list from hep-ph) [pdf, other]
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Title: Chiral pastaAuthors: Andreas SchmittComments: 19 pages, 8 figuresSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)
Interiors of neutron stars are ultra-dense and may contain a core of deconfined quark matter. Such a core connects to the outer layers either smoothly or through a sharp microscopic interface or through an intermediate macroscopic layer of inhomogeneous mixed phases, which is globally neutral but locally contains electrically charged domains. Here I employ a nucleon-meson model under neutron star conditions that shows a first-order chiral phase transition at large densities. In the vicinity of this chiral transition I calculate the free energies of various mixed phases - different 'pasta structures' - in the Wigner-Seitz approximation. Crucially, chirally broken nuclear matter and the approximately chirally symmetric phase (loosely interpreted as quark matter) are treated on the same footing. This allows me to compute the interface profiles of bubbles, rods, and slabs fully consistently, taking into account electromagnetic screening effects and without needing the surface tension as an input. I find that the full numerical results tend to disfavor mixed phases compared to a simple step-like approximation used frequently in the literature and that the predominantly favored pasta structure consists of slabs with a surface tension $\Sigma \simeq 6\, {\rm MeV}/{\rm fm}^2$.
- [67] arXiv:2002.01473 (cross-list from gr-qc) [pdf, other]
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Title: Ergostar models: where do they reside?Comments: 8 pages, 3 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
Recently we have shown that dynamically stable ergostar solutions (equilibrium neutron stars that contain an ergoregion) with a compressible and causal equation of state exist [1]. These stars are hypermassive, differentially rotating and highly compact. In this work we make a systematic study of equilibrium models in order to locate the position of ergostars in the parameter space. We adopt four equations of state that differ in the matching density of a maximally stiff core. By constructing a large number of models both with uniform and differential rotation of different degrees we identify the parameters for which ergostars appear. We find that the most favorable conditions for the appearance of dynamically stable ergostars are a significant finite density close to the surface of the star (i.e. similar to self-bound quark stars) and a small degree of differential rotation.
Replacements for Wed, 5 Feb 20
- [68] arXiv:1811.07363 (replaced) [pdf, other]
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Title: Zero point energy of composite particles: The medium effectsAuthors: Toru KojoComments: v3) 32 pages, 13 figures; published in PRDJournal-ref: Physical Review D 101, 036001 (2020)Subjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th); Nuclear Theory (nucl-th)
- [69] arXiv:1904.04493 (replaced) [pdf, other]
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Title: Weyl Symmetry Inspired Inflation and Dark MatterComments: 17 pages, 1 figure; Phenomenology updatedSubjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
- [70] arXiv:1905.12669 (replaced) [pdf, other]
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Title: Picky Partners: The Pairing of Component Masses in Binary Black Hole MergersComments: version accepted by ApJLSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)
- [71] arXiv:1906.00075 (replaced) [pdf, other]
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Title: Effects of Radiation Pressure on the Evaporative Wind of HD 209458bAuthors: Alex Debrecht, Jonathan Carroll-Nellenback, Adam Frank, Eric G. Blackman, Luca Fossati, John McCann, Ruth Murray-ClaySubjects: Earth and Planetary Astrophysics (astro-ph.EP)
- [72] arXiv:1906.01670 (replaced) [pdf, other]
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Title: NuRadioMC: Simulating the radio emission of neutrinos from interaction to detectorAuthors: Christian Glaser, Daniel García-Fernández, Anna Nelles, Jaime Alvarez-Muñiz, Steven W. Barwick, Dave Z. Besson, Brian A. Clark, Amy Connolly, Cosmin Deaconu, Krijn de Vries, Jordan C. Hanson, Ben Hokanson-Fasig, R. Lahmann, Uzair Latif, Stuart A. Kleinfelder, Christopher Persichilli, Yue Pan, Carl Pfender, Ilse Plaisier, Dave Seckel, Jorge Torres, Simona Toscano, Nick van Eijndhoven, Abigail Vieregg, Christoph Welling, Tobias Winchen, Stephanie A. WisselComments: replaced with published versionJournal-ref: Eur. Phys. J. C 80, 77 (2020)Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)
- [73] arXiv:1906.07504 (replaced) [pdf, other]
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Title: Prospect for constraining holographic dark energy with gravitational wave standard sirens from the Einstein TelescopeComments: 13 pages, 4 figuresSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [74] arXiv:1908.00078 (replaced) [pdf, other]
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Title: GRB lensing parallax: Closing primordial black hole dark matter mass windowComments: 8 pages, 4 figuresJournal-ref: Phys. Rev. Research 2, 013113 (2020)Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [75] arXiv:1908.08876 (replaced) [pdf, other]
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Title: On a possible nonequilibrium imprint in the cosmic background at low frequenciesAuthors: Marco Baiesi, Carlo Burigana, Livia Conti, Gianmaria Falasco, Christian Maes, Lamberto Rondoni, Tiziana TrombettiComments: 14 pages, 3 figures, 1 table; Sec. IV changed, 1 new reference added, two columns formatSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Statistical Mechanics (cond-mat.stat-mech)
- [76] arXiv:1908.10355 (replaced) [pdf, other]
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Title: Probing up-down quark matter ($ud$QM) via Gravitational WavesAuthors: Chen ZhangComments: Final version, to appear in Physical Review DSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); Nuclear Theory (nucl-th)
- [77] arXiv:1910.06796 (replaced) [pdf, other]
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Title: Warm brane inflation with an exponential potential: A consistent realization away from the swamplandComments: 13 pages, 4 figures. Replaced with version matching the published oneJournal-ref: Phys. Rev. D 101, 023535 (2020)Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)
- [78] arXiv:1910.07157 (replaced) [pdf, other]
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Title: Constraints on Cosmological Parameters from the 500 deg$^2$ SPTpol Lensing Power SpectrumAuthors: F. Bianchini, W. L. K. Wu, P. A. R. Ade, A. J. Anderson, J. E. Austermann, J. S. Avva, J. A. Beall, A. N. Bender, B. A. Benson, L. E. Bleem, J. E. Carlstrom, C. L. Chang, P. Chaubal, H. C. Chiang, R. Citron, C. Corbett Moran, T. M. Crawford, A. T. Crites, T. de Haan, M. A. Dobbs, W. Everett, J. Gallicchio, E. M. George, A. Gilbert, N. Gupta, N. W. Halverson, N. Harrington, J. W. Henning, G. C. Hilton, G. P. Holder, W. L. Holzapfel, J. D. Hrubes, N. Huang, J. Hubmayr, K. D. Irwin, L. Knox, A. T. Lee, D. Li, A. Lowitz, A. Manzotti, J. J. McMahon, S. S. Meyer, M. Millea, L. M. Mocanu, J. Montgomery, A. Nadolski, T. Natoli, J. P. Nibarger, G. Noble, V. Novosad, Y. Omori, S. Padin, S. Patil, C. Pryke, C. L. Reichardt, J. E. Ruhl, B. R. Saliwanchik, J.T. Sayre, K. K. Schaffer, C. Sievers, G. Simard, et al. (10 additional authors not shown)Comments: 16 pages, 8 figures, 3 tables, updated to match the version published on ApJSubjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [79] arXiv:1910.08656 (replaced) [pdf, ps, other]
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Title: Cloud fragmentation cascades and feedback: on reconciling an unfettered inertial range with a low star formation rateAuthors: Eric G. BlackmanComments: 6 pages, accepted by MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [80] arXiv:1910.10134 (replaced) [pdf, other]
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Title: Stellar Density Profiles of Dwarf Spheroidal GalaxiesComments: 23 pages, 17 figures. Accepted for publication in ApJSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [81] arXiv:1910.13225 (replaced) [pdf, ps, other]
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Title: New perspectives on the TOV equilibrium from a dual null approachComments: 10 pp, 1 figSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [82] arXiv:1911.02657 (replaced) [pdf, ps, other]
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Title: Gravitational leptogenesis with kination and gravitational reheatingComments: 15 pages; v3: published version with minor revisions and references addedJournal-ref: JCAP01(2020)016Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)
- [83] arXiv:1911.11911 (replaced) [pdf, other]
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Title: The M31/M33 tidal interaction: A hydrodynamic simulation of the extended gas distributionComments: MNRAS, in press. Radical change of title requested by referee; results and conclusions unchanged. Matches accepted versionSubjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
- [84] arXiv:1911.12277 (replaced) [pdf, other]
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Title: A method for the experimental measurement of bulk and shear loss angles in amorphous thin filmsAuthors: Gabriele Vajente, Mariana Fazio, Le Yang, Anchal Gupta, Alena Ananyeva, Garilynn Billingsley, Carmen S. MenoniSubjects: Materials Science (cond-mat.mtrl-sci); Instrumentation and Methods for Astrophysics (astro-ph.IM); General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Detectors (physics.ins-det)
- [85] arXiv:1912.08244 (replaced) [pdf]
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Title: Energetic Particle Increases Associated with Stream Interaction RegionsAuthors: C. M. S. Cohen, E. R. Christian, A. C. Cummings, A. J. Davis, M. I. Desai, J. Giacalone, M. E. Hill, C. J. Joyce, A. W. Labrador, R. A. Leske, W. H. Matthaeus, D. J. McComas, R. L. McNutt, Jr., R. A. Mewaldt, D. G. Mitchell, J. S. Rankin, E. C. Roelof, N. A. Schwadron, E. C. Stone, J. R. Szalay, M. E. Wiedenbeck, R. C. Allen, G. C. Ho, L. K. Jian, D. Lario, D. Odstrcil, S. D. Bale, S. T. Badman, M. Pulupa, R. J. MacDowall, J. C. Kasper, A. W. Case, K. E. Korreck, D. E. Larson, Roberto Livi, M. L. Stevens, Phyllis WhittleseySubjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR)
- [86] arXiv:1912.08875 (replaced) [pdf, other]
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Title: Confronting dark matter co-annihilation of Inert two Higgs Doublet Model with a compressed mass spectrumComments: 38 pages, 19 figures, references addedSubjects: High Energy Physics - Phenomenology (hep-ph); High Energy Astrophysical Phenomena (astro-ph.HE)
- [87] arXiv:1912.09345 (replaced) [pdf, other]
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Title: Detailed imaging of coronal rays with the Parker Solar ProbeAuthors: Nicolas Poirier, Athanasios Kouloumvakos, Alexis P. Rouillard, Rui F. Pinto, Angelos Vourlidas, Guillermo Stenborg, Emeline Valette, Russell A. Howard, Phillip Hess, Arnaud Thernisien, Nathan Rich, Lea Griton, Mikel Indurain, Nour-Edine Raouafi, Michael Lavarra, Victor RévilleComments: for associated mpeg file see this https URL, 21 pages, 16 figures, published in ApJS: "Early Results from Parker Solar Probe: Ushering a New Frontier in Space Exploration"Journal-ref: ApJS (2020) 246 60Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Space Physics (physics.space-ph)
- [88] arXiv:1912.11378 (replaced) [pdf, ps, other]
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Title: Evaporative cooling of icy interstellar grains. I. Basic characterizationComments: Astronomy & Astrophysics, Volume 633, A97, 2020Journal-ref: A&A 633, A97 (2020)Subjects: Astrophysics of Galaxies (astro-ph.GA); Computational Physics (physics.comp-ph); Space Physics (physics.space-ph)
- [89] arXiv:2001.01730 (replaced) [pdf, ps, other]
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Title: Upper Limit on the Dissipation of Gravitational Waves in Gravitationally Bound SystemsAuthors: Abraham Loeb (Harvard)Comments: 5 pages, accepted for publication in The Astrophysical Journal LettersSubjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [90] arXiv:2001.02231 (replaced) [pdf, other]
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Title: On the eccentricity evolution of massive black hole binaries in stellar backgroundsAuthors: Matteo Bonetti, Alexander Rasskazov, Alberto Sesana, Massimo Dotti, Francesco Haardt, Nathan W. C. Leigh, Manuel Arca Sedda, Giacomo Fragione, Elena RossiComments: 6 pages, 5 figures; accepted for publication in MNRASSubjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)
- [91] arXiv:2001.02984 (replaced) [pdf, other]
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Title: Merger rate distribution of primordial black hole binaries with electric chargesComments: V1, 2 figures, 18 pages; V2, references added;Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph)
- [92] arXiv:2001.07605 (replaced) [pdf, other]
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Title: First search for r-mode gravitational waves from J0537-6910Comments: 14 pages,12 figuresSubjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)
- [93] arXiv:2001.07807 (replaced) [pdf, other]
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Title: Accretion-Driven Sources in Spatially Resolved Ly$α$ EmittersAuthors: B. Dittenber (1), M. S. Oey (1), E. Hodges-Kluck (2,3), E. Gallo (1), M. Hayes (4), G. Oestlin (4), J. Melinder (4)Comments: 10 pages, 3 figures, 2 tables. Accepted by ApJ LettersSubjects: Astrophysics of Galaxies (astro-ph.GA)
- [94] arXiv:2001.09348 (replaced) [pdf, other]
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Title: Probabilistic fibre-to-target assignment algorithm for multi-object spectroscopic surveysAuthors: E. Tempel, P. Norberg, T. Tuvikene, T. Bensby, C. Chiappini, N. Christlieb, M.-R. L. Cioni, J. Comparat, L. J. M. Davies, G. Guiglion, A. Koch, G. Kordopatis, M. Krumpe, J. Loveday, A. Merloni, G. Micheva, I. Minchev, B. F. Roukema, J. G. Sorce, E. Starkenburg, J. Storm, E. Swann, W. F. Thi, G. Traven, R. S. de JongComments: 19 pages, 18 figures, accepted for publication in A&ASubjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Astrophysics of Galaxies (astro-ph.GA)
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