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New submissions for Mon, 20 Jan 20

[1]  arXiv:2001.06009 [pdf, other]

Title: Sausage & Mash: the dual origin of the Galactic thick disc and halo from the gas-rich Gaia-Enceladus-Sausage merger

Authors: Robert J. J. Grand, Daisuke Kawata, Vasily Belokurov, Alis J. Deason, Azadeh Fattahi, Francesca Fragkoudi, Facundo A. Gómez, Federico Marinacci, Rüdiger Pakmor

Comments: submitted to MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Solar and Stellar Astrophysics (astro-ph.SR)

We analyse a set of cosmological magneto-hydrodynamic simulations of the formation of Milky Way-mass galaxies identified to have a prominent radially anisotropic stellar halo component similar to the so-called "Gaia Sausage" found in the Gaia data. We examine the effects of the progenitor of the Sausage (the Gaia-Enceladus-Sausage, GES) on the formation of major galactic components analogous to the Galactic thick disc and inner stellar halo. We find that the GES merger is likely to have been gas-rich and contribute 10-50$\%$ of gas to a merger-induced centrally concentrated starburst that results in the rapid formation of a compact, rotationally supported thick disc that occupies the typical chemical thick disc region of chemical abundance space. We find evidence that gas-rich mergers heated the proto-disc of the Galaxy, scattering stars onto less-circular orbits such that their rotation velocity and metallicity positively correlate, thus contributing an additional component that connects the Galactic thick disc to the inner stellar halo. We demonstrate that the level of kinematic heating of the proto-galaxy correlates with the kinematic state of the population before the merger, the progenitor mass and orbital eccentricity of the merger. Furthermore, we show that the mass and time of the merger can be accurately inferred from local stars on counter-rotating orbits.

[2]  arXiv:2001.06010 [pdf, ps, other]

Title: Searching for AGN and Pulsar Candidates in 4FGL Unassociated Sources Using Machine Learning

Authors: Kerui Zhu, Shi-Ju Kang, Yong-Gang Zheng

Comments: 14 pages, 7 figures, 8 tables, Submitted, Comments welcome!

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

In a new release of the fourth \emph{Fermi} Large Area Telescope source catalog (4FGL) in September (URL: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/8yr_catalog/), 5065 $\gamma$-ray sources are reported, including 3207 active galactic nuclei (AGNs), 239 pulsars, 190 other sources and 1429 unassociated sources. We employ two different supervised machine learning classifiers, combined with the direct observation parameters given by the 4FGL fits (URL: https://fermi.gsfc.nasa.gov/ssc/data/access/lat/8yr_catalog/gll_psc_v20.fit), to search for sources potentially classified as AGNs and pulsars in the 1429 unassociated sources. In order to reduce the error caused by the large difference in the sizes of samples, we divide the classification process into two separate steps in order to identify the AGNs and the pulsars. First, we select the identified AGNs from all of the samples, and then select the identified pulsars from the remaining. Using the 4FGL sources associated or identified as AGNs, pulsars, and other sources with the features selected through the K-S test, we trained, optimized, and tested our classifier models. Then, the models are applied to classify the 1429 unassociated sources. According to the direct calculation results of the two classifiers, we show the sensitivity, specificity, accuracy in each step, and the class of unassociated sources given by each classifier. The accuracy obtained in the first step is approximately $95\%$; in the second step, the obtained overall accuracy is approximately $80\%$. Combining the results of the two classifiers, we predict that there are 674 AGN-type candidates, 86 pulsar-type candidates, 177 other types of $\gamma$-ray candidates, and 492 of uncertain type.

[3]  arXiv:2001.06011 [pdf, ps, other]

Title: A Submillimeter Perspective on the GOODS Fields (SUPER GOODS). IV. The Submillimeter Properties of X-ray Sources in the CDF-S

Authors: A. J. Barger, L. L. Cowie, F. E. Bauer, J. Gonzalez-Lopez

Comments: 20 pages, 16 figures, published in ApJ

Journal-ref: Astrophys.J. 887, 23 (2019)

Subjects: Astrophysics of Galaxies (astro-ph.GA)

The CDF-S is the deepest X-ray image available and will remain so for the near future. We provide a spectroscopic (64.5%; 64% with spectral classifications) and photometric redshift catalog for the full 7 Ms sample, but much of our analysis focuses on the central (off-axis angles <5.7') region, which contains a large, faint ALMA sample of 75 >4.5-sigma 850 micron sources. We measure the 850 micron fluxes at the X-ray positions using the ALMA images, where available, or an ultradeep SCUBA-2 map. We find that the full X-ray sample produces ~10% of the 850 micron extragalactic background light. We separate the submillimeter detected X-ray sources into star-forming galaxies and AGNs using a star formation rate (SFR) versus X-ray luminosity calibration for high SFR galaxies. We confirm this separation using the X-ray photon indices. We measure the X-ray fluxes at the accurate positions of the 75 ALMA sources and detect 70% at >3-sigma in either the 0.5-2 or 2-7 keV bands. However, many of these may produce both their X-ray and submillimeter emission by star formation. Indeed, we find that only 20% of the ALMA sources have intermediate X-ray luminosities (rest-frame 8-28 keV luminosities of 10^42.5-10^44 erg/s), and none has a high X-ray luminosity (>10^44 erg/s). Conversely, after combining the CDF-S with the CDF-N, we find extreme star formation (SFR>300 solar masses per yr) in some intermediate X-ray luminosity sources but not in any high X-ray luminosity sources. We argue that the quenching of star formation in the most luminous AGNs may be a consequence of the clearing of gas in these sources.

[4]  arXiv:2001.06012 [pdf, other]

Title: Positive feedback at the disc-halo interface

Authors: Alexander Hobbs, Robert Feldmann

Comments: 23 pages, 17 figures. Submitted to MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

The flat star formation (SF) history of the Milky Way (MW) requires gas in the Galactic disc to be replenished, most likely from a reservoir outside the Galaxy. Such a replenishment may be achieved by a form of `positive' feedback, whereby SF feedback creates a Galactic fountain cycle that collects and cools additional gas from the hot halo surrounding the Galaxy. In this paper we present a model of this process for the MW. A section of the Galactic disc is allowed to form stars which subsequently explode as supernovae (SNe) and send gas out into the hot halo. The gas that is sent out is colder than the hot halo gas and, as it mixes, the halo gas is cooled, providing fuel for further SF as the mixture falls back onto the Galactic disc. We find that this process can be sufficient to maintain a roughly-constant cold gas mass in the MW over at least 3 Gyr. Our results further suggest that there is a positive feedback trend whereby increasing SF leads to an increase in the cold gas budget at average SF rates below 0.5 solar masses per year but above which becomes negative, where further increasing the SFR causes the cold gas budget to decrease. We have constructed an analytical model for this that reproduces the data well and could have profound implications for galaxy evolution in feedback-dominated regimes.

[5]  arXiv:2001.06014 [pdf, other]

Title: Quasi-periodic behaviour in the optical and γ-ray light curves of blazars 3C 66A and B2 1633+38

Authors: J. Otero-Santos, J. A. Acosta-Pulido, J. Becerra González, C. M. Raiteri, V. M. Larionov, P. Peñil, P. S. Smith, C. Ballester Niebla, G. A. Borman, M. I. Carnerero, N. Castro Segura, T. S. Grishina, E. N. Kopatskaya, E. G. Larionova, D. A. Morozova, A. A. Nikiforova, S. S. Savchenko, Yu. V. Troitskaya, I. S. Troitsky, A. A. Vasilyev, M. Villata

Comments: Accepted for publication in MNRAS

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report on quasi-periodic variability found in two blazars included in the Steward Observatory Blazar Monitoring data sample: the BL Lac object 3C 66A and the Flat Spectrum Radio Quasar B2 1633+38. We collect optical photometric and polarimetric data in V and R bands of these sources from different observatories: St. Petersburg University, Crimean Astrophysical Observatory, WEBT-GASP, Catalina Real-Time Transient Survey, Steward Observatory, STELLA Robotic Observatory and Katzman Automatic Imaging Telescope. In addition, an analysis of the $\gamma$-ray light curves from $\textit{Fermi}$-LAT is included. Three methods are used to search for any periodic behaviour in the data: the Z-transform Discrete Correlation Function, the Lomb-Scargle periodogram and the Weighted Wavelet Z-transform. We find evidences of possible quasi-periodic variability in the optical photometric data of both sources with periods of $\sim$3 years for 3C 66A and $\sim$1.9 years for B2 1633+38, with significances between 3$\sigma$ and 5$\sigma$. Only B2 1633+38 shows evidence of this behaviour in the optical polarized data set at a confidence level of 2$\sigma$-4$\sigma$. This is the first reported evidence of quasi-periodic behaviour in the optical light curve of B2 1633+38. Also a hint of quasi-periodic behaviour is found in the $\gamma$-ray light curve of B2 1633+38 with a confidence level $\geqslant$2$\sigma$, while no periodicity is observed for 3C 66A in this energy range. We propose different jet emission models that could explain the quasi-periodic variability and the differences found between these two sources.

[6]  arXiv:2001.06015 [pdf, ps, other]

Title: On the Absence of High-Redshift AGNs: Little Growth in the Supermassive Black Hole Population at High Redshifts

Authors: L. L. Cowie, A. J. Barger, F. E. Bauer, J. Gonzalez-Lopez

Comments: 19 pages, 14 figures, accepted for publication in ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We search for high-redshift (z>4.5) X-ray AGNs in the deep central (off-axis angle <5.7') region of the 7 Ms Chandra Deep Field-South X-ray image. We compile an initial candidate sample from direct X-ray detections. We then probe more deeply in the X-ray data by using pre-selected samples with high spatial resolution NIR/MIR (HST 1.6 micron and Spitzer 4.5 micron) and submillimeter (ALMA 850 micron) observations. The combination of the NIR/MIR and submillimeter pre-selections allows us to find X-ray sources with a wide range of dust properties and spectral energy distributions (SEDs). We use the SEDs from the optical to the submillimeter to determine if previous photometric redshifts were plausible. Only five possible z>5 X-ray AGNs are found, all of which might also lie at lower redshifts. If they do lie at high redshifts, then two are Compton-thick AGNs, and three are ALMA 850 micron sources. We find that (i) the number density of X-ray AGNs is dropping rapidly at high redshifts, (ii) the detected AGNs do not contribute significantly to the photoionization at z>5, and (iii) the measured X-ray light density over z=5-10 implies a very low black hole accretion density with very little growth in the black hole mass density in this redshift range.

[7]  arXiv:2001.06016 [pdf, other]

Title: A limit on Planck-scale froth with ESPRESSO

Authors: Ryan Cooke (1), Louise Welsh (1), Michele Fumagalli (1,2,3), Max Pettini (4) ((1) Centre for Extragalactic Astronomy, Durham University, (2) Institute for Computational Cosmology, Durham University, (3) Dipartimento di Fisica G. Occhialini, Universita degli Studi di Milano Bicocca, (4) Institute of Astronomy, University of Cambridge)

Comments: 7 pages, 2 figures, Submitted for publication in Monthly Notices of the Royal Astronomical Society

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)

Some models of quantum gravity predict that the very structure of spacetime is `frothy' due to quantum fluctuations. Although the effect is expected to be tiny, if these spacetime fluctuations grow over a large distance, the initial state of a photon, such as its energy, is gradually washed out as the photon propagates. Thus, in these models, even the most monochromatic light source would gradually disperse in energy due to spacetime fluctuations over large distances. In this paper, we use science verification observations obtained with ESPRESSO at the Very Large Telescope to place a novel bound on the growth of spacetime fluctuations. To achieve this, we directly measure the width of a narrow Fe II absorption line produced by a quiescent gas cloud at redshift z=2.34, corresponding to a comoving distance of ~5.8 Gpc. Using a heuristic model where the energy fluctuations grow as sigma_E / E = (E/E_P)^alpha, where E_P = 1.22 x 10^28 eV is the Planck energy, we rule out models with alpha < 0.634, including models where the quantum fluctuations grow as a random walk process (alpha = 0.5). Finally, we present a new formalism where the uncertainty accrued at discrete spacetime steps is drawn from a continuous distribution. We conclude, if photons take discrete steps through spacetime and accumulate Planck-scale uncertainties at each step, then our ESPRESSO observations require that the step size must be at least >10^13.2 L_P, where L_P is the Planck length.

[8]  arXiv:2001.06017 [pdf, other]

Title: The significant effects of stellar mass estimation on galaxy pair fractions

Authors: Philip J. Grylls, F. Shankar, C. Conselice

Comments: Submitted to MNRAS 29-Nov-2019

Subjects: Astrophysics of Galaxies (astro-ph.GA)

There exist discrepancies in measurements of the number and evolution of galaxy pairs. The pair fraction appears to be sensitive to both the criteria used to select pair fraction and the methods used to analyze survey data. This paper explores the connection between stellar mass estimation and the pair fraction of galaxies making use of STEEL, the Statistical sEmi-Emprical modeL. Previous results have found the pair fraction is sensitive to choices made when selecting what qualifies as a pair, for example luminosity or stellar mass selections. We find that different estimations of stellar mass such as photometric choice mass-to-light ratio or IMF that effect the stellar mass function also significantly affect the derived galaxy pair fraction. By making use of the galaxy halo connection we investigate these systematic affects on the pair fraction. We constrain the galaxy halo connection using the stellar-mass-halo-mass relationship for two observed stellar mass functions, and the Illustris TNG stellar mass function. Furthermore, we also create a suite of toy models where the stellar-mass-halo-mass relationship is manually changed. For each stellar-mass-halo-mass relation the pair fraction, and its evolution, are generated. We find that enhancements to the number density of high mass galaxies cause steepening of the stellar-mass-halo mass relation, resulting in a reduction of the pair fraction. We argue this is a considerable cause of bias that must be accounted for when comparing pair fractions.

[9]  arXiv:2001.06018 [pdf, other]

Title: The Clustering of DESI-like Luminous Red Galaxies Using Photometric Redshifts

Authors: Rongpu Zhou, Jeffrey A. Newman, Yao-Yuan Mao, Aaron Meisner, John Moustakas, Adam D. Myers, Abhishek Prakash, Andrew R. Zentner, David Brooks, Yutong Duan, Martin Landriau, Michael E. Levi, Francisco Prada, Gregory Tarle

Comments: 25 pages, 24 figures, submitted to MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We present measurements of the redshift-dependent clustering of a DESI-like luminous red galaxy (LRG) sample selected from the Legacy Survey imaging dataset, and use the halo occupation distribution (HOD) framework to fit the clustering signal. The LRG sample contains 2.7 million objects over the redshift range of $0.4 < z < 0.9$ over 5655 sq. degrees. We have developed new photometric redshift (photo-$z$) estimates using the Legacy Survey DECam and WISE photometry, with $\sigma_{\mathrm{NMAD}} = 0.02$ precision for LRGs. We compute the projected correlation function using new methods that maximize signal-to-noise while incorporating redshift uncertainties. We present a novel algorithm for dividing irregular survey geometries into equal-area patches for jackknife resampling. For a 5-parameter HOD model fit using the MultiDark halo catalog, we find that there is little evolution in HOD parameters except at the highest-redshifts. The inferred large-scale structure bias is largely consistent with constant clustering amplitude over time. In an appendix, we explore limitations of MCMC fitting using stochastic likelihood estimates resulting from applying HOD methods to N-body catalogs, and present a new technique for finding best-fit parameters in this situation. Accompanying this paper we have released the PRLS (Photometric Redshifts for the Legacy Surveys) catalog of photo-$z$'s obtained by applying the methods used in this work to the full Legacy Survey Data Release 8 dataset. This catalog provides accurate photometric redshifts for objects with $z < 21$ over more than 16,000 square degrees of sky.

[10]  arXiv:2001.06019 [pdf, other]

Title: A dispersion excess from pulsar wind nebulae and supernova remnants: Implications for pulsars and FRBs

Authors: Samayra M. Straal, Liam Connor, Joeri van Leeuwen

Comments: 7 pages, 4 figures, 2 tables. Accepted for publication in A&A

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Young pulsars and the pulsar wind nebulae (PWNe) or supernova remnants (SNRs) that surround them are some of the most dynamic and high-powered environments in our Universe. With the rise of more sensitive observations, the number of pulsar-SNR and PWN associations (hereafter, SNR/PWN) has increased, yet we do not understand to which extent this environment influences the pulsars' impulsive radio signals. We studied the dispersive contribution of SNRs and PWNe on Galactic pulsars, and considered their relevance to fast radio bursts (FRBs) such as FRB 121102. We investigated the dispersion measure (DM) contribution of SNRs and PWNe by comparing the measured DMs of Galactic pulsars in a SNR/PWN to the DM expected only from the intervening interstellar electrons, using the NE2001 model. We find that a two-$\sigma$ DM contribution of SNRs and PWNe to the pulsar signal exists, amounting to $21.1 \pm 10.6$ pc cm$^{-3}$. The control sample of pulsars unassociated with a SNR/PWN shows no excess. We model the SNR and PWN electron densities for each young pulsar in our sample and show that these indeed predict an excess of this magnitude. By extrapolating to the kind of fast-spinning, high magnetic field, young pulsars that may power FRBs, we show their SNR and PWN are capable of significantly contributing to the observed DM.

[11]  arXiv:2001.06020 [pdf, ps, other]

Title: The `Red Supergiant Problem': the upper luminosity boundary of type-II supernova progenitors

Authors: Ben Davies, Emma R. Beasor

Comments: 9 pages, 7 figures, accepted for publication in MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

By comparing the properties of Red Supergiant (RSG) supernova progenitors to those of field RSGs, it has been claimed that there is an absence of progenitors with luminosities $L$ above $\log(L/L_\odot) > 5.2$. This is in tension with the empirical upper luminosity limit of RSGs at $\log(L/L_\odot) = 5.5$, a result known as the `Red Supergiant Problem'. This has been interpreted as evidence for an upper mass threshold for the formation of black-holes. In this paper, we compare the observed luminosities of RSG SN progenitors with the observed RSG $L$-distribution in the Magellanic Clouds. Our results indicate that the absence of bright SN II-P/L progenitors in the current sample can be explained at least in part by the steepness of the $L$-distribution and a small sample size, and that the statistical significance of the Red Supergiant Problem is between 1-2$\sigma$ . Secondly, we model the luminosity distribution of II-P/L progenitors as a simple power-law with an upper and lower cutoff, and find an upper luminosity limit of $\log(L_{\rm hi}/L_\odot) = 5.20^{+0.17}_{-0.11}$ (68\% confidence), though this increases to $\sim$5.3 if one fixes the power-law slope to be that expected from theoretical arguments. Again, the results point to the significance of the RSG Problem being within $\sim 2 \sigma$. Under the assumption that all progenitors are the result of single-star evolution, this corresponds to an upper mass limit for the parent distribution of $M_{\rm hi} = 19.2{\rm M_\odot}$, $\pm1.3 {\rm M_\odot (systematic)}$, $^{+4.5}_{-2.3} {\rm M_\odot}$ (random) (68\% confidence limits).

[12]  arXiv:2001.06021 [pdf, other]

Title: Reionization with galaxies and active galactic nuclei

Authors: Pratika Dayal, Marta Volonteri, Tirthankar Roy Choudhury, Raffaella Schneider, Maxime Trebitsch, Nickolay Y. Gnedin, Hakim Atek, Michaela Hirschmann, Amy Reines

Comments: Submitted to MNRAS; comments welcome

Subjects: Astrophysics of Galaxies (astro-ph.GA)

In this work we investigate the properties of the sources that reionized the intergalactic medium (IGM) in the high-redshift Universe. Using a semi-analytical model aimed at reproducing galaxies and black holes in the first 1.5 Gyr of the Universe, we revisit the relative role of star formation and black hole accretion in producing ionizing photons that can escape into the IGM. Both star formation and black hole accretion are regulated by supernova feedback, resulting in black hole accretion being stunted in low-mass halos. We explore a wide range of combinations for the escape fraction of ionizing photons (redshift-dependent, constant and scaling positively with stellar mass) from both star formation ($\langle f_{\rm esc}^{\rm sf} \rangle$) and AGN ($f_{\rm esc}^{\rm bh}$) to find: (i) the ionizing budget is dominated by stellar radiation from low stellar mass ($M_*<10^9 {\rm M_\odot}$ ) galaxies at $z>6$ with the AGN contribution (driven by $M_{bh}>10^6 {\rm M_\odot}$ black holes in $M_* > 10^9 {\rm M_\odot}$ galaxies) dominating at lower redshifts; (ii) AGN only contribute $10-25\%$ to the cumulative ionizing emissivity by $z=4$ for the models that match the observed reionization constraints; (iii) if the stellar mass dependence of $\langle f_{\rm esc}^{\rm sf} \rangle$ is shallower than $f_{\rm esc}^{\rm bh}$, at $z<7$ a transition stellar mass exists above which AGN dominate the escaping ionizing photon production rate; (iv) the transition stellar mass decreases with decreasing redshift. While AGN dominate the escaping emissivity above the knee of the stellar mass function at $z \sim 6.8$, they take-over at stellar masses that are a tenth of the knee mass by $z=4$.

[13]  arXiv:2001.06023 [pdf, other]

Title: The Relationship Between the Turbulence-Driving-Length and the Length-Scale of Density Structures in Magnetohydrodynamic Turbulence

Authors: Shmuel Bialy, Blakesley Burkhart

Comments: Submitted to ApJ Letters

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Density fluctuations produced by supersonic turbulence are of great importance to astrophysical chemical models. A property of these density fluctuations is that the two-point correlation function decreases with increasing scale separation. The relation between the density decorrelation length-scale ($L_{\rm dec}$) and the turbulence driving scale ($L_{\rm drive}$) determines how turbulence affects the density and chemical structures in the interstellar medium (ISM), and is a key component for using observations of atomic and molecular tracers to constrain turbulence properties. We run a set of numerical simulations of supersonic magnetohydrodynamic turbulence, driven on varying scales from 1/2.5 to 1/7 the box length, and derive the $L_{\rm dec}-L_{\rm drive}$ relation as a function of driving-scale and the orientation of the line-of-sight (LOS) in respect to the mean magnetic field. We find that $L_{\rm drive}$, $L_{\rm dec}/L_{\rm drive} = 0.231$ when averaging over all LOS. For LOS parallel to the magnetic field the density structures are statistically smaller and the $L_{\rm dec}-L_{\rm drive}$ relation is tighter, with $L_{\rm dec}/L_{\rm drive} = 0.129 \pm 0.011$. We discuss our results in the context of using observations of chemical tracers in the ISM to constrain the dominant turbulence driving scale.

[14]  arXiv:2001.06025 [pdf, ps, other]

Title: The high redshift SFR-M* relation is sensitive to the employed star formation rate and stellar mass indicators: Towards addressing the tension between observations and simulations

Authors: A. Katsianis, V Gonzalez, D. Barrientos, X. Yang, C.D.P. Lagos, J. Schaye, P. Camps, A. Trčka, M. Baes, M. Stalevski, G.A. Blanc, T. Theuns

Comments: 15 pages, 6 Figures, 4 tables, accepted for publication in MNRAS, Figures 1, 2, 3, 4 summarize results

Subjects: Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)

There is a severe tension between the observed star formation rate (SFR) - stellar mass (${\rm M}_{\star}$) relations reported by different authors at $z = 1-4$. In addition, the observations have not been successfully reproduced by state-of-the-art cosmological simulations which tend to predict a factor of 2-4 smaller SFRs at a fixed ${\rm M}_{\star}$. We examine the evolution of the SFR$-{\rm M}_{\star}$ relation of $z = 1-4 $ galaxies using the SKIRT simulated spectral energy distributions of galaxies sampled from the EAGLE simulations. We derive SFRs and stellar masses by mimicking different observational techniques. We find that the tension between observed and simulated SFR$-{\rm M}_{\star}$ relations is largely alleviated if similar methods are used to infer the galaxy properties. We find that relations relying on infrared wavelengths (e.g. 24 ${\rm \mu m}$, MIPS - 24, 70 and 160 ${\rm \mu m}$ or SPIRE - 250, 350, 500 ${\rm \mu m}$) have SFRs that exceed the intrinsic relation by 0.5 dex. Relations that rely on the spectral energy distribution fitting technique underpredict the SFRs at a fixed stellar mass by -0.5 dex at $z \sim 4$ but overpredict the measurements by 0.3 dex at $z \sim 1$. Relations relying on dust-corrected rest-frame UV luminosities, are flatter since they overpredict/underpredict SFRs for low/high star forming objects and yield deviations from the intrinsic relation from 0.10 dex to -0.13 dex at $z \sim 4$. We suggest that the severe tension between different observational studies can be broadly explained by the fact that different groups employ different techniques to infer their SFRs.

[15]  arXiv:2001.06030 [pdf, other]

Title: Discovery of long-period magnetic field oscillations and motions in isolated sunspots

Authors: A. B. Griñón-Marín, A. Pastor Yabar, H. Socas-Navarro, R. Centeno

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We analyse the temporal evolution of the inclination component of the magnetic field vector for the penumbral area of 25 isolated sunspots. Compared to previous works, the use of data from the HMI instrument aboard the SDO observatory facilitates the study of very long time series ($\approx$1 week), compared to previous works, with a good spatial and temporal resolution. We used the wavelet technique and we found some filamentary-shaped events with large wavelet power. Their distribution of periods is broad, ranging from the lower limit for this study of 48 minutes up to 63 hours. An interesting property of these events is that they do not appear homogeneously all around the penumbra but they seem to concentrate at particular locations. The cross-comparison of these wavelet maps with AIA data shows that the regions where these events appear are visually related to the coronal loops that connect the outer penumbra to one or more neighbouring opposite polarity flux patches.

[16]  arXiv:2001.06036 [pdf, other]

Title: A spectroscopic, photometric, polarimetric and radio study of the eclipsing polar UZ Fornacis: the first simultaneous SALT and MeerKAT observations

Authors: Zwidofhelangani N. Khangale, Stephen B. Potter, Patrick A. Woudt, David A. H. Buckley, Andrey N. Semena, Enrico J. Kotze, Danièl N. Groenewald, Dante M. Hewitt, Margaretha L. Pretorius, Rob P. Fender, Paul Groot, Steven Bloemen, Marc Klein-Wolt, Elmar Körding, Rudolf Le Poole, Vanessa A. McBride, Lee Townsend, Kerry Paterson, Danielle L. A. Pieterse, Paul M. Vreeswijk

Comments: Accepted on MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

We present phase-resolved spectroscopy, photometry and circular spectropolarimetry of the eclipsing polar UZ Fornacis. Doppler tomography of the strongest emission lines using the inside-out projection revealed the presence of three emission regions: from the irradiated face of the secondary star, the ballistic stream and the threading region, and the magnetically confined accretion stream. The total intensity spectrum shows broad emission features and a continuum that rises in the blue. The circularly polarized spectrum shows the presence of three cyclotron emission harmonics at $\sim$4500 \AA{}, 6000 \AA{} and 7700 \AA{}, corresponding to harmonic numbers 4, 3, and 2, respectively. These features are dominant before the eclipse and disappear after the eclipse. The harmonics are consistent with a magnetic field strength of $\sim$57 MG. We also present phase-resolved circular and linear photopolarimetry to complement the spectropolarimetry around the times of eclipse. MeerKAT radio observations show a faint source which has a peak flux density of 30.7 $\pm$ 5.4 $\mu$Jy/beam at 1.28 GHz at the position of UZ For.

[17]  arXiv:2001.06037 [pdf, other]

Title: Electromagnetic precursors to gravitational wave events: Numerical simulations of flaring in pre-merger binary neutron star magnetospheres

Authors: Elias R. Most, Alexander A. Philippov

Comments: 7 pages, 5 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc)

The detection of gravitational waves from neutron star merger events has opened up a new field of multi-messenger astronomy linking gravitational waves events to short-gamma ray bursts and kilonova afterglows. A further - yet to be discovered - electromagnetic counterpart is precursor emission produced by the non-trivial interaction of the magnetospheres of the two neutron stars prior to merger. By performing special-relativistic force-free simulations of orbiting neutron stars we discuss the effect of different magnetic field orientations and show how the emission can be significantly enhanced by differential motion present in the binary, either due to stellar spins or misaligned stellar magnetospheres. We find that the built-up of twist in the magnetic flux tube connecting the two stars can lead to the repeated emission of powerful flares for a variety of orbital configurations. We also discuss potential coherent radio emission mechanisms in the flaring process.

[18]  arXiv:2001.06048 [pdf]

Title: Parker Solar Probe In-Situ Observations of Magnetic Reconnection Exhausts During Encounter 1

Authors: T. D. Phan, S. D. Bale, J. P. Eastwood, B. Lavraud, J. F. Drake, M. Oieroset, M. A. Shay, M. Pulupa, M. Stevens, R. J. MacDowall, A. W. Case, D. Larson, J. Kasper, P. Whittlesey, A. Szabo, K. E. Korreck, J. W. Bonnell, T. Dudok de Wit, K. Goetz, P. R. Harvey, T. S. Horbury, R. Livi, D. Malaspina, K. Paulson, N. E. Raouafi, M. Velli

Comments: In Press (accepted by ApJS on 2019-11-08) This paper is part of the Parker Solar Probe ApJS Special Issue Current citation: Phan, T. D., S. D. Bale, J. P. Eastwood, et al. (2019), Parker Solar Probe In-Situ Observations of Magnetic Reconnection Exhausts During Encounter 1, ApJS., in press, doi: 10.3847/1538-4365/ab55ee

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph); Space Physics (physics.space-ph)

Magnetic reconnection in current sheets converts magnetic energy into particle energy. The process may play an important role in the acceleration and heating of the solar wind close to the Sun. Observations from Parker Solar Probe provide a new opportunity to study this problem, as it measures the solar wind at unprecedented close distances to the Sun. During the 1st orbit, PSP encountered a large number of current sheets in the solar wind through perihelion at 35.7 solar radii. We performed a comprehensive survey of these current sheets and found evidence for 21 reconnection exhausts. These exhausts were observed in heliospheric current sheets, coronal mass ejections, and regular solar wind. However, we find that the majority of current sheets encountered around perihelion, where the magnetic field was strongest and plasma beta was lowest, were Alfv\'enic structures associated with bursty radial jets and these current sheets did not appear to be undergoing local reconnection. We examined conditions around current sheets to address why some current sheets reconnected, while others did not. A key difference appears to be the degree of plasma velocity shear across the current sheets: The median velocity shear for the 21 reconnection exhausts was 24% of the Alfv\'en velocity shear, whereas the median shear across 43 Alfv\'enic current sheets examined was 71% of the Alfv\'en velocity shear. This finding could suggest that large, albeit sub-Alfv\'enic, velocity shears suppress reconnection. An alternative interpretation is that the Alfv\'enic current sheets are isolated rotational discontinuities which do not undergo local reconnection.

[19]  arXiv:2001.06051 [pdf, other]

Title: The Low Effective Spin of Binary Black Holes and Implications for Individual Gravitational-Wave Events

Authors: Simona Miller, Thomas A. Callister, Will Farr

Comments: 11 pages, 5 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

While the Advanced LIGO and Virgo gravitational-wave experiments now regularly observe binary black hole mergers, the evolutionary origin of these events remains a mystery. Analysis of the binary black hole spin distribution may shed light on this mystery, offering a means of discriminating between different binary formation channels. Using the data from Advanced LIGO and Virgo's first and second observing runs, here we seek to carefully characterize the distribution of effective spin among binary black holes, hierarchically measuring the distribution's mean $\mu$ and variance $\sigma^2$ while accounting for selection effects and degeneracies between spin and other black hole parameters. We demonstrate that the known population of binary black holes have spins that are both small, with $\mu \sim 0$, and very narrowly distributed, with $\sigma^2 \leq 0.07$ at 95% credibility. We then explore what these ensemble properties imply about the spins of individual binary black hole mergers, re-analyzing existing gravitational-wave events with a population-informed prior on their effective spin. The binary black hole GW170729, which previously excluded effective spin equal to zero, is now consistent with zero effective spin at ~10% credibility. More broadly, we find that uninformative spin priors generally yield overestimates for the effective spin magnitudes of compact binary mergers.

[20]  arXiv:2001.06060 [pdf, other]

Title: Dynamical Classification of Trans-Neptunian Objects Detected by the Dark Energy Survey

Authors: T. Khain, J. C. Becker, Hsing Wen Lin, D. W. Gerdes, F. C. Adams, P. Bernardinelli, G. M. Bernstein, K. Franson, L. Markwardt, S. Hamilton, K. Napier, M. Sako, T. M. C. Abbott, S. Avila, E. Bertin, D. Brooks, E. Buckley-Geer, D. L. Burke, A. Carnero Rosell, M. Carrasco Kind, J. Carretero, L. N. da Costa, J. De Vicente, S. Desai, H. T. Diehl, P. Doel, B. Flaugher, J. Frieman, J. Garcia-Bellido, E. Gaztanaga, D. Gruen, R. A. Gruendl, J. Gschwend, G. Gutierrez, D. L. Hollowood, K. Honscheid, D. J. James, N. Kuropatkin, M. A. G. Maia, J. L. Marshall, F. Menanteau, C. J. Miller, R. Miquel, A. A. Plazas, E. Sanchez, V. Scarpine, M. Schubnell, I. Sevilla-Noarbe, M. Smith, F. Sobreira, E. Suchyta, M. E. C. Swanson, G. Tarle, A. R. Walker, W. Wester (the DES Collaboration)

Comments: accepted to AJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The outer Solar System contains a large number of small bodies (known as trans-Neptunian objects or TNOs) that exhibit diverse types of dynamical behavior. The classification of bodies in this distant region into dynamical classes -- sub-populations that experience similar orbital evolution -- aids in our understanding of the structure and formation of the Solar System. In this work, we propose an updated dynamical classification scheme for the outer Solar System. This approach includes the construction of a new (automated) method for identifying mean-motion resonances. We apply this algorithm to the current dataset of TNOs observed by the Dark Energy Survey (DES) and present a working classification for all of the DES TNOs detected to date. Our classification scheme yields 1 inner centaur, 19 outer centaurs, 21 scattering disk objects, 47 detached TNOs, 48 securely resonant objects, 7 resonant candidates, and 97 classical belt objects. Among the scattering and detached objects, we detect 8 TNOs with semi-major axes greater than 150 AU.

[21]  arXiv:2001.06064 [pdf, ps, other]

Title: Mirror principle and the red-giant bump: the battle of entropy in low-mass stars

Authors: S. Hekker, G.C. Angelou, Y. Elsworth, S. Basu

Comments: 10 pages, 11 figures, accepted for publication by MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The evolution of low-mass stars into red giants is still poorly understood. During this evolution the core of the star contracts and, simultaneously, the envelope expands -- a process known as the `mirror'. Additionally, there is a short phase where the trend for increasing luminosity is reversed. This is known as the red-giant-branch bump. We explore the underlying physical reasons for these two phenomena by considering the specific entropy distribution in the star and its temporal changes. We find that between the luminosity maximum and luminosity minimum of the bump there is no mirror present and the star is fully contracting. The contraction is halted and the star regains its mirror when the hydrogen-burning shell reaches the mean molecular weight discontinuity. This marks the luminosity minimum of the bump.

[22]  arXiv:2001.06070 [pdf, other]

Title: The Deepest Radio Observations of Nearby Type IA Supernovae: Constraining Progenitor Types and Optimizing Future Surveys

Authors: Peter Lundqvist, Esha Kundu, Miguel A. Perez-Torres, Stuart D. Ryder, Claes-Ingvar Bjornsson, Javier Moldon, Megan K. Argo, Robert J. Beswick, Antxon Alberdi, Erik C. Kool

Comments: Accepted for publication in the Astrophysical Journal

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We report deep radio observations of nearby Type Ia Supernovae (SNe Ia) with the electronic Multi-Element Radio Linked Interferometer Net-work (e-MERLIN), and the Australia Telescope Compact Array (ATCA). No detections were made. With standard assumptions for the energy densities of relativistic electrons going into a power-law energy distribution, and the magnetic field strength (epsilon_e = epsilon_B = 0.1), we arrive at the upper limits on mass-loss rate for the progenitor system of SN 2013dy (2016coj, 2018gv, 2018pv, 2019np), to be less than 12 (2.8,1.3, 2.1, 1.7)EE(-8) solar masses per year (for a wind speed of 100 km/s). To SNe 2016coj, 2018gv, 2018pv and 2019np we add radio data for 17 other nearby SNe Ia, and model their non-detections. With the same model as described, all 21 SNe Ia have mass-loss rates less than 4EE(-8) solar masses per year (for a wind speed of 100 km/s). We compare those limits with the expected mass loss rates in different single-degenerate progenitor scenarios. We also discuss how information on epsilon_e and epsilon_B can be obtained from late observations of SNe Ia and the youngest SN Ia remnant detected in radio, G1.9+0.3, as well as stripped-envelope core-collapse SNe. We highlight SN 2011dh, and argue for epsilon_e approximately equal to 0.1 and epsilon_B approximately equal to 0.0033. Finally, we discuss strategies to observe at radio frequencies to maximize the chance of detection, given the time since explosion, the distance to the supernova and the telescope sensitivity.

[23]  arXiv:2001.06084 [pdf, other]

Title: Analysis methods to search for transient events in ground-based Very High Energy gamma-ray astronomy

Authors: F. Brun, Q. Piel, M. de Naurois, S. Bernhard

Comments: 9 pages, 4 figures, accepted for publication in Astroparticle Physics

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

Transient and variable phenomena in astrophysical sources are of particular importance to understand the underlying gamma-ray emission processes. In the very-high energy gamma-ray domain, transient and variable sources are related to charged particle acceleration processes that could for instance help understanding the origin of cosmic-rays. The imaging atmospheric Cherenkov technique used for gamma-ray astronomy above $\sim 100$ GeV is well suited for detecting such events. However, the standard analysis methods are not optimal for such a goal and more sensitive methods are specifically developed in this publication. The sensitivity improvement could therefore be helpful to detect brief and faint transient sources such as Gamma-Ray Bursts.

[24]  arXiv:2001.06092 [pdf, other]

Title: H$α$ kinematics of the isolated interacting galaxy pair KPG 486 (NGC 6090)

Authors: M. M. Sardaneta (1), M. Rosado (2), M. Sánchez-Cruces (1) ((1) Aix Marseille Univ, CNRS, CNES, LAM, Marseille, France, (2) Instituto de Astronomía, UNAM, México.)

Comments: 27 pages, 7 figures. Manuscript for Revista Mexicana de Astronom\'ia y Astrof\'isica

Subjects: Astrophysics of Galaxies (astro-ph.GA)

In optical images, the not amply studied isolated interacting galaxy pair KPG 486 (NGC 6090) displays similar features to the galaxy pair The Antennae (NGC 4038/39). To compare the distribution of ionized hydrogen gas, morphology and kinematic and dynamic behaviour between both galaxy pairs, we present observations in the H$\alpha$ emission line of NGC 6090 acquired with the scanning Fabry-Perot interferometer, PUMA. For each galaxy in NGC 6090 we obtained several kinematic parameters, its velocity field and its rotation curve, we also analysed some of the perturbations induced by their encounter. We verified the consistency of our results by comparing them with kinematic results from the literature. The comparison of our results on NGC 6090 with those obtained in a previous similar kinematic analysis made for The Antennae highlighted great differences between these galaxy pairs.

[25]  arXiv:2001.06102 [pdf, other]

Title: Gravitational waves or deconfined quarks: what causes the premature collapse of neutron stars born in short gamma-ray bursts?

Authors: Nikhil Sarin, Paul D. Lasky, Gregory Ashton

Comments: Submitted to PRD. 12 pages, 6 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); General Relativity and Quantum Cosmology (gr-qc); Nuclear Theory (nucl-th)

We infer the collapse times of long-lived neutron stars into black holes using the X-ray afterglows of 18 short gamma-ray bursts. We then apply hierarchical inference to infer properties of the neutron star equation of state and dominant spin-down mechanism. We measure the maximum non-rotating neutron star mass $M_\mathrm{TOV} = 2.31 ^{+0.36}_{-0.21} M_{\odot}$ and constrain the fraction of remnants spinning down predominantly through gravitational-wave emission to $\eta = 0.69 ^{+0.21}_{-0.39}$ with $68 \%$ uncertainties. In principle, this method can determine the difference between hadronic and quark equation of states. In practice, however, the data is not yet informative with indications that these neutron stars do not have hadronic equation of states at the $1\sigma$ level. These inferences all depend on the underlying progenitor mass distribution for short gamma-ray bursts produced by binary neutron star mergers. The recently announced gravitational-wave detection of GW190425 suggests this underlying distribution is different from the locally-measured population of double neutron stars. We show that $M_\mathrm{TOV}$ and $\eta$ constraints depend on the fraction of binary mergers that form through a distribution consistent with the locally-measured population and a distribution that can explain GW190425. The more binaries that form from the latter distribution, the larger $M_\mathrm{TOV}$ needs to be to satisfy the X-ray observations. Our measurements above are marginalised over this unknown fraction. If instead, we assume GW190425 is not a binary neutron star merger, i.e the underlying mass distribution of double neutron stars is the same as observed locally, we measure $M_\mathrm{TOV} = 2.26 ^{+0.31}_{-0.17} M_{\odot}$.

[26]  arXiv:2001.06109 [pdf, other]

Title: Simulating Star Clusters Across Cosmic Time: II. Escape Fraction of Ionizing Photons from Molecular Clouds

Authors: Chong-Chong He, Massimo Ricotti, Sam Geen

Comments: 17 pages, 13 figures, accepted for publication in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We calculate the hydrogen and helium-ionizing radiation escaping star-forming molecular clouds, as a function of the star cluster mass and compactness, using a set of high-resolution radiation-magneto-hydrodynamic simulations of star formation in self-gravitating, turbulent molecular clouds. In these simulations, presented in He, Ricotti and Geen (2019), the formation of individual massive stars are well resolved, and their UV radiation feedback and lifetime on the main sequence are modeled self-consistently. We find that the escape fraction of ionizing radiation from molecular clouds, $\langle f_{\rm esc}^{\scriptscriptstyle \rm MC}\rangle$, decreases with increasing mass of the star cluster and with decreasing compactness. Molecular clouds with densities typically found in the local Universe have negligible $\langle f_{\rm esc}^{\scriptscriptstyle \rm MC}\rangle$, ranging between $0.5\%$ to $5\%$. Ten times denser molecular clouds have $\langle f_{\rm esc}^{\scriptscriptstyle \rm MC}\rangle \approx 10\%-20\%$, while $100\times$ denser clouds, which produce globular cluster progenitors, have $\langle f_{\rm esc}^{\scriptscriptstyle \rm MC}\rangle \approx 20\%-60\%$. We find that $\langle f_{\rm esc}^{\scriptscriptstyle \rm MC}\rangle$ increases with decreasing gas metallicity, even when ignoring dust extinction, due to stronger radiation feedback. However, the total number of escaping ionizing photons decreases with decreasing metallicity because the star formation efficiency is reduced. We conclude that the sources of reionization at $z>6$ must have been very compact star clusters forming in molecular clouds about $100\times$ denser than in today's Universe, which leads to a significant production of old globular clusters progenitors.

[27]  arXiv:2001.06114 [pdf, other]

Title: A Family of Phase Masks For Broadband Coronagraphy Example of the Wrapped Vortex Phase Mask Theory and Laboratory demonstration

Authors: Raphaël Galicher, Pierre Baudoz, Elsa Huby, Olivier Dupuis

Comments: 11 pages, 17 figures, accepted in Astronomy & Astrophysics

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

Future instruments need efficient coronagraphs over large spectral ranges to enable broadband imaging or spectral characterization of exoplanets 1e8 fainter than their star. Several solutions were proposed. Pupil apodizers can attenuate the star intensity by a 1e10 factor but they transmit a few percents of the planet light only. Cascades of phase/amplitude masks can both attenuate the starlight and transmit most of the planet light but the number of optics to align is not a practical solution for an instrument. Finally, vector phase masks can be used to detect faint sources close to bright stars but they require the use of high quality circular polarizers and as for the previous solution, this leads to a complex instrument with numerous optics to align and stabilize. We propose simple coronagraphs that need one scalar phase mask and one binary Lyot stop only providing high transmission for the planet light (>50%) and high attenuation of the starlight over a large spectral bandpass (~30%) and a 360 degree field-of-view. From mathematical considerations, we find a family of 2D-phase masks optimized for an unobscured pupil. One mask is an azimuthal wrapped vortex phase ramp. We probe its coronagraphic performance using numerical simulations and laboratory tests. From numerical simulations, we predict the wrapped vortex can attenuate the peak of the star image by a factor of 1e4 over a 29% bandpass and 1e5 over a 18% bandpass with transmission of more than 50% of the planet flux at ~4 lambda/D. We confirm these predictions in laboratory in visible light between 550nm and 870nm. We also obtain laboratory dark hole images in which exoplanets with fluxes that are 3e-8 times the host star flux could be detected at 3sigma. Taking advantage of a new technology for etching continuous 2D-functions, new type of masks can be easily manufactured opening new possibilities for broadband coronagraphy.

[28]  arXiv:2001.06119 [pdf, other]

Title: Halo Counts-in-cells for Cosmological Models with Different Dark Energy

Authors: Di Wen, Athol J. Kemball, William C. Saslaw

Comments: 24 pages, 15 figures, 1 table; submitted to ApJ

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

We examine the counts-in-cells probability distribution functions that describe dark matter halos in the Dark Energy Universe Simulations (DEUS). We describe the measurements between redshifts $z=0$ to $z=4$ on both linear and non-linear scales. The best-fits of the gravitational quasi-equilibrium distribution (GQED), the negative binomial distribution (NBD), the Poisson-Lognormal distribution (PLN), and the Poisson-Lognormal distribution with a bias parameter (PLNB) are compared to simulations. The fits agree reasonably consistently over a range of redshifts and scales. To distinguish quintessence (RPCDM) and phantom ($w$CDM) dark energy from $\Lambda$ dark energy, we present a new method that compares the model parameters of the counts-in-cells probability distribution functions. We find that the mean and variance of the halo counts-in-cells on $2-25h^{-1}$Mpc scales between redshifts $0.65<z<4$ show significant percentage differences for different dark energy cosmologies. On $15-25h^{-1}$Mpc scales, the $g$ parameter in NBD, $\omega$ parameter in PLN, $b$ and $C_b$ parameters in PLNB show larger percentage differences for different dark energy cosmologies than on smaller scales. On $2-6h^{-1}$Mpc scales, kurtosis and the $b$ parameter in the GQED show larger percentage differences for different dark energy cosmologies than on larger scales. For cosmologies explored in the DEUS simulations, the percentage differences between these statistics for the RPCDM and $w$CDM dark energy cosmologies relative to $\Lambda$CDM generally increases with redshift from a few percent to significantly larger percentages at $z=4$. Applying our method to simulations and galaxy surveys can provide a useful way to distinguish among dark energy models and cosmologies in general.

[29]  arXiv:2001.06123 [pdf, other]

Title: Multi-line single point coronal magnetometry

Authors: Gabriel I. Dima, Thomas A. Schad

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Applied Physics (physics.app-ph)

Polarized magnetic dipole (M1) emission lines provide important diagnostics for the magnetic field dominating the evolution of the solar corona. This paper advances a multi-line technique using specific combinations of M1 lines to infer the full vector magnetic field for regions of optically thin emission that can be localized along a given line of sight. Our analytical formalism is a generalization of the "single-point inversion" approach introduced by Plowman. We show that combinations of M1 transitions for which each is either a $J=1\rightarrow0$ transition or has equal Land\'e g-factors for the upper and lower levels contain degenerate spectropolarimetric information that prohibits the application of the single-point inversion technique. This may include the pair of infrared Fe XIII lines discussed by Plowman. We identify the Fe XIII 1074.7 nm and Si X 1430.1 nm lines as one alternative combination for implementing this technique. Our sensitivity analysis, based on coronal loop properties, suggests that for photon noise levels around $10^{-4}$ of the line intensity, which will be achievable with the National Science Foundation's Daniel K. Inouye Solar Telescope, magnetic fields with sufficient strength (${\sim}10$ G) and not severely inclined to the line-of-sight ($\lesssim 35^{\circ}$) can be recovered with this method. Degenerate solutions exist; though, we discuss how added constraints may help resolve them or reduce their number.

[30]  arXiv:2001.06141 [pdf, ps, other]

Title: The radial acceleration relation in galaxy clusters

Authors: Man Ho Chan, Antonino Del Popolo

Comments: Accepted in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

Recently, the discovery of the radial acceleration relation (RAR) in galaxies has been regarded as an indirect support of alternative theories of gravity such as Modified Newtonian Dynamics (MOND) and modified gravity. This relation indicates a tight correlation between dynamical mass and baryonic mass in galaxies with different sizes and morphology. However, if the RAR relation is scale-independent and could be explained by alternative theories of gravity, this relation should be universal and true for galaxy clusters as well. In this article, by using the x-ray data of a sample of galaxy clusters, we investigate if there exists any tight correlation between dynamical mass and baryonic mass in galaxy clusters, assuming hot gas mass distribution almost representing baryonic distribution and that the galaxy clusters are virialized. We show that the resulting RAR of 52 non-cool-core galaxy clusters scatters in a large parameter space, possibly due to our simplifying assumptions and unclear matter content in galaxy clusters. This might indicate that the RAR is unlikely to be universal and scale-independent.

[31]  arXiv:2001.06180 [pdf, other]

Title: MAGMO: Polarimetry of 1720-MHz OH Masers towards Southern Star Forming Regions

Authors: C. S. Ogbodo (1, 2 and 9), J. A. Green (2), J. R. Dawson (3), S. L. Breen (4), S. A. Mao (5), N. M. McClure-Griffiths (6), T. Robishaw (7), L. Harvey-Smith (7 and 8). ((1) Department of Physics and Astronomy and MQ Research Centre in Astronomy, Astrophysics and Astrophotonics, Macquarie University, (2) Australia Telescope National Facility, CSIRO Astronomy and Space Science, NSW, Australia, (3) Sydney Institute for Astronomy (SIfA), School of Physics, University of Sydney, NSW, Australia, (4) Max Planck Institute for Radio Astronomy, Bonn, Germany, (5) Research School of Astronomy and Astrophysics, Australian National University, (6) National Research Council, Herzberg Institute of Astrophysics, Dominion Radio Astrophysical Observatory, Penticton, Canada, (7) Deans Unit, Faculty of Science, the University of New South Wales, (8) School of Computing, Engineering and Mathematics, Western Sydney University, (9) Department of Physics/Geology/Geophysics, Alex Ekwueme Federal University Ndufu-Alike, Ikwo, Ebonyi State, Nigeria.)

Subjects: Astrophysics of Galaxies (astro-ph.GA)

From targeted observations of ground-state OH masers towards 702 Multibeam (MMB) survey 6.7-GHz methanol masers, between Galactic longitudes 186$^{\circ}$ through the Galactic centre to 20$^{\circ}$, made as part of the `MAGMO' project, we present the physical and polarisation properties of the 1720-MHz OH maser transition, including the identification of Zeeman pairs. We present 10 new and 23 previously catalogued 1720-MHz OH maser sources detected towards star formation regions. In addition, we also detected 16 1720-MHz OH masers associated with supernova remnants and two sites of diffuse OH emission. Towards the 33 star formation masers, we identify 44 Zeeman pairs, implying magnetic field strengths ranging from $-$11.4 to $+$13.2 mG, and a median magnetic field strength of $|B_{LOS}|$ $\sim$ 6 mG. With limited statistics, we present the in-situ magnetic field orientation of the masers and the Galactic magnetic field distribution revealed by the 1720-MHz transition. We also examine the association statistics of 1720-MHz OH SFR masers with other ground-state OH masers, excited-state OH masers, class I and class II methanol masers and water masers, and compare maser positions with mid-infrared images of the parent star forming regions. Of the 33 1720-MHz star formation masers, ten are offset from their central exciting sources, and appear to be associated with outflow activity.

[32]  arXiv:2001.06193 [pdf, other]

Title: Status of direct and indirect dark matter searches

Authors: Carlos Pérez de los Heros

Comments: Proceedings of European Physical Society Conference on High Energy Physics - EPS-HEP2019, 10-17 July, 2019. Submitted to Proceedings of Science

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Experiment (hep-ex)

I review the current status of dark matter searches using direct, indirect and accelerator techniques. A detailed review of individual experiments is beyond the scope of these proceedings. I focus instead on the challenges (sometimes limitations) faced by each of the approaches, which is what make them complementary, and the reason we must ensure that they are developed concurrently.

[33]  arXiv:2001.06201 [pdf, ps, other]

Title: Resonance Line Polarization in Spherically Symmetric Moving Media: a Parametric Study

Authors: A. Megha, M. Sampoorna, K. N. Nagendra, L. S. Anusha, K. Sankarasubramanian

Comments: 10 pages, 6 figures, Proceedings of the 9th Solar Polarization Workshop SPW9, A workshop held in Gottingen, Germany, from August 26 to August 30, 2019

Journal-ref: Proceedings of the 9th Solar Polarization Workshop SPW9, Published open access by MPS 2020

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

In the present paper we consider the problem of resonance line polarization formed in the spherically symmetric expanding atmospheres. For the solution of the concerned polarized transfer equation we use the comoving frame formulation, and apply the Accelerated Lambda Iteration (ALI) method. We restrict ourselves to the non-relativistic regime of velocities wherein mainly Doppler shift effects are significant. For our studies, we consider the scattering on a two-level atom, including the effects of partial frequency redistribution (PFR). We present the dependence of linearly polarized profiles on different atmospheric and atomic parameters.

[34]  arXiv:2001.06222 [pdf, other]

Title: Chemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars. VII. Lithium

Authors: T. Bensby, S. Feltzing, J.C. Yee, J.A. Johnson, A. Gould, M. Asplund, J. Meléndez, S. Lucatello

Comments: 8 pages, 6 figures, resubmitted to A&A after referee comments

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Lithium abundances are presented for 91 dwarf and subgiant stars in the Galactic bulge. The analysis is based on line synthesis of the 7Li line at 6707 {\AA} in high-resolution spectra obtained during gravitational microlensing events, when the brightnesses of the targets were highly magnified. Our main finding is that the bulge stars at sub-solar metallicities, and that are older than about eight billion years, does not show any sign of Li production, that is, the Li trend with metallicity is flat (or even slightly declining). This indicates that no lithium was produced during the first few billion years in the history of the bulge. This finding is essentially identical to what is seen for the (old) thick disk stars in the Solar neighbourhood, and adds another piece of evidence for a tight connection between the metal-poor bulge and the Galactic thick disk. For the bulge stars younger than about eight billion years, the sample contains a group of stars at very high metallicities at [Fe/H]~+0.4 that have lithium abundances in the range A(Li)=2.6-2.8. In the Solar neighbourhood the lithium abundances have been found to peak at a A(Li)~3.3 at [Fe/H]~ +0.1 and then decrease by 0.4-0.5 dex when reaching [Fe/H]~+0.4. The few bulge stars that we have at these metallicities, seem to support this declining A(Li) trend. This could indeed support the recent claim that the low A(Li) abundances at the highest metallicities seen in the Solar neighbourhood could be due to stars from the inner disk, or the bulge region, that have migrated to the Solar neighbourhood.

[35]  arXiv:2001.06224 [pdf, other]

Title: Fragmentation favoured in discs around higher mass stars

Authors: James Cadman, Ken Rice, Cassandra Hall, Thomas J. Haworth, Beth Biller

Comments: Accepted for publication in MNRAS

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

We investigate how a protoplanetary disc's susceptibility to gravitational instabilities and fragmentation depends on the mass of its host star. We use 1D disc models in conjunction with 3D SPH simulations to determine the critical disc-to-star mass ratios at which discs become unstable against fragmentation, finding that discs become increasingly prone to the effects of self-gravity as we increase the host star mass. The actual limit for stability is sensitive to the disc temperature, so if the disc is optically thin stellar irradiation can dramatically stabilise discs against gravitational instability. However, even when this is the case we find that discs around $2$M$_{\odot}$ stars are prone to fragmentation, which will act to produce wide-orbit giant planets and brown dwarfs. The consequences of this work are two-fold: that low mass stars could in principle support high disc-to-star mass ratios, and that higher mass stars have discs that are more prone to fragmentation, which is qualitatively consistent with observations that favour high-mass wide-orbit planets around higher mass stars. We also find that the initial masses of these planets depends on the temperature in the disc at large radii, which itself depends on the level of stellar irradiation.

[36]  arXiv:2001.06225 [pdf, other]

Title: Massive discs around low-mass stars

Authors: Thomas J. Haworth, James Cadman, Farzana Meru, Cassandra Hall, Emma Albertini, Duncan Forgan, Ken Rice, James E. Owen

Comments: 21 pages, submitted to MNRAS

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA)

We use a suite of SPH simulations to investigate the susceptibility of protoplanetary discs to the effects of self-gravity as a function of star-disc properties. We also include passive irradiation from the host star using different models for the stellar luminosities. The critical disc-to-star mass ratio for axisymmetry (for which we produce criteria) increases significantly for low-mass stars. This could have important consequences for increasing the potential mass reservoir in a proto Trappist-1 system, since even the efficient Ormel et al. (2017) formation model will be influenced by processes like external photoevaporation, which can rapidly and dramatically deplete the dust reservoir. The aforementioned scaling of the critical $M_d/M_*$ for axisymmetry occurs in part because the Toomre $Q$ parameter has a linear dependence on surface density (which promotes instability) and only an $M_*^{1/2}$ dependence on shear (which reduces instability), but also occurs because, for a given $M_d/M_*$, the thermal evolution depends on the host star mass. The early phase stellar irradiation of the disc (for which the luminosity is much higher than at the zero age main sequence, particularly at low stellar masses) can also play a key role in significantly reducing the role of self-gravity, meaning that even Solar mass stars could support axisymmetric discs a factor two higher in mass than usually considered possible. We apply our criteria to the DSHARP discs with spirals, finding that self-gravity can explain the observed spirals so long as the discs are optically thick to the host star irradiation.

[37]  arXiv:2001.06239 [pdf, other]

Title: The effects of surface fossil magnetic fields on massive star evolution: II. Implementation of magnetic braking in MESA and implications for the evolution of surface rotation in OB stars

Authors: Z. Keszthelyi, G. Meynet, M.E. Shultz, A. David-Uraz, A. ud-Doula, R.H.D. Townsend, G.A. Wade, C. Georgy, V. Petit, S.P. Owocki

Comments: accepted for publication in MNRAS, a zenodo record is available at: this https URL

Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The time evolution of angular momentum and surface rotation of massive stars is strongly influenced by fossil magnetic fields via magnetic braking. We present a new module containing a simple, comprehensive implementation of such a field at the surface of a massive star within the Modules for Experiments in Stellar Astrophysics (MESA) software instrument. We test two limiting scenarios for magnetic braking: distributing the angular momentum loss throughout the star in the first case, and restricting the angular momentum loss to a surface reservoir in the second case. We perform a systematic investigation of the rotational evolution using a grid of OB star models with surface magnetic fields ($M_\star=5-60$ M$_\odot$, $\Omega/\Omega_{\rm crit} =0.2-1.0$, $B_{\rm p} =1-20$ kG). We then employ a representative grid of B-type star models ($M_\star=5, 10, 15$ M$_\odot$, $\Omega/\Omega_{\rm crit} =0.2 , 0.5, 0.8$, $B_{\rm p} = 1, 3 ,10, 30$ kG) to compare to the results of a recent self-consistent analysis of the sample of known magnetic B-type stars. We infer that magnetic massive stars arrive at the zero age main sequence with a range of rotation rates, rather than with one common value. In particular, some stars are required to have close-to-critical rotation at the ZAMS. However, magnetic braking yields surface rotation rates converging to a common low value, making it difficult to infer the initial rotation rates of evolved, slowly-rotating stars.

[38]  arXiv:2001.06269 [pdf, other]

Title: Atmospheric circulation of tidally locked gas giants with increasing rotation and implications for white-dwarf-brown-dwarf systems

Authors: Xianyu Tan, Adam P. Showman

Comments: 19 pages, 11 figures, submitted to ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Tidally locked gas giants are typically in several-day orbits, implying a modest role for rotation in the atmospheric circulation. Nevertheless, there exist a class of gas-giant, highly irradiated objects---brown dwarfs orbiting white dwarfs in extremely tight orbits---whose orbital and hence rotation periods are as short as 1-2 hours. Phase curves and other observations have already been obtained for this class of objects, raising fundamental questions about the role of increasing planetary rotation rate in controlling the circulation. So far, most modeling studies have investigated rotation periods exceeding a day, as appropriate for typical hot Jupiters. Here we investigate atmospheric circulation of tidally locked atmospheres with decreasing rotation periods down to 2.5 hours. With decreasing rotation period, the width of the equatorial eastward jet decreases, consistent with the narrowing of the equatorial waveguide due to a decrease of the equatorial deformation radius. The eastward-shifted equatorial hot spot offset decreases accordingly, and the off-equatorial westward-shifted hot areas become increasingly distinctive. At high latitudes, winds become weaker and more rotationally dominated. The day-night temperature contrast becomes larger due to the stronger influence of rotation. Our simulated atmospheres exhibit variability, presumably caused by instabilities and wave interactions. Unlike typical hot Jupiter models, thermal phase curves of rapidly rotating models show a near alignment of peak flux to secondary eclipse. This result helps to explain why, unlike hot Jupiters, many brown dwarfs orbiting white dwarfs exhibit IR flux peaks aligned with secondary eclipse. Our results have important implications for understanding fast-rotating, tidally locked atmospheres.

[39]  arXiv:2001.06293 [pdf, other]

Title: The Quest for Dual and Binary Supermassive Black Holes: A Multi-Messenger View

Authors: Alessandra De Rosa, Cristian Vignali, Tamara Bogdanović, Pedro R. Capelo, Maria Charisi, Massimo Dotti, Bernd Husemann, Elisabeta Lusso, Lucio Mayer, Zsolt Paragi, Jessie Runnoe, Alberto Sesana, Lisa Steinborn, Stefano Bianchi, Monica Colpi, Luciano Del Valle, Sándor Frey, Krisztina É. Gabányi, Margherita Giustini, Matteo Guainazzi, Zoltan Haiman, Noelia Herrera Ruiz, Rubén Herrero-Illana, Kazushi Iwasawa, S. Komossa, Davide Lena, Nora Loiseau, Miguel Perez-Torres, Enrico Piconcelli, Marta Volonteri

Comments: 69 pages, 21 figures. Accepted for publication in New Astronomy Reviews

Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

The quest for binary and dual supermassive black holes (SMBHs) at the dawn of the multi-messenger era is compelling. Detecting dual active galactic nuclei (AGN) -- active SMBHs at projected separations larger than several parsecs -- and binary AGN -- probing the scale where SMBHs are bound in a Keplerian binary -- is an observational challenge. The study of AGN pairs (either dual or binary) also represents an overarching theoretical problem in cosmology and astrophysics. The AGN triggering calls for detailed knowledge of the hydrodynamical conditions of gas in the imminent surroundings of the SMBHs and, at the same time, their duality calls for detailed knowledge on how galaxies assemble through major and minor mergers and grow fed by matter along the filaments of the cosmic web. This review describes the techniques used across the electromagnetic spectrum to detect dual and binary AGN candidates and proposes new avenues for their search. The current observational status is compared with the state-of-the-art numerical simulations and models for formation of dual and binary AGN. Binary SMBHs are among the loudest sources of gravitational waves (GWs) in the Universe. The search for a background of GWs at nHz frequencies from inspiralling SMBHs at low redshifts, and the direct detection of signals from their coalescence by the Laser Interferometer Space Antenna in the next decade, make this a theme of major interest for multi-messenger astrophysics. This review discusses the future facilities and observational strategies that are likely to significantly advance this fascinating field.

[40]  arXiv:2001.06318 [pdf, other]

Title: Assessing and improving on current semi-analytical models for cosmic defect network evolution

Authors: P. P. Avelino

Comments: 7 pages, 4 figures. arXiv admin note: text overlap with arXiv:1910.07011

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Phenomenology (hep-ph); High Energy Physics - Theory (hep-th)

We establish a correspondence between a recently proposed parameter-free velocity-dependent one-scale model and the standard parametric model for the cosmological evolution of domain wall networks. We find that the latter overestimates the damping of the wall motion due to the Hubble expansion and neglects the direct impact of wall decay on the evolution of the root-mean-square velocity of the network. We show that these effects are significant but may be absorbed into a redefinition of the momentum parameter. We also discuss the implications of these findings for cosmic strings. We compute the energy loss and momentum parameters of the standard parametric model for cosmological domain wall evolution using our parameter-free velocity-dependent one-scale model in the context of cosmological models having a power law evolution of the scale factor $a$ with the cosmic time $t$ ($a \propto t^\lambda$, $0 < \lambda < 1$), and compare with the results obtained from numerical field theory simulations. We further provide simple linear functions which roughly approximate the dependence of the the energy loss and momentum parameters on $\lambda$. Finally, we extend our formalism to account for the dynamics of $p$-branes in $N+1$-dimensional Friedmann-Lemaitre-Robertson-Walker spacetimes, thus proving the basis for future developments which, at least for $p<N-1$, should take into account $p$-brane intersections.

[41]  arXiv:2001.06340 [pdf, ps, other]

Title: Inhibited Coagulation of Micron-size Dust Due to the Electrostatic Barrier

Authors: V.V. Akimkin, A.V. Ivlev, P. Caselli

Comments: accepted for publication in ApJ

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

The collisional evolution of solid material in protoplanetary disks is a crucial step in the formation of planetesimals, comets, and planets. Although dense protoplanetary environments favor fast dust coagulation, there are several factors that limit the straightforward pathway from interstellar micron-size grains to pebble-size aggregates. Apart from the grain bouncing, fragmentation, and fast drift to the central star, a notable limiting factor is the electrostatic repulsion of like-charged grains. In this study we aim at theoretical modeling of the dust coagulation coupled with the dust charging and disk ionization calculations. We show that the electrostatic barrier is a strong restraining factor to the coagulation of micrometer-size dust in dead zones of the disk (where the turbulence is suppressed). While the sustained turbulence helps to overcome the electrostatic barrier, low fractal dimensions of dust aggregates can potentially block their further coagulation even in this case. Coulomb repulsion may keep a significant fraction of small dust in the disk atmosphere and outer regions.

[42]  arXiv:2001.06349 [pdf, other]

Title: Non-thermal desorption of complex organic molecules: Cosmic-ray sputtering of CH3OH embedded in CO2 ice

Authors: E. Dartois, M. Chabot, A. Bacmann, P. Boduch, A. Domaracka, H. Rothard

Comments: arXiv admin note: text overlap with arXiv:1906.03084

Subjects: Astrophysics of Galaxies (astro-ph.GA)

Methanol ice is embedded in interstellar ice mantles present in dense molecular clouds. We aim to measure the sputtering efficiencies starting from different ice mantles of varying compositions experimentally, in order to evaluate their potential impact on astrochemical models. The sputtering yields of complex organic molecules is of particular interest, since few mechanisms are efficient enough to induce a significant feedback to the gas phase. We irradiated methanol and carbon dioxide ice mixtures of varying ratios with swift heavy ions in the electronic sputtering regime. We monitored the evolution of the infrared spectra and the species released to the gas phase with a mass spectrometer. Methanol and 13C-methanol isotopologue were used to remove any ambiguity on the measured irradiation products. The sputtering of methanol embedded in carbon dioxide ice is an efficient process leading to the ejection of intact methanol in the gas phase. We establish that when methanol is embedded in a carbon-dioxide-rich mantle exposed to cosmic rays, a significant fraction is sputtered as intact molecules. The sputtered fraction follows the time-dependent bulk composition of the ice mantle, the latter evolving with time due to the radiolysis-induced evolution of the bulk. If methanol is embedded in a carbon dioxide ice matrix, as the analyses of the spectral shape of the CO2 bending mode observations in some lines of sight suggest, the overall methanol sputtering yield is higher than if embedded in a water ice mantle. The sputtering is increased by a factor close to the dominant ice matrix sputtering yield, which is about six times higher for pure carbon dioxide ice when compared to water ice. These experiments are further constraining the cosmic-ray-induced ice mantle sputtering mechanisms important role in the gas-phase release of complex organic molecules from the interstellar solid phase.

[43]  arXiv:2001.06355 [pdf, other]

Title: Searching for kinematic evidence of Keplerian disks around Class 0 protostars with CALYPSO

Authors: S. Maret, A. J. Maury, A. Belloche, M. Gaudel, Ph. André, S. Cabrit, C. Codella, C. Lefèvre, L. Podio, S. Anderl, F. Gueth, P. Hennebelle

Comments: Accepted for publication in Astronomy & Astrophysics

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

The formation of protoplanetary disks is not well understood. To understand how and when these disks are formed, it is crucial to characterize the kinematics of the youngest protostars at a high angular resolution. Here we study a sample of 16 Class 0 protostars to measure their rotation profile at scales from 50 to 500~au and search for Keplerian rotation. We used high-angular-resolution line observations obtained with the Plateau de Bure Interferometer as part of the CALYPSO large program. From $\mathrm{^{13}CO}$ ($J=2-1$), $\mathrm{C^{18}O}$ ($J=2-1$) and SO ($N_{j}=5_{6}-4_{5}$) moment maps, we find that seven sources show rotation about the jet axis at a few hundred au scales: SerpS-MM18, L1448-C, L1448-NB, L1527, NGC1333- IRAS2A, NGC1333-IRAS4B, and SVS13-B. We analyzed the kinematics of these sources in the $uv$ plane to derive the rotation profiles down to 50~au scales. We find evidence for Keplerian rotation in only two sources, L1527 and L1448-C. Overall, this suggests that Keplerian disks larger than 50 au are uncommon around Class 0 protostars. However, in some of the sources, the line emission could be optically thick and dominated by the envelope emission. Due to the optical thickness of these envelopes, some of the disks could have remained undetected in our observations.

[44]  arXiv:2001.06363 [pdf, other]

Title: COBRaS: The e-MERLIN 21 cm Legacy survey of Cygnus OB2

Authors: J. C. Morford, D. M. Fenech, R. K. Prinja, R. Blomme, J. A. Yates, J. J. Drake, S. P. S. Eyres, A. M. S. Richards, I. R. Stevens, N. J. Wright, J. S. Clark, S. Dougherty, J. M. Pittard, H. Smith, J. S. Vink

Comments: 41 pages, 12 figures, accepted in A&A

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

The role of massive stars is central to an understanding of galactic ecology. It is important to establish the details of how massive stars provide radiative, chemical, and mechanical feedback in galaxies. Central to these issues is an understanding of the evolution of massive stars, and the critical role of mass loss via strongly structured winds and stellar binarity. Ultimately, massive stellar clusters shape the structure and energetics of galaxies. We aim to conduct high-resolution, deep field mapping at 21cm of the core of the massive Cygnus OB2 association and to characterise the properties of the massive stars and colliding winds at this waveband. We used seven stations of the e-MERLIN radio facility, with its upgraded bandwidth and enhanced sensitivity to conduct a 21cm census of Cygnus OB2. Based on 42 hours of observations, seven overlapping pointings were employed over multiple epochs during 2014 resulting in 1 sigma sensitivities down to ~21microJy and a resolution of ~180mas. A total of 61 sources are detected at 21cm over a ~0.48deg x 0.48deg region centred on the heart of the Cyg OB2 association. Of these 61 sources, 33 are detected for the first time. We detect a number of previously identified sources including four massive stellar binary systems, two YSOs, and several known X-ray and radio sources. We also detect the LBV candidate (possible binary system) and blue hypergiant (BHG) star of Cyg OB2 #12. The 21cm observations secured in the COBRaS Legacy project provide data to constrain conditions in the outer wind regions of massive stars; determine the non-thermal properties of massive interacting binaries; examine evidence for transient sources, including those associated with young stellar objects; and provide unidentified sources that merit follow-up observations. The 21cm data are of lasting value and will serve in combination with other key surveys of Cyg OB2.

[45]  arXiv:2001.06376 [pdf, other]

Title: The paradox of youth for ALMA planet candidates

Authors: Sergei Nayakshin

Comments: Accepted to MNRAS

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

Recent ALMA observations indicate that the majority of bright protoplanetary discs show signatures of young moderately massive planets. I show that this result is paradoxical. The planets should evolve away from their observed states by radial migration and gas accretion in about 1\% of the system age. These systems should then hatch tens of giant planets in their lifetime, and there should exist a very large population of bright planet-less discs; none of this is observationally supported. An alternative scenario, in which the population of bright ALMA discs is dominated by secondary discs recently rejuvenated by deposition of new gas, is proposed. The data are well explained if the gaseous mass of the discs is comparable to a Jovian planet mass, and they last a small fraction of a Million years. Self-disruptions of dusty gas giant protoplanets, previously predicted in the context of the Tidal Downsizing theory of planet formation, provide a suitable mechanism for such injections of new fuel, and yield disc and planet properties commensurate with ALMA observations. If this scenario is correct, then the secondary discs have gas-to-dust ratios considerably smaller than 100, and long look ALMA and NIR/optical observations of dimmer targets should uncover dusty, not yet disrupted, gas clumps with sizes of order an AU. Alternatively, secondary discs could originate from late external deposition of gas into the system, in which case we expect widespread signatures of warped outer discs that have not yet come into alignment with the planets.

[46]  arXiv:2001.06379 [pdf, other]

Title: A Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE).VI. Environmental quenching on HII region scales

Authors: A. Boselli, M. Fossati, A. Longobardi, S. Boissier, M. Boquien, J. Braine, P. Cote, J.C. Cuillandre, B. Epinat, L. Ferrarese, G. Gavazzi, S. Gwyn, G. Hensler, H. Plana, Y. Roehlly, C. Schimd, M. Sun, G. Trinchieri

Comments: Accepted for publication on A&A Letter

Subjects: Astrophysics of Galaxies (astro-ph.GA)

The Virgo Environmental Survey Tracing Ionised Gas Emission (VESTIGE) is a blind narrow-band Halpha+[NII] imaging survey of the Virgo cluster carried out with MegaCam at the Canada-French-Hawaii telescope (CFHT). We use a new set of data extracted from VESTIGE to study the impact of the hostile cluster environment on the star formation process down to the scale of HII regions (~ 50 pc). HII regions are identified and their parameters measured using the HIIphot code on a sample of 114 late-type galaxies spanning a wide range in morphological type (Sa-Sd, Im, BCD), stellar mass (10^6.5 <= M_star <= 10^11 Mo), and star formation activity (10^-3 <= SFR <= 10 Mo yr^-1). Owing to the exquisite average resolution of the VESTIGE data (0.65 arcsec), we detect 11302 HII regions with an Halpha luminosity L(Halpha) >= 10^37 erg s^-1. We show that the typical number of HII regions in gas-stripped objects is significantly lower than in healthy late-types of similar stellar mass. We also show that in these gas-stripped galaxies the number of HII regions significantly drops outside the effective radius, suggesting that the quenching process occurs outside-in, in agreement with other multifrequency observations. These new results consistently confirm that the main mechanism responsible for the decrease of the star formation activity observed in cluster galaxies is ram pressure, allowing us to discard other milder processes such as starvation or strangulation unable to reproduce the observed radially truncated profiles.

[47]  arXiv:2001.06382 [pdf, other]

Title: Resonances in non-axisymmetric gravitational potentials

Authors: Bruno Sicardy

Comments: 20 pages, 2 figures

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We study sectoral resonances of the form $j\kappa= m(n-\Omega)$ around a non-axisymmetric body with spin rate $\Omega$, where $\kappa$ and $n$ are the epicyclic frequency and mean motion of a particle, respectively, where $j>0$ and $m$ ($<0$ or $>0$) are integers, $j$ being the resonance order. This describes $n/\Omega \sim m/(m-j)$ resonances inside and outside the corotation radius,as well as prograde and retrograde resonances. Results are: (1) the kinematics of a periodic orbit depends only on $(m',j')$, the irreducible (relatively prime) version of $(m,j)$. In a rotating frame, the periodic orbit has $j'$ braids, $|m'|$ identical sectors and $|m'|(j'-1)$ self-crossing points; (2) thus, Lindblad resonances (with $j=1$) are free of self-crossing points; (3) resonances with same $j'$ and opposite $m'$ have the same kinematics, and are called $twins$; (4) the order of a resonance at a given $n/\Omega$ depends on the symmetry of the potential. A potential that is invariant under a $2\pi/k$-rotation creates only resonances with $m$ multiple of $k$; (5) resonances with same $j$ and opposite $m$ have the same kinematics and same dynamics, and are called $true~twins$; (6) A retrograde resonance ($n/\Omega < 0$) is always of higher order than its prograde counterpart ($n/\Omega > 0$); (7) the resonance strengths can be calculated in a compact form with the classical operators used in the case of a perturbing satellite. Applications to Chariklo and Haumea are made.

[48]  arXiv:2001.06391 [pdf, other]

Title: The PIPER Survey: I. An Initial Look at the Intergalactic Globular Cluster Population in the Perseus Cluster

Authors: William E. Harris, Rachel A. Brown, Patrick R. Durrell, Aaron J. Romanowsky, John Blakeslee, Jean Brodie, Steven Janssens, Thorsten Lisker, Sakurako Okamoto, Carolin Wittmann

Comments: In press for The Astrophysical Journal

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We describe the goals and first results of a Program for Imaging of the PERseus cluster of galaxies (PIPER). The first phase of the program builds on imaging of fields obtained with the Hubble Space Telescope (HST) ACS/WFC and WFC3/UVIS cameras. Our PIPER target fields with HST include major early-type galaxies including the active central giant NGC 1275; known Ultra-Diffuse Galaxies; and the Intracluster Medium. The resulting two-color photometry in F475W and F814W reaches deep enough to resolve and measure the globular cluster (GC) populations in the Perseus member galaxies. Here we present initial results for eight pairs of outer fields that confirm the presence of Intergalactic GCs (IGCs) in fields as distant as 740 kpc from the Perseus center (40\% of the virial radius of the cluster). Roughly 90% of these IGCs are identifiably blue (metal-poor) but there is a clear trace of a red (metal-rich) component as well, even at these very remote distances.

[49]  arXiv:2001.06400 [pdf, other]

Title: The ALMA-PILS survey: Inventory of complex organic molecules towards IRAS 16293-2422 A

Authors: S. Manigand, J. K. Jørgensen, H. Calcutt, H. S. P. Müller, N. F. W. Ligterink, A. Coutens, M. N. Drozdovskaya, E. F. van Dishoeck, S. F. Wampfler

Comments: Accepted for publication in A&A. 31 pages, 17 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

Complex organic molecules (COM) are detected in many sources in the warm inner regions of envelopes surrounding deeply embedded protostars. Exactly how these COM form remains an open question. This study aims to constrain the formation of complex organic molecules through comparisons of their abundances towards the Class 0 protostellar binary IRAS 16293-2422 (IRAS16293). We utilised observations from the ALMA Protostellar Interferometric Line Survey of IRAS16293. The species identification and the rotational temperature and column density estimation were derived by fitting the extracted spectra towards IRAS16293 A and IRAS16293 B with synthetic spectra. The majority of the work in this paper pertains to the analysis of IRAS16293 A for a comparison with the results from the other binary component, which have already been published. We detect 15 different COM, as well as 16 isotopologues towards the most luminous companion protostar IRAS16293 A. Tentative detections of an additional 11 isotopologues are reported. We also searched for and report on the first detections of CH3OCH2OH and t-C2H5OCH3 towards IRAS16293 B and the follow-up detection of CH2DCHO and CH3CDO. Twenty-four lines of CHD2OH are also identified. The comparison between the two protostars of the binary system shows significant differences in abundance for some of the species, which are partially correlated to their spatial distribution. The spatial distribution is consistent with the sublimation temperature of the species; those with higher expected sublimation temperatures are located in the most compact region of the hot corino towards IRAS16293 A. This spatial differentiation is not resolved in IRAS16293 B and will require observations at a higher angular resolution. In parallel, the list of identified CHD2OH lines shows the need of accurate spectroscopic data including their line strength.

[50]  arXiv:2001.06430 [pdf, other]

Title: Detection of Fe I in the atmosphere of the ultra-hot Jupiter WASP-121b, and a new likelihood-based approach for Doppler-resolved spectroscopy

Authors: Neale P. Gibson, Stephanie Merritt, Stevanus K. Nugroho, Patricio E. Cubillos, Ernst J. W. de Mooij, Thomas Mikal-Evans, Luca Fossati, Joshua Lothringer, Nikolay Nikolov, David K. Sing, Jessica J. Spake, Chris A. Watson, Jamie Wilson

Comments: Accepted for publication in MNRAS. 14 pages, 7 figures

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

High-resolution Doppler-resolved spectroscopy has opened up a new window into the atmospheres of both transiting and non-transiting exoplanets. Here, we present VLT/UVES observations of a transit of WASP-121b, an 'ultra-hot' Jupiter previously found to exhibit a temperature inversion and detections of multiple species at optical wavelengths. We present initial results using the blue arm of UVES ($\approx$3700-5000A), recovering a clear signal of neutral Fe in the planet's atmosphere at >8$\sigma$, which could contribute to (or even fully explain) the temperature inversion in the stratosphere. However, using standard cross-correlation methods, it is difficult to extract physical parameters such as temperature and abundances. Recent pioneering efforts have sought to develop likelihood `mappings' that can be used to directly fit models to high-resolution datasets. We introduce a new framework that directly computes the likelihood of the model fit to the data, and can be used to explore the posterior distribution of parameterised model atmospheres via MCMC techniques. Our method also recovers the physical extent of the atmosphere, as well as account for time- and wavelength-dependent uncertainties. We measure a temperature of $3710^{+490}_{-510}$K, indicating a higher temperature in the upper atmosphere when compared to low-resolution observations. We also show that the Fe I signal is physically separated from the exospheric Fe II. However, the temperature measurements are highly degenerate with aerosol properties; detection of additional species, using more sophisticated atmospheric models, or combining these methods with low-resolution spectra should help break these degeneracies.

[51]  arXiv:2001.06431 [pdf, other]

Title: Are the Carriers of Diffuse Interstellar Bands and Extended Red Emission the same?

Authors: Thomas S. -Y. Lai, Adolf N. Witt, Carlos Alvarez, Jan Cami

Comments: 13 pages, 9 figures

Subjects: Astrophysics of Galaxies (astro-ph.GA)

We report the first spectroscopic observations of a background star seen through the region between the ionization front and the dissociation front of the nebula IC 63. This photodissociation region (PDR) exhibits intense extended red emission (ERE) attributed to fluorescence by large molecules/ions. We detected strong diffuse interstellar bands (DIB) in the stellar spectrum, including an exceptionally strong and broad DIB at $\lambda$4428. The detection of strong DIBs in association with ERE could be consistent with the suggestion that the carriers of DIBs and ERE are identical. The likely ERE process is recurrent fluorescence, enabled by inverse internal conversions from highly excited vibrational levels of the ground state to low-lying electronic states with subsequent transitions to ground. This provides a path to rapid radiative cooling for molecules/molecular ions, greatly enhancing their ability to survive in a strongly irradiated environment. The ratio of the equivalent widths (EW) of DIBs $\lambda$5797 and $\lambda$5780 in IC 63 is the same as that observed in the low-density interstellar medium with UV interstellar radiation fields (ISRF) weaker by at least two orders of magnitude. This falsifies suggestions that the ratio of these two DIBs can serve as a measure of the UV strength of the ISRF. Observations of the nebular spectrum of the PDR of IC 63 at locations immediately adjacent to where DIBs were detected failed to reveal any presence of sharp emission features seen in the spectrum of the Red Rectangle nebula. This casts doubts upon proposals that the carriers of these features are the same as those of DIBs seen at slightly shorter wavelengths.

[52]  arXiv:2001.06450 [pdf, other]

Title: Two new outbursts and transient hard X-rays from 1E 1048.1$-$5937

Authors: R. F. Archibald, P. Scholz, V. M. Kaspi, S. P. Tendulkar, A. P. Beardmore

Comments: 11 pages, 5 figures, accepted in ApJ

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Since its discovery, 1E 1048.1$-$5937 has been one of the most active magnetars, both in terms of radiative outbursts, and changes to its spin properties. Here we report on a continuing monitoring campaign with the Neil Gehrels Swift Observatory X-ray Telescope in which we observe two new outbursts from this source. The first outburst occurred in 2016 July, and the second in 2017 December, reaching peak 0.5-10 keV absorbed fluxes of $3.2^{+0.2}_{-0.3}\times 10^{-11}$ erg s$^{-1}$ cm$^{-2}$ and $2.2^{+0.2}_{-0.2}\times10^{-11}$ erg s$^{-1}$ cm$^{-2}$, respectively, factors of $\sim$5 and $\sim 4$ above the quiescent flux. Both new outbursts were accompanied by spin-up glitches with amplitudes of $\Delta\nu= 4.47(6)\times10^{-7}$ Hz and $\Delta\nu= 4.32(5)\times10^{-7}$ Hz, respectively. Following the 2016 July outburst, we observe, as for past outbursts, a period of delayed torque fluctuations, which reach a peak spin-down of $1.73\pm0.01$ times the quiescent rate, and which dominates the spin evolution compared to the spin-up glitches. We also report an observation near the peak of the first of these outbursts with NuSTAR in which hard X-ray emission is detected from the source. This emission is well characterized by an absorbed blackbody plus a broken power law, with a power-law index above $13.4\pm0.6$ keV of $0.5_{-0.2}^{+0.3}$, similar to those observed in both persistent and transient magnetars. The hard X-ray results are broadly consistent with models of electron/positron cooling in twisted magnetic field bundles in the outer magnetosphere. However the repeated outbursts and associated torque fluctuations in this source remain puzzling.

[53]  arXiv:2001.06454 [pdf]

Title: A dynamic black hole corona in an active galaxy through X-ray reverberation mapping

Authors: William N. Alston, Andrew C. Fabian, Erin Kara, Michael L. Parker, Michal Dovciak, Ciro Pinto, Jiachen Jiang, Matthew J. Middleton, Giovanni Miniutti, Dominic J. Walton, Dan R. Wilkins, Douglas J. K. Buisson, Maria D. Caballero-Garcia, Edward M. Cackett, Barbara De Marco, Luigi C. Gallo, Anne M. Lohfink, Chris S. Reynolds, Phil Uttley, Andrew J. Young, Abderahmen Zogbhi

Comments: Accepted for publication. 3 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA); General Relativity and Quantum Cosmology (gr-qc)

X-ray reverberation echoes are assumed to be produced in the strongly distorted spacetime around accreting supermassive black holes. This signal allows us to spatially map the geometry of the inner accretion flow - a region which cannot yet be spatially resolved by any telescope - and provides a direct measure of the black hole mass and spin. The reverberation timescale is set by the light travel path between the direct emission from a hot X-ray corona and the reprocessed emission from the inner edge of the accretion disc. However, there is an inherent degeneracy in the reverberation signal between black hole mass, inner disc radius and height of the illuminating corona above the disc. Here, we use a long X-ray observation of the highly-variable active galaxy, IRAS 13224-3809, to track the reverberation signal as the system evolves on timescales of a day. With the inclusion of all the relativistic effects, modelling reveals that the height of the X-ray corona increases with increasing luminosity, providing a dynamic view of the inner accretion region. This simultaneous modelling allows us to break the inherent degeneracies and obtain an independent timing-based estimate for the mass and spin of the black hole. The uncertainty on black hole mass is comparable to the leading optical reverberation method, making X-ray reverberation a powerful technique, particularly for sources with low optical variability.

[54]  arXiv:2001.06469 [pdf, other]

Title: Application of peaks theory to the abundance of primordial black holes

Authors: Sam Young, Marcello Musso

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We consider the application of peaks theory to the calculation of the number density of peaks relevant for primordial black hole (PBH) formation. For PBHs, the final mass is related to the amplitude and scale of the perturbation from which it forms, where the scale is defined as the scale at which the compaction function peaks. We therefore extend peaks theory to calculate not only the abundance of peaks of a given amplitude, but peaks of a given amplitude and scale. A simple fitting formula is given in the high-peak limit relevant for PBH formation. We also adapt the calculation to use a Gaussian smoothing function, ensuring convergence regardless of the choice of power spectrum.

Cross-lists for Mon, 20 Jan 20

[55]  arXiv:2001.06004 (cross-list from hep-ph) [pdf, other]

Title: White dwarf cooling via gravity portals

Authors: Grigoris Panotopoulos, Ilídio Lopes

Comments: 6 pages, 3 figures, accepted for publication in PRD

Subjects: High Energy Physics - Phenomenology (hep-ph); Solar and Stellar Astrophysics (astro-ph.SR); General Relativity and Quantum Cosmology (gr-qc)

We investigate the impact of gravity portal to properties of white dwarfs, such as equation-of-state as well as cooling time. We find that the interaction between dark matter spin-zero bosons and electrons in the mean field approximation softens the equation-of-state, and the object coolers down slower compared to the usual case.

[56]  arXiv:2001.06006 (cross-list from gr-qc) [pdf, other]

Title: II. A GR Source Term $T^{μν}$ For Dark Matter

Authors: H. L. Helfer

Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA)

Two forms are suggested for the energy-momentum source term associated with an aggregate of dark matter (with the properties described in Paper I). Both have large pressure-like components which dominate the density terms. Using one form a simple model of the spiral galaxy halos is developed which can match the observed `flat' outer rotation curves of some galaxies,including the Milky Way. It can also represent the ascending outer rotational curves of small spiral galaxies such as M33. See Figs. 1, 2. The halo dark matter (DM)`missing mass' results from ignoring the pressure term's contribution to the source tensor.
The analysis of the Milky Way rotation curve gives parameters characterizing the DM intergalactic medium in which the halo is situated.. The dark matter cannot come closer to the galactic center than $R \sim 4$ kpc. It reaches a maximum flux at $R_h \simeq 8$ kpc and then falls rapidly with distance. It is hoped that by analyzing other galactic rotation curves these models can be used to infer properties of the intergalactic DM matter.
The other form for $T^{\mu \nu}$ for DM is useful in cosmology. Then a (non-constant) cosmological `constant' term $\Lambda$ needs to be added to Einstein's equation in order to allow use for DM of the standard equation of state relation of ordinary matter.. We suggest that at least some of the `dark energy' present results from this requirement and may not be real; it simply results from adopting an improper equation of state for DM.

[57]  arXiv:2001.06100 (cross-list from gr-qc) [pdf, ps, other]

Title: General parametrization of black holes: the only parameters that matter

Authors: R. A. Konoplya, A. Zhidenko

Comments: 5 pages, 1 figure

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)

The general parametrization of a black-hole spacetime in arbitrary metric theories of gravity includes an infinite set of parameters. It is natural to suppose that essential astrophysically observable quantities, such as quasinormal modes, parameters of shadow, electromagnetic radiation and accreting matter in the vicinity of a black hole, must depend only on a few of these parameters. Starting from the parametrization for spherically symmetric configurations in the form of infinite continued fraction, we suggest a compact representation of the asymptotically flat spherically symmetric and slowly rotating black holes in terms of only three and four parameters respectively. This approximate representation of a black-hole metric should allow one to describe physical observables in the region of strong gravity.

[58]  arXiv:2001.06121 (cross-list from physics.chem-ph) [pdf, other]

Title: Diatomic rovibronic transitions as potential probes for proton-to-electron mass ratio across cosmological time

Authors: Anna-Maree Syme, Adam Mousley, Maria Cunningham, Laura K McKemmish

Subjects: Chemical Physics (physics.chem-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Atomic Physics (physics.atom-ph)

Astrophysical molecular spectroscopy is an important method of searching for new physics through probing the variation of the proton-to-electron mass ratio, $\mu$, with existing constraints limiting variation to a fractional change of less than 10$^{-17}$/year. To improve on this constraint and therefore provide better guidance to theories of new physics, new molecular probes will be useful. These probes must have spectral transitions that are observable astrophysically and have different sensitivities to variation in the proton-to-electron mass ratio. Here, we concisely detail how astrophysical observations constrain the set of potential molecular probes and promising sensitive transitions based on how the frequency and intensity of these transitions align with available telescopes and observational constraints. Our detailed investigation focuses on rovibronic transitions in astrophysical diatomic molecules, using the spectroscopic models of 11 diatomics to identify sensitive transitions and probe how they generally arise in real complex molecules with many electronic states and fine structure. While none of the 11 diatomics investigated have sensitive transitions likely to be astrophysically observable, we have found that at high temperatures (1000 K) five of these diatomics have a significant number of low intensity sensitive transitions arising from an accidental near-degeneracy between vibrational levels in the ground and excited electronic state. This insight enables screening of all astrophysical diatomics as potential probes of proton-to-electron mass variation, with CN, CP, SiN and SiC being the most promising candidates for further investigation for sensitivity in rovibronic transitions.

[59]  arXiv:2001.06129 (cross-list from gr-qc) [pdf, other]

Title: A Simple Three-Dimensional Laser Interferometer Gravitational-Wave Detector

Authors: Mengxu Liu, Biping Gong

Comments: 5 pages, 5 figures, Submitted

Subjects: General Relativity and Quantum Cosmology (gr-qc); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The Gravitational wave (GW) has opened a new window to the universe beyond the electromagnetic spectrum. Since 2015, dozens of GW events have been caught by ground based GW detectors through laser interferometry. However, both the ground based and future space-based detectors are two-dimensional, which have very limited directional response to the GW. Here we propose a simple three-dimensional (3-D) laser interferometer in the shape of a regular triangular pyramid. Such a 3-D detector can provide much stronger direction constraints for GW sources and wider directional response than the two-dimensional ones, which is more efficient in the research jointing GW and electromagnetic emission. The most sensitive band of such a detector is around kilo-Hz, which is suitable for measuring the post-merger signal from the binary neutron stars. Such a detection will be of importance in the restriction of the equation of state of the neutron stars.

[60]  arXiv:2001.06132 (cross-list from physics.ins-det) [pdf, other]

Title: Depth-profile study of $^{210}$Pb in the surface of an NaI(Tl) crystal

Authors: G. H. Yu, C. Ha, E. J. Jeon, K. W. Kim, N.Y. Kim, Y. D. Kim, H. S. Lee, H.K. Park, C. Rott

Subjects: Instrumentation and Detectors (physics.ins-det); Instrumentation and Methods for Astrophysics (astro-ph.IM)

The surface $^{210}$Pb is one of the main background sources for dark-matter-search experiments using NaI(Tl) crystals, its spectral features associated with the beta-decay events for energies less than 60 keV depends on the depth distribution of $^{210}$Pb in the surface of an NaI(Tl) crystal. Therefore, we must understand the profile of surface $^{210}$Pb to precisely model the background measurement in the low-energy region for the low-background experiment using NaI(Tl) crystals. We estimate the depth profile of the surface $^{210}$Pb contamination by modeling the measured spectrum of the alpha emission from the decay of $^{210}$Po at the decay sequence of the surface $^{210}$Pb contamination that is obtained using an $^{222}$Rn-contaminated crystal. Moreover, we describe the energy spectra of the surface contaminations by performing Geant4 Monte Carlo simulations that are used for fitting an exponential curve, which is a function of the surface depth, with the measured data, by using the log likelihood method. The low- and high-energy events from the beta decay of surface $^{210}$Pb are also modeled to improve the depth profile for shallow depths. We simulate the energy spectra from beta decays of $^{210}$Pb that are exponentially distributed in the surface by following two exponential functions that consider mean-depth parameters in the data fitting; we observed that the energy spectra are in good agreement with the measured data.

Replacements for Mon, 20 Jan 20

[61]  arXiv:1711.00862 (replaced) [pdf, other]

Title: The Highly Luminous Type Ibn Supernova ASASSN-14ms

Authors: P. J. Vallely, J. L. Prieto, K. Z. Stanek, C. S. Kochanek, T. Sukhbold, D. Bersier, J. S. Brown, Ping Chen, Subo Dong, E. Falco, P. Berlind, M. Calkins, R. A. Koff, S. Kiyota, J. Brimacombe, B. J. Shappee, T. W.-S. Holoien, T. A. Thompson, M. D. Stritzinger

Comments: 12 pages, 2 tables, 6 figures. Photometric data presented in this submission are included as ancillary files. For a brief video explaining this paper, see this https URL

Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 475, Issue 2, April 2018, Pages 2344-2354

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[62]  arXiv:1901.06582 (replaced) [pdf, other]

Title: Inferring the parallax of Westerlund 1 from Gaia DR2

Authors: Mojgan Aghakhanloo, Jeremiah W. Murphy, Nathan Smith, John Parejko, Mariangelly Díaz-Rodríguez, Maria R. Drout, Jose H. Groh, Joseph Guzman, Keivan G. Stassun

Comments: 14 pages, 10 figures

Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA)

[63]  arXiv:1902.10045 (replaced) [pdf, other]

Title: Fermi Large Area Telescope Fourth Source Catalog

Authors: The Fermi-LAT collaboration

Comments: Accepted by ApJS; data files at this https URL arXiv admin note: text overlap with arXiv:1501.02003 (this is the previous version of the same catalog)

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[64]  arXiv:1903.03120 (replaced) [pdf, other]

Title: The spectral evolution of AT 2018dyb and the presence of metal lines in tidal disruption events

Authors: Giorgos Leloudas, Lixin Dai, Iair Arcavi, Paul M. Vreeswijk, Brenna Mockler, Rupak Roy, Daniele B. Malesani, Steve Schulze, Thomas Wevers, Morgan Fraser, Enrico Ramirez-Ruiz, Katie Auchettl, Jamison Burke, Giacomo Cannizzaro, Panos Charalampopoulos, Ting-Wan Chen, Aleksandar Cikota, Massimo Della Valle, Lluis Galbany, Mariusz Gromadzki, Kasper E. Heintz, Daichi Hiramatsu, Peter G. Jonker, Zuzanna Kostrzewa-Rutkowska, Kate Maguire, Ilya Mandel, Francesca Onori, Matt Nicholl, Nathaniel Roth, Stephen J. Smartt, Lukasz Wyrzykowski, Dave R. Young

Comments: Accepted version. Updated with new photometry and spectra, including an X-shooter spectrum used to determine the BH mass. Two more figures added and line measurements tabulated. No significant scientific updates and the conclusions remain unaffected

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[65]  arXiv:1903.08665 (replaced) [pdf, other]

Title: ASASSN-18tb: A Most Unusual Type Ia Supernova Observed by TESS and SALT

Authors: P. J. Vallely, M. Fausnaugh, S. W. Jha, M. A. Tucker, Y. Eweis, B. J. Shappee, C. S. Kochanek, K. Z. Stanek, Ping Chen, Subo Dong, J. L. Prieto, T. Sukhbold, Todd A. Thompson, J. Brimacombe, M. D. Stritzinger, T. W.-S. Holoien, D. A. H. Buckley, M. Gromadzki, Subhash Bose

Comments: 13 pages, 8 figures

Journal-ref: Monthly Notices of the Royal Astronomical Society, Volume 487, Issue 2, August 2019, Pages 2372-2384

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

[66]  arXiv:1906.06305 (replaced) [pdf, other]

Title: Long Baseline Observations of the HD100546 Protoplanetary Disk with ALMA

Authors: Sebastián Pérez, Simon Casassus, Antonio Hales, Sebastián Marino, Anthony Cheetham, Alice Zurlo, Lucas Cieza, Ruobing Dong, Felipe Alarcón, Pablo Benítez-Llambay, Ed Fomalont, Henning Avenhaus

Comments: 10 pages, 6 figures. Accepted for publication in ApJ Letters

Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Solar and Stellar Astrophysics (astro-ph.SR)

[67]  arXiv:1906.11311 (replaced) [pdf, other]

Title: Exact solutions for compact stars with CFL quark matter

Authors: L. S. Rocha (IAG - USP, Brazil), A. Bernardo (IAG - USP, Brazil), M. G. B. de Avellar (UNIFESP - Diadema and ITA - São José dos Campos, Brazil), J. E. Horvath (IAG - USP, Brazil)

Comments: Submitted to IJMPD on January 2020, 13 pages, 6 figures, anisotropy discussion enlarged and clarified

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

[68]  arXiv:1907.02156 (replaced) [pdf, other]

Title: Fractional Polarisation of Extragalactic Sources in the 500-square-degree SPTpol Survey

Authors: N. Gupta, C. L. Reichardt, P. A. R. Ade, A. J. Anderson, M. Archipley, J. E. Austermann, J. S. Avva, J. A. Beall, A. N. Bender, B. A. Benson, F. Bianchini, L. E. Bleem, J. E. Carlstrom, C. L. Chang, H. C. Chiang, R. Citron, C. Corbett Moran, T. M. Crawford, A. T. Crites, T. de Haan, M. A. Dobbs, W. Everett, C. Feng, J. Gallicchio, E. M. George, A. Gilbert, N. W. Halverson, N. Harrington, J. W. Henning, G. C. Hilton, G. P. Holder, W. L. Holzapfel, Z. Hou, J. D. Hrubes, N. Huang, J. Hubmayr, K. D. Irwin, L. Knox, A. T. Lee, D. Li, A. Lowitz, D. Luong-Van, D. P. Marrone, A. Manzotti, J. J. McMahon, S. S. Meyer, M. Millea, L. M. Mocanu, J. J. Mohr, J. Montgomery, A. Nadolski, T. Natoli, J. P. Nibarger, G. I. Noble, V. Novosad, Y. Omori, S. Padin, S. Patil, C. Pryke, J. E. Ruhl, B. R. Saliwanchik, et al. (19 additional authors not shown)

Comments: 10 pages, 5 figures

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[69]  arXiv:1907.03897 (replaced) [pdf, other]

Title: Future Prospects for Probing Scalar-Tensor Theories with Gravitational Waves from Mixed Binaries

Authors: Zack Carson, Brian C. Seymour, Kent Yagi

Comments: 8 pages, 8 figures; updated to match with the version published in CQG Letters

Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE)

[70]  arXiv:1907.05425 (replaced) [pdf, other]

Title: Cosmological Constraints on Invisible Neutrino Decays Revisited

Authors: Miguel Escudero, Malcolm Fairbairn

Comments: 9 pages, 6 figures, 2 tables. v2: updated analysis with Planck legacy data and BAO data, new results are in good agreement with the Planck 2015 analysis. References and minor clarifications added. Conclusions unchanged. Matches the published version

Journal-ref: Phys. Rev. D 100, 103531 (2019)

Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Experiment (hep-ex)

[71]  arXiv:1907.06660 (replaced) [pdf, other]

Title: Nekhoroshev Estimates for the Survival Time of Tightly Packed Planetary Systems

Authors: Almog Yalinewich, Cristobal Petrovich

Comments: accepted for publication in the Astrophysical Journal

Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

[72]  arXiv:1908.00480 (replaced) [pdf, other]

Title: The CLASS 150/220 GHz Polarimeter Array: Design, Assembly, and Characterization

Authors: Sumit Dahal, Mandana Amiri, John W. Appel, Charles L. Bennett, Lance Corbett, Rahul Datta, Kevin Denis, Thomas Essinger-Hileman, Mark Halpern, Kyle Helson, Gene Hilton, Johannes Hubmayr, Benjamin Keller, Tobias Marriage, Carolina Nunez, Matthew Petroff, Carl Reintsema, Karwan Rostem, Kongpop U-Yen, Edward Wollack

Comments: 8 pages, 5 figures, Published in J Low Temp Phys

Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[73]  arXiv:1908.05431 (replaced) [pdf, ps, other]

Title: Nonlocal Gravitomagnetism

Authors: Bahram Mashhoon, Friedrich W. Hehl

Comments: 24 pages; v2: presentation improved, references added; v3: minor corrections

Journal-ref: Universe 5, 195 (2019)

Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA); High Energy Physics - Theory (hep-th)

[74]  arXiv:1909.09102 (replaced) [pdf, other]

Title: Tomographic measurement of the intergalactic gas pressure through galaxy-tSZ cross-correlations

Authors: Nick Koukoufilippas, David Alonso, Maciej Bilicki, John A. Peacock

Comments: 19 pages, 10 figures. Published in MNRAS. Analysis pipeline available at this https URL

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)

[75]  arXiv:1909.09375 (replaced) [pdf, other]

Title: Likelihood methods for CMB experiments

Authors: Martina Gerbino, Massimiliano Lattanzi, Marina Migliaccio, Luca Pagano, Laura Salvati, Loris Colombo, Alessandro Gruppuso, Paolo Natoli, Gianluca Polenta

Comments: 71 pages, 5 figures. Matching version to be published in Frontiers in Physics, section Cosmology, as a contribution to the collection "Status and Prospects of Cosmic Microwave Background Analysis"

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

[76]  arXiv:1910.06979 (replaced) [pdf, other]

Title: The Fast Radio Burst Luminosity Function and Death Line in the Low-Twist Magnetar Model

Authors: Zorawar Wadiasingh, Paz Beniamini, Andrey Timokhin, Matthew G. Baring, Alexander J. van der Horst, Alice K. Harding, Demosthenes Kazanas

Comments: 23 pages, 3 figures, accepted to The Astrophysical Journal

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

[77]  arXiv:1910.07556 (replaced) [pdf, ps, other]

Title: Direct collapse to supermassive black hole seeds: the critical conditions for suppression of $\rm H_2$ cooling

Authors: Yang Luo (1), Isaac Shlosman (2,3), Kentaro Nagamine (3,4,5), Taotao Fang (1) ((1) Xiamen University, (2) University of Kentucky, (3) Osaka University, (4) University of Nevada, (5) Kavli IPMU, University of Tokyo)

Comments: 10 pages, 5 figures, accepted for publication in MNRAS

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[78]  arXiv:1910.11270 (replaced) [pdf, other]

Title: Stellar Feedback and Resolved Stellar IFU Spectroscopy in the nearby Spiral Galaxy NGC 300

Authors: Anna F. McLeod, J. M. Diederik Kruijssen, Daniel R. Weisz, Peter Zeidler, Andreas Schruba, Julianne J. Dalcanton, Steven N. Longmore, Mélanie Chevance, Christopher M. Faesi, Nell Byler

Comments: Accepted for publication in ApJ

Subjects: Astrophysics of Galaxies (astro-ph.GA)

[79]  arXiv:1911.00013 (replaced) [pdf, other]

Title: Multi-wavelength Emission from Galactic Jets: the Case of the Microquasar SS433

Authors: Takahiro Sudoh, Yoshiyuki Inoue, Dmitry Khangulyan

Comments: Main text 11 pages, 3 figures. To appear in ApJ

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Astrophysics of Galaxies (astro-ph.GA)

[80]  arXiv:1911.08471 (replaced) [pdf, other]

Title: Modelling the large scale structure of the Universe as a function of cosmology and baryonic physics

Authors: Giovanni Aricò, Raul E. Angulo, Carlos Hernández-Monteagudo, Sergio Contreras, Matteo Zennaro, Marcos Pellejero-Ibañez, Yetli Rosas-Guevara

Comments: 20 pages, 15 figures. Submitted to MNRAS

Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)

[81]  arXiv:1911.11912 (replaced) [pdf, other]

Title: The nearby luminous transient AT2018cow: a magnetar formed in a sub-relativistically expanding non-jetted explosion

Authors: P. Mohan, T. An, J. Yang

Comments: 12 pages, 4 figures, 4 tables. Accepted for publication in ApJ Letters

Journal-ref: ApJL, 2020, 888, L24

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[82]  arXiv:1912.00274 (replaced) [pdf, other]

Title: Fast Neutrino Flavor Instability in the Neutron-star Convection Layer of Three-dimensional Supernova Models

Authors: Robert Glas (1,2), H.-Thomas Janka (1), Francesco Capozzi (3), Manibrata Sen (4,5), Basudeb Dasgupta (6), Alessandro Mirizzi (7,8), Guenter Sigl (9) ((1) MPI Astrophysics, Garching, (2) TUM, Munich, (3) MPI Physik, Munich, (4) UC Berkeley, Berkeley, (5) Northwestern University, Evanston, (6) Tata Institute of Fundamental Research, Mumbai, (7) Dipartimento Interateneo di Fisica, Bari, (8) Istituto Nazionale di Fisica Nucleare, Bari, (9) Inst. Theor. Physik, Hamburg University)

Comments: 21 pages, 13 figures; more detailed explanations added due to referee comments; accepted by PRD

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)

[83]  arXiv:1912.07771 (replaced) [pdf, other]

Title: Luminous Red Novae: population models and future prospects

Authors: George Howitt, Simon Stevenson, Alejandro Vigna-Gómez, Stephen Justham, Natasha Ivanova, Tyrone E. Woods, Coenraad J. Neijssel, Ilya Mandel

Comments: 13 pages, 8 Figures. MNRAS Accepted

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Solar and Stellar Astrophysics (astro-ph.SR)

[84]  arXiv:1912.09809 (replaced) [pdf, other]

Title: Twin stars and the stiffness of the nuclear equation of state: ruling out strong phase transitions below $1.7n_0$ with the new NICER radius measurements

Authors: Jan-Erik Christian, Jürgen Schaffner-Bielich

Comments: 7 pages, 6 figures

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Nuclear Theory (nucl-th)

[85]  arXiv:1912.12926 (replaced) [pdf, ps, other]

Title: Finite Action Principle Revisited

Authors: John D. Barrow

Comments: 14 pages, no figures or tables. Amended title, additions to introduction, conclusions, section 2.3 and refs. To appear in Phys. Rev. D

Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

[86]  arXiv:2001.03716 (replaced) [src]

Title: Self-similar Blast Wave for A Two-component Fluid with Variable Adiabatic Index

Authors: Yiran Zhang, Edison Liang, Siming Liu

Comments: Submitted to ApJ. But during proof reading we just find that identical results had been published a while before: this https URL

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[87]  arXiv:2001.04548 (replaced) [pdf, other]

Title: Tidal Disruption Flares from Stars on Marginally Bound and Unbound Orbits

Authors: Gwanwoo Park, Kimitake Hayasaki

Comments: 37 pages, 11 figures, 2 tables, comments welcome

Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

[88]  arXiv:2001.05225 (replaced) [pdf]

Title: C-RED 3: A SWIR camera for FSO applications

Authors: J.L. Gach, David Boutolleau, Cecile Brun, Thomas Carmignani, Fabien Clop, Philippe Feautrier, Stephane Lemarchand, Eric Stadler, Yann Wanwanscappel

Subjects: Optics (physics.optics); Instrumentation and Methods for Astrophysics (astro-ph.IM)

[89]  arXiv:2001.05570 (replaced) [pdf, other]

Title: A survey for variable young stars with small telescopes: II -- Mapping a protoplanetary disk with stable structures at 0.15 AU

Authors: Jack J. Evitts, Dirk Froebrich, Aleks Scholz, Jochen Eislöffel, Justyn Campbell-White, Will Furnell, Thomas Urtly, Roger Pickard, Klaas Wiersema, Pavol A. Dubovský, Igor Kudzej, Ramon Naves, Mario Morales Aimar, Rafael Castillo García, Tonny Vanmunster, Erik Schwendeman, Francisco C. Soldán Alfaro, Stephen Johnstone, Rafael Gonzalez Farfán, Thomas Killestein, Jesús Delgado Casal, Faustino García de la Cuesta, Dean Roberts, Ulrich Kolb, Luís Montoro, Domenico Licchelli, Alex Escartin Perez, Carlos Perelló Perez, Marc Deldem, Stephen R.L. Futcher, Tim Nelson, Shawn Dvorak, Dawid Moździerski, Nick Quinn, Krzysztof Kotysz, Katarzyna Kowalska, Przemysław Mikołajczyk, George Fleming, Mark Phillips, Tony Vale, Franky Dubois, Ludwig Logie, et al. (18 additional authors not shown)

Comments: 27 pages, 17 figures, accepted by MNRAS, full version with full appendix available at this http URL

Subjects: Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

• New submissions
• Cross-lists
• Replacements