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Astrophysics

New submissions

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New submissions for Mon, 25 May 20

[1]  arXiv:2005.10838 [pdf, other]
Title: Chandra and XMM-Newton observations of A2256: cold fronts, merger shocks, and constraint on the IC emission
Comments: 12 pages, 10 figures, submitted to MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE)

We present the results of deep Chandra and XMM-Newton observations of a complex merging galaxy cluster Abell 2256 (A2256) that hosts a spectacular radio relic. The temperature and metallicity maps show clear evidence of a merger between the western subcluster and the primary cluster. We detect five X-ray surface brightness edges. Three of them near the cluster center are cold fronts (CFs): CF1 is associated with the infalling subcluster; CF2 is located in the east of the primary cluster and CF3 is to the west of the primary cluster core. The other two edges at cluster outskirts are shock fronts (SFs): SF1 near the radio relic in the NW has Mach numbers derived from the temperature and the density jumps respectively of $M_T=1.62\pm0.12$ and $M_\rho=1.23\pm0.06$; SF2 in the SE has $M_T=1.54\pm0.05$ and $M_\rho=1.16\pm0.13$. In the region of the radio relic there is no evidence for the correlation between X-ray and radio substructures, from which we estimate an upper limit for the inverse Compton emission, and therefore set a lower limit on the magnetic field ($\sim$ 450 kpc from primary cluster center) of $B>1.0\ \mu$G for a single power-law electron spectrum or $B>0.4\ \mu$G for a broken power-law electron spectrum. We propose a merger scenario including a primary cluster, a subcluster, and a group. Our merger scenario accounts for the X-ray edges, diffuse radio features, and galaxy kinematics, as well as projection effects.

[2]  arXiv:2005.10842 [pdf, other]
Title: Magnetic Field Geometry and Composition Variation in Slow Solar Winds: The Case of Sulfur
Comments: 16 pages, 6 figures, accepted to Astrophysical Journal
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We present an examination of the First Ionization Potential (FIP) fractionation scenario invoking the ponderomotive force in the chromosphere, and its implications for the source(s) of slow speed solar winds by using observations from The Advanced Composition Explorer (ACE). Following a recent conjecture that the abundance enhancements of intermediate FIP elements, S, P, and C, in slow solar winds can be explained by the release of plasma fractionated on open fields, though from regions of stronger magnetic field than usually associated with fast solar wind source regions, we identify a period in 2008 containing four solar rotation cycles that show repeated pattern of sulfur abundance enhancement corresponding to a decrease in solar wind speed. We identify the source regions of these slow winds in global magnetic field models and find that they lie at the boundaries between a coronal hole and its adjacent active region, with origins in both closed and open initial field configurations. Based on magnetic field extrapolations, we model the fractionation and compare our results with element abundances measured by ACE to estimate the solar wind contributions from open and closed field, and to highlight potentially useful directions for further work.

[3]  arXiv:2005.10846 [pdf, ps, other]
Title: HD 62542: Probing the Bare, Dense Core of a Translucent Interstellar Cloud
Authors: Daniel E. Welty (1), Paule Sonnentrucker (1), Theodore P. Snow (2), Donald G. York (3) ((1) Space Telescope Science Institute, (2) University of Colorado, (3) University of Chicago)
Comments: accepted to ApJ, 89 pages, 13 tables, 26 figures
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We discuss the interstellar absorption from many atomic and molecular species seen in high-resolution $HST$/STIS UV and high-S/N optical spectra of the moderately reddened B3-5~V star HD~62542. This remarkable sight line exhibits both very steep far-UV extinction and a high fraction of hydrogen in molecular form -- with strong absorption from CH, C$_2$, CN, and CO, but weak absorption from CH$^+$ and most of the commonly observed diffuse interstellar bands. Most of the material resides in a single narrow velocity component -- offering a rare opportunity to probe the primarily molecular core of a single interstellar cloud with little associated diffuse atomic gas. Detailed analyses of the spectra indicate that: (1) the molecular fraction in the main cloud is high [$f$(H$_2$) $>$ 0.8]; (2) the gas is fairly cold ($T_{\rm k}$ = 40--43 K, from the rotational excitation of H$_2$ and C$_2$); (3) the local hydrogen density $n_{\rm H}$ $\sim$ 1500 cm$^{-3}$ (from the C$_2$ excitation, the fine-structure excitation of C$^0$, and simple chemical models); (4) the unusually high excitation temperatures for $^{12}$CO and $^{13}$CO may be largely due to radiative excitation; (5) $N$(C$^+$):$N$(CO):$N$(C) $\sim$ 100:10:1; (6) the depletions of many elements are more severe than those seen in any other sight line, and the detailed pattern of depletions differs from those derived from larger samples of Galactic sight lines; and (7) the various neutral/first ion ratios do not yield consistent estimates for the electron density, even when the effects of grain-assisted recombination and low-temperaure dielectronic recombination are considered.

[4]  arXiv:2005.10868 [pdf, other]
Title: Giant planet formation at the pressure maxima of protoplanetary disks II. A hybrid accretion scenario
Comments: Submitted to Astronomy & Astrophysics. Comments are welcome
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

Recent observations of protoplanetary disks have revealed ring-like structures that can be associated to pressure maxima. Pressure maxima are known to be dust collectors and planet migration traps. Most of planet formation works are based either on the pebble accretion model or on the planetesimal accretion model. However, recent studies proposed the possible formation of Jupiter by the hybrid accretion of pebbles and planetesimals. We aim to study the full process of planet formation consisting of dust evolution, planetesimal formation and planet growth at a pressure maximum in a protoplanetary disk. We compute, through numerical simulations, the gas and dust evolution, including dust growth, fragmentation, radial drift and particle accumulation at a pressure bump. We also consider the formation of planetesimals by streaming instability and the formation of a moon-size embryo that grows into a giant planet by the hybrid accretion of pebbles and planetesimals. We find that pressure maxima in protoplanetary disks are efficient collectors of dust drifting inwards. The condition of planetesimal formation by streaming instability is fulfilled due to the large amount of dust accumulated at the pressure bump. Then, a massive core is quickly formed (in $\sim 10^4$ yr) by the accretion of pebbles. After the pebble isolation mass is reached, the growth of the core slowly continues by the accretion of planetesimals. The energy released by planetesimal accretion delays the onset of runaway gas accretion, allowing a gas giant to form after $\sim$1 Myr of disk evolution. The pressure maximum also acts as a migration trap. Pressure maxima in protoplanetary disks are preferential locations for dust traps, planetesimal formation by streaming instability and planet migration traps. All these conditions allow the fast formation of a giant planet by the hybrid accretion of pebbles and planetesimals.

[5]  arXiv:2005.10896 [pdf, other]
Title: Possible Interstellar meteoroids detected by the Canadian Meteor Orbit Radar
Comments: 74 pages, 23 figures, 11 figures, 12 appendix figures, 1 appendix table
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We examine meteoroid orbits recorded by the Canadian Meteor Orbit Radar (CMOR) from 2012-2019, consisting of just over 11 million orbits in a search for potential interstellar meteoroids. Our 7.5 year survey consists of an integrated time-area product of $\sim$ 7$\times$ 10$^6$ km$^2$ hours. Selecting just over 160000 six station meteor echoes having the highest measured velocity accuracy from within our sample, we found five candidate interstellar events. These five potential interstellar meteoroids were found to be hyperbolic at the 2$\sigma$-level using only their raw measured speed. Applying a new atmospheric deceleration correction algorithm developed for CMOR, we show that all five candidate events were likely hyperbolic at better than 3$\sigma$, the most significant being a 3.7$\sigma$ detection. Assuming all five detections are true interstellar meteoroids, we estimate the interstellar meteoroid flux at Earth to be at least 6.6 $\times$ 10$^{-7}$ meteoroids/km$^{2}$/hr appropriate to a mass of 2 $\times$ 10$^{-7}$kg.
Using estimated measurement uncertainties directly extracted from CMOR data, we simulated CMOR's ability to detect a hypothetical 'Oumuamua - associated hyperbolic meteoroid stream. Such a stream was found to be significant at the 1.8$\sigma$ level, suggesting that CMOR would likely detect such a stream of meteoroids as hyperbolic. We also show that CMOR's sensitivity to interstellar meteoroid detection is directionally dependent.

[6]  arXiv:2005.10901 [pdf, other]
Title: Self-consistent method to extract non-linearities from pulsating stars light curves I. Combination frequencies
Comments: 10 pages, 4 figures. Submitted to MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Combination frequencies are not solutions of the perturbed stellar structure equations. In dense power spectra from a light curve of a given multi-periodic pulsating star, they can compromise the mode identification in an asteroseismic analysis, hence they must be treated as spurious frequencies and conveniently removed. In this paper, a method based on fitting the set of frequencies that best describe a general non-linear model, like the Volterra series, is presented. The method allows to extract these frequencies from the power spectrum, so helping to improve the frequency analysis enabling hidden frequencies to emerge from the initially considered as noise. Moreover, the method yields frequencies with uncertainties several orders of magnitude smaller than the Rayleigh dispersion, usually taken as the present error in a standard frequency analysis. Furthermore, it is compatible with the classical counting cycles method, the so-called O-C method, which is valid only for mono-periodic stars. The method opens the possibility to characterise the non-linear behaviour of a given pulsating star by studying in detail the complex generalised transfer functions.

[7]  arXiv:2005.10924 [pdf, other]
Title: Spectral Characteristics and Formation Height of Off-Limb Flare Ribbons
Comments: 18 pages, 10 figures, accepted in ApJ
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

Flare ribbons are bright manifestations of flare energy dissipation in the lower solar atmosphere. For the first time, we report on high-resolution imaging spectroscopy observations of flare ribbons situated off-limb in the H$\beta$ and Ca II 8542 {\AA} lines and make a detailed comparison with radiative hydrodynamic simulations. Observations of the X8.2-class solar flare SOL2017-09-10T16:06 UT obtained with the Swedish Solar Telescope reveal bright horizontal emission layers in H$\beta$ line wing images located near the footpoints of the flare loops. The apparent separation between the ribbon observed in the H$\beta$ wing and the nominal photospheric limb is about 300 - 500 km. The Ca II 8542 {\AA} line wing images show much fainter ribbon emissions located right on the edge of the limb, without clear separation from the limb. RADYN models are used to investigate synthetic spectral line profiles for the flaring atmosphere, and good agreement is found with the observations. The simulations show that, towards the limb, where the line of sight is substantially oblique with respect to the vertical direction, the flaring atmosphere model reproduces the high contrast of the off-limb H$\beta$ ribbons and their significant elevation above the photosphere. The ribbons in the Ca II 8542 {\AA} line wing images are located deeper in the lower solar atmosphere with a lower contrast. A comparison of the height deposition of electron beam energy and the intensity contribution function shows that the H$\beta$ line wing intensities can be an useful tracer of flare energy deposition in the lower solar atmosphere

[8]  arXiv:2005.10945 [pdf, other]
Title: New Grids of Pure-Hydrogen White-Dwarf NLTE Model Atmospheres \newline and the HST/STIS Flux Calibration
Comments: 14 figures
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); Astrophysics of Galaxies (astro-ph.GA); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Non-local Thermodynamic Equilibrium (NLTE) calculations of hot white dwarf (WD) model atmospheres are the cornerstone of modern flux calibrations for the Hubble Space Telescope (HST) and for the CALSPEC database. These theoretical spectral energy distributions (SEDs) provide the relative flux vs. wavelength, and only the absolute flux level remains to be set by reconciling the measured absolute flux of Vega in the visible with the Midcourse Space Experiment (MSX) values for Sirius in the mid-IR. The most recent SEDs calculated by the \textsc{tlusty} and \textsc{tmap} NLTE model atmosphere codes for the primary WDs G191-B2B, GD153, and GD71 show improved agreement to 1\% from 1500~\AA\ to 30~\micron, in comparison to the previous 1\% consistency only from 2000~\AA\ to 5~\micron. These new NLTE models of hot WDs now provide consistent flux standards from the FUV to the mid-IR.

[9]  arXiv:2005.10950 [pdf, other]
Title: Imaging the 511 keV positron annihilation sky with COSI
Comments: 24 pages, 21 figures, accepted by ApJ
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Data Analysis, Statistics and Probability (physics.data-an)

The balloon-borne Compton Spectrometer and Imager (COSI) had a successful 46-day flight in 2016. The instrument is sensitive to photons in the energy range $0.2$-$5$ MeV. Compton telescopes have the advantage of a unique imaging response and provide the possibility of strong background suppression. With its high-purity germanium detectors, COSI can precisely map $\gamma$-ray line emission. The strongest persistent and diffuse $\gamma$-ray line signal is the 511 keV emission line from the annihilation of electrons with positrons from the direction of the Galactic centre. While many sources have been proposed to explain the amount of positrons, $\dot{N}_{\mathrm{e^+}} \sim 10^{50}\,\mathrm{e^+\,yr^{-1}}$, the true contributions remain unsolved. In this study, we aim at imaging the 511 keV sky with COSI and pursue a full-forward modelling approach, using a simulated and binned imaging response. For the strong instrumental background, we describe an empirical approach to take the balloon environment into account. We perform two alternative methods to describe the signal: Richardson-Lucy deconvolution, an iterative method towards the maximum likelihood solution, and model fitting with pre-defined emission templates. Consistently with both methods, we find a 511 keV bulge signal with a flux between $0.9$ and $3.1 \times 10^{-3}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$, confirming earlier measurements, and also indications of more extended emission. The upper limit we find for the 511 keV disk, $< 4.3 \times 10^{-3}\,\mathrm{ph\,cm^{-2}\,s^{-1}}$, is consistent with previous detections. For large-scale emission with weak gradients, coded aperture mask instruments suffer from their inability to distinguish isotropic emission from instrumental background, while Compton-telescopes provide a clear imaging response, independent of the true emission.

[10]  arXiv:2005.10958 [pdf, other]
Title: Recurring Outbursts of P/2019 LM$_4$ (Palomar)
Comments: Submitted to RNAAS
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We present a preliminary analysis of comet P/2019 LM$_4$ (Palomar) as observed by the Zwicky Transient Facility (ZTF) survey in 2019 and 2020. We find that the discovery of the comet in 2019 and the recovery in 2020 is largely attributed to two separate outbursts that are $\gtrsim2$ and $\gtrsim3.9$ mag in strength. The outbursts occurred around the end of April to early May of 2019 as well as between 2020 May 8.31 and 9.52 UTC, respectively.

[11]  arXiv:2005.10959 [pdf, other]
Title: K2-HERMES II. Planet-candidate properties from K2 Campaigns 1-13
Comments: Accepted for publication in MNRAS. Full versions of online-only Tables 2 and 3 available on request. Same for Table 4, in exchange for the trick to make MNRAS style break long tables across pages
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

Accurate and precise radius estimates of transiting exoplanets are critical for understanding their compositions and formation mechanisms. To know the planet, we must know the host star in as much detail as possible. We present complete results for planet-candidate hosts from the K2-HERMES survey, which uses the HERMES multi-object spectrograph on the Anglo-Australian Telescope to obtain R$\sim$28,000 spectra for more than 30,000 K2 stars. We present complete host-star parameters and planet-candidate radii for 224 K2 candidate planets from C1-C13. Our results cast severe doubt on 30 K2 candidates, as we derive unphysically large radii, larger than 2 $R_{Jup}$. This work highlights the importance of obtaining accurate, precise, and self-consistent stellar parameters for ongoing large planet search programs - something that will only become more important in the coming years, as TESS begins to deliver its own harvest of exoplanets.

[12]  arXiv:2005.10974 [pdf, other]
Title: The Preservation of Super Earths and the Emergence of Gas Giants after Their Progenitor Cores have Entered the Pebble Isolation Phase
Comments: 23 pages, 10 figures, accepted by ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

The omnipresence of super-Earths suggests that they are able to be retained in natal disks around low-mass stars, whereas exoplanets' mass distribution indicates that some cores have transformed into gas giants through runaway gas accretion at 1AU from solar-type stars. In this paper, we show that transition to runaway gas accretion by cores may be self-impeded by an increase of the grain opacity in their envelope after they have acquired sufficient mass (typically 10Mearth) to enter a pebble-isolation phase. The accumulation of mm-m size pebbles in their migration barriers enhances their local fragmentation rates. The freshly produced sub-mm grains pass through the barrier, elevate the effective dust opacity and reduce the radiative flux in the cores envelope. These effects alone are adequate to suppress the transition to runaway accretion and preserve super-Earths in the stellar proximity (0.1 AU), albeit entropy advection between the envelope and the disk can further reduce the accretion rate. At intermediate distance (1AU) from their host stars, the escalation in the dust opacity dominates over entropy advection in stalling the transition to runaway accretion for marginally pebble-isolated cores. Beyond a few AU, the transformation of more massive cores to gas giants is reachable before severe depletion of disk gas. This requirement can be satisfied either in extended disks with large scale height via orderly accretion of migrating pebbles or through the mergers of oligarchic protoplanetary embryos, and can account for the correlated occurrence of long-period gas giants and close-in super-Earths.

[13]  arXiv:2005.11027 [pdf, ps, other]
Title: Neon Abundances of B-stars in the Solar Neighborhood
Comments: 20 pages, 9 figures, accepted to Astrophysical Journal
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We constructed a comprehensive model atom for NeI -- NeII using the most up-to-date atomic data available and evaluated the non-local thermodynamic equilibrium (NLTE) line formation for NeI and NeII in classical 1D models representing the atmospheres of B-type stars. We find that the large NLTE strengthening of the NeI lines corresponding to the 2p$^5$3p $-$ 2p$^5$3s transitions array occurs due to extremely small photoionization cross-sections of 2p$^5$3s levels that leads to strong overpopulation of these levels relative to their LTE populations. The deviations from LTE for the most NeII lines are small and do not exceed 0.11~dex in the absolute value. We analysed 20 lines of NeI and 13 lines of NeII for twenty-four B-type stars in the temperature range of 10\,400 $\le$ \Teff\ $\le$ 33\,400~K. For five stars, the NLTE leads to consistent abundances of NeI and NeII, while the difference in LTE abundance can reach up to 0.50~dex. The using of the experimental oscillator strengths recently measured by Piracha et al. (2015) leads to smaller line-by-line scatter for the most investigated stars. The averaged neon abundance in twenty-four B-type stars in solar neighborhood is 8.02$\pm$0.05. This value may provide indirect constraints on solar photospheric neon abundance.

[14]  arXiv:2005.11066 [pdf, other]
Title: Applying saliency-map analysis in searches for pulsars and fast radio bursts
Comments: 16 pages, 6 figures, accepted for publication in A&A
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)

To investigate the use of saliency-map analysis to aid in searches for transient signals, such as fast radio bursts and individual pulses from radio pulsars. We aim to demonstrate that saliency maps provide the means to understand predictions from machine learning algorithms and can be implemented in piplines used to search for transient events. We have implemented a new deep learning methodology to predict whether or not any segment of the data contains a transient event. The algorithm has been trained using real and simulated data sets. We demonstrate that the algorithm is able to identify such events. The output results are visually analysed via the use of saliency maps. We find that saliency maps can produce an enhanced image of any transient feature without the need for de-dispersion or removal of radio frequency interference. Such maps can be used to understand which features in the image were used in making the machine learning decision and to visualise the transient event. Even though the algorithm reported here was developed to demonstrate saliency-map analysis, we have detected, in archival data, a single burst event with dispersion measure of $41$\,cm$^{-3}$pc that is not associated with any currently known pulsar.

[15]  arXiv:2005.11069 [pdf, other]
Title: Non-minimally coupled curvaton
Comments: 45 pages, 4 figures
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc); High Energy Physics - Theory (hep-th)

We investigate two-field inflationary models in which scalar cosmological pertubations are generated via a spectator field nonminimally coupled to gravity, with the particular emphasis on curvaton scenarios. The principal advantage of these models is in the possibility to tune the spectator spectral index via the nonminimal coupling. Our models naturally yield red spectrum of the adiabatic perturbation demanded by observations. We study how the nonminimal coupling affects the spectrum of the curvature perturbation generated in the curvaton scenarios. In particular we find that for small, negative nonminimal couplings the spectral index gets a contribution that is negative and linear in the nonminimal coupling. Since in this way the curvature spectrum becomes redder, some of curvaton scenarios can be saved, which would otherwise be ruled out. In the power law inflation we find that a large nonminimal coupling is excluded since it gives the principal slow roll parameter that is of the order of unity. Finally, we point out that nonminimal coupling can affect the postinflationary growth of the spectator perturbation, and in this way the effectiveness of the curvaton mechanism.

[16]  arXiv:2005.11071 [pdf, ps, other]
Title: Identification of a non-thermal X-ray burst with the Galactic magnetar SGR 1935+2154 and a fast radio burst with Insight-HXMT
Comments: 24 pages, 10 figures, Submitted to Nature on May 9th, 2020. Subject to press embargo until date TBA
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)

Fast radio bursts (FRBs) are short pulses observed in radio band from cosmological distances, some of which emit repeating bursts. The physical origins of these mysterious events have been subject to wide speculations and heated debates. One class of models invoke soft gamma-ray repeaters (SGRs), or magnetars, as the sources of FRBs. Magnetars are rotating neutron stars with extremely strong magnetic field and can sporadically emit bursts from X-ray ($\sim$keV) to soft gamma-ray ($\sim$sub-MeV) with duration from $10^{-2}$~s to $10^2$~s. However, even though some bright radio bursts have been observed from some magnetars, no FRB-like events had been detected to be associated with any magnetar burst, including one giant flare, and no radio burst has been associated with any X-ray event from any magnetar. Therefore, there is still no observational evidence for magnetar-FRB association up to today. Recently, a pair of FRB-like bursts (FRB~200428 hereafter) separated by 30 milliseconds (ms) were detected from the general direction of the Galactic magnetar SGR~J1935+2154. Here we report the detection of a non-thermal X-ray burst in the 1-250 keV energy band with the Insight-HXMT satellite, which we identify as emitted from SGR~J1935+2154. The burst showed two hard peaks with a separation of $\sim30$ ms, consistent with the separation between the two bursts in FRB~200428. The delay time between the double radio and X-ray peaks is $\sim8.57$ s, fully consistent with the dispersion delay of FRB~200428. We thus identify the non-thermal X-ray burst is associated with FRB~200428 whose high energy counterpart is the two hard peaks in X-ray. Our results suggest that the non-thermal X-ray burst and FRB~200428 share the same physical origin in an explosive event from SGR~J1935+2154.

[17]  arXiv:2005.11076 [pdf, other]
Title: Following up the afterglow: strategy for X-ray observation triggered by gravitational wave events
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The multi-messenger observation of compact binary coalescence promises great scientific treasure. However, a synthetic observation from both gravitational wave and electromagnetic channels remains challenging. Relying on the day-to-week long macronova emission, GW170817 remains the only event with successful electromagnetic followup. In this manuscript, we explore the possibility of using the early stage X-ray afterglow to search for the electromagnetic counterpart of gravitational wave events. Two algorithms, the sequential observation and the local optimization are considered and applied to three simulated events. We consider the proposed Einstein probe as a candidate X-ray telescope. Benefiting from the large field of view and high sensitivity, we find that the sequential observation algorithm not only is easy to implement, but also promises a good chance of actual detection.

[18]  arXiv:2005.11078 [pdf, other]
Title: The Mean Absorption Line Spectra of a Selection of Luminous z~6 Lyman Break Galaxies
Comments: 12 pages, 9 figures, 3 tables, submitted to the Astrophysical Journal
Subjects: Astrophysics of Galaxies (astro-ph.GA)

We examine the absorption line spectra of a sample of 31 luminous (M_UV~-23) Lyman break galaxies at redshift z~6 using data taken with the FOCAS and OSIRIS spectrographs on the Subaru and GTC telescopes. For two of these sources we present longer exposure data taken at higher spectral resolution from ESO's X-shooter spectrograph. Using these data, we demonstrate the practicality of stacking our lower resolution data to measure the depth of various interstellar and stellar absorption lines to probe the covering fraction of low ionization gas and the gas-phase and stellar metallicities near the end of the era of cosmic reionization. From maximum absorption line depths of SiII1260 and CII1334, we infer a mean covering fraction of >0.85 +/-0.16 for our sample. This is larger than that determined using similar methods for lower luminosity galaxies at slightly lower redshifts, suggesting luminous galaxies do not play a prominent role in concluding reionization. Using various interstellar absorption lines we deduce gas-phase metallicities close to solar indicative of substantial early enrichment. Using selected stellar absorption lines, we model our spectra with a range of metallicities using techniques successfully employed at lower redshift and deduce a stellar metallicity of 0.4 +0.3/-0.1 solar, consistent with the stellar mass - stellar metallicity relation recently found at z~3-5. We discuss the implications of these metallicity estimates for the typical ages of our luminous galaxies and conclude our results imply initial star formation at redshifts z~10, consistent with independent analyses of earlier objects.

[19]  arXiv:2005.11089 [pdf, other]
Title: A new study of the spectroscopic binary 7 Vul with a Be star primary
Comments: 17 pages, 23 figures, accepted for publication in Astronomy and Astrophysics
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

We confirmed the binary nature of the Be star 7~Vul, derived a~more accurate spectroscopic orbit with an orbital period of (69.4212+/-0.0034) d, and improved the knowledge of the basic physical elements of the system. Analyzing available photometry and the strength of the \ha emission, we also document the long-term spectral variations of the Be primary. In addition, we confirmed rapid light changes with a~period of 0.5592 d, which is comparable to the expected rotational period of the Be primary, but note that its amplitude and possibly its period vary with time. We were able to disentangle only the He I 6678 A line of the secondary, which could support our tentative conclusion that the secondary appears to be a hot subdwarf. A search for this object in high-dispersion far-UV spectra could provide confirmation. Probable masses of the binary components are ($6\pm1$)~Mnom \ and ($0.6\pm0.1$)~Mnom. If the presence of a hot subdwarf is firmly confirmed, 7 Vul might be identified as a rare object with a B4-B5 primary; all Be + hot subdwarf systems found so far contain B0-B3 primaries.

[20]  arXiv:2005.11099 [pdf, other]
Title: Cosmic Rays and Spectral Distortions from Collapsing Textures
Authors: Robert Brandenberger, Bryce Cyr, Hao Jiao (McGill University and USTC)
Comments: 7 pages
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 compute the energy spectrum of photons produced by the unwinding of a scaling distribution of cosmic textures, and discuss the implications for the spectrum of high energy cosmic rays, and for CMB spectral distortions. Textures lead to a contribution to the photon flux which scales as $E^3 F(E) \sim E^{3/2}$. Hence, the tightest constraints on the texture model come from the highest energies from which primordial photons can reach us without being scattered by the CMB and other foregrounds. Textures lead to both $\mu$ type and $y$ type distortions. While the constraints on the texture model coming from the current COBE bounds are weaker than the bounds from the angular power spectrum of the CMB, future surveys such as PIXIE can lead to stronger bounds.

[21]  arXiv:2005.11109 [pdf, ps, other]
Title: On the Distance of SGR 1935+2154 Associated with FRB 200428
Comments: 7 pages in emulateapj format, 3 figures
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Owing to the detection of an extremely bright fast radio burst (FRB) 200428 from SGR 1935+2154 associated with a hard X-ray counterpart, the distance of SGR 1935+2154 potentially hosted in the supernova remnant (SNR) G57.2+0.8 can be revisited. Under the assumption that the SGR and the SNR are realistically related, in this Letter, we investigate the dispersion measure (DM) of this radio burst contributed by the foreground medium of our Galaxy and the local environments including a magnetar wind nebula and SNR, and by combining the current observational results about the SGR and SNR, we find that the distance is in a narrow range of $9.06$ to $9.11$\,kpc and the SNR radius falls into $14.5-14.6$\,pc since the local DM contribution is as low as $0-5$\,pc cm$^{-3}$. These results are basically consistent with the previous studies but appear to be more constrained. Additionally, the study for the Faraday rotation measure of the SGR and SNR is also available.

[22]  arXiv:2005.11118 [pdf, other]
Title: Supermassive Binary Black Hole Evolution can be traced by a small SKA Pulsar Timing Array
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

Supermassive black holes are commonly found in the center of galaxies and evolve with their hosts. The supermassive binary black holes (SMBBH) are thus expected to exist in close galaxy pairs, however, none has been unequivocally detected. The square kilometre array (SKA) is a multi-purpose radio telescope with a collecting area approaching 1 million square metres, with great potential for detecting nanohertz gravitational waves (GWs). In this paper, we quantify the GW detectability by SKA for a realistic SMBBH population using pulsar timing array (PTA) technique and quantify its impact on revealing SMBBH evolution with redshift for the first time. With only $\sim20$ pulsars, much smaller a requirement than in previous work, the SKA PTA is expected to obtain detection within about 5 years of operation and to achieve a detection rate of more than 100 SMBBHs/yr after about 10 years. Although beyond the scope of this paper, we must acknowledge that the presence of persistent red noise will reduce the number of expected detections here. It is thus imperative to understand and mitigate red noise in the PTA data. The GW signatures from a few well-known SMBBH candidates, such as OJ 287, 3C 66B, NGC 5548 and Ark 120, will be detected given the currently best-known parameters of each system. Within 30 years of operation, about 60 individual SMBBHs detection with $z<0.05$ and more than $10^4$ with $z<1$ are expected. The detection rate drops precipitately beyond $z=1$ and completely cuts off at $z > 2$, primarily due to their expected long orbital periods. The substantial number of expected detections and their discernible evolution with redshift by SKA PTA will make SKA a significant tool for studying SMBBHs.

[23]  arXiv:2005.11136 [pdf, other]
Title: Wavelet analysis of the long-term activity of V833 Tau
Comments: accepted in MNRAS
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)

The bulk of available stellar activity observations is frequently checked for the manifestation of signs in comparison with the known characteristic of solar magnetic modulation. The problem is that stellar activity records are usually an order of magnitude shorter than available observations of solar activity variation. Therefore, the resolved time scales of stellar activity are insufficient to decide reliably that a cyclic variation for a particular star is similar to the well-known 11-yr sunspot cycles. As a result, recent studies report several stars with double or multiple cycles which serve to challenge the underlying theoretical understanding. This is why a consistent method to separate 'true' cycles from stochastic variations is required. In this paper, we suggest that a conservative method, based on the best practice of wavelet analysis previously applied to the study of solar activity, for studying and interpreting the longest available stellar activity record - photometric monitoring of V833 Tau for more than 100 years. We find that the observed variations of V833 Tau with timescales of 2-50 yr should be comparable with the known quasi-periodic solar mid-term variations, whereas the true cycle of V833 Tau, if it exists, should be of about a century or even longer. We argue that this conclusion does not contradict the expectations from stellar dynamo theory.

[24]  arXiv:2005.11143 [pdf]
Title: Photometric observations of ecliptic comet 47P/Ashbrook-Jackson and selected quasi-Hilda and main-belt comets at Kyiv Comet Station (MPC code - 585) in 2017
Comments: 14 pages, 1 figures, 2 tables
Journal-ref: Icarus, Volume 317, 1 January 2019, Pages 44-47
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We present an analysis of the photometric data of comets 47P/Ashbrook -Jackson, 65P/Gunn, 362P/2008 GO98, and P/2017 S5 (ATLAS) observed at Kyiv Comet Station (MPC code - 585) in 2017. The upper limits of radii for cometary nuclei, Afrho parameters, and color-indexes are measured.

[25]  arXiv:2005.11178 [pdf, other]
Title: A peculiar hard X-ray counterpart of a Galactic fast radio burst
Comments: 25 pages, 6 figures, 3 tables. Submitted to Nature
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

Fast radio bursts are bright, millisecond-scale radio flashes of yet unknown physical origin. Recently, their extragalactic nature has been demonstrated, and an increasing number of the sources have been found to repeat. Young, highly magnetized, isolated neutron stars - magnetars - have been suggested as the most promising candidates for fast radio burst progenitors owing to their energetics and high X-ray flaring activity. Here we report the detection with the Konus-Wind detector of a hard X-ray event of April 28, 2020, temporarily coincident with a bright, two-peak radio burst with properties remarkably similar to those of fast radio bursts. The source of the radio burst is located in the direction to the Galactic magnetar SGR 1935+2154, which recently entered an active state. We show that a separation between two peaks of the double-peaked X-ray burst is nearly the same as that of the radio peaks, confirming that the X-ray and radio emission most likely have a common origin. Thus, this is the first simultaneous detection of a fast radio burst from a Galactic magnetar and its high-energy counterpart. The total energy emitted in X-rays in this burst is typical of bright short magnetar bursts, but its spiky light curve and an unusual hardness of the energy spectrum distinguish the April 28 event among multiple 'ordinary' flares detected from SGR 1935+2154 previously. This, and a recent non-detection of radio emission from two typical bright soft bursts from the same magnetar, may imply the existence of a special class of magnetar flares capable of producing fast radio bursts.

[26]  arXiv:2005.11208 [pdf, other]
Title: Fermi Large Area Telescope Fourth Source Catalog Data Release 2
Authors: J. Ballet, T.H. Burnett, S.W. Digel, B. Lott (for the Fermi-LAT collaboration)
Comments: data files at this https URL
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

We present an incremental version (4FGL-DR2, for Data Release 2) of the fourth Fermi-LAT catalog of gamma-ray sources. Based on the first ten years of science data in the energy range from 50 MeV to 1 TeV, it uses the same analysis methods as the 4FGL catalog did for eight years of data. The spectral parameters, spectral energy distributions and associations are updated for all sources. Light curves are rebuilt for all sources with 1-year intervals (not 2-month intervals). Among the 5064 4FGL sources, 120 are formally below the detection threshold over 10 years (but are kept in the list), while 40 are newly associated. We report 723 new sources, mostly just above the detection threshold, among which two are considered identified and 342 have a plausible counterpart at other wavelengths.

[27]  arXiv:2005.11209 [pdf, other]
Title: Tidal Inflation Reconciles Low-Density Sub-Saturns with Core Accretion
Comments: Accepted for publication in ApJ, 17 pages, 8 figures. Code available at this URL: this https URL
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

While the Solar System contains no planets between the sizes of Uranus and Saturn, our current exoplanet census includes several dozen such planets with well-measured masses and radii. These sub-Saturns exhibit a diversity of bulk densities, ranging from ~$0.1-3\ \rm{g\ cm}^{-3}$. When modeled simply as hydrogen/helium envelopes atop rocky cores, this diversity in densities translates to a diversity in planetary envelope fractions, $f_\rm{env}=M_\rm{env}/M_p$ ranging from ~$10\%$ to ~$50\%$. Planets with $f_\rm{env}\sim50\%$ pose a challenge to traditional models of giant planet formation by core-nucleated accretion, which predict the onset of runaway gas accretion when $M_\rm{env}\sim M_\rm{core}$. Here we show that many of these apparent $f_\rm{env}\sim50\%$ planets are less envelope rich than they seem, after accounting for tidal heating. We present a new framework for modeling sub-Saturn interiors that incorporates envelope inflation due to tides, which are driven by the observed non-zero eccentricities, as well as potential obliquities. Consequently, when we apply our models to known sub-Saturns, we infer lower $f_\rm{env}$ than tides-free estimates. We present a case study of K2-19 b, a moderately eccentric sub-Saturn. Neglecting tides, K2-19 b appears to have $f_\rm{env}\sim50\%$, poised precariously near the runaway threshold; by including tides, we find $f_\rm{env}\sim10\%$, resolving the tension. Through a systematic analysis of $4-8\ R_{\oplus}$ planets, we find that most (but not all) of the similarly envelope-rich planets have more modest envelopes of $f_\rm{env}\sim10\%-20\%$. Thus, many sub-Saturns may be understood as sub-Neptunes that have undergone significant radius inflation, rather than a separate class of objects. Tidal radius inflation likely plays an important role in other size classes of planets including ultra-low-density Jupiter-size planets like WASP-107 b.

[28]  arXiv:2005.11215 [pdf, other]
Title: Galaxy And Mass Assembly (GAMA): Assimilation of KiDS into the GAMA database
Comments: 23 pages, 18 figures, accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)

The Galaxy And Mass Assembly Survey (GAMA) covers five fields with highly complete spectroscopic coverage ($>95$ per cent) to intermediate depths ($r<19.8$ or $i < 19.0$ mag), and collectively spans 250 square degrees of Equatorial or Southern sky. Four of the GAMA fields (G09, G12, G15 and G23) reside in the ESO VST KiDS and ESO VISTA VIKING survey footprints, which combined with our GALEX, WISE and Herschel data provide deep uniform imaging in the $FUV\,NUV\,ugriZYJHK_s\,W1\,W2\,W3\,W4\,P100\,P160\,S250\,S350\,S500$ bands. Following the release of KiDS DR4, we describe the process by which we ingest the KiDS data into GAMA (replacing the SDSS data previously used for G09, G12 and G15), and redefine our core optical and near-IR catalogues to provide a complete and homogeneous dataset. The source extraction and analysis is based on the new ProFound image analysis package, providing matched-segment photometry across all bands. The data are classified into stars, galaxies, artefacts, and ambiguous objects, and objects are linked to the GAMA spectroscopic target catalogue. Additionally, a new technique is employed utilising ProFound to extract photometry in the unresolved MIR-FIR regime. The catalogues including the full FUV-FIR photometry are described and will be fully available as part of GAMA DR4. They are intended for both standalone science, selection for targeted follow-up with 4MOST, as well as an accompaniment to the upcoming and ongoing radio arrays now studying the GAMA $23^h$ field.

[29]  arXiv:2005.11219 [pdf, other]
Title: A Physical Background Model for the Fermi Gamma-ray Burst Monitor
Comments: Accepted for publication in A&A, 15 pages, 22 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); High Energy Astrophysical Phenomena (astro-ph.HE)

We present the first physically motivated background model for the Gamma-Ray Burst Monitor (GBM) onboard the Fermi satellite. Such a physically motivated background model has the potential to significantly improve the scientific output of Fermi/GBM, as it can be used to improve the background estimate for spectral analysis and localization of Gamma-Ray Bursts (GRBs) and other sources. Additionally, it can also lead to detections of new transient events, since long/weak or slowly rising ones do not activate one of the existing trigger algorithms. In this paper we show the derivation of such a physically motivated background model, which includes the modeling of the different background sources and the correct handling of the response of GBM. While the goal of the paper is to introduce the model rather than developing a transient search algorithm, we demonstrate the ability of the model to fit the background seen by GBM by showing four applications, namely (1) for a canonical GRB, (2) for the ultra-long GRB 091024, (3) for the V404 Cygni outburst in June 2015, and (4) the ultra-long GRB 130925A.

[30]  arXiv:2005.11260 [pdf, other]
Title: Cradle(s) of the Sun
Comments: 19 pages, 7 figures, accepted by ApJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Astrophysics of Galaxies (astro-ph.GA); Solar and Stellar Astrophysics (astro-ph.SR)

The Sun likely formed as part of a group of stars. A close stellar flyby by one of the solar siblings is probably responsible for the sharp outer edge in the solar system`s mass distribution. The frequency of such close flybys can be used to determine the likely type of birth environment of the solar system. Young stellar groups develop very quickly, expanding significantly within just a few Myr. Here we model this strong dynamical development of young stellar groups and determine the resulting close flyby history. We find that solar system equivalents are predominantly produced in areas with stellar densities in the range 5 $\times$ 10$^4$ pc$^{-3}<$ n$_{local} <$ 2 $\times$ 10$^5$pc$^{-3}$. Remarkably we find that only two very distinct types of stellar groups can be considered as serious contestants as the cradle of the Sun -- high-mass, extended associations ($M_c >$ 20 000 $M_{sun}$) and intermediate-mass mass, compact clusters ($M_c <$ 3000 $M_{sun}$). Current day counterparts would be the association NGC 2244 and the M44 cluster, respectively. In these two types of stellar groups, close flybys take place at a sufficiently high rate, while not being too destructive either. A final decision between these two remaining options will require incorporation of constraints from cosmo-chemical studies.

[31]  arXiv:2005.11281 [pdf, ps, other]
Title: Magnetar outburst and spin-down glitch
Authors: H. Tong, L. Huang
Comments: 8 pages, submitted
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)

The outburst and spin-down glitch of magnetars are modeled from the magnetospheric point of view. We try to answer the following four questions: (1) Which pulsar on the period and peirod-derivative diagram are more likely to show magnetar outburst? (2) Which outburst will make the glitch that triggered the outburst to become a spin-down glitch? (3) Can we model the outburst and spin-down glitch in PSR J1119$-$6127 simultaneously? (4) Why the torque variation is delayed compared with the peak of the X-ray luminosity in 1E 1048.1$-$5937 and PSR J1119$-$6127? It is found that both the global and local twisted magnetic field will affect the radiation and timing behaviors of magnetars. Especially, the delay of torque variations may due to the combined effect of increasing twist in the j-bundle and untwisting of the global magnetosphere. A toy model is build for magnetar outburst and torque variations. It can catch the general trend of magnetar outburst: decaying flux, shrinking hot spot, and torque variations.

[32]  arXiv:2005.11293 [pdf, other]
Title: The HST PanCET Program: An Optical to Infrared Transmission Spectrum of HAT-P-32Ab
Comments: 30 pages, 13 figures, accepted for publication in AJ
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)

We present a 0.3-5 micron transmission spectrum of the hot Jupiter HAT-P-32Ab observed with the Space Telescope Imaging Spectrograph (STIS) and Wide Field Camera 3 (WFC3) instruments mounted on the Hubble Space Telescope, combined with Spitzer Infrared Array Camera (IRAC) photometry. The spectrum is composed of 51 spectrophotometric bins with widths ranging between 150 and 400 \AA, measured to a median precision of 215 ppm. Comparisons of the observed transmission spectrum to a grid of 1D radiative-convective equilibrium models indicate the presence of clouds/hazes, consistent with previous transit observations and secondary eclipse measurements. To provide more robust constraints on the planet's atmospheric properties, we perform the first full optical to infrared retrieval analysis for this planet. The retrieved spectrum is consistent with a limb temperature of 1248$\pm$92 K, a thick cloud deck, enhanced Rayleigh scattering, and $\sim$10x solar H2O abundance. We find log($Z/Z_{\odot}$) = 2.41$_{-0.07}^{+0.06}$, in agreement with the mass-metallicity relation derived for the Solar System.

Cross-lists for Mon, 25 May 20

[33]  arXiv:2005.10844 (cross-list from gr-qc) [pdf, other]
Title: Limiting extrinsic curvature theory and stable non-singular anisotropic universe
Comments: 19 pages, 2 figures
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Theory (hep-th)

We propose a class of theories that can limit scalars constructed from the extrinsic curvature. Applied to cosmology, this framework allows us to control not only the Hubble parameter but also anisotropies without the problem of Ostrogradsky ghost, which is in sharp contrast to the case of limiting spacetime curvature scalars. Our theory can be viewed as a generalization of mimetic and cuscuton theories (thus clarifying their relation), which are known to possess a structure that limits only the Hubble parameter on homogeneous and isotropic backgrounds. As an application of our framework, we construct a model where both anisotropies and the Hubble parameter are kept finite at any stage in the evolution of the universe in the diagonal Bianchi type I setup. The universe starts from a constant-anisotropy phase and recovers Einstein gravity at low energies. We also show that the cosmological solution is stable against essentially all modes of perturbation, provided some reasonable conditions are satisfied.

[34]  arXiv:2005.10875 (cross-list from hep-th) [pdf, other]
Title: Field theoretic derivation of bubble wall force
Comments: 64 pages (32 pages main text + 32 pages appendix and references), 15 figures
Subjects: High Energy Physics - Theory (hep-th); Cosmology and Nongalactic Astrophysics (astro-ph.CO); High Energy Physics - Phenomenology (hep-ph)

We derive a general quantum field theoretic formula for the force acting on the expanding bubbles of a first order phase transition in the early Universe setting. In the thermodynamic limit the force is proportional to the entropy increase across the bubble of active species that exert a force on the bubble interface. When local thermal equilibrium is attained, the force grows as the Lorentz factor squared, such that the bubbles cannot run away. We apply our formalism to a massive real scalar field, the standard model and its simple portal extension. Next, we compare with the existing literature. In particular we discuss the differences and similarities of our work with that of B\"odeker and Moore [arXiv:0903.4099]. We find that a bubble can run away if scatterings are negligible across the wall (ballistic limit), but it always attains a finite Lorentz factor if scatterings are efficient across the bubble. For completeness, we also present a derivation of the renormalized, one-loop, thermal energy-momentum tensor for the standard model and demonstrate its gauge independence.

[35]  arXiv:2005.11039 (cross-list from nlin.CD) [pdf, other]
Title: The analysis of periodic orbits generated by Lagrangian solutions of the restricted three-body problem with non-spherical primaries
Journal-ref: New Astronomy, 2020
Subjects: Chaotic Dynamics (nlin.CD); Earth and Planetary Astrophysics (astro-ph.EP)

The present paper deals with the periodic orbits generated by Lagrangian solutions of the restricted three-body problem when both the primaries are oblate bodies. We have illustrated the periodic orbits for different values of $\mu, h,\sigma_1$ and $\sigma_2$ ($h$ is energy constant, $\mu$ mass ratio of the two primaries, $\sigma_1$ and $\sigma_2$ are oblateness factors). These orbits have been determined by giving displacements along the tangent and normal to the mobile coordinates as defined by Karimov and Sokolsky \cite{Kari}. We have applied the predictor-corrector algorithm to construct the periodic orbits in an attempt to unveil the effect of oblateness of the primaries by taking the fixed values of parameters $\mu, h, \sigma_1$ and $\sigma_2$.

[36]  arXiv:2005.11090 (cross-list from gr-qc) [pdf, ps, other]
Title: Super-Penrose process for extremal charged white holes
Authors: O. B. Zaslavskii
Comments: 11 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Theory (hep-th)

We consider collision of two particles 1 and 2 near the horizon of the extremal Reissner-Nordstr\"{o}m (RN) black hole that produce two other particles 3 and 4. There exists such a scenario that both new particles fall in a black hole. One of them emerges from the white hole horizon in the asymptotically flat region, the other one oscillates between turning points. However, the unbounded energies $E$ at infinity (super-Penrose process - SPP) turn out to be impossible for any finite angular momenta $L_{3.4}$. In this sense, the situation for such a white hole scenarios is opposite to the black hole ones, where the SPP is found earlier to be possible for the RN metric even for all $L_{i}=0$. However, if $L_{3,4}$ themselves are unbounded, the SPP does exist for white holes.

[37]  arXiv:2005.11181 (cross-list from physics.space-ph) [pdf, other]
Title: The Electromagnetic Signature of Outward Propagating Ion-Scale Waves
Subjects: Space Physics (physics.space-ph); Solar and Stellar Astrophysics (astro-ph.SR); Plasma Physics (physics.plasm-ph)

First results from the Parker Solar Probe (PSP) mission have revealed ubiquitous coherent ion-scale waves in the inner heliosphere, which are signatures of kinetic wave-particle interactions and fluid-scale instabilities. However, initial studies of the circularly polarized ion-scale waves observed by PSP have only thoroughly analyzed magnetic field signatures, precluding a determination of solar-wind frame propagation direction and intrinsic wave-polarization. A comprehensive determination of wave-properties requires measurements of both electric and magnetic fields. Here, we use full capabilities of the PSP/FIELDS instrument suite to measure both the electric and magnetic components of circularly polarized waves. Comparing spacecraft frame magnetic field measurements with the Doppler-shifted cold-plasma dispersion relation for parallel transverse waves constrains allowable plasma frame polarizations and wave-vectors. We demonstrate that the Doppler-shifted cold-plasma dispersion has a maximum spacecraft frequency $f_{sc}^{*}$ for which intrinsically right-handed fast-magnetosonic waves (FMWs) propagating sunwards can appear left-handed in the spacecraft frame. Observations of left-handed waves with $|f|>f_{sc}^{*}$ are uniquely explained by intrinsically left-handed, ion-cyclotron, waves (ICWs). We demonstrate that electric field measurements for waves with $|f|>f_{sc}^{*}$ are consistent with ICWs propagating away from the sun, verifying the measured electric field. Applying the verified electric field measurements to the full distribution of waves suggests that, in the solar wind frame, the vast majority of waves propagate away from the sun, indicating that the observed population of coherent ion-scale waves contains both intrinsically left and right hand polarized modes.

[38]  arXiv:2005.11261 (cross-list from nlin.CD) [pdf, other]
Title: The analysis of restricted five-body problem within frame of variable mass
Journal-ref: New Astronomy, 2019
Subjects: Chaotic Dynamics (nlin.CD); Earth and Planetary Astrophysics (astro-ph.EP)

In the framework of restricted five bodies problem, the existence and stability of the libration points are explored and analysed numerically, under the effect of non--isotropic mass variation of the fifth body (test particle or infinitesimal body). The evolution of the positions of these points and the possible regions of motion are illustrated, as a function of the perturbation parameter. We perform a systematic investigation in an attempt to understand how the perturbation parameter due to variable mass of the fifth body, affects the positions, movement and stability of the libration points. In addition, we have revealed how the domain of the basins of convergence associated with the libration points are substantially influenced by the perturbation parameter.

[39]  arXiv:2005.11288 (cross-list from gr-qc) [pdf, other]
Title: EinsteinPy: A Community Python Package for General Relativity
Comments: We plan to submit it to A&A. 9 pages
Subjects: General Relativity and Quantum Cosmology (gr-qc); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Instrumentation and Methods for Astrophysics (astro-ph.IM)

This paper presents EinsteinPy (version 0.3), a community-developed Python package for gravitational and relativistic astrophysics. Python is a free, easy to use a high-level programming language which has seen a huge expansion in the number of its users and developers in recent years. Specifically, a lot of recent studies show that the use of Python in Astrophysics and general physics has increased exponentially. We aim to provide a very high level of abstraction, an easy to use interface and pleasing user experience. EinsteinPy is developed keeping in mind the state of a theoretical gravitational physicist with little or no background in computer programming and trying to work in the field of numerical relativity or trying to use simulations in their research. Currently, EinsteinPy supports simulation of time-like and null geodesics and calculates trajectories in different background geometries some of which are Schwarzschild, Kerr, and KerrNewmann along with coordinate inter-conversion pipeline. It has a partially developed pipeline for plotting and visualization with dependencies on libraries like Plotly, matplotlib, etc. One of the unique features of EinsteinPy is a sufficiently developed symbolic tensor manipulation utilities which are a great tool in itself for teaching yourself tensor algebra which for many beginner students can be overwhelmingly tricky. EinsteinPy also provides few utility functions for hypersurface embedding of Schwarzschild spacetime which further will be extended to model gravitational lensing simulation.

Replacements for Mon, 25 May 20

[40]  arXiv:1609.07325 (replaced) [pdf, other]
Title: GaiaNIR: Combining optical and Near-Infra-Red (NIR) capabilities with Time-Delay-Integration (TDI) sensors for a future Gaia-like mission
Comments: 27 Pages
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[41]  arXiv:1904.00120 (replaced) [pdf]
Title: Air-Sea Interactions on Titan: Lake Evaporation, Atmospheric Circulation, and Cloud Formation
Comments: 105 papers, 23 figures; in review at Icarus; new version based on comments from reviewers
Subjects: Earth and Planetary Astrophysics (astro-ph.EP); Atmospheric and Oceanic Physics (physics.ao-ph)
[42]  arXiv:1906.05812 (replaced) [pdf, ps, other]
Title: Type IIn supernova light-curve properties measured from an untargeted survey sample
Comments: Matches journal version. Table 2 on CDS. Durations in Fig. 13 corrected, conclusions unchanged. Abstract abridged. 33 pages, 22 figures, 7 tables
Journal-ref: A&A 637, A73 (2020)
Subjects: Solar and Stellar Astrophysics (astro-ph.SR); High Energy Astrophysical Phenomena (astro-ph.HE)
[43]  arXiv:1908.08950 (replaced) [pdf, other]
Title: Multi-messenger tests of gravity with weakly lensed gravitational waves
Comments: 7 pages, 3 figures. Matches the published version
Journal-ref: Phys. Rev. D 101, 103509 (2020)
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); General Relativity and Quantum Cosmology (gr-qc)
[44]  arXiv:1908.11375 (replaced) [pdf, other]
Title: The Missing Link in Gravitational-Wave Astronomy: Discoveries waiting in the decihertz range
Comments: 51 pages, 5 figures, 3 tables. Submitted to Classical & Quantum Gravity. Based upon a white paper for ESA's Voyage 2050 on behalf of the LISA Consortium 2050 Task Force
Subjects: General Relativity and Quantum Cosmology (gr-qc); Astrophysics of Galaxies (astro-ph.GA); High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[45]  arXiv:1909.02946 (replaced) [pdf, other]
Title: Astroalign: A Python module for astronomical image registration
Comments: 4 pages, 2 figures, Python package
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Computer Vision and Pattern Recognition (cs.CV)
[46]  arXiv:1909.07001 (replaced) [pdf, other]
Title: Rotational disruption of dust grains by mechanical torques for high-velocity gas-grain collisions
Comments: 14 pages, 6 figures; accepted to ApJ, Appendix A added
Subjects: Astrophysics of Galaxies (astro-ph.GA); Earth and Planetary Astrophysics (astro-ph.EP); High Energy Astrophysical Phenomena (astro-ph.HE); Space Physics (physics.space-ph)
[47]  arXiv:1910.00665 (replaced) [pdf, other]
Title: On the Ejection of Dark Matter from Globular Clusters
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[48]  arXiv:1910.02083 (replaced) [pdf, other]
Title: Gravitational Wave Signals from Multiple Hidden Sectors
Comments: 15 pages, 3 figures
Journal-ref: Phys. Rev. D 101, 095016 (2020)
Subjects: High Energy Physics - Phenomenology (hep-ph); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[49]  arXiv:1910.08113 (replaced) [pdf, ps, other]
Title: Stellar speckle and correlation functions derived from classical wave expansions for spherical antennas
Comments: 18 pages, 5 figures
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM); Classical Physics (physics.class-ph)
[50]  arXiv:1912.03986 (replaced) [pdf, other]
Title: Updated fundamental constant constraints from Planck 2018 data and possible relations to the Hubble tension
Comments: 8 pages, 8 figures, 4 tables; modified to copy the accepted MNRAS version
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[51]  arXiv:1912.09695 (replaced) [pdf, other]
Title: The parameter-free Finger-Of-God model and its application to 21cm intensity mapping
Comments: 10 pages, 5 figures, 1 table, published on ApJ, updated to match the published version
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO); Astrophysics of Galaxies (astro-ph.GA)
[52]  arXiv:2001.00648 (replaced) [pdf, other]
Title: Peculiar prompt emission and afterglow in H.E.S.S. detected GRB 190829A
Comments: Accepted for publication in ApJ. The shock breakout origin of the prompt emission and central engine activity for the flare are revised with more counter-evidences. Major changes are marked in bold-face
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[53]  arXiv:2001.00941 (replaced) [pdf, other]
Title: The LSST DESC Data Challenge 1: Generation and Analysis of Synthetic Images for Next Generation Surveys
Comments: 21 pages, 21 figures. Submitted to MNRAS
Subjects: Instrumentation and Methods for Astrophysics (astro-ph.IM)
[54]  arXiv:2001.03531 (replaced) [pdf, other]
Title: Supercritically charged objects and electron-positron pair creation
Journal-ref: Phys. Rev. D 101 (2020) 103031
Subjects: Nuclear Theory (nucl-th); High Energy Astrophysical Phenomena (astro-ph.HE); High Energy Physics - Phenomenology (hep-ph)
[55]  arXiv:2002.11707 (replaced) [pdf, other]
Title: Can Late Dark Energy Transitions Raise the Hubble constant?
Comments: 7 pages, 3 figures. Minor changes from v1, matches the version published in PRD
Subjects: Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[56]  arXiv:2004.00628 (replaced) [pdf, other]
Title: Massive donors in interacting binaries: effect of metallicity
Comments: 15 pages, 8 figures (+ 4 pages, 4 fig. appendix), to appear in A&A
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[57]  arXiv:2004.03792 (replaced) [pdf, ps, other]
Title: Accretion Flow Evolution of a New Black Hole Candidate MAXI J1348-630 During the 2019 Outburst
Comments: 15 Pages, 6 Figures, 2 Tables (Accepted for Publication in ApJ)
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE)
[58]  arXiv:2004.08050 (replaced) [pdf, other]
Title: Stellar migrations and metal flows -- Chemical evolution of the thin disc of a simulated Milky Way analogous galaxy
Comments: Accepted for publication in MNRAS
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[59]  arXiv:2004.12189 (replaced) [pdf, ps, other]
Title: Supernova neutrino scattering off Gadolinium odd isotopes in water Cherenkov detectors
Comments: 10 pages, 5 figures, 2 Tables. arXiv admin note: substantial text overlap with arXiv:1808.01677; text overlap with arXiv:nucl-th/9709006 by other authors
Subjects: High Energy Physics - Phenomenology (hep-ph); Instrumentation and Methods for Astrophysics (astro-ph.IM)
[60]  arXiv:2005.06273 (replaced) [pdf, other]
Title: Zwicky Transient Facility constraints on the optical emission from the nearby repeating FRB 180916.J0158+65
Comments: Accepted for publication in ApJL, 9 pages, 4 figures, 1 table
Subjects: High Energy Astrophysical Phenomena (astro-ph.HE); Instrumentation and Methods for Astrophysics (astro-ph.IM); Solar and Stellar Astrophysics (astro-ph.SR)
[61]  arXiv:2005.06310 (replaced) [pdf, other]
Title: The changing circumgalactic medium over the last 10 Gyr I: physical and dynamical properties
Comments: 16 pages, 15 figures. Submitted to MNRAS. Comments welcome. (revision submitted on May 22, 2020 fixes Fig. 3. right panel that mistakenly displayed metal mass and now correctly displays total gas mass)
Subjects: Astrophysics of Galaxies (astro-ph.GA)
[62]  arXiv:2005.09131 (replaced) [pdf, other]
Title: Connecting the local stellar halo and its dark matter density to dwarf galaxies via blue stragglers
Authors: Luca Casagrande (Australian National University)
Comments: ApJ accepted. Video of Figure 1 at this https URL
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO); Solar and Stellar Astrophysics (astro-ph.SR)
[63]  arXiv:2005.09663 (replaced) [pdf, ps, other]
Title: What has quenched the massive spiral galaxies?
Authors: Yu Luo (1), Zongnan Li (2), Xi Kang (3 and 1), Zhiyuan Li (2), Peng Wang (4) ((1) PMO, (2) NJU, (3) ZJU, (4) AIP)
Comments: 5 papes, 3 figures, accepted for publication in MNRAS Letters
Subjects: Astrophysics of Galaxies (astro-ph.GA); Cosmology and Nongalactic Astrophysics (astro-ph.CO)
[64]  arXiv:2005.09817 (replaced) [pdf, other]
Title: Alfvén-wave driven magnetic rotator winds from low-mass stars I: rotation dependences of magnetic braking and mass-loss rate
Comments: accepted for publication in The Astrophysical Journal
Subjects: Solar and Stellar Astrophysics (astro-ph.SR)
[65]  arXiv:2005.09895 (replaced) [pdf, other]
Title: Jupiter in the ultraviolet: acetylene and ethane abundances in the stratosphere of Jupiter from Cassini observations between 0.15 and 0.19 $μ$m
Comments: Accepted for publication in The Astronomical Journal 28 pages, 23 figures, 3 tables
Subjects: Earth and Planetary Astrophysics (astro-ph.EP)
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