bluuebunny/crossref_metadata_2025_split huggingface dataset:
Comparing implementations of self-interacting dark matter in the gizmo and arepo codes
Authors: Meskhidze Helen , Mercado Francisco J , Sameie Omid , Robles Victor H , Bullock James S , Kaplinghat Manoj , Weatherall James O 
Published: April 2022

ABSTRACT
Self-interacting dark matter (SIDM) models have received great attention over the past decade as solutions to the small-scale puzzles of astrophysics. Though there are different implementations of dark matter (DM) self-interactions in N-body codes of structure formation, there has not been a systematic study to compare the predictions of these different implementations. We investigate the implementation of dark matter self-interactions in two simulation codes:gizmo and arepo. We begin with identical initial conditions for an isolated 1010 M⊙ dark matter halo and investigate the evolution of the density and velocity dispersion profiles in gizmo and arepo for SIDM cross-section over mass of 1, 5, and 50 $\rm cm^2\, g^{-1}$. Our tests are restricted to the core expansion phase, where the core density decreases and core radius increases with time. We find better than 30 per cent agreement between the codes for the density profile in this phase of evolution, with the agreement improving at higher resolution. We find that varying code-specific SIDM parameters changes the central halo density by less than 10 per cent outside of the convergence radius. We argue that SIDM core formation is robust across the two different schemes and conclude that these codes can reliably differentiate between cross-sections of 1, 5, and 50 $\rm cm^2\, g^{-1}$, but finer distinctions would require further investigation.
Ejection–accretion connection in NLS1 AGN 1H 1934-063
Authors: Xu Y , Pinto C , Kara E , Masterson M , García J A , Fabian A C , Parker M L , Barret D , Alston W N , Cusumano G 
Published: April 2022

ABSTRACT
Accretion and ejection of matter in active galactic nuclei (AGNs) are tightly connected phenomena and represent fundamental mechanisms regulating the growth of the central supermassive black hole and the evolution of the host galaxy. However, the exact physical processes involved are not yet fully understood. We present a high-resolution spectral analysis of a simultaneous XMM–Newton and NuSTAR observation of the narrow line Seyfert 1 (NLS1) AGN 1H 1934-063, during which the X-ray flux dropped by a factor of ∼6 and subsequently recovered within 140 kiloseconds. By means of the time-resolved and flux-resolved X-ray spectroscopy, we discover a potentially variable warm absorber and a relatively stable ultra-fast outflow (UFO, $v_\mathrm{UFO}\sim -0.075\, c$) with a mild ionization state ($\log (\xi /\mathrm{erg\, cm\, s^{-1})}\sim 1.6$). The detected emission lines (especially a strong and broad feature around 1 keV) are of unknown origin and cannot be explained with emission from plasmas in photo- or collisional-ionization equilibrium. Such emission lines could be well described by a strongly blueshifted (z ∼ −0.3) secondary reflection off the base of the equatorial outflows, which may reveal the link between the reprocessing of the inner accretion flow photons and the ejection. However, this scenario although being very promising is only tentative and will be tested with future observations.
The absence of periodicity in repeating FRB
Authors: Katz J I 
Published: April 2022

ABSTRACT
Popular fast radio burst (FRB) models involve rotating magnetized neutron stars, yet no rotational periodicities have been found. Small data sets exclude exact periodicity in FRB 121102. Recent observations of over 1500 bursts from each of FRB 121102 and FRB 20201124A have also not found periodicity. Periodograms of events with cosine-distributed random offsets as large as ±0.6P from a strict period P would still reveal the underlying periodicity. The sensitivity of periodograms of long data series, such as bursts observed on multiple days, to slow frequency drifts is mitigated by considering individual observing sessions, and results are shown for FRB 121102. Models of repeating FRB without intrinsic periodicity are considered, as are models of apparently non-repeating FRBs.
The contribution of non-central radio galaxies to AGN feedback in rich galaxy clusters
Authors: Seth Ruchika , O’Sullivan Ewan , Sebastian Biny , Raychaudhury Somak , Schellenberger Gerrit , Haines Christopher P 
Published: April 2022

ABSTRACT
We present a combined radio/X-ray study of six massive galaxy clusters, aimed at determining the potential for heating of the intra-cluster medium (ICM) by non-central radio galaxies. Since X-ray cavities associated with the radio lobes of non-central galaxies are generally not detectable, we use Giant Metrewave Radio Telescope 610 MHz observations to identify jet sources and estimate their size, and Chandra data to estimate the pressure of the surrounding ICM. In the radio, we detect 4.5 per cent of galaxies above the spectroscopic survey limit (M$^{*}_{K}$ + 2.0) of the Arizona cluster redshift survey (ACReS) that covers five of our six clusters. Approximately one-tenth of these are extended radio sources. Using star formation (SF) rates determined from mid-infrared data, we estimate the expected contribution to radio luminosity from the stellar population of each galaxy, and find that most of the unresolved or poorly resolved radio sources are likely SF dominated. The relatively low frequency and good spatial resolution of our radio data allows us to trace SF emission down to galaxies of stellar mass ∼10 9.5 M⊙. We estimate the enthalpy of the (AGN-dominated) jet/lobe and tailed sources, and place limits on the energy available from unresolved radio jets. We find jet powers in the range ∼1043 to 1046 erg s−1, comparable to those of brightest cluster galaxies. Our results suggest that while cluster-central sources are the dominant factor balancing ICM cooling over the long-term, non-central sources may have a significant impact, and that further investigation is possible and warranted.
Probing the Galactic halo with RR Lyrae stars – II. The substructures of the Milky Way
Authors: Wang F , Zhang H-W , Xue X-X , Huang Y , Liu G-C , Zhang L , Yang C-Q 
Published: April 2022

ABSTRACT
We identify substructures of the Galactic halo using 3003 type ab RR Lyrae stars with six-dimensional position–velocity information from the Sloan Digital Sky Survey, the Large Sky Area Multi-Object Fiber Spectroscopic Telescope and the Gaia Early Data Release 3. Based on this information, we define the separation of any two of the stars in the integrals of motion space and we identify substructures by utilizing the friends-of-friends algorithm. We identify members belonging to several known substructures: the Sagittarius stream, the Gaia-Enceladus-Sausage (GES), the Sequoia and the Helmi streams. In addition to these known substructures, there are three other substructures possibly associated with globular clusters NGC 5272, 6656 and 5024, respectively. Finally, we also find three remaining unknown substructures, one of which has large angular momentum and a mean metallicity −2.13 dex, which may be a new substructure. As for the GES, we find that it accounts for a large part of substructures in the inner halo and the apocentre distance is in the range 10–34 kpc, which suggests that the GES is mainly distributed in the inner halo. The near one-third proportion of the GES and the peak value of 20 kpc of the apocentre distance suggest that the GES could account for the break in the density profile of the Galactic halo at the Galactocentric distance ~20–25 kpc. The similarity when comparing the kinematic properties of the GES with the Hercules–Aquila Cloud and Virgo Overdensity suggests that the three substructures may have similar origins.
Kinetic simulation of electron, proton and helium acceleration in a non-relativistic quasi-parallel shock
Authors: Fang Jun , Xia Qi , Tian Shiting , Zhou Liancheng , Yu Huan 
Published: April 2022

ABSTRACT
In addition to accelerating electrons and protons, non-relativistic quasi-parallel shocks are expected to possess the ability to accelerate heavy ions. The shocks in supernova remnants are generally supposed to be accelerators of Galactic cosmic rays, which consist of many species of particles. We investigate the diffusive shock acceleration of electrons, protons and helium ions in a non-relativistic quasi-parallel shock through a 1D particle-in-cell simulation with a helium-to-proton number density ratio of 0.1, which is relevant for Galactic cosmic rays. The simulation indicates that waves can be excited by the flow of energetic protons and helium ions upstream of a non-relativistic quasi-parallel shock with a sonic Mach number of 14 and an Alfvén Mach number of 19.5 in the shock rest frame, and that the charged particles are scattered by the self-generated waves and accelerated gradually. Moreover, the spectra of the charged particles downstream of the shock are thermal with a non-thermal tail, and the acceleration is efficient, with about $7{{\ \rm per\ cent}}$ and $5.4{{\ \rm per\ cent}}$ of the bulk kinetic energy transferred into the non-thermal protons and helium ions, respectively, in the near downstream region by the end of the simulation.
Temporal and spectral study of PKS 0208−512 during the 2019–2020 flare
Authors: Khatoon Rukaiya , Prince Raj , Shah Zahir , Sahayanathan Sunder , Gogoi Rupjyoti 
Published: April 2022

ABSTRACT
We present a temporal and spectral study of the blazar PKS 0208−512, using recent flaring activity from 2019 November to 2020 May, as detected by the Fermi Large Area Telescope. The contemporaneous X-ray and optical/ultraviolet observations from theSwift X-Ray Telescope and UltraViolet and Optical Telescope are also used. During the activity state, the 2-d binned γ-ray light curve shows multiple peaks indicating subflares. To understand the possible physical mechanisms behind flux enhancement, we divided the activity state of the source into several flux states and carried out detailed temporal and spectral studies. The timing analysis of light curves suggests that peaks of subflares have rise and decay times of the order of days, with the flux doubling time ∼ 2 d. The 2-d binned γ-ray light curve shows double-lognormal flux distribution. The broad-band spectral energy distribution (SED) for three selected flux states can be well fitted under synchrotron, synchrotron self-Compton and external Compton emission mechanisms. We obtained the physical parameters of the jet by SED modelling and their confidence intervals through χ2-statistics. Our SED modelling results suggest that during the quiescent state, the γ-ray spectrum can be explained by considering the external Compton scattering of infrared photons from the dusty torus. However, γ-ray spectra corresponding to flares demand additional target photons from the broad-line region (BLR) along with infrared. These suggest that, during flares, the emission region is close to the edge of the BLR, while for the quiescent state, the emission region is away from the BLR. The best-fitting results suggest that a marginal increase in the magnetic field during the flaring episode can result in flux enhancement. This is possibly associated with the efficiency of particle acceleration during flaring states compared with the quiescent state.
On the physical nature of the Wilson–Bappu effect: revising the gravity and temperature dependence
Authors: Rosas-Portilla F , Schröder K -P , Jack D 
Published: April 2022

ABSTRACT
We present a sample of 32 stars of spectral types G and K and luminosity classes I–V, with moderate activity levels, covering four orders of magnitude of surface gravity and a representative range of effective temperature. For each star we obtained high signal-to-noise ratio (S/N) spectra from the Telescopio Internacional de Guanajuato Robótico-Espectroscópico (TIGRE–HEROS) with a spectral resolving power of $R\approx 20\, 000$ and measured the Ca ii K line widths of interest, W0 and W1. The main physical parameters are determined by means of iSpec synthesis and Gaia EDR3 parallaxes. Mass estimates are based on matching to evolution models. Using this stellar sample, which is highly uniform in terms of spectral quality and assessment, we derive the best-fitting relation between emission-line width and gravity g, including a notable dependence on effective temperature Teff, of the form $W_1 \propto g^{-0.229} T_{\rm eff}^{+2.41}$. This result confirms the physical interpretation of the Wilson–Bappu effect as a line saturation and photon redistribution effect in the chromospheric Ca ii column density, under the assumption of hydrostatic equilibrium at the bottom of the chromosphere. While the column density (and hence W1) increases towards lower gravities, the observed temperature dependence is then understood as a simple ionization effect: in cooler stars, Ca ii densities decrease in favour of Ca i.
Pushchino multibeam pulsar search – II. Long-term variability of rotating radio transients
Authors: Smirnova T V , Tyul’bashev S A , Brylyakova E A , Kitaeva M A , Chashei I V , Tyul’basheva G E , Oreshko V V , Logvinenko S V 
Published: April 2022

ABSTRACT
Pulses from 16 previously known rotating radio transients (RRATs) have been searched for with the 111 MHz daily monitoring program for 4 to 5.5 yr using the Large Phased Array (LPA) at Pushchino. The total number of pulses detected in such a long observation interval is only 90 for RRAT J0640+07, but is as high as 10 751 for RRAT J0302+22. The number and amplitude of pulses vary on time-scales from 6 to 20 months for RRATs J1336+33, J1404+11, J1848+15, J2051+12 and J2105+22, and the pulse number can increase by one or two orders of magnitude in active phases. Long-term trends are found for RRATs J0139+33 and J0302+22, which show a 2–3 times increase in detected pulse number over 1959 d. Some RRATs show annual variations in both pulse number and pulse amplitude. It is hard to explain all these variation time-scales by refractive scintillation on the interstellar medium. The annual and semi-annual variations are probably caused by scintillations on the inhomogeneous interplanetary plasma. Our data show that the number of observational sessions with no pulse detection over the threshold decreases exponentially with the length of pulse silence.
Astrometric identification of nearby binary stars – I. Predicted astrometric signals
Authors: Penoyre Zephyr , Belokurov Vasily , Evans N Wyn 
Published: April 2022

ABSTRACT
We examine the capacity to identify binary systems from astrometric errors and deviations alone. Until the release of the fourth Gaia data release, we lack the full astrometric time-series that the satellite records, but as we show can still infer the presence of binaries from the best-fitting models, and their error, already available. We generate a broad catalogue of simulated binary systems within 100 pc, and examine synthetic observations matching the Gaia survey’s scanning law and astrometric data processing routine. We show how the unit weight error (UWE) and proper motion anomaly (PMA) vary as a function of period, and the properties of the binary. Both UWE and PMA peak for systems with a binary period close to the time baseline of the survey. Thus UWE can be expected to increase or remain roughly constant as we observe the same system over a longer baseline, and we suggest UWEeDR3 &gt; 1.25 and ΔUWE/UWEeDR3 &gt; −0.25 as criteria to select astrometric binaries. For stellar binaries, we find detectable significant astrometric deviations for 80–90 per cent of our simulated systems in a period range from months to decades. We confirm that for systems with periods less than the survey’s baseline the observed UWE scales ∝ ϖ (parallax), a (semimajor axis), and $\Delta =\frac{|q-l|}{(1+q)(1+l)}$, where q and l are the mass and light ratio, respectively, with a modest dependence on viewing angle. For longer periods the signal is suppressed by a factor of roughly ∝P−2 (period). PMA is largest in orbits with slightly longer periods but obeys the same approximate scaling relationships.
Amplified J-factors in the Galactic Centre for velocity-dependent dark matter annihilation in FIRE simulations
Authors: McKeown Daniel , Bullock James S , Mercado Francisco J , Hafen Zachary , Boylan-Kolchin Michael , Wetzel Andrew , Necib Lina , Hopkins Philip F , Yu Sijie 
Published: April 2022

ABSTRACTWe use FIRE-2 zoom cosmological simulations of Milky Way size Galaxy haloes to calculate astrophysical J-factors for dark matter annihilation and indirect detection studies. In addition to velocity-independent (s-wave) annihilation cross-sections 〈σv〉, we also calculate effective J-factors for velocity-dependent models, where the annihilation cross-section is either p-wave (∝ v2/c2) or d-wave (∝ v4/c4). We use 12 pairs of simulations, each run with dark matter-only (DMO) physics and FIRE-2 physics. We observe FIRE runs produce central dark matter velocity dispersions that are systematically larger than in DMO runs by factors of ∼2.5–4. They also have a larger range of central (∼400 pc) dark matter densities than the DMO runs (ρFIRE/ρDMO ≃ 0.5–3) owing to the competing effects of baryonic contraction and feedback. At 3 deg from the Galactic Centre, FIRE J-factors are 3–60 (p-wave) and 10–500 (d-wave) times higher than in the DMO runs. The change in s-wave signal at 3 deg is more modest and can be higher or lower (∼0.3–7), though the shape of the emission profile is flatter (less peaked towards the Galactic Centre) and more circular on the sky in FIRE runs. Our results for s-wave are broadly consistent with the range of assumptions in most indirect detection studies. We observe p-wave J-factors that are significantly enhanced compared to most past estimates. We find that thermal models with p-wave annihilation may be within range of detection in the near future.
Discovery of cyclotron and narrow Fe Kα lines in HMXB GRO J1750–27
Authors: Sharma Prince , Jain Chetana , Dutta Anjan 
Published: April 2022

ABSTRACT
We report on the timing and spectral analysis of transient Be X-ray pulsar GRO J1750–27 using the Nuclear Spectroscopic Telescope Array(NuSTAR) observation from 2021 September. This is the fourth outburst of the system since 1995. The NuSTAR observation was performed during the rising phase of the outburst. Pulsations at a period of 4.450710(1) s were observed in the 3–60 keV energy range. The average pulse profile comprised of a broad peak with a weak secondary peak, which evolved with energy. We did not find any appreciable variation in the X-ray emission during this observation. The broad-band phase-averaged spectrum is described by a blackbody, a power law, or Comptonization component. We report the discovery of Fe Kα line at 6.4 keV, along with the presence of two cyclotron resonant scattering features of around 36 and 42 keV. These lines indicate a magnetic field with the strength of $3.7_{-0.3}^{+0.1} \times 10^{12}$ and 4.4 ± 0.10 × 1012 G for the neutron star. We have estimated a source distance of ∼13.6–16.4 kpc based on the accretion-disc torque models.
The Holy and the God-Loved: The Dilemma in Plato’sEuthyphro
Authors: Frede Dorothea 
Published: April 2022

AbstractIs the holy holy because the gods love it or do the gods love it because it is holy? On the basis of this dilemma Plato works out the manifold and complex relationship between God and Morality in his dialogue Euthyphro. This dialogue not only plays a central role within Plato’s work on the question of the relationship between ethics and religion, but it also represents the starting point of the entire further Western debate about God and Morality. This article gives a basic interpretation of the text, situates the dilemma within the dialogue, traces its character, intention, and structure, unfolds the course of the argument, and offers a brief outlook on its reception.
St. Anselm of Canterbury on God and Morality
Authors: Rogers Katherin 
Published: April 2022

Abstract
Anselm of Canterbury, as a classical theist, does not hold that there is a moral, or value, order independent of God. What is good, indeed what is necessary and possible, depends on the will of God. But Anselm’s development of this claim does not succumb to the problems entailed by divine-command theory. One such problem addresses the question of whether or not the moral order is available to reason, bracketing Scripture and Church teaching. Anselm holds that to be just is to conform to God’s will. Nevertheless Anselm proposes a eudaimonistic ethical theory that allows reason to assess moral principles. And Anselm holds that the non-believer recognizes justice, even before he can appreciate the more general category of “good.”
Mismatch discrimination and sequence bias during end-joining by DNA ligases
Authors: Bilotti Katharina , Potapov Vladimir , Pryor John M , Duckworth Alexander T , Keck James L , Lohman Gregory J S 
Published: April 2022

Abstract
DNA ligases, critical enzymes for in vivo genome maintenance and modern molecular biology, catalyze the joining of adjacent 3′-OH and 5′-phosphorylated ends in DNA. To determine whether DNA annealing equilibria or properties intrinsic to the DNA ligase enzyme impact end-joining ligation outcomes, we used a highly multiplexed, sequencing-based assay to profile mismatch discrimination and sequence bias for several ligases capable of efficient end-joining. Our data reveal a spectrum of fidelity and bias, influenced by both the strength of overhang annealing as well as sequence preferences and mismatch tolerances that vary both in degree and kind between ligases. For example, while T7 DNA ligase shows a strong preference for ligating high GC sequences, other ligases show little GC-dependent bias, with human DNA Ligase 3 showing almost none. Similarly, mismatch tolerance varies widely among ligases, and while all ligases tested were most permissive of G:T mismatches, some ligases also tolerated bulkier purine:purine mismatches. These comprehensive fidelity and bias profiles provide insight into the biology of end-joining reactions and highlight the importance of ligase choice in application design.
A molecular beacon assay for monitoring RNA splicing
Authors: Omran Qusay Q , Fedorova Olga , Liu Tianshuo , Pyle Anna M 
Published: April 2022

Abstract
Small molecule targeting of self-splicing RNAs like group I and II introns has been limited in part by the lack of a universal high-throughput screening platform for studies of splicing inhibition and kinetics. Here, we present the development of a molecular beacon assay for monitoring the accumulation of spliced exons during RNA splicing reactions. In this case, we applied it to the autocatalyzed reaction of the H.c.LSU group II intron found in the mitochondria of the pathogenic dimorphic fungus Histoplasma capsulatum. We find that a molecular beacon with the loop length of 18 nucleotides selectively recognizes ligated exons formed during self-splicing and exhibits high fluorescent signal upon binding of its target. We demonstrate that the fluorescent assay using molecular beacons can be successfully applied to kinetic characterization of the splicing reaction and determination of inhibition constants for small molecules. The results presented herein offer support for a molecular beacon approach to identifying small molecule inhibitors of intron splicing.