bluuebunny/crossref_metadata_2025_split huggingface dataset:
Milky Way mass with K giants and BHB stars using LAMOST, SDSS/SEGUE, and Gaia: 3D spherical Jeans equation and tracer mass estimator
Authors: Bird Sarah A , Xue Xiang-Xiang , Liu Chao , Flynn Chris , Shen Juntai , Wang Jie , Yang Chengqun , Zhai Meng , Zhu Ling , Zhao Gang , Tian Hai-Jun 
Published: July 2022

ABSTRACT
We measure the enclosed Milky Way mass profile to Galactocentric distances of ∼70 and ∼50 kpc using the smooth, diffuse stellar halo samples of Bird et al. The samples are Large Sky Area Multi-Object Fiber Spectroscopic Telescope (LAMOST) and Sloan Digital Sky Survey/Sloan Extension for Galactic Understanding and Exploration (SDSS/SEGUE) K giants (KG) and SDSS/SEGUE blue horizontal branch (BHB) stars with accurate metallicities. The 3D kinematics are available through LAMOST and SDSS/SEGUE distances and radial velocities and Gaia DR2 proper motions. Two methods are used to estimate the enclosed mass: 3D spherical Jeans equation and Evans et al. tracer mass estimator (TME). We remove substructure via the Xue et al. method based on integrals of motion. We evaluate the uncertainties on our estimates due to random sampling noise, systematic distance errors, the adopted density profile, and non-virialization and non-spherical effects of the halo. The tracer density profile remains a limiting systematic in our mass estimates, although within these limits we find reasonable agreement across the different samples and the methods applied. Out to ∼70 and ∼50 kpc, the Jeans method yields total enclosed masses of 4.3 ± 0.95 (random) ±0.6 (systematic) × 1011 M⊙ and 4.1 ± 1.2 (random) ±0.6 (systematic) × 1011 M⊙ for the KG and BHB stars, respectively. For the KG and BHB samples, we find a dark matter virial mass of $M_{200}=0.55^{+0.15}_{-0.11}$ (random) ±0.083 (systematic) × 1012 M⊙ and $M_{200}=1.00^{+0.67}_{-0.33}$ (random) ±0.15 (systematic) × 1012 M⊙, respectively.
Testing a varying-Λ model for dark energy within co-varying physical couplings framework
Authors: Cuzinatto R R , Gupta R P , Holanda R F L , Jesus J F , Pereira S H 
Published: July 2022

ABSTRACT
The Co-varying Physical Couplings (CPC) framework is a modified gravity set up assuming Einstein Field Equations wherein the quantities {G, c, Λ} are promoted to space–time functions. Bianchi identity and the requirement of stress-energy tensor conservation entangle the possible variations of the couplings {G, c, Λ}, which are forced to co-vary as dictated by the General Constraint (GC). In this paper, we explore a cosmological model wherein G, c, and Λ are functions of the redshift respecting the GC of the CPC framework. We assume a linear parametrization of Λ in terms of the scale factor a. We use the ansatz $\dot{G}/G = \sigma \left(\dot{c}/c \right)$ with σ = constant to deduce the functional forms of c = c(z) and G = G(z). We show that this varying-{G, c, Λ} model fits SNe Ia data and H(z) data with σ = 3. The model parameters can be constrained to describe dark energy at the background level.
Companion mass limits for 17 binary systems obtained with binary differential imaging and MagAO/Clio
Authors: Pearce Logan A , Males Jared R , Weinberger Alycia J , Long Joseph D , Morzinski Katie M , Close Laird M , Hinz Philip M 
Published: July 2022

ABSTRACT
Improving direct detection capability close to the star through improved star subtraction and post-processing techniques is vital for discovering new low-mass companions and characterizing known ones at longer wavelengths. We present results of 17 binary star systems observed with the Magellan adaptive optics system (MagAO) and the Clio infrared camera on the Magellan Clay Telescope using binary differential imaging (BDI). BDI is an application of reference differential imaging (RDI) and angular differential imaging (ADI) applied to wide binary star systems (2 arcsec &lt;Δρ &lt; 10 arcsec) within the isoplanatic patch in the infrared. Each star serves as the point spread function (PSF) reference for the other, and we performed PSF estimation and subtraction using principal component analysis. We report contrast and mass limits for the 35 stars in our initial survey using BDI with MagAO/Clio in L′ and 3.95 µm bands. Our achieved contrasts varied between systems, and spanned a range of contrasts from 3.0 to 7.5 magnitudes and a range of separations from 0.2 to 2 arcsec. Stars in our survey span a range of masses, and our achieved contrasts correspond to late-type M-dwarf masses down to ∼10 MJup. We also report detection of a candidate companion signal at 0.2 arcsec (18 au) around HIP 67506 A (SpT G5V, mass ∼1.2 M⊙), which we estimate to be $\sim 60-90 \, \rm{M_{Jup}}$. We found that the effectiveness of BDI is highest for approximately equal brightness binaries in high-Strehl conditions.
Satellite mass functions and the faint end of the galaxy mass–halo mass relation in LCDM
Authors: Santos-Santos Isabel M E , Sales Laura V , Fattahi Azadeh , Navarro Julio F 
Published: July 2022

ABSTRACT
The abundance of the faintest galaxies provides insight into the nature of dark matter and the process of dwarf galaxy formation. In the LCDM scenario, low-mass haloes are so numerous that the efficiency of dwarf formation must decline sharply with decreasing halo mass in order to accommodate the relative scarcity of observed dwarfs and satellites in the Local Group. The nature of this decline contains important clues to the mechanisms regulating the onset of galaxy formation in the faintest systems. We explore here two possible models for the stellar mass (M*)–halo mass (M200) relation at the faint end, motivated by some of the latest LCDM cosmological hydrodynamical simulations. One model includes a sharp mass threshold below which no luminous galaxies form, as expected if galaxy formation proceeds only in systems above the hydrogen-cooling limit. In the second model, M* scales as a steep power law of M200 with no explicit cut-off, as suggested by recent semi-analytical work. Although both models predict satellite numbers around Milky Way-like galaxies consistent with current observations, they predict vastly different numbers of ultrafaint dwarfs and of satellites around isolated dwarf galaxies. Our results illustrate how the satellite mass function around dwarfs may be used to probe the M*–M200 relation at the faint end and to elucidate the mechanisms that determine which low-mass haloes ‘light up’ or remain dark in the LCDM scenario.
The interplay between AGN feedback and precipitation of the intracluster medium in simulations of galaxy groups and clusters
Authors: Nobels Folkert S J , Schaye Joop , Schaller Matthieu , Bahé Yannick M , Chaikin Evgenii 
Published: July 2022

ABSTRACT
Using high-resolution hydrodynamical simulations of idealized galaxy clusters, we study the interaction between the brightest cluster galaxy, its supermassive black hole (BH), and the intracluster medium (ICM). We create initial conditions for which the ICM is in hydrostatic equilibrium within the gravitational potential from the galaxy and an NFW dark matter halo. Two free parameters associated with the thermodynamic profiles determine the cluster gas fraction and the central temperature, where the latter can be used to create cool-core or non-cool-core systems. Our simulations include radiative cooling, star formation, BH accretion, and stellar and active galactic nucleus (AGN) feedback. Even though the energy of AGN feedback is injected thermally and isotropically, it leads to anisotropic outflows and buoyantly rising bubbles. We find that the BH accretion rate (BHAR) is highly variable and only correlates strongly with the star formation rate (SFR) and the ICM when it is averaged over more than $1~\rm Myr$. We generally find good agreement with the theoretical precipitation framework. In $10^{13}~\rm M_\odot$ haloes, AGN feedback quenches the central galaxy and converts cool-core systems into non-cool-core systems. In contrast, higher mass, cool-core clusters evolve cyclically. Episodes of high BHAR raise the entropy of the ICM out to the radius, where the ratio of the cooling time and the local dynamical time tcool/tdyn &gt; 10, thus suppressing condensation and, after a delay, the BHAR. The corresponding reduction in AGN feedback allows the ICM to cool and become unstable to precipitation, thus initiating a new episode of high SFR and BHAR.
On the inconsistency of [C/Fe] abundances and the fractions of carbon-enhanced metal-poor stars among various stellar surveys
Authors: Arentsen Anke , Placco Vinicius M , Lee Young Sun , Aguado David S , Martin Nicolas F , Starkenburg Else , Yoon Jinmi 
Published: July 2022

ABSTRACT
Carbon-enhanced metal-poor (CEMP) stars are a unique resource for Galactic archaeology because they probe the properties of the First Stars, early chemical evolution, and binary interactions at very low metallicity. Comparing the fractions and properties of CEMP stars in different Galactic environments can provide us with unique insights into the formation and evolution of the Milky Way halo and its building blocks. In this work, we investigate whether directly comparing fractions of CEMP stars from different literature samples of very metal-poor ($\rm {[Fe/H]}\,\lt\, -2.0$) stars is valid. We compiled published CEMP fractions and samples of Galactic halo stars from the past 25 years, and find that they are not all consistent with each other. Focusing on giant stars, we find significant differences between various surveys when comparing their trends of [Fe/H] versus [C/Fe] and their distributions of CEMP stars. To test the role of the analysis pipelines for low-resolution spectroscopic samples, we re-analysed giant stars from various surveys with the sspp and ferre pipelines. We found systematic differences in [C/Fe] of ∼0.1−0.4 dex, partly independent of degeneracies with the stellar atmospheric parameters. These systematics are likely due to the different pipeline approaches, different assumptions in the employed synthetic grids, and/or the comparison of different evolutionary phases. We conclude that current biases in (the analysis of) very metal-poor samples limit the conclusions one can draw from comparing different surveys. We provide some recommendations and suggestions that will hopefully aid the community to unlock the full potential of CEMP stars for Galactic archaeology.
Evolution of dipolar mixed-mode coupling factor in red giant stars: impact of buoyancy spike
Authors: Jiang C , Cunha M , Christensen-Dalsgaard J , Zhang Q S , Gizon L 
Published: July 2022

ABSTRACT
Mixed modes observed in red giants allow for investigation of the stellar interior structures. One important feature in these structures is the buoyancy spike caused by the discontinuity of the chemical gradient left behind during the first dredge-up. The buoyancy spike emerges at the base of the convective zone in low-luminosity red giants and later becomes a glitch when the g-mode cavity expands to encompass the spike. Here, we study the impact of the buoyancy spike on the dipolar mixed modes using stellar models with different properties. We find that the applicability of the asymptotic formalisms for the coupling factor, q, varies depending on the location of the evanescent zone, relative to the position of the spike. Significant deviations between the value of q inferred from fitting the oscillation frequencies and either of the formalisms proposed in the literature are found in models with a large frequency separation in the interval 5–15 μHz, with evanescent zones located in a transition region that may be thin or thick. However, it is still possible to reconcile q with the predictions from the asymptotic formalisms, by choosing which formalism to use according to the value of q. For stars approaching the luminosity bump, the buoyancy spike becomes a glitch and strongly affects the mode frequencies. Fitting the frequencies without accounting for the glitch leads to unphysical variations in the inferred q, but we show that this is corrected when properly accounting for the glitch in the fitting.
Connecting radio emission to AGN wind properties with broad absorption line quasars
Authors: Petley J W , Morabito L K , Alexander D M , Rankine A L , Fawcett V A , Rosario D J , Matthews J H , Shimwell T M , Drabent A 
Published: July 2022

ABSTRACT
Broad absorption line quasars (BALQSOs) show strong signatures of powerful outflows, with the potential to alter the cosmic history of their host galaxies. These signatures are only seen in ∼10 per cent of optically selected quasars, although the fraction significantly increases in IR and radio selected samples. A proven physical explanation for this observed fraction has yet to be found, along with a determination of why this fraction increases at radio wavelengths. We present the largest sample of radio matched BALQSOs using the LOFAR Two-metre Sky Survey Data Release 2 and employ it to investigate radio properties of BALQSOs. Within the DR2 footprint, there are 3537 BALQSOs from Sloan Digital Sky Survey DR12 with continuum signal-to-noise ≥5. We find radio-detections for 1108 BALQSOs, with an important subpopulation of 120 LoBALs, an unprecedented sample size for radio matched BALQSOs given the sky coverage to date. BALQSOs are a radio-quiet population that show an increase of ×1.50 radio-detection fraction compared to non-BALQSOs. LoBALs show an increase of ×2.22 that of non-BALQSO quasars. We show that this detection fraction correlates with wind-strength, reddening, and C iv emission properties of BALQSOs and that these features may be connected, although no single property can fully explain the enhanced radio detection fraction. We create composite spectra for subclasses of BALQSOs based on wind strength and colour, finding differences in the absorption profiles of radio-detected and radio-undetected sources, particularly for LoBALs. Overall, we favour a wind-ISM interaction explanation for the increased radio-detection fraction of BALQSOs.
Broadband spectro-temporal study on blazar TXS 1700+685
Authors: Banerjee Anuvab , Nandi Prantik , Prince Raj , Khatoon Rukaiya , Bose Debanjan 
Published: July 2022

ABSTRACT
We attempt to present a multiwavelength variability and correlation study as well as detailed multiwaveband spectral characteristics of the May 2021 gamma-ray flare of the blazar source TXS 1700+685. The multiwavelength observation from Fermi-LAT, Swift-XRT/UVOT as well as radio archival data are used for our spectro-temporal investigation. We estimate the variability time-scale of the source from the flux doubling time in different flaring region detected in Fermi-LAT observation and the shortest variability time is used to put a constraint on the minimum Doppler factor and on the size of the emission region. We have detected a statistically significant quasi-periodic oscillation feature at ∼17 d. The broad-band emission is satisfactorily represented during its flaring state with a leptonic synchrotron and inverse Compton component. From the broad-band spectral modelling, we observe the external Comptonization of the seed photons originating in the broad-line region to be dominant compared to the dusty torus. The equipartition value implies the energy density of the magnetic field in the jet comoving frame is weak. In order to produce the high-energy hump, we need the injection of a large population of high-energy electrons and/or the presence of strong magnetic field; and we observe the later component to be subdominant in our case. The gamma-ray spectral energy distribution shows the flat rising and steep falling profile, as well as the break or spectral curvature at ∼1 GeV, which has been seen for other flat-spectrum radio quasar sources before.
Can we reveal the core-chemical composition of ultra-massive white dwarfs through their magnetic fields?
Authors: Camisassa Maria E , Raddi Roberto , Althaus Leandro G , Isern Jordi , Rebassa-Mansergas Alberto , Torres Santiago , Córsico Alejandro H , Korre Lydia 
Published: July 2022

ABSTRACT
Ultra-massive white dwarfs ($1.05\, \rm M_\odot \lesssim M_{WD}$) are particularly interesting objects that allow us to study extreme astrophysical phenomena such as type Ia supernovae explosions and merger events. Traditionally, ultra-massive white dwarfs are thought to harbour oxygen–neon (ONe) cores. However, recent theoretical studies and new observations suggest that some ultra-massive white dwarfs could harbour carbon–oxygen (CO) cores. Although several studies have attempted to elucidate the core composition of ultra-massive white dwarfs, to date, it has not been possible to distinguish them through their observed properties. Here, we present a new method for revealing the core-chemical composition in ultra-massive white dwarfs that is based on the study of magnetic fields generated by convective mixing induced by the crystallization process. ONe white dwarfs crystallize at higher luminosities than their CO counterparts. Therefore, the study of magnetic ultra-massive white dwarfs in the particular domain where ONe cores have reached the crystallization conditions but CO cores have not, may provide valuable support to their ONe core-chemical composition, since ONe white dwarfs would display signs of magnetic fields and CO would not. We apply our method to eight white dwarfs with magnetic field measurements and we suggest that these stars are candidate ONe white dwarfs.
Fast prograde coronal flows in solar active regions
Authors: Hudson Hugh S , Mulay Sargam M , Fletcher Lyndsay , Docherty Jennifer , Fitzpatrick Jimmy , Pike Eleanor , Strong Morven , Chamberlin Phillip C , Woods Thomas N 
Published: July 2022

ABSTRACT
We report the discovery and characterization of high-speed (&gt;100 km s−1) horizontal flows in solar active regions, making use of the Sun-as-a-star spectroscopy in the range 5–105 nm provided by the EVE (Extreme Ultraviolet Variability Experiment) spectrometers on the Solar Dynamics Observatory. These apparent flows are persistent on time-scales of days, and are well observed in lines of Mg x, Si xii, and Fe xvi for example. They are prograde, as evidenced directly by blueshifts/redshifts peaking at the east/west limb passages of isolated active regions. The high-speed flow behaviour does not depend upon active-region latitude or solar cycle, with similar behaviour in Cycles 24 and 25.
Precession and Jitter in FRB 180916B
Authors: Katz J I 
Published: July 2022

ABSTRACT
Recent CHIME/FRB observations of the periodic repeating fast radio bursts (FRB) 180916B have produced a homogeneous sample of 44 bursts. These permit a redetermination of the modulation period and phase window, in agreement with earlier results. If the periodicity results from the precession of an accretion disc, in analogy with those of Her X-1, SS 433, and many other superorbital periods, the width of the observable phase window indicates that the disc axis jitters by an angle of about 0.14 of the inclination angle, similar to the ratio of 0.14 in the well-observed jittering jet source SS 433.
On energetics and progenitors of odd radio circles: a causal connection with tidal disruption of stars?
Authors: Omar Amitesh 
Published: July 2022

ABSTRACT
Odd Radio Circles or ORCs are recently discovered edge-brightened, low surface brightness circular radio sources. The progenitors and astrophysical processes responsible for their origins are presently debated. Some ORCs are host-less and some appear to be hosted in distant quiescent galaxies. Two plausible explanations consider ORCs as nearby supernova remnants with sizes a few hundred parsec in the intragroup medium of the Local Group of galaxies or alternatively shocked haloes of a few hundred kpc extent around distant galaxies. The input shock energy required to create ORCs of a few hundred kpc size is estimated in a range of 1055–1059 erg. It is shown here that the cumulative energy in unbound debris ejected from multiple (105–109) tidal disruption events over ∼100 Myr period around a central massive black hole can meet the required energies to generate ORCs around some galaxies, which have recently undergone a merger. The potential hosts for ORCs are identified here as abundant post-starburst galaxies at intermediate redshifts having massive black holes. A causal connection between ORC around quiescent galaxies and tidal disruption may find support in the observed dominance of tidal disruption events in post-starburst galaxies.
Double-stranded RNA drives SARS-CoV-2 nucleocapsid protein to undergo phase separation at specific temperatures
Authors: Roden Christine A , Dai Yifan , Giannetti Catherine A , Seim Ian , Lee Myungwoon , Sealfon Rachel , McLaughlin Grace A , Boerneke Mark A , Iserman Christiane , Wey Samuel A , Ekena Joanne L , Troyanskaya Olga G , Weeks Kevin M , You Lingchong , Chilkoti Ashutosh , Gladfelter Amy S 
Published: July 2022

Abstract
Nucleocapsid protein (N-protein) is required for multiple steps in betacoronaviruses replication. SARS-CoV-2-N-protein condenses with specific viral RNAs at particular temperatures making it a powerful model for deciphering RNA sequence specificity in condensates. We identify two separate and distinct double-stranded, RNA motifs (dsRNA stickers) that promote N-protein condensation. These dsRNA stickers are separately recognized by N-protein's two RNA binding domains (RBDs). RBD1 prefers structured RNA with sequences like the transcription-regulatory sequence (TRS). RBD2 prefers long stretches of dsRNA, independent of sequence. Thus, the two N-protein RBDs interact with distinct dsRNA stickers, and these interactions impart specific droplet physical properties that could support varied viral functions. Specifically, we find that addition of dsRNA lowers the condensation temperature dependent on RBD2 interactions and tunes translational repression. In contrast RBD1 sites are sequences critical for sub-genomic (sg) RNA generation and promote gRNA compression. The density of RBD1 binding motifs in proximity to TRS-L/B sequences is associated with levels of sub-genomic RNA generation. The switch to packaging is likely mediated by RBD1 interactions which generate particles that recapitulate the packaging unit of the virion. Thus, SARS-CoV-2 can achieve biochemical complexity, performing multiple functions in the same cytoplasm, with minimal protein components based on utilizing multiple distinct RNA motifs that control N-protein interactions.
Structural basis of AlpA-dependent transcription antitermination
Authors: Wen Aijia , Zhao Minxing , Jin Sha , Lu Yuan-Qiang , Feng Yu 
Published: July 2022

Abstract
AlpA positively regulates a programmed cell death pathway linked to the virulence of Pseudomonas aeruginosa by recognizing an AlpA binding element within the promoter, then binding RNA polymerase directly and allowing it to bypass an intrinsic terminator positioned downstream. Here, we report the single-particle cryo-electron microscopy structures of both an AlpA-loading complex and an AlpA-loaded complex. These structures indicate that the C-terminal helix-turn-helix motif of AlpA binds to the AlpA binding element and that the N-terminal segment of AlpA forms a narrow ring inside the RNA exit channel. AlpA was also revealed to render RNAP resistant to termination signals by prohibiting RNA hairpin formation in the RNA exit channel. Structural analysis predicted that AlpA, 21Q, λQ and 82Q share the same mechanism of transcription antitermination.