bluuebunny/crossref_metadata_2025_split huggingface dataset:
Disentangling the Entangled Linkages of Relative Magnetic Helicity
Authors: Schuck Peter W. , Linton Mark G. 
Published: January 2024

Abstract
Magnetic helicity, H, measures magnetic linkages in a volume. The early theoretical development of helicity focused on magnetically closed systems in

V

bounded by

∂
V

. For magnetically closed systems,

V
∈

R

3

=
V
+

V

*

, no magnetic flux threads the boundary,

n

ˆ

·
B

∣

∂
V

=
0

. Berger & Field and Finn & Antonsen extended the definition of helicity to relative helicity,

H

, for magnetically open systems where magnetic flux may thread the boundary. Berger expressed this relative helicity as two gauge-invariant terms that describe the self-helicity of the magnetic field that closes inside

V

and the mutual helicity between the magnetic field that threads the boundary

∂
V

and the magnetic field that closes inside

V

. The total magnetic field that permeates

V

entangles magnetic fields that are produced by current sources

J

in

V

with magnetic fields that are produced by current sources

J
*

in

V

*

. Building on this fact, we extend Berger's expressions for relative magnetic helicity to eight gauge-invariant quantities that simultaneously characterize both of these self and mutual helicities and attribute their origins to currents

J

in

V

and/or

J
*

in

V

*

, thereby disentangling the domain of origin for these entangled linkages. We arrange these eight terms into novel expressions for internal and external helicity (self) and internal-external helicity (mutual) based on their domain of origin. The implications of these linkages for interpreting magnetic energy are discussed and new boundary observables are proposed for tracking the evolution of the field that threads the boundary.
Disentangling Magnetic Fields in NGC 6946 with Wide-band Polarimetry
Authors: Williams A. L. , Heald G. , Wilcots E. M. , Zweibel E. G. 
Published: January 2024

Abstract
We present λ13 cm polarization observations of the nearby spiral galaxy NGC 6946 with the Westerbork Synthesis Radio Telescope (WSRT) to examine the nearside halo magnetic fields. Despite λ13 cm exhibiting similar two-dimensional morphology as observed at longer (λ18–22 cm) or shorter (λ3 and λ6 cm) wavelengths, more complete frequency coverage will be required to explain the gap in polarization in the southwest quadrant of the galaxy. We fit models of the turbulent and coherent line-of-sight magnetic fields to the fractional degree of linearly polarized emission at λ3, λ6, λ13, λ18, and λ22 cm from observations taken with the WSRT, Karl G. Jansky Very Large Array, and Effelsberg telescopes. The results favor a multilayer turbulent magneto-ionized medium consistent with current observations of edge-on galaxies. We constrain the physical properties of the synchrotron-emitting thin and thick disks (scale heights of 300 pc and 1.4 kpc, respectively) along with the thermal thick disk and halo (scale heights of 1 and 5 kpc, respectively). Our preferred model indicates a clumpy and highly turbulent medium within 1 kpc of the midplane, and a diffuse extraplanar layer with a substantially lower degree of Faraday depolarization. In the halo, we estimate a regular magnetic field strength of 0.4–2.2 μG and that turbulence and a total magnetic field strength of ∼6 μG result in a Faraday dispersion of σ
RM = 4–48 rad m−2. This work is an example of how the advanced capabilities of modern radio telescopes are opening a new frontier for the study of cosmic magnetism.
Environment Matters: Predicted Differences in the Stellar Mass–Halo Mass Relation and History of Star Formation for Dwarf Galaxies
Authors: Christensen Charlotte R. , Brooks Alyson M. , Munshi Ferah , Riggs Claire , Van Nest Jordan , Akins Hollis , Quinn Thomas R. , Chamberland Lucas 
Published: January 2024

Abstract
We are entering an era in which we will be able to detect and characterize hundreds of dwarf galaxies within the Local Volume. It is already known that a strong dichotomy exists in the gas content and star formation properties of field dwarf galaxies versus satellite dwarfs of larger galaxies. In this work, we study the more subtle differences that may be detectable in galaxies as a function of distance from a massive galaxy, such as the Milky Way. We compare smoothed particle hydrodynamic simulations of dwarf galaxies formed in a Local Volume-like environment (several megaparsecs away from a massive galaxy) to those formed nearer to Milky Way–mass halos. We find that the impact of environment on dwarf galaxies extends even beyond the immediate region surrounding Milky Way–mass halos. Even before being accreted as satellites, dwarf galaxies near a Milky Way–mass halo tend to have higher stellar masses for their halo mass than more isolated galaxies. Dwarf galaxies in high-density environments also tend to grow faster and form their stars earlier. We show observational predictions that demonstrate how these trends manifest in lower quenching rates, higher H i fractions, and bluer colors for more isolated dwarf galaxies.
Reading between the (Spectral) Lines: Magellan/IMACS Spectroscopy of the Ultrafaint Dwarf Galaxies Eridanus IV and Centaurus I
Authors: Heiger M. E. , Li T. S. , Pace A. B. , Simon J. D. , Ji A. P. , Chiti A. , Bom C. R. , Carballo-Bello J. A. , Carlin J. L. , Cerny W. , Choi Y. , Drlica-Wagner A. , James D. J. , Martínez-Vázquez C. E. , Medina G. E. , Mutlu-Pakdil B. , Navabi M. , Noël N. E. D. , Sakowska J. D. , Stringfellow G. S. ,   (DELVE Collaboration)
Published: January 2024

Abstract
We present a spectroscopic analysis of Eridanus IV (Eri IV) and Centaurus I (Cen I), two ultrafaint dwarf galaxies of the Milky Way. Using IMACS/Magellan spectroscopy, we identify 28 member stars of Eri IV and 34 member stars of Cen I. For Eri IV, we measure a systemic velocity of

v

sys

=
−

31.5

−
1.2

+
1.3

km

s

−
1

, and velocity dispersion

σ

v

=

6.1

−
0.9

+
1.2

km

s

−
1

. Additionally, we measure the metallicities of 16 member stars of Eri IV. We find a metallicity of

[
Fe

/

H
]
=
−

2.87

−
0.07

+
0.08

, and resolve a dispersion of σ
[Fe/H]=0.20 ± 0.09. The mean metallicity is marginally lower than all other known ultrafaint dwarf galaxies, making it one of the most metal-poor galaxies discovered thus far. Eri IV also has a somewhat unusual right-skewed metallicity distribution. For Cen I, we find a velocity v
sys = 44.9 ± 0.8 km s−1, and velocity dispersion

σ

v

=

4.2

−
0.5

+
0.6

km

s

−
1

. We measure the metallicities of 27 member stars of Cen I, and find a mean metallicity [Fe/H] = −2.57 ± 0.08, and metallicity dispersion

σ

[
Fe

/

H
]

=

0.38

−
0.05

+
0.07

. We calculate the systemic proper motion, orbit, and the astrophysical J-factor for each system, the latter of which indicates that Eri IV is a good target for indirect dark matter detection. We also find no strong evidence for tidal stripping of Cen I or Eri IV. Overall, our measurements confirm that Eri IV and Cen I are dark-matter-dominated galaxies with properties largely consistent with other known ultrafaint dwarf galaxies. The low metallicity, right-skewed metallicity distribution, and high J-factor make Eri IV an especially interesting candidate for further follow-up.
VLA FRAMEx. I. Wideband Radio Properties of the AGN in NGC 4388
Authors: Sargent Andrew J. , Fischer Travis C. , Johnson Megan C. , van der Horst Alexander J. , Secrest Nathan J. , Shuvo Onic I. , Cigan Phil J. , Smith Krista L. 
Published: January 2024

Abstract
We present the first results from Karl G. Jansky Very Large Array (VLA) observations as a part of the Fundamental Reference Active Galactic Nucleus (AGN) Monitoring Experiment, a program to understand the relationship between AGN accretion physics and wavelength-dependent position as a function of time. With this VLA survey, we investigate the radio properties from a volume-complete sample of 25 hard X-ray-selected AGNs using the VLA in its wideband mode. We observed the targets in the A-array configuration at 4–12 GHz with all polarization products. In this work, we introduce our calibration and imaging methods for this survey, and we present our results and analysis for the radio-quiet AGN NGC 4388. We calibrated and imaged these data using the multiterm, multifrequency synthesis imaging algorithm to determine its spatial, spectral, and polarization structure across a continuous 4–12 GHz band. In the AGN, we measure a broken power law spectrum with α = − 0.06 below a break frequency of 7.3 GHz and α = − 0.34 above. We detect polarization at subarcsecond resolution across both the AGN and a secondary radio knot. We compare our results to ancillary data and find that the VLA radio continuum is likely due to AGN winds interacting with the local interstellar medium that gets resolved away at subparsec spatial scales as probed by the Very Long Baseline Array. A well-known ionization cone to the southwest of the AGN appears likely to be projected material onto the underside of the disk of the host galaxy.
Ring Gap Structure around Class I Protostar WL 17
Authors: Shoshi Ayumu , Harada Naoto , Tokuda Kazuki , Kawasaki Yoshihiro , Yamasaki Hayao , Sato Asako , Omura Mitsuki , Yamaguchi Masayuki , Tachihara Kengo , Machida Masahiro N. 
Published: January 2024

Abstract
WL 17 is a Class I object and was considered to have a ring–hole structure. We analyzed the structure around WL 17 to investigate the detailed properties of this object. We used Atacama Large Millimeter/submillimeter Array archival data, which have a higher angular resolution than previous observations. We investigated the WL 17 system with the 1.3 mm dust continuum and 12CO and C18O (J = 2–1) line emissions. The dust continuum emission showed a clear ring structure with inner and outer edges of ∼11 and ∼21 au, respectively. In addition, we detected an inner disk of <5 au radius enclosing the central star within the ring, the first observation of this structure. Thus, WL 17 has a ring–gap structure, not a ring–hole structure. We did not detect any marked emission in either the gap or inner disk, indicating that there is no sign of a planet, circumplanetary disk, or binary companion. We identified the source of both blueshifted and redshifted outflows based on the 12CO emission, which is clearly associated with the disk around WL 17. The outflow mass ejection rate is ∼3.6 × 10−7
M
⊙ yr−1 and the dynamical timescale is as short as ∼104 yr. The C18O emission showed that an inhomogeneous infalling envelope, which can induce episodic mass accretion, is distributed in the region within ∼1000 au from the central protostar. With these new findings, we can constrain the scenarios of planet formation and dust growth in the accretion phase of star formation.
A Comparative Study between M30 and M92: M92 is a Merger Remnant with a Large Helium Enhancement
Authors: Lee Jae-Woo 
Published: January 2024

Abstract
We perform a comparative study of the ex situ second-parameter pair globular clusters (GCs) M30 and M92, having similar metallicities but different horizontal branch morphologies. We obtain similar mean primordial carbon abundances for both clusters. However, M92 shows a large dispersion in carbon due to a more extended C–N anticorrelation, while M30 exhibits a higher primordial nitrogen abundance, suggesting that they have different chemical enrichment histories. Our new results confirm our previous result that M92 is a metal-complex GC showing a bimodal metallicity distribution. We also find that the metal-rich group of stars in M92 shows a helium enhancement as large as ΔY ∼ 0.05 from the red giant branch bump V magnitudes, which can also be supported by (i) a lack of bright red giant branch stars, (ii) synthetic evolutionary horizontal branch population models and (iii) the more extended spatial distribution due to different degree of the diffusion process from their lower masses. We reinterpret the [Eu/Fe] measurements by others, finding that the two metallicity groups of stars in M92 have significantly different [Eu/Fe] abundances with small scatters. This strongly suggests that they formed independently out of well-mixed interstellar media in different environments. We suggest that M92 is a more complex system than a normal GC, most likely a merger remnant of two GCs or an even more complex system. In the Appendix, we address the problems with the recently developed color–temperature relations and the usage of broadband photometry in the populational taggings.
An ALMA Spectroscopic Survey of the Brightest Submillimeter Galaxies in the SCUBA-2-COSMOS Field (AS2COSPEC): Physical Properties of z = 2–5 Ultra- and Hyperluminous Infrared Galaxies
Authors: Liao 廖 Cheng-Lin 政霖 , Chen 陳 Chian-Chou 建州 , Wang 王 Wei-Hao 為豪 , Smail Ian , Ao Y. , Chapman S. C. , Dudzevičiūtė U. , Frias Castillo M. , Lee Minju M. , Serjeant Stephen , Swinbank A. M. , Taylor Dominic J. , Umehata Hideki , Zhao Y. 
Published: January 2024

Abstract
We report the physical properties of the 18 brightest (S
870 μm = 12.4–19.2 mJy) and not strongly lensed 870 μm–selected dusty star-forming galaxies (DSFGs), also known as submillimeter galaxies (SMGs), in the COSMOS field. This sample is part of an ALMA band 3 spectroscopic survey (AS2COSPEC), and spectroscopic redshifts are measured in 17 of them at z = 2–5. We perform spectral energy distribution analyses and deduce a median total infrared luminosity of L
IR = (1.3 ± 0.1) × 1013
L
⊙, infrared-based star formation rate (SFR) of SFRIR = 1390 ± 150 M
⊙ yr−1, stellar mass of M
* = (1.4 ± 0.6) × 1011
M
⊙, dust mass of M
dust = (3.7 ± 0.5) × 109
M
⊙, and molecular gas mass of M
gas = (α
CO/0.8)(1.2 ± 0.1) × 1011
M
⊙, suggesting that they are one of the most massive, ISM-enriched, and actively star-forming systems at z = 2–5. In addition, compared to less massive and less active galaxies at similar epochs, SMGs have comparable gas fractions; however, they have a much shorter depletion time, possibly caused by more active dynamical interactions. We determine a median dust emissivity index of β = 2.1 ± 0.1 for our sample, and by combining our results with those from other DSFG samples, we find no correlation of β with redshift or infrared luminosity, indicating similar dust grain compositions across cosmic time for infrared luminous galaxies. We also find that AS2COSPEC SMGs have one of the highest dust-to-stellar mass ratios, with a median of 0.02 ± 0.01, significantly higher than model predictions, possibly due to too-strong active galactic nucleus feedback implemented in the model. Finally, our complete and uniform survey enables us to put constraints on the most massive end of the dust and molecular gas mass functions.
Disentangling Multiple Emitting Components in Molecular Observations with Nonnegative Matrix Factorization
Authors: de Mijolla Damien , Holdship Jonathan , Viti Serena , Heyl Johannes 
Published: January 2024

Abstract
Molecular emission from the galactic and extragalactic interstellar medium (ISM) is often used to determine the physical conditions of the dense gas. However, even from spatially resolved regions, the observed molecules do not necessarily arise from a single component. Disentangling multiple gas components is often a degenerate problem in radiative transfer studies. In this paper, we investigate the use of the nonnegative matrix factorization (NMF) approach as a means to recover gas components from a set of blended line intensity maps of molecular transitions that may trace different physical conditions. We run a series of experiments on synthetic data sets designed to replicate conditions in two very different environments: galactic pre-stellar cores and the ISM in high-redshift galaxies. We find that the NMF algorithm often recovers the multiple components resembling those used in the data-generating process, provided that the different components have similar column densities. When NMF fails to recover all the individual components it does however group together the most similarly emitting ones. We further found that initialization and regularisation are key factors in the efficiency of the NMF algorithm.
The Presolar Grain Database. I. Silicon Carbide
Authors: Stephan Thomas , Trappitsch Reto , Hoppe Peter , Davis Andrew M. , Bose Maitrayee , Boujibar Asmaa , Gyngard Frank , Hynes K. Mairin , Liu Nan , Nittler Larry R. , Ogliore Ryan C. 
Published: January 2024

Abstract
The Presolar Grain Database (PGD) contains the vast majority of isotope data (published and unpublished) on presolar grains and was first released as a collection of spreadsheets in 2009. It has been a helpful tool used by many researchers in cosmochemistry and astrophysics. However, over the years, accumulated errors compromised major parts of the PGD. Here, we provide a fresh start, with the PGD for silicon carbide (SiC) grains rebuilt from the ground up. We also provide updated rules for SiC grain type classification to unify previous efforts, taking into account newly discovered grain types. We also define a new grain type D, which includes some grains previously classified as ungrouped. Future work will focus on rebuilding the PGD for other kinds of presolar grains: graphite, oxides, silicates, and rarer phases.
Is the Far-ultraviolet Flux of 21 Com Anticorrelated to its Optical Brightness?
Authors: Monier Richard 
Published: January 2024

Abstract
The comparison of 20 ultraviolet spectra of 21 Com taken over continuous 24 hr to the optical counts collected by the Fine Error Sensor on board IUE reveals that large variations observed shortwards of 1700 Å occur in anti-phase with the optical brightness for part of the observations but not all. In this data, the FUV flux at 1540 Å reaches a minimum at rotational phase 0.32 and increases afterwards while the FES counts continue to increase after this phase. The Fe ii resonance line at 1608.45 Å is Doppler shifted by 0.13 Å at phase 0.00 and −0.13 Å at phase of FUV flux minimum.
A Possible Orbital Period of MAXI J0158-744
Authors: Chan Alex C. H. , Li K. L. 
Published: January 2024

Abstract
Optical Gravitational Lensing Experiment (OGLE) has observed Monitor of All-sky X-ray Image J0158-744 for at least 10 yr since the X-ray/optical burst in 2011, which is a Be+ White Dwarf Supersoft source. By analyzing the OGLE light curve, we noticed that the optical brightness was changing periodically, indicating a possible orbital period of

439

−
80

+
114

days.
Dust Production Rates in Jupiter-family Comets: A Two Year Study with
ATLAS Photometry
Authors: Gillan A. Fraser , Fitzsimmons Alan , Denneau Larry , Siverd Robert J. , Smith Ken W. , Tonry John L. , Young David R. 
Published: January 2024

Abstract
Jupiter-family comets (JFCs) exhibit a wide range of activity levels and mass
loss over their orbits. We analyzed high-cadence observations of 42 active JFCs
with the wide-field Asteroid Terrestrial-impact Last Alert System (ATLAS) in
2020–2021. We measured the dust production rates of the JFCs using the Af
ρ parameter and its variation as a function of
heliocentric distance. There is a tendency for our JFC sample to exhibit a
maximum Af
ρ after perihelion, with 254P/McNaught and P/2020
WJ5 (Lemmon) having their maximum Af
ρ over a year after perihelion. On average, the
rate of change of activity postperihelion was shallower than preperihelion. We
also estimated the maximum mass-loss rate for 17 of the JFCs in our sample,
finding 4P/Faye to be the most active. We present a subset of comets whose
measured Af
ρ have been interpolated and extrapolated to a
common distance of 2 au preperihelion and postperihelion. From these
measurements we found no correlation of intrinsic activity with current
perihelion distance. For three of the JFCs in our sample, 6P/d’Arrest,
156P/Russell–LINEAR, and 254P/McNaught, there was no visible coma but a constant
absolute magnitude, which we attribute to a probable detection of the nucleus.
We derived upper limits for the nuclear radii of ≤2.1 ± 0.3 km, ≤2.0 ± 0.2 km,
and ≤4.0 ± 0.8 km, respectively. Finally, we found that 4P/Faye, 108P/Ciffreo,
132P/Helin–Roman–Alu 2, 141P/Machholz 2, and 398P/Boattini experienced outbursts
between 2020 and 2022.
À qui appartient l’islam ? Prisme de l’authenticité et spectre de l’appropriation parmi les musulmans américains
Authors: Galonnier Juliette 
Published: January 2024

Cet article traite des controverses relatives à l’articulation souhaitable entre « religion » et « culture » au sein de l’islam américain contemporain, où plusieurs communautés d’interprétation (formées au croisement de positionnements théologiques, d’appartenances de classe et de catégorisations raciales) expriment des conceptions divergentes, à la fois de l’islam et des États-Unis. À partir d’une enquête mobilisant entretiens et observations ethnographiques parmi des musulmans convertis à Chicago, l’article déplie ces controverses en les resituant dans le contexte social dans lequel elles prennent corps. Il montre que les musulmans américains mobilisent souvent le prisme de « l’authenticité », qu’elle soit culturelle ou religieuse, pour définir ce qui est « véritablement » islamique ou « véritablement » américain, mais que ces qualifications d’authenticité sont aussi travaillées par le spectre de l’appropriation et indissociables d’une évaluation des rapports de domination qui traversent la minorité musulmane américaine. Après avoir retracé une brève histoire des emprunts à la tradition islamique par des groupes positionnés différemment dans le système de stratification sociale et raciale des États-Unis, l’article examine tour à tour trois registres de discours sur la notion de culture en milieu islamique : l’acculturation, l’exculturation et l’inculturation. Ces trois registres reposent sur des appréhensions différentes de « l’authenticité » et suscitent des positionnements contrastés sur ce qui constitue une appropriation.
Essai de logopolitique. Langue, politique, historicité
Authors: Moatti Claudia 
Published: January 2024

L’article offre une réflexion sur la place de la langue dans l’écriture de l’histoire. La première partie rappelle l’influence récente de la linguistique sur les historiens, et évoque de manière critique les principaux travaux qui s’en sont inspirés. La deuxième partie définit le projet singulier d’une logopolitique, qui propose trois approches conjuguées : formaliste, qui consiste à travailler sur le concept initial d’une notion ; discursive, qui, mettant au jour les conflictualités d’un moment, s’attache à analyser la construction d’un discours dominant ; praxéologique, qui étudie les relations entre les mots et les pratiques politiques des différents acteurs. Dans la troisième partie, l’auteure rappelle certaines conclusions obtenues, selon cette méthode, dans son livre sur la res publica : elle montre notamment que la définition de cette notion originellement indéterminée a constitué un enjeu essentiel dans les conflits politiques de la fin de la République romaine, puis, comment res publica a servi de principe de légitimation aux empereurs, notamment contre toute menace intérieure, avant d’être utilisée à partir du IIIe siècle de notre ère comme concept civilisationnel.