bluuebunny/crossref_metadata_2025_split huggingface dataset:
Another Superdense Sub-Neptune in K2-182 b and Refined Mass Measurements for K2-199 b and c*
Authors: Akana Murphy Joseph M. , Kosiarek Molly R. , Batalha Natalie M. , Gonzales Erica J. , Isaacson Howard , Petigura Erik A , Weiss Lauren M. , Grunblatt Samuel K. , Ciardi David R. , Fulton Benjamin , Hirsch Lea A. , Behmard Aida , Rosenthal Lee J. 
Published: December 2021

Abstract
We combine multiple campaigns of K2 photometry with precision radial velocity measurements from Keck-HIRES to measure the masses of three sub-Neptune-sized planets. We confirm the planetary nature of the massive sub-Neptune K2-182 b (P
b = 4.7 days, R
b = 2.69 R
⊕) and derive refined parameters for K2-199 b and c (P
b = 3.2 days, R
b = 1.73 R
⊕ and P
c = 7.4 days, R
c = 2.85 R
⊕). These planets provide valuable data points in the mass–radius plane, especially as TESS continues to reveal an increasingly diverse sample of sub-Neptunes. The moderately bright (V = 12.0 mag) early K dwarf K2-182 (EPIC 211359660) was observed during K2 campaigns 5 and 18. We find that K2-182 b is potentially one of the densest sub-Neptunes known to date (20 ± 5 M
⊕ and 5.6 ± 1.4 g cm−3). The K5V dwarf K2-199 (EPIC 212779596; V = 12.3 mag), observed in K2 campaigns 6 and 17, hosts two recently confirmed planets. We refine the orbital and planetary parameters for K2-199 b and c by modeling both campaigns of K2 photometry and adding 12 Keck-HIRES measurements to the existing radial velocity data set (N = 33). We find that K2-199 b is likely rocky, at 6.9 ± 1.8 M
⊕ and

7.2

−
2.0

+
2.1

g cm−3, and that K2-199 c has an intermediate density at 12.4 ± 2.3 M
⊕ and

2.9

−
0.6

+
0.7

g cm−3. We contextualize these planets on the mass–radius plane, discuss a small but intriguing population of “superdense” sub-Neptunes (R
p < 3 R
⊕, M
p >20 M
⊕), and consider our prospects for the planets’ atmospheric characterization.
The HETDEX Instrumentation: Hobby–Eberly Telescope Wide-field Upgrade and VIRUS
Authors: Hill Gary J. , Lee Hanshin , MacQueen Phillip J. , Kelz Andreas , Drory Niv , Vattiat Brian L. , Good John M. , Ramsey Jason , Kriel Herman , Peterson Trent , DePoy D. L. , Gebhardt Karl , Marshall J. L. , Tuttle Sarah E. , Bauer Svend M. , Chonis Taylor S. , Fabricius Maximilian H. , Froning Cynthia , Häuser Marco , Indahl Briana L. , Jahn Thomas , Landriau Martin , Leck Ron , Montesano Francesco , Prochaska Travis , Snigula Jan M. , Zeimann Greg , Bryant Randy , Damm George , Fowler J. R. , Janowiecki Steven , Martin Jerry , Mrozinski Emily , Odewahn Stephen , Rostopchin Sergey , Shetrone Matthew , Spencer Renny , Mentuch Cooper Erin , Armandroff Taft , Bender Ralf , Dalton Gavin , Hopp Ulrich , Komatsu Eiichiro , Nicklas Harald , Ramsey Lawrence W. , Roth Martin M. , Schneider Donald P. , Sneden Chris , Steinmetz Matthias 
Published: December 2021

Abstract
The Hobby–Eberly Telescope (HET) Dark Energy Experiment (HETDEX) is undertaking a blind wide-field low-resolution spectroscopic survey of 540 deg2 of sky to identify and derive redshifts for a million Lyα-emitting galaxies in the redshift range 1.9 < z < 3.5. The ultimate goal is to measure the expansion rate of the universe at this epoch, to sharply constrain cosmological parameters and thus the nature of dark energy. A major multiyear Wide-Field Upgrade (WFU) of the HET was completed in 2016 that substantially increased the field of view to 22′ diameter and the pupil to 10 m, by replacing the optical corrector, tracker, and Prime Focus Instrument Package and by developing a new telescope control system. The new, wide-field HET now feeds the Visible Integral-field Replicable Unit Spectrograph (VIRUS), a new low-resolution integral-field spectrograph (LRS2), and the Habitable Zone Planet Finder, a precision near-infrared radial velocity spectrograph. VIRUS consists of 156 identical spectrographs fed by almost 35,000 fibers in 78 integral-field units arrayed at the focus of the upgraded HET. VIRUS operates in a bandpass of 3500−5500 Å with resolving power R ≃ 800. VIRUS is the first example of large-scale replication applied to instrumentation in optical astronomy to achieve spectroscopic surveys of very large areas of sky. This paper presents technical details of the HET WFU and VIRUS, as flowed down from the HETDEX science requirements, along with experience from commissioning this major telescope upgrade and the innovative instrumentation suite for HETDEX.
Diving Beneath the Sea of Stellar Activity: Chromatic Radial Velocities of the Young AU Mic Planetary System
Authors: Cale Bryson L. , Reefe Michael , Plavchan Peter , Tanner Angelle , Gaidos Eric , Gagné Jonathan , Gao Peter , Kane Stephen R. , Béjar Víctor J. S. , Lodieu Nicolas , Anglada-Escudé Guillem , Ribas Ignasi , Pallé Enric , Quirrenbach Andreas , Amado Pedro J. , Reiners Ansgar , Caballero José A. , Rosa Zapatero Osorio María , Dreizler Stefan , Howard Andrew W. , Fulton Benjamin J. , Xuesong Wang Sharon , Collins Kevin I. , El Mufti Mohammed , Wittrock Justin , Gilbert Emily A. , Barclay Thomas , Klein Baptiste , Martioli Eder , Wittenmyer Robert , Wright Duncan , Addison Brett , Hirano Teruyuki , Tamura Motohide , Kotani Takayuki , Narita Norio , Vermilion David , Lee Rena A. , Geneser Claire , Teske Johanna , Quinn Samuel N. , Latham David W. , Esquerdo Gilbert A. , Calkins Michael L. , Berlind Perry , Zohrabi Farzaneh , Stibbards Caitlin , Kotnana Srihan , Jenkins Jon , Twicken Joseph D. , Henze Christopher , Kidwell Richard , Burke Christopher , Villaseñor Joel , Boyd Patricia 
Published: December 2021

Abstract
We present updated radial-velocity (RV) analyses of the AU Mic system. AU Mic is a young (22 Myr) early-M dwarf known to host two transiting planets—P

b
∼ 8.46 days,

R

b

=

4.38

−
0.18

+
0.18

R

⊕

, P

c
∼ 18.86 days,

R

c

=

3.51

−
0.16

+
0.16

R

⊕

. With visible RVs from Calar Alto high-Resolution search for M dwarfs with Exo-earths with Near-infrared and optical echelle Spectrographs (CARMENES)-VIS, CHIRON, HARPS, HIRES, Minerva-Australis, and Tillinghast Reflector Echelle Spectrograph, as well as near-infrared (NIR) RVs from CARMENES-NIR, CSHELL, IRD, iSHELL, NIRSPEC, and SPIRou, we provide a 5σ upper limit to the mass of AU Mic c of M

c
≤ 20.13 M
⊕ and present a refined mass of AU Mic b of

M

b

=

20.12

−
1.57

+
1.72

M

⊕

. Used in our analyses is a new RV modeling toolkit to exploit the wavelength dependence of stellar activity present in our RVs via wavelength-dependent Gaussian processes. By obtaining near-simultaneous visible and near-infrared RVs, we also compute the temporal evolution of RV “color” and introduce a regressional method to aid in isolating Keplerian from stellar activity signals when modeling RVs in future works. Using a multiwavelength Gaussian process model, we demonstrate the ability to recover injected planets at 5σ significance with semi-amplitudes down to ≈10 m s−1 with a known ephemeris, more than an order of magnitude below the stellar activity amplitude. However, we find that the accuracy of the recovered semi-amplitudes is ∼50% for such signals with our model.
Quasi-simultaneous Radio/X-Ray Observations of the Candidate Transitional Millisecond Pulsar 3FGL J1544.6−1125 during its Low-luminosity Accretion-disk State
Authors: Jaodand Amruta D. , Deller Adam T. , Gusinskaia Nina , Hessels Jason W. T. , Miller-Jones James C. A. , Archibald Anne M. , Bogdanov Slavko , Bassa Cees , Wijnands Rudy , Patruno Alessandro , Sanidas Sotiris 
Published: December 2021

Abstract
3FGL J1544.6−1125 is a candidate transitional millisecond pulsar (tMSP). Similar to the well-established tMSPs—PSR J1023+0038, IGR J18245−2452, and XSS J12270−4859—3FGL J1544.6−1125 shows γ-ray emission and discrete X-ray “low” and “high” modes during its low-luminosity accretion-disk state. Coordinated radio/X-ray observations of PSR J1023+0038 in its current low-luminosity accretion-disk state showed rapidly variable radio continuum emission—possibly originating from a compact, self-absorbed jet, the “propellering” of accretion material, and/or pulsar moding. 3FGL J1544.6−1125 is currently the only other (candidate) tMSP system in this state, and can be studied to see whether tMSPs are typically radio-loud compared to other neutron star binaries. In this work, we present a quasi-simultaneous Very Large Array and Swift radio/X-ray campaign on 3FGL J1544.6−1125. We detect 10 GHz radio emission varying in flux density from 47.7 ± 6.0 μJy down to ≲15 μJy (3σ upper limit) at four epochs spanning three weeks. At the brightest epoch, the radio luminosity is L
5 GHz = (2.17 ± 0.17) × 1027 erg s−1 for a quasi-simultaneous X-ray luminosity L
2–10 keV = (4.32 ± 0.23) × 1033 erg s−1 (for an assumed distance of 3.8 kpc). These luminosities are close to those of PSR J1023+0038, and the results strengthen the case that 3FGL J1544.6−1125 is a tMSP showing similar phenomenology to PSR J1023+0038.
Characterizing Long-term Optical Variability Properties of γ-Ray-bright Blazars
Authors: Bhatta Gopal 
Published: December 2021

Abstract
Optical observations of a sample of 12 γ-ray-bright blazars from four optical data archives—American Association of Variable Star Observers, Small and Moderate Aperture Research Telescope System, Catalina, and Steward Observatory—are compiled to create densely sampled light curves spanning more than a decade. As a part of the blazar multiwavelength studies, several methods of analysis, e.g., flux distribution and rms–flux relation, are performed on the observations with the aim to compare the results with the similar ones in the γ-ray band presented in Bhatta & Dhital. It is found that, similar to the γ-ray band, blazars display significant variability in the optical band that can be characterized with lognormal flux distribution and a power-law dependence of rms on flux. It could be an indication of a possible inherent linear rms–flux relation, yet the scatter in the data does not allow to rule out other possibilities. When comparing variability properties in the two bands, the blazars in the γ-rays are found to exhibit stronger variability with a steeper possible linear rms–flux relation and a flux distribution that is more skewed toward higher fluxes. The cross-correlation study shows that except for source 3C 273, the overall optical and the γ-ray emission in the sources are highly correlated, suggesting a cospatial existence of the particles responsible for both the optical and γ-ray emission. Moreover, sources S5 0716+714, Mrk 421, Mrk 501, PKS 1424-418, and PKS 2155-304 revealed possible evidence of quasiperiodic oscillations in the optical emission with the characteristic timescales, which are comparable to those in the γ-ray band detected in our previous work.
Interplanetary Coronal Mass Ejections from MAVEN Orbital Observations at Mars
Authors: Zhao Dan , Guo Jianpeng , Huang Hui , Lin Haibo , Hong Yichun , Feng Xueshang , Cui Jun , Wei Yong , Wang Yang , Feng Yongyong , Li Lei , Liu Libo 
Published: December 2021

Abstract
The measurements from the Mars Atmosphere and Volatile EvolutioN spacecraft, in orbit around Mars, are utilized to investigate interplanetary coronal mass ejections (ICMEs) near 1.52 au. We identify 24 ICMEs from 2014 December 6 to 2019 February 21. The ICME list is used to examine the statistical properties of ICMEs. On average, the magnetic field strength of 5.99 nT in ICMEs is higher than that of 5.38 nT for stream interaction regions (SIRs). The density of 5.27 cm−3 for ICMEs is quite comparable to that of 5.17 cm−3 for SIRs, the velocity of 394.7 km s−1 for ICMEs is slightly lower than that of 432.8 km s−1 for SIRs, and the corresponding dynamic pressure of 1.34 nPa for ICMEs is smaller than that of 1.50 nPa for SIRs. Using existing databases of ICMEs at 1 au for the same time period, we compare ICME average properties at 1.52 au with those at 1 au. The averages of the characteristic quantities decrease by a factor of 1.1–1.7 from 1 to 1.52 au. In addition, we analyze an unusual space weather event associated with the ICME on 2015 March 9–10, and propose that the extremely strong dynamic pressure with a maximum of ∼18 nPa on March 8 is caused by the combined effects of the enhanced density inside a heliospheric plasma sheet (HPS), the compression of the HPS by the forward shock, and the high velocity of the sheath ahead of the ICME.
Magnetic Topology in Coupled Binaries, Spin-orbital Resonances, and Flares
Authors: Cherkis Sergey A. , Lyutikov Maxim 
Published: December 2021

Abstract
We consider topological configurations of the magnetically coupled spinning stellar binaries (e.g., merging neutron stars or interacting star–planet systems). We discuss conditions when the stellar spins and the orbital motion nearly “compensate” each other, leading to very slow overall winding of the coupled magnetic fields; slowly winding configurations allow gradual accumulation of magnetic energy, which is eventually released in a flare when the instability threshold is reached. We find that this slow winding can be global and/or local. We describe the topology of the relevant space

F
=

T

1

S

2

as the unit tangent bundle of the two-sphere and find conditions for slowly winding configurations in terms of magnetic moments, spins, and orbital momentum. These conditions become ambiguous near the topological bifurcation points; in certain cases, they also depend on the relative phases of the spin and orbital motions. In the case of merging magnetized neutron stars, if one of the stars is a millisecond pulsar, spinning at ∼10 ms, the global resonance ω
1 + ω
2 = 2Ω (spin-plus beat is two times the orbital period) occurs approximately one second before the merger; the total energy of the flare can be as large as 10% of the total magnetic energy, producing bursts of luminosity ∼1044 erg s−1. Higher order local resonances may have similar powers, since the amount of involved magnetic flux tubes may be comparable to the total connected flux.
Finding High-redshift Galaxies with JWST
Authors: Steinhardt Charles L. , Jespersen Christian Kragh , Linzer Nora B. 
Published: December 2021

Abstract
One of the primary goals for the upcoming James Webb Space Telescope is to observe the first galaxies. Predictions for planned and proposed surveys have typically focused on average galaxy counts, assuming a random distribution of galaxies across the observed field. The first and most-massive galaxies, however, are expected to be tightly clustered, an effect known as cosmic variance. We show that cosmic variance is likely to be the dominant contribution to uncertainty for high-redshift mass and luminosity functions, and that median high-redshift and high-mass galaxy counts for planned observations lie significantly below average counts. Several different strategies are considered for improving our understanding of the first galaxies, including adding depth, area, and independent pointings. Adding independent pointings is shown to be the most efficient both for discovering the single highest-redshift galaxy and also for constraining mass and luminosity functions.
Evolution of the Ultraviolet Upturn at 0.3 < z < 1: Exploring Helium-rich Stellar Populations
Authors: Ali Sadman S. , De Propris Roberto , Chung Chul , Phillipps Steven , Bremer Malcolm N. 
Published: December 2021

Abstract
We measure the near-UV (rest-frame ∼2400 Å) to optical color for early-type galaxies in 12 clusters at 0.3 < z < 1.0. We show that this is a suitable proxy for the more common far-ultraviolet bandpass used to measure the ultraviolet upturn and find that the upturn is detected to z = 0.6 in these data, in agreement with previous work. We find evidence that the strength of the upturn starts to wane beyond this redshift and largely disappears at z = 1. Our data are most consistent with models where early-type galaxies contain minority stellar populations with non-cosmological helium abundances, up to around 46%, formed at z ≥ 3, resembling globular clusters with multiple stellar populations in our Galaxy. This suggests that elliptical galaxies and globular clusters share similar chemical evolution and star formation histories. The vast majority of the stellar mass in these galaxies also must have been in place at z > 3.
Fast Radio Burst Morphology in the First CHIME/FRB Catalog
Authors: Pleunis Ziggy , Good Deborah C. , Kaspi Victoria M. , Mckinven Ryan , Ransom Scott M. , Scholz Paul , Bandura Kevin , Bhardwaj Mohit , Boyle P. J. , Brar Charanjot , Cassanelli Tomas , Chawla Pragya , (Adam) Dong Fengqiu , Fonseca Emmanuel , Gaensler B. M. , Josephy Alexander , Kaczmarek Jane F. , Leung Calvin , Lin Hsiu-Hsien , Masui Kiyoshi W. , Mena-Parra Juan , Michilli Daniele , Ng Cherry , Patel Chitrang , Rafiei-Ravandi Masoud , Rahman Mubdi , Sanghavi Pranav , Shin Kaitlyn , Smith Kendrick M. , Stairs Ingrid H. , Tendulkar Shriharsh P. 
Published: December 2021

Abstract
We present a synthesis of fast radio burst (FRB) morphology (the change in flux as a function of time and frequency) as detected in the 400–800 MHz octave by the FRB project on the Canadian Hydrogen Intensity Mapping Experiment (CHIME/FRB), using events from the first CHIME/FRB catalog. The catalog consists of 62 bursts from 18 repeating sources, plus 474 one-off FRBs, detected between 2018 July 25 and 2019 July 2. We identify four observed archetypes of burst morphology (“simple broadband,” “simple narrowband,” “temporally complex,” and “downward drifting”) and describe relevant instrumental biases that are essential for interpreting the observed morphologies. Using the catalog properties of the FRBs, we confirm that bursts from repeating sources, on average, have larger widths, and we show, for the first time, that bursts from repeating sources, on average, are narrower in bandwidth. This difference could be due to beaming or propagation effects, or it could be intrinsic to the populations. We discuss potential implications of these morphological differences for using FRBs as astrophysical tools.
Comprehensive Broadband X-Ray and Multiwavelength Study of Active Galactic Nuclei in 57 Local Luminous and Ultraluminous Infrared Galaxies Observed with NuSTAR and/or Swift/BAT
Authors: Yamada Satoshi , Ueda Yoshihiro , Tanimoto Atsushi , Imanishi Masatoshi , Toba Yoshiki , Ricci Claudio , Privon George C. 
Published: December 2021

Abstract
We perform a systematic X-ray spectroscopic analysis of 57 local luminous and ultraluminous infrared galaxy systems (containing 84 individual galaxies) observed with the Nuclear Spectroscopic Telescope Array and/or Swift/BAT. Combining soft X-ray data obtained with Chandra, XMM-Newton, Suzaku, and/or Swift/XRT, we identify 40 hard (>10 keV) X-ray–detected active galactic nuclei (AGNs) and constrain their torus parameters with the X-ray clumpy torus model XCLUMPY. Among the AGNs at z < 0.03, for which sample biases are minimized, the fraction of Compton-thick (N
H ≥ 1024 cm−2) AGNs reaches

64

−
15

+
14

% (6/9 sources) in late mergers, while it is

24

−
10

+
12

% (3/14 sources) in early mergers, consistent with the tendency reported by Ricci et al. We find that the bolometric AGN luminosities derived from the infrared data increase but the X-ray to bolometric luminosity ratios decrease with merger stage. The X-ray-weak AGNs in late mergers ubiquitously show massive outflows at subparsec to kiloparsec scales. Among them, the most luminous AGNs (L
bol,AGN ∼ 1046 erg s−1) have relatively small column densities of ≲1023 cm−2 and almost super-Eddington ratios (λ
Edd ∼ 1.0). Their torus covering factors (C
T
(22) ∼ 0.6) are larger than those of Swift/BAT-selected AGNs with similarly high Eddington ratios. These results suggest a scenario where, in the final stage of mergers, multiphase strong outflows are produced due to chaotic quasi-spherical inflows, and the AGN becomes extremely X-ray weak and deeply buried due to obscuration by inflowing and/or outflowing material.
Systematically Measuring Ultra-diffuse Galaxies (SMUDGes). II. Expanded Survey Description and the Stripe 82 Catalog
Authors: Zaritsky Dennis , Donnerstein Richard , Karunakaran Ananthan , Barbosa C. E. , Dey Arjun , Kadowaki Jennifer , Spekkens Kristine , Zhang Huanian 
Published: December 2021

Abstract
We present 226 large ultra-diffuse galaxy (UDG) candidates (r

e
> 5.″3, μ
0,g
> 24 mag arcsec−2) in the SDSS Stripe 82 region recovered using our improved procedure developed in anticipation of processing the entire Legacy Surveys footprint. The advancements include less constrained structural parameter fitting, expanded wavelet filtering criteria, consideration of Galactic dust, estimates of parameter uncertainties and completeness based on simulated sources, and refinements of our automated candidate classification. We have a sensitivity ∼1 mag fainter in μ
0,g
than the largest published catalog of this region. Using our completeness-corrected sample, we find that (1) there is no significant decline in the number of UDG candidates as a function of μ
0,g
to the limit of our survey (∼26.5 mag arcsec−2); (2) bluer candidates have smaller Sérsic n; (3) most blue (g–r < 0.45 mag) candidates have μ
0,g
≲ 25 mag arcsec−2 and will fade to populate the UDG red sequence we observe to ∼26.5 mag arcsec−2; (4) any red UDGs that exist significantly below our μ
0,g
sensitivity limit are not descendent from blue UDGs in our sample; and (5) candidates with lower μ
0,g
tend to smaller n. We anticipate that the final SMUDGes sample will contain ∼30 × as many candidates.
KAPPA: A Package for the Synthesis of Optically Thin Spectra for the Non-Maxwellian κ-distributions. II. Major Update to Compatibility with CHIANTI Version 10
Authors: Dzifčáková Elena , Dudík Jaroslav , Zemanová Alena , Lörinčík Juraj , Karlický Marian 
Published: December 2021

Abstract
KAPPA is a database and software for the calculation of the optically thin spectra for the non-Maxwellian κ-distributions that were recently diagnosed in the plasma of solar coronal loops, flares, as well as in the transition region. KAPPA is based on the widely used CHIANTI database and reproduces many of its capabilities for κ-distributions. Here we perform a major update of the KAPPA database, including a near-complete recalculation of the ionization, recombination, excitation, and deexcitation rates for all ions in the database, as well as an implementation of the two-ion model for calculations of relative-level populations (and intensities) if these are modified by ionization and recombination from or to excited levels. As an example of KAPPA usage, we explore novel diagnostics of κ, and show that O iii lines near 500 and 700 Å provide a strong sensitivity to κ, with some line intensity ratios changing by a factor of up to 2–4 compared to Maxwellian. This is much larger than previously employed diagnostics of κ.