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1. Supermassive Black Holes with High Accretion Rates in Active Galactic Nuclei. XIII. Ultraviolet Time Lag of Hβ Emission in Mrk 142

   https://doi.org/10.3847/1538-4357/acfb72  

   Khatu, Viraja C.; Gallagher, Sarah C.; Horne, Keith; Cackett, Edward M.; Hu, Chen; Pasquini, Sofia; Hall, Patrick; Wang, Jian-Min; Bian, Wei-Hao; Li, Yan-Rong; et al (November 2023, The Astrophysical Journal)

   Abstract We performed a rigorous reverberation-mapping analysis of the broad-line region (BLR) in a highly accreting (L/L_Edd= 0.74–3.4) active galactic nucleus, Markarian 142 (Mrk 142), for the first time using concurrent observations of the inner accretion disk and the BLR to determine a time lag for the Hβλ4861 emission relative to the ultraviolet (UV) continuum variations. We used continuum data taken with the Niel Gehrels Swift Observatory in theUVW2 band, and the Las Cumbres Observatory, Dan Zowada Memorial Observatory, and Liverpool Telescope in thegband, as part of the broader Mrk 142 multiwavelength monitoring campaign in 2019. We obtained new spectroscopic observations covering the Hβbroad emission line in the optical from the Gemini North Telescope and the Lijiang 2.4 m Telescope for a total of 102 epochs (over a period of 8 months) contemporaneous to the continuum data. Our primary result states a UV-to-Hβtime lag of ${8.68}_{-0.72}^{+0.75}$days in Mrk 142 obtained from light-curve analysis with a Python-based running optimal average algorithm. We placed our new measurements for Mrk 142 on the optical and UV radius–luminosity relations for NGC 5548 to understand the nature of the continuum driver. The positions of Mrk 142 on the scaling relations suggest that UV is closer to the “true” driving continuum than the optical. Furthermore, we obtain $\log \left(M_{•}/M_{\odot }\right)$= 6.32 ± 0.29 assuming UV as the primary driving continuum. 

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2. Optical and Near-infrared Continuum Emission Region Size Measurements in the Lensed Quasar FBQ J0951+2635

   https://doi.org/10.3847/1538-4357/acdb4f  

   Rivera, Angelica B.; Morgan, Christopher W.; Florence, Steven M.; Dahm, Scott E.; Vrba, Frederick J.; Tilleman, Trudy M.; Cornachione, Matthew A.; Falco, Emilio E. (July 2023, The Astrophysical Journal)

   Abstract We present 10 seasons of Sloan Digital Sky Surveyr-band monitoring observations and five seasons ofH-band observations of the two-image system FBQ J0951+2635 from the Kaj Strand Astrometric Reflector at the United States Naval Observatory, Flagstaff Station. We supplement our light curves with six seasons of monitoring data from the literature to yield a 10 + 6 season combined data set, which we analyzed with our Monte Carlo microlensing analysis routine to generate constraints on the structure of this system’s continuum emission source and the properties of the lens galaxy. Complementing our optical light curves with the five-season near-infrared light curves, we ran a joint Monte Carlo analysis to measure the size of the continuum emission region at both wavelengths, yielding log(r_1/2cm⁻¹) = ${16.24}_{-0.36}^{+0.33}$in therband and ${17.04}_{-0.30}^{+0.26}$in theHband at rest wavelengths of 2744 and 7254 Å, respectively, correcting for an assumed inclination angle of 60°. Modeling the accretion disk temperature profile as a power lawT(r) ∝r^−β, we successfully constrain the slope for FBQ J0951+2635 to $\beta ={0.50}_{-0.18}^{+0.50}$, shallower than, but nominally consistent with, the predictions of standard thin-disk theory,β= 0.75. 

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3. The Bimodal Absorption System Imaging Campaign (BASIC). I. A Dual Population of Low-metallicity Absorbers at z < 1

   https://doi.org/10.3847/1538-4357/acb047  

   Berg, Michelle_A; Lehner, Nicolas; Howk, J_Christopher; O’Meara, John_M; Schaye, Joop; Straka, Lorrie_A; Cooksey, Kathy_L; Tripp, Todd_M; Prochaska, J_Xavier; Oppenheimer, Benjamin_D; et al (February 2023, The Astrophysical Journal)

   Abstract The bimodal absorption system imaging campaign (BASIC) aims to characterize the galaxy environments of a sample of 36 Hi-selected partial Lyman limit systems (pLLSs) and Lyman limit systems (LLSs) in 23 QSO fields atz≲ 1. These pLLSs/LLSs provide a unique sample of absorbers with unbiased and well-constrained metallicities, allowing us to explore the origins of metal-rich and low-metallicity circumgalactic medium (CGM) atz< 1. Here we present Keck/KCWI and Very Large Telescope/MUSE observations of 11 of these QSO fields (19 pLLSs) that we combine with Hubble Space Telescope/Advanced Camera for Surveys imaging to identify and characterize the absorber-associated galaxies at 0.16 ≲z≲ 0.84. We find 23 unique absorber-associated galaxies, with an average of one associated galaxy per absorber. For seven absorbers, all with <10% solar metallicities, we find no associated galaxies with $\log M_{\star }\gtrsim 9.0$withinρ/R_virand ∣Δv∣/v_esc≤ 1.5 with respect to the absorber. We do not find any strong correlations between the metallicities or Hicolumn densities of the gas and most of the galaxy properties, except for the stellar mass of the galaxies: the low-metallicity ([X/H] ≤ −1.4) systems have a probability of ${0.39}_{-0.15}^{+0.16}$for having a host galaxy with $\log M_{\star }\ge 9.0$withinρ/R_vir≤ 1.5, while the higher metallicity absorbers have a probability of ${0.78}_{-0.13}^{+0.10}$. This implies metal-enriched pLLSs/LLSs atz< 1 are typically associated with the CGM of galaxies with $\log M_{\star }>9.0$, whereas low-metallicity pLLSs/LLSs are found in more diverse locations, with one population arising in the CGM of galaxies and another more broadly distributed in overdense regions of the universe. Using absorbers not associated with galaxies, we estimate the unweighted geometric mean metallicity of the intergalactic medium to be [X/H] ≲ −2.1 atz< 1, which is lower than previously estimated. 

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4. Three Quenched, Faint Dwarf Galaxies in the Direction of NGC 300: New Probes of Reionization and Internal Feedback

   https://doi.org/10.3847/2041-8213/ad927c  

   Sand, David J; Mutlu-Pakdil, Burçin; Jones, Michael G; Karunakaran, Ananthan; Andrews, Jennifer E; Bennet, Paul; Crnojević, Denija; Donatiello, Giuseppe; Drlica-Wagner, Alex; Fielder, Catherine; et al (December 2024, The Astrophysical Journal Letters)

   Abstract We report the discovery of three faint and ultrafaint dwarf galaxies—Sculptor A, Sculptor B, and Sculptor C—in the direction of NGC 300 (D= 2.0 Mpc), a Large Magellanic Cloud–mass galaxy. Deep ground-based imaging with Gemini/GMOS resolves all three dwarf galaxies into stars, each displaying a red giant branch indicative of an old, metal-poor stellar population. No young stars or Higas are apparent, and the lack of a GALEX UV detection suggests that all three systems are quenched. Sculptor C (D= 2.04 ${}_{-0.13}^{+0.10}$Mpc;M_V=  −9.1 ± 0.1 mag orL_V= (3.7 ${}_{-0.3}^{+0.4}$) × 10⁵L_⊙) is consistent with being a satellite of NGC 300. Sculptor A (D= 1.35 ${}_{-0.08}^{+0.22}$Mpc;M_V= −6.9 ± 0.3 mag orL_V= (5 ${}_{-1}^{+1}$) × 10⁴L_⊙) is likely in the foreground of NGC 300 and at the extreme edge of the Local Group, analogous to the recently discovered ultrafaint Tucana B in terms of its physical properties and environment. Sculptor B (D= 2.48 ${}_{-0.24}^{+0.21}$Mpc;M_V= −8.1 ± 0.3 mag orL_V= (1.5 ${}_{-0.4}^{+0.5}$) × 10⁵L_⊙) is likely in the background, but future distance measurements are necessary to solidify this statement. It is also of interest due to its quiescent state and low stellar mass. Both Sculptor A and B are ≳2–4r_virfrom NGC 300 itself. The discovery of three dwarf galaxies in isolated or low-density environments offers an opportunity to study the varying effects of ram-pressure stripping, reionization, and internal feedback in influencing the star formation history of the faintest stellar systems. 

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5. 3D CMZ. I. Central Molecular Zone Overview

   https://doi.org/10.3847/1538-4357/adb5f0  

   Battersby, Cara; Walker, Daniel L; Barnes, Ashley; Ginsburg, Adam; Lipman, Dani; Alboslani, Danya; Hatchfield, H Perry; Bally, John; Glover, Simon_C O; Henshaw, Jonathan D; et al (May 2025, The Astrophysical Journal)

   Abstract The Central Molecular Zone (CMZ) is the largest reservoir of dense molecular gas in the Galaxy and is heavily obscured in the optical and near-IR. We present an overview of the far-IR dust continuum, where the molecular clouds are revealed, provided by Herschel in the inner 40° (∣l∣ < 20°) of the Milky Way with a particular focus on the CMZ. We report a total dense gas (N(H₂) > 10²³cm⁻²) CMZ mass of $\sim 2_{-1}^{+2}\times 10^7$M_⊙and confirm that there is a highly asymmetric distribution of dense gas, with about 70%–75% at positive longitudes. We create and publicly release complete fore/background-subtracted column density and dust temperature maps in the inner 40° (∣l∣ < 20°) of the Galaxy. We find that the CMZ clearly stands out as a distinct structure, with an average mass per longitude that is at least 3× higher than the rest of the inner Galaxy contiguously from 1 $\stackrel{\text{°}}{.}$8 >ℓ> −1 $\stackrel{\text{°}}{.}$3. This CMZ extent is larger than previously assumed, but is consistent with constraints from velocity information. The inner Galaxy’s column density peaks towards the SgrB2 complex with a value of about 2 × 10²⁴cm⁻², and typical CMZ molecular clouds are aboutN(H₂) ∼ 10²³cm⁻². Typical CMZ dust temperatures range from ∼12–35 K with relatively little variation. We identify a ridge of warm dust in the inner CMZ that potentially traces the base of the northern Galactic outflow seen with MEERKAT. 

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