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1. Modeling ALMA Observations of the Warped Molecular Gas Disk in the Red Nugget Relic Galaxy NGC 384

   https://doi.org/10.3847/1538-4357/ad7bb0  

   Cohn, Jonathan_H; Curliss, Maeve; Walsh, Jonelle_L; Kabasares, Kyle_M; Boizelle, Benjamin_D; Barth, Aaron_J; Gebhardt, Karl; Gültekin, Kayhan; Buote, David_A; Darling, Jeremy; et al (November 2024, The Astrophysical Journal)

   Abstract We present 0.″22 resolution CO(2–1) observations of the circumnuclear gas disk in the local compact galaxy NGC 384 with the Atacama Large Millimeter/submillimeter Array (ALMA). While the majority of the disk displays regular rotation with projected velocities rising to 370 km s⁻¹, the inner ∼0.″5 exhibits a kinematic twist. We develop warped disk gas-dynamical models to account for this twist, fit those models to the ALMA data cube, and find a stellar mass-to-light ratio in theHband ofM/L_H= 1.34 ± 0.01 [1σstatistical] ±0.02 [systematic]M_⊙/L_⊙and a supermassive black hole (BH) mass (M_BH) ofM_BH $=\left({7.26}_{-0.48}^{+0.43}\right[1\sigma \mathrm{statistical}{]}_{-1.00}^{+0.55}\left[\mathrm{systematic}\right])\times {10}^8{M}_{\odot }$. In contrast to most previous dynamicalM_BHmeasurements in local compact galaxies, which typically found over-massive BHs compared to the local BH mass−bulge luminosity and BH mass−bulge mass relations, NGC 384 lies within the scatter of those scaling relations. NGC 384 and other local compact galaxies are likely relics ofz∼ 2 red nuggets, and over-massive BHs in these relics indicate BH growth may conclude before the host galaxy stars have finished assembly. Our NGC 384 results may challenge this evolutionary picture, suggesting there may be increased scatter in the scaling relations than previously thought. However, this scatter could be inflated by systematic differences between stellar- and gas-dynamical measurement methods, motivating direct comparisons between the methods for NGC 384 and the other compact galaxies in the sample. 

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2. The Sloan Digital Sky Survey Reverberation Mapping Project: The Black Hole Mass–Stellar Mass Relations at 0.2 ≲ z ≲ 0.8

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

   Li, Jennifer_I-Hsiu; Shen, Yue; Ho, Luis_C; Brandt, W_N; Grier, Catherine_J; Hall, Patrick_B; Homayouni, Y.; Koekemoer, Anton_M; Schneider, Donald_P; Trump, Jonathan_R (September 2023, The Astrophysical Journal)

   Abstract We measure the correlation between black hole massM_BHand host stellar massM_*for a sample of 38 broad-line quasars at 0.2 ≲z≲ 0.8 (median redshiftz_med= 0.5). The black hole masses are derived from a dedicated reverberation mapping program for distant quasars, and the stellar masses are derived from two-band optical+IR Hubble Space Telescope imaging. Most of these quasars are well centered within ≲1 kpc from the host galaxy centroid, with only a few cases in merging/disturbed systems showing larger spatial offsets. Our sample spans two orders of magnitude in stellar mass (∼10⁹–10¹¹M_⊙) and black hole mass (∼10⁷–10⁹M_⊙) and reveals a significant correlation between the two quantities. We find a best-fit intrinsic (i.e., selection effects corrected)M_BH–M_*,hostrelation of $\log \left(M_{\mathrm{BH}}/M_{\odot }\right)={7.01}_{-0.33}^{+0.23}+{1.74}_{-0.64}^{+0.64}\log \left(M_{*,\mathrm{host}}/{10}^{10}{M}_{\odot }\right)$, with an intrinsic scatter of ${0.47}_{-0.17}^{+0.24}$dex. Decomposing our quasar hosts into bulges and disks, there is a similarM_BH–M_*,bulgerelation with slightly larger scatter, likely caused by systematic uncertainties in the bulge–disk decomposition. TheM_BH–M_*,hostrelation atz_med= 0.5 is similar to that in local quiescent galaxies, with negligible evolution over the redshift range probed by our sample. With direct black hole masses from reverberation mapping and the large dynamical range of the sample, selection biases do not appear to affect our conclusions significantly. Our results, along with other samples in the literature, suggest that the locally measured black hole mass–host stellar mass relation is already in place atz∼ 1. 

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3. UNCOVER: The Growth of the First Massive Black Holes from JWST/NIRSpec—Spectroscopic Redshift Confirmation of an X-Ray Luminous AGN at z = 10.1

   https://doi.org/10.3847/2041-8213/acf7c5  

   Goulding, Andy_D; Greene, Jenny_E; Setton, David_J; Labbe, Ivo; Bezanson, Rachel; Miller, Tim_B; Atek, Hakim; Bogdán, Ákos; Brammer, Gabriel; Chemerynska, Iryna; et al (September 2023, The Astrophysical Journal Letters)

   Abstract The James Webb Space Telescope is now detecting early black holes (BHs) as they transition from “seeds” to supermassive BHs. Recently, Bogdan et al. reported the detection of an X-ray luminous supermassive BH, UHZ-1, with a photometric redshift atz> 10. Such an extreme source at this very high redshift provides new insights on seeding and growth models for BHs given the short time available for formation and growth. Harnessing the exquisite sensitivity of JWST/NIRSpec, here we report the spectroscopic confirmation of UHZ-1 atz= 10.073 ± 0.002. We find that the NIRSpec/Prism spectrum is typical of recently discoveredz≈ 10 galaxies, characterized primarily by star formation features. We see no clear evidence of the powerful X-ray source in the rest-frame UV/optical spectrum, which may suggest heavy obscuration of the central BH, in line with the Compton-thick column density measured in the X-rays. We perform a stellar population fit simultaneously to the new NIRSpec spectroscopy and previously available photometry. The fit yields a stellar-mass estimate for the host galaxy that is significantly better constrained than prior photometric estimates ( $M_{\star }\sim {1.4}_{-0.4}^{+0.3}\times {10}^8$M_⊙). Given the predicted BH mass (M_BH∼ 10⁷–10⁸M_⊙), the resulting ratio ofM_BH/M_⋆remains 2 to 3 orders of magnitude higher than local values, thus lending support to the heavy seeding channel for the formation of supermassive BHs within the first billion years of cosmic evolution. 

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4. Resolving the Peak of the Black Hole Mass Spectrum

   https://doi.org/10.3847/1538-4357/ac8b83  

   Farag, Ebraheem; Renzo, Mathieu; Farmer, Robert; Chidester, Morgan_T; Timmes, F_X (October 2022, The Astrophysical Journal)

   Abstract Gravitational-wave (GW) detections of binary black hole (BH) mergers have begun to sample the cosmic BH mass distribution. The evolution of single stellar cores predicts a gap in the BH mass distribution due to pair-instability supernovae (PISNe). Determining the upper and lower edges of the BH mass gap can be useful for interpreting GW detections of merging BHs. We useMESAto evolve single, nonrotating, massive helium cores with a metallicity ofZ= 10⁻⁵, until they either collapse to form a BH or explode as a PISN, without leaving a compact remnant. We calculate the boundaries of the lower BH mass gap for S-factors in the range S(300 keV) = (77,203) keV b, corresponding to the ±3σuncertainty in our high-resolution tabulated¹²C(α,γ)¹⁶O reaction rate probability distribution function. We extensively test temporal and spatial resolutions for resolving the theoretical peak of the BH mass spectrum across the BH mass gap. We explore the convergence with respect to convective mixing and nuclear burning, finding that significant time resolution is needed to achieve convergence. We also test adopting a minimum diffusion coefficient to help lower-resolution models reach convergence. We establish a new lower edge of the upper mass gap asM_lower≃ ${60}_{-14}^{+32}$M_⊙from the ±3σuncertainty in the¹²C(α,γ)¹⁶O rate. We explore the effect of a larger 3αrate on the lower edge of the upper mass gap, findingM_lower≃ ${69}_{-18}^{+34}$M_⊙. We compare our results with BHs reported in the Gravitational-Wave Transient Catalog. 

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5. 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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