More Like this

1. Black Hole Mass Measurements of Early-type Galaxies NGC 1380 and NGC 6861 through ALMA and HST Observations and Gas-dynamical Modeling*

   https://doi.org/10.3847/1538-4357/ac7a38  

   Kabasares, Kyle M.; Barth, Aaron J.; Buote, David A.; Boizelle, Benjamin D.; Walsh, Jonelle L.; Baker, Andrew J.; Darling, Jeremy; Ho, Luis C.; Cohn, Jonathan (August 2022, The Astrophysical Journal)

   Abstract We present Atacama Large Millimeter/submillimeter Array (ALMA) Cycle 2 observations of CO(2–1) emission from the circumnuclear disks in two early-type galaxies, NGC 1380 and NGC 6861. The disk in each galaxy is highly inclined (i∼ 75°), and the projected velocities of the molecular gas near the galaxy centers are ∼300 km s⁻¹in NGC 1380 and ∼500 km s⁻¹in NGC 6861. We fit thin disk dynamical models to the ALMA data cubes to constrain the masses of the central black holes (BHs). We created host galaxy models using Hubble Space Telescope images for the extended stellar mass distributions and incorporated a range of plausible central dust extinction values. For NGC 1380, our best-fit model yieldsM_BH= 1.47 × 10⁸M_⊙with a ∼40% uncertainty. For NGC 6861, the lack of dynamical tracers within the BH’s sphere of influence due to a central hole in the gas distribution precludes a precise measurement ofM_BH. However, our model fits require a value forM_BHin the range of (1–3) × 10⁹M_⊙in NGC 6861 to reproduce the observations. The BH masses are generally consistent with predictions from local BH–host galaxy scaling relations. Systematic uncertainties associated with dust extinction of the host galaxy light and choice of host galaxy mass model dominate the error budget of both measurements. Despite these limitations, the measurements demonstrate ALMA’s ability to provide constraints on BH masses in cases where the BH’s projected radius of influence is marginally resolved or the gas distribution has a central hole. 

   more » « less
2. The Karl G. Jansky Very Large Array Local Group L -Band Survey (LGLBS)

   https://doi.org/10.3847/1538-4365/ade0ad  

   Koch, Eric W; Leroy, Adam K; Rosolowsky, Erik W; Chomiuk, Laura; Dalcanton, Julianne J; Pingel, Nickolas M; Sarbadhicary, Sumit K; Stanimirović, Snežana; Walter, Fabian; Archer, Haylee N; et al (July 2025, The Astrophysical Journal Supplement Series)

   Abstract We present the Local GroupL-Band Survey, a Karl G. Jansky Very Large Array (VLA) survey producing the highest-quality 21 cm and 1–2 GHz radio continuum images to date, for the six VLA-accessible, star-forming, Local Group galaxies. Leveraging the VLA’s spectral multiplexing power, we simultaneously survey the 21 cm line at high 0.4 km s⁻¹velocity resolution, the 1–2 GHz polarized continuum, and four OH lines. For the massive spiral M31, the dwarf spiral M33, and the dwarf irregular galaxies NGC 6822, IC 10, IC 1613, and the Wolf–Lundmark–Melotte Galaxy, we use all four VLA configurations and the Green Bank Telescope to reach angular resolutions of <5″ (10–20 pc) for the 21 cm line with <10²⁰cm⁻²column density sensitivity, and even sharper views (<2″; 5–10 pc) of the continuum. Targeting these nearby galaxies (D ≲ 1 Mpc) reveals a sharp, resolved view of the atomic gas, including 21 cm absorption, and continuum emission from supernova remnants and Hiiregions. These data sets can be used to test theories of the abundance and formation of cold clouds, the driving and dissipation of interstellar turbulence, and the impact of feedback from massive stars and supernovae. Here, we describe the survey design and execution, scientific motivation, data processing, and quality assurance. We provide a first look at and publicly release the wide-field 21 cm Hidata products for M31, M33, and four dwarf irregular targets in the survey, which represent some of the highest-physical-resolution 21 cm observations of any external galaxies beyond the LMC and SMC. 

   more » « less
3. The MeerKAT Fornax Survey: I. Survey description and first evidence of ram pressure in the Fornax galaxy cluster

   https://doi.org/10.1051/0004-6361/202346071  

   Serra, P.; Maccagni, F. M.; Kleiner, D.; Molnár, D.; Ramatsoku, M.; Loni, A.; Loi, F.; de Blok, W. J.; Bryan, G. L.; Dettmar, R. J.; et al (May 2023, Astronomy & Astrophysics)

   The MeerKAT Fornax Survey maps the distribution and kinematics of atomic neutral hydrogen gas (H  I ) in the nearby Fornax galaxy cluster using the MeerKAT telescope. The 12 deg 2 survey footprint covers the central region of the cluster out to ∼ R vir and stretches south-west out to ∼2 R vir to include the NGC 1316 galaxy group. The H  I column density sensitivity (3 σ over 25 km s −1 ) ranges from 5 × 10 19 cm −2 at a resolution of ∼10″ (∼1 kpc at the 20 Mpc distance of Fornax) down to ∼10 18 cm −2 at ∼1′ (∼6 kpc), and slightly below this level at the lowest resolution of ∼100″ (∼10 kpc). The H  I mass sensitivity (3 σ over 50 km s −1 ) is 6 × 10 5 M ⊙ . The H  I velocity resolution is 1.4 km s −1 . In this paper, we describe the survey design and H  I data processing, and we present a sample of six galaxies with long, one-sided, starless H  I tails (only one of which was previously known) radially oriented within the cluster and with measurable internal velocity gradients. We argue that the joint properties of the H  I tails represent the first unambiguous evidence of ram pressure shaping the distribution of H  I in the Fornax cluster. The disturbed optical morphology of all host galaxies supports the idea that the tails consist of H  I that was initially pulled out of the galaxies’ stellar body by tidal forces. Ram pressure was then able to further displace the weakly bound H  I and give the tails their current direction, length, and velocity gradient. 

   more » « less
4. DIISC-I: The Discovery of Kinematically Anomalous H i Clouds in M 100

   https://doi.org/10.3847/1538-4357/ac2303  

   Gim, Hansung B.; Borthakur, Sanchayeeta; Momjian, Emmanuel; Padave, Mansi; Jansen, Rolf A.; Nelson, Dylan; Heckman, Timothy M.; Kennicutt Jr., Robert C.; Fox, Andrew J.; Pineda, Jorge L.; et al (November 2021, The Astrophysical Journal)

   Abstract We report the discovery of two kinematically anomalous atomic hydrogen (H i ) clouds in M 100 (NGC 4321), which was observed as part of the Deciphering the Interplay between the Interstellar medium, Stars, and the Circumgalactic medium (DIISC) survey in H i 21 cm at 3.3 km s −1 spectroscopic and 44″ × 30″ spatial resolution using the Karl G. Jansky Very Large Array. 15 15 The National Radio Astronomy Observatory is a facility of the National Science Foundation operated under cooperative agreement by Associated Universities, Inc. These clouds were identified as structures that show significant kinematic offsets from the rotating disk of M 100. The velocity offsets of 40 km s −1 observed in these clouds are comparable to the offsets seen in intermediate-velocity clouds (IVCs) in the circumgalactic medium (CGM) of the Milky Way and nearby galaxies. We find that one anomalous cloud in M 100 is associated with star-forming regions detected in H α and far-ultraviolet imaging. Our investigation shows that anomalous clouds in M 100 may originate from multiple mechanisms, such as star formation feedback-driven outflows, ram pressure stripping, and tidal interactions with satellite galaxies. Moreover, we do not detect any cool CGM at 38.8 kpc from the center of M 100, giving an upper limit of N(H i ) ≤1.7 × 10 13 cm −2 (3 σ ). Since M 100 is in the Virgo cluster, the nonexistence of neutral/cool CGM is a likely pathway for turning it into a red galaxy. 

   more » « less
5. Globular clusters as tracers of the dark matter content of dwarfs in galaxy clusters

   https://doi.org/10.1093/mnras/staa3915  

   Doppel, Jessica E; Sales, Laura V; Navarro, Julio F; Abadi, Mario G; Peng, Eric W; Toloba, Elisa; Ramos-Almendares, Felipe (February 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT Globular clusters (GCs) are often used to estimate the dark matter content of galaxies, especially dwarf galaxies, where other kinematic tracers are lacking. These estimates typically assume spherical symmetry and dynamical equilibrium, assumptions that may not hold for the sparse GC population of dwarfs in galaxy clusters. We use a catalogue of GCs tagged on to the Illustris simulation to study the accuracy of GC-based mass estimates. We focus on galaxies in the stellar mass range 108–1011.8 M⊙ identified in nine simulated Virgo-like clusters. Our results indicate that mass estimates are, on average, accurate in systems with GC numbers NGC ≥ 10 and where the uncertainty of individual GC line-of-sight velocities is smaller than the inferred velocity dispersion, σGC. In cases where NGC ≤ 10, however, biases may result, depending on how σGC is computed. We provide calibrations that may help alleviate these biases in methods widely used in the literature. As an application, we find a number of dwarfs with $$M_{*} \sim 10^{8.5}\, \mathrm{M}_{\odot }$$ – comparable with the ultra-diffuse galaxy NGC 1052-DF2 (DF2), notable for the low σGC of its 10 GCs – that have $$\sigma _{\rm GC} \sim 7\!-\!15\, {\rm km \,s}^{-1}$$. These DF2 analogues correspond to relatively massive systems at their infall time (M200 ∼ 1–3 × 1011 M⊙), which have retained only 3–17 GCs and have been stripped of more than 95 per cent of their dark matter. Our results suggest that extreme tidal mass loss in otherwise normal dwarf galaxies may be a possible formation channel for ultra-diffuse objects such as DF2. 

   more » « less