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1. Spatially Resolved Galactic Winds at Cosmic Noon: Outflow Kinematics and Mass Loading in a Lensed Star-forming Galaxy at z = 1.87

   https://doi.org/10.3847/1538-4357/ada95b  

   G_C, Keerthi Vasan; Jones, Tucker; Shajib, Anowar J; Rhoades, Sunny; Chen, Yuguang; Sanders, Ryan L; Stark, Daniel P; Ellis, Richard S; Leethochawalit, Nicha; Kacprzak, Glenn G; et al (March 2025, The Astrophysical Journal)

   We study the spatially resolved outflow properties of CSWA13, an intermediate-mass (M_* = 10⁹M_⊙), gravitationally lensed star-forming galaxy atz= 1.87. We use Keck/KCWI to map outflows in multiple rest-frame UV interstellar medium (ISM) absorption lines, along with fluorescent Siii* emission, and nebular emission from Ciii] tracing the local systemic velocity. The spatial structure of the outflow velocity mirrors that of the nebular kinematics, which we interpret to be a signature of a young galactic wind that is pressurizing the ISM of the galaxy but is yet to burst out. From the radial extent of Siii* emission, we estimate that the outflow is largely encapsulated within 3.5 kpc. We explore the geometry (e.g., patchiness) of the outflow by measuring the covering fraction at different velocities, finding that the maximum covering fraction is at velocitiesv ≃ −150 km s⁻¹. Using the outflow velocity (v_out), radius (R), column density (N), and solid angle (Ω) based on the covering fraction, we measure the mass-loss rate $\log {\dot{m}}_{\mathrm{out}}/\left(M_{\odot }{\text{yr}}^{-1}\right)=1.73\pm 0.23$and mass loading factor $\log \eta =0.04\pm 0.34$for the low-ionization outflowing gas in this galaxy. These values are relatively large and the bulk of the outflowing gas is moving with speeds less than the escape velocity of the galaxy halo, suggesting that the majority of the outflowing mass will remain in the circumgalactic medium and/or recycle back into the galaxy. The results support a picture of high outflow rates transporting mass and metals into the inner circumgalactic medium, providing the gas reservoir for future star formation. 

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2. Extending the Dynamic Range of Galaxy Outflow Scaling Relations: Massive Compact Galaxies with Extreme Outflows

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

   Davis, Julie D.; Tremonti, Christy A.; Swiggum, Cameren N.; Moustakas, John; Diamond-Stanic, Aleksandar M.; Coil, Alison L.; Geach, James E.; Hickox, Ryan C.; Perrotta, Serena; Petter, Grayson C.; et al (July 2023, The Astrophysical Journal)

   Abstract We investigate galactic winds in the HizEA galaxies, a collection of 46 late-stage galaxy mergers atz= 0.4–0.8, with stellar masses of $\log \left(M_{*}/M_{\odot }\right)=10.4–11.5$, star formation rates (SFRs) of 20–500M_⊙yr⁻¹, and ultra-compact (a few 100 pc) central star-forming regions. We measure their gas kinematics using the Mgiiλλ2796,2803 absorption lines in optical spectra from MMT, Magellan, and Keck. We find evidence of outflows in 90% of targets, with maximum outflow velocities of 550–3200 km s⁻¹. We combine these data with ten samples from the literature to construct scaling relations for outflow velocity versus SFR, star formation surface density (Σ_SFR),M_*, and SFR/M_*. The HizEA galaxies extend the dynamic range of the scaling relations by a factor of ∼2–4 in outflow velocity and an order of magnitude in SFR and Σ_SFR. The ensemble scaling relations exhibit strong correlations between outflow velocity, SFR, SFR/R, and Σ_SFR, and weaker correlations withM_*and SFR/M_*. The HizEA galaxies are mild outliers on the SFR andM_*scaling relations, but they connect smoothly with more typical star-forming galaxies on plots of outflow velocity versus SFR/Rand Σ_SFR. These results provide further evidence that the HizEA galaxies’ exceptional outflow velocities are a consequence of their extreme star formation conditions rather than hidden black hole activity, and they strengthen previous claims that Σ_SFRis one of the most important properties governing the velocities of galactic winds. 

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3. Multiphase Gas in Elliptical Galaxies: The Role of Type Ia Supernovae

   https://doi.org/10.3847/1538-4357/ad2940  

   Mohapatra, Rajsekhar; Quataert, Eliot (April 2024, The Astrophysical Journal)

   Abstract Massive elliptical galaxies harbor large amounts of hot gas (T≳ 10⁶K) in their interstellar medium (ISM) but are typically quiescent in star formation. The jets of active galactic nuclei (AGNs) and Type Ia supernovae (SNe Ia) inject energy into the ISM, which offsets its radiative losses and keeps it hot. SNe Ia deposit their energy locally within the galaxy compared to the larger few ×10 kiloparsec-scale AGN jets. In this study, we perform high-resolution (512³) hydrodynamic simulations of a local (1 kpc³) density-stratified patch of the ISM of massive galaxies. We include radiative cooling and shell-averaged volume heating, as well as randomly exploding SN Ia. We study the effect of different fractions of supernova (SN) heating (with respect to the net cooling rate), different initial ISM density/entropy (which controls the growth timet_tiof the thermal instability), and different degrees of stratification (which affect the freefall timet_ff). We find that SNe Ia drive predominantly compressive turbulence in the ISM with a velocity dispersion ofσ_vup to 40 km s⁻¹and logarithmic density dispersion ofσ_s∼ 0.2–0.4. These fluctuations trigger multiphase condensation in regions of the ISM, where $\min \left(t_{\mathrm{ti}}\right)/t_{\mathrm{ff}}\lesssim 0.6\exp \left(6{\sigma }_s\right)$, in agreement with theoretical expectations that large density fluctuations efficiently trigger multiphase gas formation. Since the SN Ia rate is not self-adjusting, when the net cooling drops below the net heating rate, SNe Ia drive a hot wind which sweeps out most of the mass in our local model. Global simulations are required to assess the ultimate fate of this gas. 

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4. The Cosmic Ultraviolet Baryon Survey (CUBS). VII. On the Warm-hot Circumgalactic Medium Probed by O vi and Ne viii at 0.4 ≲ z ≲ 0.7

   https://doi.org/10.3847/1538-4357/ad410b  

   Qu, Zhijie; Chen, Hsiao-Wen; Johnson, Sean D; Rudie, Gwen C; Zahedy, Fakhri S; DePalma, David; Schaye, Joop; Boettcher, Erin T; Cantalupo, Sebastiano; Chen, Mandy C; et al (June 2024, The Astrophysical Journal)

   Abstract This paper presents a newly established sample of 103 unique galaxies or galaxy groups at 0.4 ≲z≲ 0.7 from the Cosmic Ultraviolet Baryon Survey (CUBS) for studying the warm-hot circumgalactic medium (CGM) probed by both Oviand Neviiiabsorption. The galaxies and associated neighbors are identified at <1 physical Mpc from the sightlines toward 15 CUBS QSOs atz_QSO≳ 0.8. A total of 30 galaxies or galaxy groups exhibit associated Oviλλ1031, 1037 doublet absorption within a line-of-sight velocity interval of ±250 km s⁻¹, while the rest show no trace of Ovito a detection limit of $\log N_{\mathrm{OVI}}/{\mathrm{cm}}^{-2}\approx 13.7$. Meanwhile, only five galaxies or galaxy groups exhibit the Neviiiλλ770, 780 doublet absorption, down to a limiting column density of $\log N_{\mathrm{NeVIII}}/{\mathrm{cm}}^{-2}\approx 14.0$. These Ovi- and Neviii-bearing halos reside in different galaxy environments with stellar masses ranging from $\log M_{\mathrm{star}}/M_{\odot }\approx 8$to ≈11.5. The warm-hot CGM around galaxies of different stellar masses and star formation rates exhibits different spatial profiles and kinematics. In particular, star-forming galaxies with $\log M_{\mathrm{star}}/M_{\odot }\approx 9–11$show a significant concentration of metal-enriched warm-hot CGM within the virial radius, while massive quiescent galaxies exhibit flatter radial profiles of both column densities and covering fractions. In addition, the velocity dispersion of Oviabsorption is broad withσ_υ> 40 km s⁻¹for galaxies of $\log M_{\mathrm{star}}/M_{\odot }>9$within the virial radius, suggesting a more dynamic warm-hot halo around these galaxies. Finally, the warm-hot CGM probed by Oviand Neviiiis suggested to be the dominant phase in sub-L* galaxies with $\log M_{\mathrm{star}}/M_{\odot }\approx 9–10$based on their high ionization fractions in the CGM. 

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5. 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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