More Like this

1. The Scatter Matters: Circumgalactic Metal Content in the Context of the M−σ Relation

   Sanchez, N. Nicole; Werk, Jessica K.; Christensen, Charlotte; Telford, O. Grace; Tremmel, Michael; Quinn, Thomas; Mead, Jennifer; Sharma, Ray; Brooks, Alyson Abstract (May 2023, arXivorg)

   The interaction between supermassive black hole (SMBH) feedback and the circumgalactic medium (CGM) continues to be an open question in galaxy evolution. In our study, we use SPH simulations to explore the impact of SMBH feedback on galactic metal retention and the motion of metals and gas into and through the CGM of L ∗ galaxies. We examine 140 galaxies from the 25 Mpc cosmological volume, Romulus25, with stellar masses between 3 × 10 9 - 3 × 10 11 M ⊙ . We measure the fraction of metals remaining in the ISM and CGM of each galaxy, and calculate the expected mass of its SMBH based on the M−σ relation. The deviation of each SMBH from its expected mass, ΔMBH is compared to the potential of its host via σ . We find that SMBHs with accreted mass above the empirical M−σ relation are about 15\% more effective at removing metals from the ISM than under-massive SMBHs in star forming galaxies. Over-massive SMBHs suppress the overall star formation of their host galaxies and more effectively move metals from the ISM into the CGM. However, we see little evidence for the evacuation of gas from their halos, in contrast with other simulations. Finally, we predict that C IV column densities in the CGM of L ∗ galaxies may depend on host galaxy SMBH mass. Our results show that the scatter in the low mass end of M−σ relation may indicate how effective a SMBH is at the local redistribution of mass in its host galaxy. 

   more » « less
2. The COS-Holes Survey: Connecting Galaxy Black Hole Mass with the State of the CGM

   https://doi.org/10.3847/1538-4357/ad4ecc  

   Garza, Samantha L; Werk, Jessica K; Oppenheimer, Benjamin D; Tchernyshyov, Kirill; Sanchez, N Nicole; Faerman, Yakov; Rubin, Kate_H R; Bentz, Misty C; Davies, Jonathan J; Burchett, Joseph N; et al (July 2024, The Astrophysical Journal)

   Abstract We present an analysis of Hubble Space Telescope COS/G160M observations of CIVin the inner circumgalactic medium (CGM) of a novel sample of eightz∼ 0,L≈L^⋆galaxies, paired with UV-bright QSOs at impact parameters (R_proj) between 25 and 130 kpc. The galaxies in this stellar-mass-controlled sample (log₁₀M_⋆/M_⊙∼ 10.2–10.9M_⊙) host supermassive black holes (SMBHs) with dynamically measured masses spanning log₁₀M_BH/M_⊙∼ 6.8–8.4; this allows us to compare our results with models of galaxy formation where the integrated feedback history from the SMBH alters the CGM over long timescales. We find that the CIVcolumn density measurements (N_{C IV}; average log₁₀N_{C IV,CH}= 13.94 ± 0.09 cm⁻²) are largely consistent with existing measurements from other surveys ofN_{C IV}in the CGM (average log₁₀N_{C IV,Lit}= 13.90 ± 0.08 cm⁻²), but do not show obvious variation as a function of the SMBH mass. By contrast, specific star formation rate (sSFR) is highly correlated with the ionized content of the CGM. We find a large spread in sSFR for galaxies with log₁₀M_BH/M_⊙> 7.0, where the CGM CIVcontent shows a clear dependence on galaxy sSFR but notM_BH. Our results do not indicate an obvious causal link between CGM CIVand the mass of the galaxy’s SMBH; however, through comparisons to the EAGLE, Romulus25, and IllustrisTNG simulations, we find that our sample is likely too small to constrain such causality. 

   more » « less
3. Regulation of Star Formation by a Hot Circumgalactic Medium

   https://doi.org/10.3847/1538-4357/acc4c7  

   Carr, Christopher; Bryan, Greg L.; Fielding, Drummond B.; Pandya, Viraj; Somerville, Rachel S. (May 2023, The Astrophysical Journal)

   Abstract Galactic outflows driven by supernovae (SNe) are thought to be a powerful regulator of a galaxy’s star-forming efficiency. Mass, energy, and metal outflows (η_M,η_E, andη_Z, here normalized by the star formation rate, the SNe energy, and metal production rates, respectively) shape galaxy properties by both ejecting gas and metals out of the galaxy and by heating the circumgalactic medium (CGM), preventing future accretion. Traditionally, models have assumed that galaxies self-regulate by ejecting a large fraction of the gas, which enters the interstellar medium (ISM), although whether such high mass loadings agree with observations is still unclear. To better understand how the relative importance of ejective (i.e., high mass loading) versus preventative (i.e., high energy loading) feedback affects the present-day properties of galaxies, we develop a simple gas-regulator model of galaxy evolution, where the stellar mass, ISM, and CGM are modeled as distinct reservoirs which exchange mass, metals, and energy at different rates within a growing halo. Focusing on the halo mass range from 10¹⁰to 10¹²M_⊙, we demonstrate that, with reasonable parameter choices, we can reproduce the stellar-to-halo mass relation and the ISM-to-stellar mass relation with low-mass-loaded (η_M∼ 0.1–10) but high-energy-loaded (η_E∼ 0.1–1) winds, with self-regulation occurring primarily through heating and cooling of the CGM. We show that the model predictions are robust against changes to the mass loading of outflows but are quite sensitive to our choice of the energy loading, preferringη_E∼ 1 for the lowest-mass halos and ∼0.1 for Milky Way–like halos. 

   more » « less
4. It’s a Breeze: The Circumgalactic Medium of a Dwarf Galaxy Is Easy to Strip

   https://doi.org/10.3847/1538-4357/ad6c3f  

   Zhu, Jingyao; Tonnesen, Stephanie; Bryan, Greg_L; Putman, Mary_E (October 2024, The Astrophysical Journal)

   Abstract The circumgalactic medium (CGM) of star-forming dwarf galaxies plays a key role in regulating the galactic baryonic cycle. We investigate how susceptible the CGM of dwarf satellite galaxies is to ram pressure stripping in Milky Way–like environments. In a suite of hydrodynamical wind tunnel simulations, we model an intermediate-mass dwarf satellite galaxy (M_*= 10^7.2M_⊙) with a multiphase interstellar medium (ISM;M_ISM= 10^7.9M_⊙) and CGM (M_CGM,vir= 10^8.5M_⊙) along two first-infall orbits to more than 500 Myr past pericenter of a Milky Way–like host. The spatial resolution is ∼79 pc in the star-forming ISM and 316−632 pc in the CGM. Our simulations show that the dwarf satellite CGM removal is fast and effective: more than 95% of the CGM mass is ram pressure stripped within a few hundred megayears, even under a weak ram pressure orbit where the ISM stripping is negligible. The conditions for CGM survival are consistent with the analytical halo gas stripping predictions in McCarthy et al. We also find that including the satellite CGM does not effectively shield its galaxy, and therefore the ISM stripping rate is unaffected. Our results imply that a dwarf galaxy CGM is unlikely to be detected in satellite galaxies; and that the star formation of gaseous dwarf satellites is likely devoid of replenishment from a CGM. 

   more » « less
5. Ejective and preventative: the IllustrisTNG black hole feedback and its effects on the thermodynamics of the gas within and around galaxies

   https://doi.org/10.1093/mnras/staa2607  

   Zinger, Elad; Pillepich, Annalisa; Nelson, Dylan; Weinberger, Rainer; Pakmor, Rüdiger; Springel, Volker; Hernquist, Lars; Marinacci, Federico; Vogelsberger, Mark (October 2020, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT Supermassive black holes (SMBHs) that reside at the centres of galaxies can inject vast amounts of energy into the surrounding gas and are thought to be a viable mechanism to quench star formation in massive galaxies. Here, we study the $$10^{9-12.5}\, \mathrm{M_\odot }$$ stellar mass central galaxy population of the IllustrisTNG simulation, specifically the TNG100 and TNG300 volumes at z = 0, and show how the three components – SMBH, galaxy, and circumgalactic medium (CGM) – are interconnected in their evolution. We find that gas entropy is a sensitive diagnostic of feedback injection. In particular, we demonstrate how the onset of the low-accretion black hole (BH) feedback mode, realized in the IllustrisTNG model as a kinetic, BH-driven wind, leads not only to star formation quenching at stellar masses $$\gtrsim 10^{10.5}\, \mathrm{M_\odot }$$ but also to a change in thermodynamic properties of the (non-star-forming) gas, both within the galaxy and beyond. The IllustrisTNG kinetic feedback from SMBHs increases the average gas entropy, within the galaxy and in the CGM, lengthening typical gas cooling times from $$10\!-\!100\, \mathrm{Myr}$$ to $$1\!-\!10\, \mathrm{Gyr}$$, effectively ceasing ongoing star formation and inhibiting radiative cooling and future gas accretion. In practice, the same active galactic nucleus (AGN) feedback channel is simultaneously ‘ejective’ and ‘preventative’ and leaves an imprint on the temperature, density, entropy, and cooling times also in the outer reaches of the gas halo, up to distances of several hundred kiloparsecs. In the IllustrisTNG model, a long-lasting quenching state can occur for a heterogeneous CGM, whereby the hot and dilute CGM gas of quiescent galaxies contains regions of low-entropy gas with short cooling times. 

   more » « less