More Like this

1. Introducing the BRAHMA simulation suite: signatures of low-mass black hole seeding models in cosmological simulations

   https://doi.org/10.1093/mnras/stae1386  

   Bhowmick, Aklant_K; Blecha, Laura; Torrey, Paul; Kelley, Luke_Zoltan; Weinberger, Rainer; Vogelsberger, Mark; Hernquist, Lars; Somerville, Rachel_S; Evans, Analis_Eolyn (June 2024, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT While the first “seeds” of supermassive black holes (BH) can range from $$\sim 10^2-10^6 \rm ~{\rm M}_{\odot }$$, the lowest mass seeds ($$\lesssim 10^3~\rm {\rm M}_{\odot }$$) are inaccessible to most cosmological simulations due to resolution limitations. We present our new BRAHMA simulations that use a novel flexible seeding approach to predict the $$z\ge 7$$ BH populations for low-mass seeds. We ran two types of boxes that model $$\sim 10^3~\rm {\rm M}_{\odot }$$ seeds using two distinct but mutually consistent seeding prescriptions at different simulation resolutions. First, we have the highest resolution $$[9~\mathrm{Mpc}]^3$$ (BRAHMA-9-D3) boxes that directly resolve $$\sim 10^3~\rm {\rm M}_{\odot }$$ seeds and place them within haloes with dense, metal-poor gas. Second, we have lower resolution, larger volume $$[18~\mathrm{Mpc}]^3$$ (BRAHMA-18-E4), and $$\sim [36~\mathrm{Mpc}]^3$$ (BRAHMA-36-E5) boxes that seed their smallest resolvable $$\sim 10^4~\&~10^5~\mathrm{{\rm M}_{\odot }}$$ BH descendants using new stochastic seeding prescriptions calibrated using BRAHMA-9-D3. The three boxes together probe key BH observables between $$\sim 10^3\,\mathrm{ and}\,10^7~\rm {\rm M}_{\odot }$$. The active galactic nuclei (AGN) luminosity function variations are small (factors of $$\sim 2-3$$) at the anticipated detection limits of potential future X-ray facilities ($$\sim 10^{43}~ \mathrm{ergs~s^{-1}}$$ at $$z\sim 7$$). Our simulations predict BHs $$\sim 10-100$$ times heavier than the local $$M_*$$ versus $$M_{\mathrm{ bh}}$$ relations, consistent with several JWST-detected AGN. For different seed models, our simulations merge binaries at $$\sim 1-15~\mathrm{kpc}$$, with rates of $$\sim 200-2000$$ yr−1 for $$\gtrsim 10^3~\rm {\rm M}_{\odot }$$ BHs, $$\sim 6-60$$ yr−1 for $$\gtrsim 10^4~\rm {\rm M}_{\odot }$$ BHs, and up to $$\sim 10$$ yr−1 amongst $$\gtrsim 10^5~\rm {\rm M}_{\odot }$$ BHs. These results suggest that Laser Interferometer Space Antenna mission has promising prospects for constraining seed models. 

   more » « less
2. The MOSDEF survey: the mass–metallicity relationship and the existence of the FMR at z ∼ 1.5

   https://doi.org/10.1093/mnras/stab1793  

   Topping, Michael W; Shapley, Alice E; Sanders, Ryan L; Kriek, Mariska; Reddy, Naveen A; Coil, Alison L; Mobasher, Bahram; Siana, Brian; Freeman, William R; Shivaei, Irene; et al (July 2021, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We analyse the rest-optical emission-line ratios of z ∼ 1.5 galaxies drawn from the Multi-Object Spectrometer for Infra-Red Exploration Deep Evolution Field (MOSDEF) survey. Using composite spectra, we investigate the mass–metallicity relation (MZR) at z ∼ 1.5 and measure its evolution to z = 0. When using gas-phase metallicities based on the N2 line ratio, we find that the MZR evolution from z ∼ 1.5 to z = 0 depends on stellar mass, evolving by $$\Delta \rm log(\rm O/H) \sim 0.25$$ dex at M*< $$10^{9.75}\, \mathrm{M}_{\odot }$$ down to $$\Delta \rm log(\rm O/H) \sim 0.05$$ at M* ≳ $$10^{10.5}\, \mathrm{M}_{\odot }$$. In contrast, the O3N2-based MZR shows a constant offset of $$\Delta \rm log(\rm O/H) \sim 0.30$$ across all masses, consistent with previous MOSDEF results based on independent metallicity indicators, and suggesting that O3N2 provides a more robust metallicity calibration for our z ∼ 1.5 sample. We investigated the secondary dependence of the MZR on star formation rate (SFR) by measuring correlated scatter about the mean M*-specific SFR and M*−$$\log (\rm O3N2)$$ relations. We find an anticorrelation between $$\log (\rm O/H)$$ and sSFR offsets, indicating the presence of a M*−SFR−Z relation, though with limited significance. Additionally, we find that our z ∼ 1.5 stacks lie along the z = 0 metallicity sequence at fixed μ = log (M*/M⊙) − 0.6 × $$\log (\rm SFR / M_{\odot } \, yr^{-1})$$ suggesting that the z ∼ 1.5 stacks can be described by the z = 0 fundamental metallicity relation (FMR). However, using different calibrations can shift the calculated metallicities off of the local FMR, indicating that appropriate calibrations are essential for understanding metallicity evolution with redshift. Finally, understanding how [N ii]/H α scales with galaxy properties is crucial to accurately describe the effects of blended [N ii] and H α on redshift and H α fiux measurements in future large surveys utilizing low-resolution spectra such as with Euclid and the Roman Space Telescope. 

   more » « less
3. Supermassive black holes in cosmological simulations I: M BH − M ⋆ relation and black hole mass function

   https://doi.org/10.1093/mnras/stab496  

   Habouzit, Mélanie; Li, Yuan; Somerville, Rachel S; Genel, Shy; Pillepich, Annalisa; Volonteri, Marta; Davé, Romeel; Rosas-Guevara, Yetli; McAlpine, Stuart; Peirani, Sébastien; et al (March 2021, Monthly Notices of the Royal Astronomical Society)

   null (Ed.)

   ABSTRACT The past decade has seen significant progress in understanding galaxy formation and evolution using large-scale cosmological simulations. While these simulations produce galaxies in overall good agreement with observations, they employ different sub-grid models for galaxies and supermassive black holes (BHs). We investigate the impact of the sub-grid models on the BH mass properties of the Illustris, TNG100, TNG300, Horizon-AGN, EAGLE, and SIMBA simulations, focusing on the MBH − M⋆ relation and the BH mass function. All simulations predict tight MBH − M⋆ relations, and struggle to produce BHs of $$M_{\rm BH}\leqslant 10^{7.5}\, \rm M_{\odot }$$ in galaxies of $$M_{\star }\sim 10^{10.5}\!-\!10^{11.5}\, \rm M_{\odot }$$. While the time evolution of the mean MBH − M⋆ relation is mild ($$\rm \Delta M_{\rm BH}\leqslant 1\, dex$$ for 0 $$\leqslant z \leqslant$$ 5) for all the simulations, its linearity (shape) and normalization varies from simulation to simulation. The strength of SN feedback has a large impact on the linearity and time evolution for $$M_{\star }\leqslant 10^{10.5}\, \rm M_{\odot }$$. We find that the low-mass end is a good discriminant of the simulation models, and highlights the need for new observational constraints. At the high-mass end, strong AGN feedback can suppress the time evolution of the relation normalization. Compared with observations of the local Universe, we find an excess of BHs with $$M_{\rm BH}\geqslant 10^{9}\, \rm M_{\odot }$$ in most of the simulations. The BH mass function is dominated by efficiently accreting BHs ($$\log _{10}\, f_{\rm Edd}\geqslant -2$$) at high redshifts, and transitions progressively from the high-mass to the low-mass end to be governed by inactive BHs. The transition time and the contribution of active BHs are different among the simulations, and can be used to evaluate models against observations. 

   more » « less
4. Probing the z ≳ 6 quasars in a universe with IllustrisTNG physics: impact of gas-based black hole seeding models

   https://doi.org/10.1093/mnras/stac2238  

   Bhowmick, Aklant K.; Blecha, Laura; Ni, Yueying; Matteo, Tiziana Di; Torrey, Paul; Kelley, Luke Zoltan; Vogelsberger, Mark; Weinberger, Rainer; Hernquist, Lars (August 2022, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We explore implications of a range of black hole (BH) seeding prescriptions on the formation of the brightest $$z$$ ≳ 6 quasars in cosmological hydrodynamic simulations. The underlying galaxy formation model is the same as in the IllustrisTNG simulations. Using constrained initial conditions, we study the growth of BHs in rare overdense regions (forming $$\gtrsim 10^{12}\, {\rm M}_{\odot }\,h^{-1}$$ haloes by $$z$$ = 7) using a  (9 Mpc h−1)3 simulated volume. BH growth is maximal within haloes that are compact and have a low tidal field. For these haloes, we consider an array of gas-based seeding prescriptions wherein $$M_{\mathrm{seed}}=10^4\!-\!10^6\, {\rm M}_{\odot }\,h^{-1}$$ seeds are inserted in haloes above critical thresholds for halo mass and dense, metal-poor gas mass (defined as $$\tilde{M}_{\mathrm{h}}$$ and $$\tilde{M}_{\mathrm{sf,mp}}$$, respectively, in units of Mseed). We find that a seed model with $$\tilde{M}_{\mathrm{sf,mp}}=5$$ and $$\tilde{M}_{\mathrm{h}}=3000$$ successfully produces a $$z$$ ∼ 6 quasar with $$\sim 10^9\, {\rm M}_{\odot }$$ mass and ∼1047 erg s−1 luminosity. BH mergers play a crucial role at $$z$$ ≳ 9, causing an early boost in BH mass at a time when accretion-driven BH growth is negligible. With more stringent seeding conditions (e.g. $$\tilde{M}_{\mathrm{sf,mp}}=1000$$), the relative paucity of BH seeds results in a much lower merger rate. In this case, $$z$$ ≳ 6 quasars can only be formed if we enhance the maximum allowed BH accretion rates (by factors ≳10) compared to the accretion model used in IllustrisTNG. This can be achieved either by allowing for super-Eddington accretion, or by reducing the radiative efficiency. Our results demonstrate that progenitors of $$z$$ ∼ 6 quasars have distinct BH merger histories for different seeding models, which will be distinguishable with Laser Interferometer Space Antenna observations. 

   more » « less
5. Be it therefore resolved: cosmological simulations of dwarf galaxies with 30 solar mass resolution

   https://doi.org/10.1093/mnras/stz2887  

   Wheeler, Coral; Hopkins, Philip F.; Pace, Andrew B.; Garrison-Kimmel, Shea; Boylan-Kolchin, Michael; Wetzel, Andrew; Bullock, James S.; Kereš, Dušan; Faucher-Giguère, Claude-André; Quataert, Eliot (October 2019, Monthly Notices of the Royal Astronomical Society)

   ABSTRACT We study a suite of extremely high-resolution cosmological Feedback in Realistic Environments simulations of dwarf galaxies ($$M_{\rm halo} \lesssim 10^{10}\rm \, M_{\odot }$$), run to z = 0 with $$30\, \mathrm{M}_{\odot }$$ resolution, sufficient (for the first time) to resolve the internal structure of individual supernovae remnants within the cooling radius. Every halo with $$M_{\rm halo} \gtrsim 10^{8.6}\, \mathrm{M}_{\odot }$$ is populated by a resolved stellar galaxy, suggesting very low-mass dwarfs may be ubiquitous in the field. Our ultra-faint dwarfs (UFDs; $$M_{\ast }\lt 10^{5}\, \mathrm{M}_{\odot }$$) have their star formation (SF) truncated early (z ≳ 2), likely by reionization, while classical dwarfs ($$M_{\ast }\gt 10^{5}\, \mathrm{M}_{\odot }$$) continue forming stars to z < 0.5. The systems have bursty star formation histories, forming most of their stars in periods of elevated SF strongly clustered in both space and time. This allows our dwarf with M*/Mhalo > 10−4 to form a dark matter core $${\gt}200\rm \, pc$$, while lower mass UFDs exhibit cusps down to $${\lesssim}100\rm \, pc$$, as expected from energetic arguments. Our dwarfs with $$M_{\ast }\gt 10^{4}\, \mathrm{M}_{\odot }$$ have half-mass radii (R1/2) in agreement with Local Group (LG) dwarfs (dynamical mass versus R1/2 and stellar rotation also resemble observations). The lowest mass UFDs are below surface brightness limits of current surveys but are potentially visible in next-generation surveys (e.g. LSST). The stellar metallicities are lower than in LG dwarfs; this may reflect pre-enrichment of the LG by the massive hosts or Pop-III stars. Consistency with lower resolution studies implies that our simulations are numerically robust (for a given physical model). 

   more » « less