Abstract:We investigate black hole-host galaxy scaling relations in cosmological simulations with a self-consistent black hole growth and feedback model. The sub-grid accretion model captures the key scalings governing angular momentum transport from galactic scales down to parsec scales, while our kinetic feedback implementation enables the injection of outflows with properties chosen to match observed nuclear outflows. We show that "quasar mode" feedback can have a large impact on the thermal properties of the interg… Show more
“…The results in this Letter are consistent with cosmological hydrodynamic simulations performed by Anglés-Alcázar et al (2015 which suggest that the MBH -M bulge relation converges independently of the seed BH mass at M bulge 10 10 M⊙ while at M bulge 10 10 M⊙, seed BH mass becomes important in the scaling relation. Anglés-Alcázar et al (2016) compare BH mass -galaxy stellar mass relations at z ∼ 0 with 10 4 h −1 M⊙ and 10 6 h −1 M⊙ seed BHs. They find that in the case with 10 6 h −1 M⊙ seed BHs, the relation has a floor which also appears in the MBH -M bulge relation in our massive seed model.…”
We explore the effect of varying the mass of the seed black hole on the resulting black hole mass -bulge mass relation at z ∼ 0, using a semi-analytic model of galaxy formation combined with large cosmological N -body simulations. We constrain our model by requiring the observed properties of galaxies at z ∼ 0 are reproduced. In keeping with previous semi-analytic models, we place a seed black hole immediately after a galaxy forms. When the mass of the seed is set at 10 5 M ⊙ , we find that the model results become inconsistent with recent observational results of the black hole mass -bulge mass relation for dwarf galaxies. In particular, the model predicts that bulges with ∼ 10 9 M ⊙ harbour larger black holes than observed. On the other hand, when we employ seed black holes with 10 3 M ⊙ , or randomly select their mass within a 10 3−5 M ⊙ range, the resulting relation is consistent with observation estimates, including the observed dispersion. We find that to obtain stronger constraints on the mass of seed black holes, observations of less massive bulges at z ∼ 0 are a more powerful comparison than the relations at higher redshifts.
“…The results in this Letter are consistent with cosmological hydrodynamic simulations performed by Anglés-Alcázar et al (2015 which suggest that the MBH -M bulge relation converges independently of the seed BH mass at M bulge 10 10 M⊙ while at M bulge 10 10 M⊙, seed BH mass becomes important in the scaling relation. Anglés-Alcázar et al (2016) compare BH mass -galaxy stellar mass relations at z ∼ 0 with 10 4 h −1 M⊙ and 10 6 h −1 M⊙ seed BHs. They find that in the case with 10 6 h −1 M⊙ seed BHs, the relation has a floor which also appears in the MBH -M bulge relation in our massive seed model.…”
We explore the effect of varying the mass of the seed black hole on the resulting black hole mass -bulge mass relation at z ∼ 0, using a semi-analytic model of galaxy formation combined with large cosmological N -body simulations. We constrain our model by requiring the observed properties of galaxies at z ∼ 0 are reproduced. In keeping with previous semi-analytic models, we place a seed black hole immediately after a galaxy forms. When the mass of the seed is set at 10 5 M ⊙ , we find that the model results become inconsistent with recent observational results of the black hole mass -bulge mass relation for dwarf galaxies. In particular, the model predicts that bulges with ∼ 10 9 M ⊙ harbour larger black holes than observed. On the other hand, when we employ seed black holes with 10 3 M ⊙ , or randomly select their mass within a 10 3−5 M ⊙ range, the resulting relation is consistent with observation estimates, including the observed dispersion. We find that to obtain stronger constraints on the mass of seed black holes, observations of less massive bulges at z ∼ 0 are a more powerful comparison than the relations at higher redshifts.
“…Besides less dynamic range, we also do not yet explicitly track central black hole growth and feedback as the other simulations do (this is in progress; see e.g. Anglés-Alcázar et al 2016). Nevertheless, compared to recent state-of-the-art galaxy formation simulations, Mufasa generally is as good or better at reproducing the observed stellar mass buildup in galaxies across the majority of cosmic time as traced by the GSMF.…”
Section: Comparison To Other Simulationsmentioning
We present the Mufasa suite of cosmological hydrodynamic simulations, which employs the Gizmo meshless finite mass (MFM) code including H 2 -based star formation, nine-element chemical evolution, two-phase kinetic outflows following scalings from the Feedback in Realistic Environments zoom simulations, and evolving halo mass-based quenching. Our fiducial (50h −1 Mpc) 3 volume is evolved to z = 0 with a quarter billion elements. The predicted galaxy stellar mass functions (GSMF) reproduces observations from z = 4 → 0 to 1.2σ in cosmic variance, providing an unprecedented match to this key diagnostic. The cosmic star formation history and stellar mass growth show general agreement with data, with a strong archaeological downsizing trend such that dwarf galaxies form the majority of their stars after z ∼ 1. We run 25h −1 Mpc and 12.5h −1 Mpc volumes to z = 2 with identical feedback prescriptions, the latter resolving all hydrogen-cooling halos, and the three runs display fair resolution convergence. The specific star formation rates broadly agree with data at z = 0, but are underpredicted at z ∼ 2 by a factor of three, re-emphasizing a longstanding puzzle in galaxy evolution models. We compare runs using MFM and two flavours of Smoothed Particle Hydrodynamics, and show that the GSMF is sensitive to hydrodynamics methodology at the ∼ ×2 level, which is sub-dominant to choices for parameterising feedback.
“…Since the data hint at a rather strong correlation, this calls for revamped AGN feedback recipes in the next generation of cosmological galaxyevolution models, or for a re-assessment of the importance of gravitational torques in regulating the black hole-galaxy coevolution (Anglés-Alcázar et al 2017).…”
Recent work has confirmed that the scaling relations between the masses of supermassive black holes and host-galaxy properties such as stellar masses and velocity dispersions may be biased high. Much of this may be caused by the requirement that the black-hole sphere of influence must be resolved for the black-hole mass to be reliably estimated. We revisit this issue with a comprehensive galaxy evolution semi-analytic model. Once tuned to reproduce the (mean) correlation of black-hole mass with velocity dispersion, the model cannot account for the correlation with stellar mass. This is independent of the model's parameters, thus suggesting an internal inconsistency in the data. The predicted distributions, especially at the low-mass end, are also much broader than observed. However, if selection effects are included, the model's predictions tend to align with the observations. We also demonstrate that the correlations between the residuals of the scaling relations are more effective than the relations themselves at constraining AGN feedback models. In fact, we find that our model, while in apparent broad agreement with the scaling relations when accounting for selection biases, yields very weak correlations between their residuals at fixed stellar mass, in stark contrast with observations. This problem persists when changing the AGN feedback strength, and is also present in the hydrodynamic cosmological simulation Horizon-AGN, which includes state-of-the-art treatments of AGN feedback. This suggests that current AGN feedback models are too weak or simply not capturing the effect of the black hole on the stellar velocity dispersion.
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