Velocity dispersion ( σ) is a key driver for galaxy structure and evolution. We here present a comprehensive semi-empirical approach to compute σvia detailed Jeans modelling assuming both a constant and scale-dependent mass-to-light ratio M ∗/ L . We compare with a large sample of local galaxies from MaNGA and find that both models can reproduce the Faber–Jackson (FJ) relation and the weak dependence of σon bulge-to-total (B/T) ratio (for B/T 0.25). The dynamical-to-stellar mass ratio within R R e can be fully accounted for by a gradient in M ∗/ L . We then build velocity dispersion evolutionary tracks σap [ M ∗, z] (within an aperture) along the main progenitor dark matter haloes assigning stellar masses, ef fecti ve radii, and S ´ersic indices via a variety of abundance matching and empirically moti v ated relations. We find: (1) clear e vidence for do wnsizing in σap [ M ∗, z] along the progenitor tracks; (2) at fixed stellar mass σ∝ (1 + z) 0.2 −0.3 depending on the presence or not of a gradient in M ∗/ L . We extract σap [ M ∗, z] from the TNG50 hydrodynamic simulation and find very similar results to our models with constant M ∗/ L . The increasing dark matter fraction within R e tends to flatten the σap [ M ∗, z] along the progenitors at z 1 in constant M ∗/ L models, while σap [ M ∗, z] have a steeper evolution in the presence of a stellar gradient. We then show that a combination of mergers and gas accretion is likely responsible for the constant or increasing σap [ M ∗, z] with time. Finally, our σap [ M ∗, z] are consistent with a nearly constant and steep M bh −σrelation at z 2, with black hole masses derived from the L X −M ∗relation.

The weak dependence of velocity dispersion on disc fractions, mass-to-light ratio, and redshift: implications for galaxy and black hole evolution / Marsden, Christopher; Shankar, Francesco; Bernardi, Mariangela; Sheth, Ravi K; Fu, Hao; Lapi, Andrea. - In: MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY. - ISSN 0035-8711. - 510:4(2022), pp. 5639-5660. [10.1093/mnras/stab3705]

The weak dependence of velocity dispersion on disc fractions, mass-to-light ratio, and redshift: implications for galaxy and black hole evolution

Lapi, Andrea
2022

Abstract

Velocity dispersion ( σ) is a key driver for galaxy structure and evolution. We here present a comprehensive semi-empirical approach to compute σvia detailed Jeans modelling assuming both a constant and scale-dependent mass-to-light ratio M ∗/ L . We compare with a large sample of local galaxies from MaNGA and find that both models can reproduce the Faber–Jackson (FJ) relation and the weak dependence of σon bulge-to-total (B/T) ratio (for B/T 0.25). The dynamical-to-stellar mass ratio within R R e can be fully accounted for by a gradient in M ∗/ L . We then build velocity dispersion evolutionary tracks σap [ M ∗, z] (within an aperture) along the main progenitor dark matter haloes assigning stellar masses, ef fecti ve radii, and S ´ersic indices via a variety of abundance matching and empirically moti v ated relations. We find: (1) clear e vidence for do wnsizing in σap [ M ∗, z] along the progenitor tracks; (2) at fixed stellar mass σ∝ (1 + z) 0.2 −0.3 depending on the presence or not of a gradient in M ∗/ L . We extract σap [ M ∗, z] from the TNG50 hydrodynamic simulation and find very similar results to our models with constant M ∗/ L . The increasing dark matter fraction within R e tends to flatten the σap [ M ∗, z] along the progenitors at z 1 in constant M ∗/ L models, while σap [ M ∗, z] have a steeper evolution in the presence of a stellar gradient. We then show that a combination of mergers and gas accretion is likely responsible for the constant or increasing σap [ M ∗, z] with time. Finally, our σap [ M ∗, z] are consistent with a nearly constant and steep M bh −σrelation at z 2, with black hole masses derived from the L X −M ∗relation.
510
4
5639
5660
https://arxiv.org/abs/2112.09720
Marsden, Christopher; Shankar, Francesco; Bernardi, Mariangela; Sheth, Ravi K; Fu, Hao; Lapi, Andrea
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Utilizza questo identificativo per citare o creare un link a questo documento: https://hdl.handle.net/20.500.11767/126149
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