Coevolution of the galactic cores and spiral galaxies

Takayuki R. Saitoh; Keiichi Wada

doi:10.1086/426119

paper

Coevolution of the galactic cores and spiral galaxies

arXiv:astro-ph/0409708 · doi:10.1086/426119

Abstract

Using high-resolution N-body/SPH simulations with $2 \times 1 0^{6}$ particles, we investigate the evolution of stellar and gaseous galactic cores during the hierarchical formation of a spiral galaxy. We find that the galactic core ( $r < 300$ pc) coevolves with the host galaxy. The average mass ratio between the baryonic core and the halo is nearly constant, $\sim$ 0.04 from $z \sim 10$ to $z \sim 2$ . However, there are several `rapid-growing phases' during the evolution, in which the rate of mass accretion to the central sub-kpc region is ten times higher ( $\sim 1 M_{⊙}$ yr pc $^{- 1}$ ) than the average accretion rate. The rapid growth of the inner core is associated with the major merger events with a time-delay. We also find that the spin-axis of the gas core frequently changes. As a result, the angular momentum vector of the central part of the galaxy is independent of the rotation of the outer part. Our results suggest that if a constant fraction of the baryonic mass in the central several 100 pc of a galaxy is converted into a massive black hole, the black hole mass should correlate with the total mass of the galaxies.

4 pages, 4 figures, Accepted for publication in ApJL

Coevolution of the galactic cores and spiral galaxies

Abstract

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