Growth of Galactic Bulges by Mergers: I. Dense Satellites

J. A. L. Aguerri; M. Balcells; R. F. Peletier

doi:10.1051/0004-6361:20000441

paper

Growth of Galactic Bulges by Mergers: I. Dense Satellites

arXiv:astro-ph/0012156 · doi:10.1051/0004-6361:20000441

Abstract

Andredakis, Peletier & Balcells (1995) fit Sersic's law $μ (r) \sim r^{1/ n}$ to the bulges of the Balcells & Peletier (1994) galaxy sample, and infer that $n$ drops with morphological type T from $n \approx$ 4--6 for S0 to $n = 1$ (exponential) for Sc's. We use collisionless N body simulations to test the assumption that initially the surface brightness profiles of all bulges were exponential, and that the steepening of the profiles toward the early-types is due to satellite accretion. The results are positive. After the accretion of a satellite, bulge-disk fits show that the bulge grows and that the bulge profile index $n$ increases proportional to the satellite mass. For a satellite as massive as the bulge, $n$ rises from 1 to 4. We present kinematic diagnostics on the remnants and disk thickening. The latter suggests that the bulge growth must have occurred before the last formation of a thin disk in the galaxy. The thick disks created by the merger are reminiscent of thick disks seen in early-type edge-on galaxies. The efficiency of the process suggests that present day bulges of late-type spirals showing exponential profiles cannot have grown significantly by collisionless mergers.

10 figures (8 poscript and 2 gif). accepted for publication in A&A

Growth of Galactic Bulges by Mergers: I. Dense Satellites

Abstract

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