Issue |
A&A
Volume 367, Number 2, February IV 2001
|
|
---|---|---|
Page(s) | 428 - 442 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20000441 | |
Published online | 15 February 2001 |
Growth of galactic bulges by mergers
I. Dense satellites
1
Instituto de Astrofísica de Canarias, 38200 La Laguna, Tenerife, Canary Islands, Spain
2
Astronomisches Institut der Universitat Basel, 4102 Binningen, Switzerland
3
School of Physics and Astronomy, University of Nottingham, NG7 2RD, UK e-mail: jalfonso@astro.unibas.ch; balcells@ll.iac.es; Reynier.Peletier@nottingham.ac.uk
Corresponding author: J. A. L. Aguerri, jalfonso@astro.unibas.ch
Received:
21
September
2000
Accepted:
1
December
2000
Andredakis et al. ([CITE]) fit Sersic's law
to the bulges of the Balcells & Peletier
([CITE]) galaxy sample, and infer that n drops with morphological type T
from
4-6 for S0 to
(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.
Key words: galaxies: evolution / galaxies: interactions / galaxies: kinematics and dynamics / galaxies: nuclei / galaxies: spiral / galaxies: structure
© ESO, 2001
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