Bibcode
DOI
Stanghellini, Letizia; González-García, A. Cesar; Manchado, A.
Bibliographical reference
The Astrophysical Journal, Volume 644, Issue 2, pp. 843-849.
Advertised on:
6
2006
Journal
Citations
16
Refereed citations
15
Description
We present N-body simulations of elliptical galaxy encounters into dry
mergers to study the resulting unbound intergalactic stellar population,
in particular that of the post-main-sequence stars. The systems studied
are pairs of spherical galaxies without dark halos. The stellar content
of the model galaxies is distributed into mass bins representing low-
and intermediate-mass stars (0.85-8 Msolar) according to the
Salpeter initial mass function. Our models follow the dynamical
evolution of galaxy encounters colliding head-on from initial low-energy
parabolic or high-energy mildly hyperbolic orbits and for a choice of
initial mass ratios. The merging models with initial parabolic orbits
have M2/M1=1 and 10, and they leave behind,
respectively, 5.5% and 10% of the total initial mass as unbound stellar
mass. The merging model with an initial hyperbolic orbit has
M2/M1=1 and leaves behind 21% of its initial
stellar mass as unbound mass, showing that the efficiency in producing
intergalactic stars through a high-energy hyperbolic encounter is about
4 times that of a parabolic encounter of the same initial mass ratio. By
assuming that all progenitor galaxies, as well as the merger remnants,
are homologous systems we find that the intergalactic starlight is 17%
and 28% of the total starlight, respectively, for the parabolic and
hyperbolic encounters with M2/M1=1. In all models,
stars of different mass have the same probability of becoming unbound
and feeding the intergalactic stellar population.