Bibcode
La Barbera, F.; de Carvalho, R. R.; de la Rosa, I. G.; Sorrentino, G.; Gal, R. R.; Kohl-Moreira, J. L.
Bibliographical reference
The Astronomical Journal, Volume 137, Issue 4, pp. 3942-3960 (2009).
Advertised on:
4
2009
Citations
45
Refereed citations
42
Description
We use SDSS-DR4 photometric and spectroscopic data out to redshift z ~
0.1 combined with ROSAT All Sky Survey X-ray data to produce a sample of
25 fossil groups (FGs), defined as bound systems dominated by a single,
luminous elliptical galaxy with extended X-ray emission. We examine
possible biases introduced by varying the parameters used to define the
sample, and the main pitfalls are also discussed. The spatial density of
FGs, estimated via the V/V MAX test, is 2.83 ×
10-6 h 3 75 Mpc-3 for
LX > 0.89 × 1042 h -2
75 erg s-1 consistent with Vikhlinin et al., who
examined an X-ray overluminous elliptical galaxy sample (OLEG). We
compare the general properties of FGs identified here with a sample of
bright field ellipticals generated from the same data set. These two
samples show no differences in the distribution of neighboring faint
galaxy density excess, distance from the red sequence in the
color-magnitude diagram, and structural parameters such as a
4 and internal color gradients. Furthermore, examination of
stellar populations shows that our 25 FGs have similar ages,
metallicities, and α-enhancement as the bright field ellipticals,
undermining the idea that these systems represent fossils of a physical
mechanism that occurred at high redshift. Our study reveals no
difference between FGs and field ellipticals, suggesting that FGs might
not be a distinct family of true fossils, but rather the final stage of
mass assembly in the universe.
Related projects
Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro