Bibcode
Peng, Eric W.; Ferguson, Henry C.; Goudfrooij, Paul; Hammer, Derek; Lucey, John R.; Marzke, Ronald O.; Puzia, Thomas H.; Carter, David; Balcells, M.; Bridges, Terry; Chiboucas, Kristin; del Burgo, Carlos; Graham, Alister W.; Guzmán, Rafael; Hudson, Michael J.; Matković, Ana; Merritt, David; Miller, Bryan W.; Mouhcine, Mustapha; Phillipps, Steven; Sharples, Ray; Smith, Russell J.; Tully, Brent; Verdoes Kleijn, Gijs
Bibliographical reference
The Astrophysical Journal, Volume 730, Issue 1, article id. 23 (2011).
Advertised on:
3
2011
Journal
Citations
110
Refereed citations
97
Description
Intracluster stellar populations are a natural result of tidal
interactions in galaxy clusters. Measuring these populations is
difficult, but important for understanding the assembly of the most
massive galaxies. The Coma cluster of galaxies is one of the nearest
truly massive galaxy clusters and is host to a correspondingly large
system of globular clusters (GCs). We use imaging from the HST/ACS Coma
Cluster Survey to present the first definitive detection of a large
population of intracluster GCs (IGCs) that fills the Coma cluster core
and is not associated with individual galaxies. The GC surface density
profile around the central massive elliptical galaxy, NGC 4874, is
dominated at large radii by a population of IGCs that extend to the
limit of our data (R < 520 kpc). We estimate that there are 47, 000
± 1600 (random) +4000 -5000 (systematic)
IGCs out to this radius, and that they make up ~70% of the central GC
system, making this the largest GC system in the nearby universe. Even
including the GC systems of other cluster galaxies, the IGCs still make
up ~30%-45% of the GCs in the cluster core. Observational limits from
previous studies of the intracluster light (ICL) suggest that the IGC
population has a high specific frequency. If the IGC population has a
specific frequency similar to high-SN dwarf galaxies, then
the ICL has a mean surface brightness of μ V ≈ 27 mag
arcsec-2 and a total stellar mass of roughly 10^{12}
{M}_&sun; within the cluster core. The ICL makes up approximately half
of the stellar luminosity and one-third of the stellar mass of the
central (NGC 4874+ICL) system. The color distribution of the IGC
population is bimodal, with blue, metal-poor GCs outnumbering red,
metal-rich GCs by a ratio of 4:1. The inner GCs associated with NGC 4874
also have a bimodal distribution in color, but with a redder metal-poor
population. The fraction of red IGCs (20%), and the red color of those
GCs, implies that IGCs can originate from the halos of relatively
massive, L* galaxies, and not solely from the disruption of dwarf
galaxies.
Based on observations with the NASA/ESA Hubble Space Telescope obtained
at the Space Telescope Science Institute, which is operated by the
Association of Universities for Research in Astronomy, Inc., under NASA
contract NAS 5-26555.
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