The galaxy group NGC 5044 consists of a luminous giant elliptical galaxy surrounded by a cluster of 160 low-luminosity and dwarf galaxies, mostly of early type. The cumulative projected radial distribution of dwarf galaxies in the NGC 5044 group, unlike distributions of more luminous galaxies in rich clusters, does not follow a projected dark matter (NFW ) profile. A deficiency or absence of low-luminosity galaxies is apparent in NGC 5044 within about 350 kpc. Most of the dwarf galaxies in NGC 5044 entered the virial radius at redshifts z P2:5(af =0:25), where af ¼ 1=(1þ zf ) is the epoch of group formation, and very few entered during redshifts z k2:5(af =0:25). The peculiar, non-NFW shape of the projected cumulative dwarf galaxy distribution in NGC 5044 within 350 kpc resembles the characteristic cumulative distribution of dark subhalos that are also known to be relatively young. Dynamical friction is unlikely to explain the apparent lack of group member galaxies at small radii in NGC 5044.
MATHEWS W.G., CHOMIUK L., BRIGHENTI F., BUOTE D.A. (2004). Absence of Dwarf Galaxies at High Redshifts: Evidence from a Galaxy Group. THE ASTROPHYSICAL JOURNAL, 616, 745-751 [10.1086/424995].
Absence of Dwarf Galaxies at High Redshifts: Evidence from a Galaxy Group
BRIGHENTI, FABRIZIO;
2004
Abstract
The galaxy group NGC 5044 consists of a luminous giant elliptical galaxy surrounded by a cluster of 160 low-luminosity and dwarf galaxies, mostly of early type. The cumulative projected radial distribution of dwarf galaxies in the NGC 5044 group, unlike distributions of more luminous galaxies in rich clusters, does not follow a projected dark matter (NFW ) profile. A deficiency or absence of low-luminosity galaxies is apparent in NGC 5044 within about 350 kpc. Most of the dwarf galaxies in NGC 5044 entered the virial radius at redshifts z P2:5(af =0:25), where af ¼ 1=(1þ zf ) is the epoch of group formation, and very few entered during redshifts z k2:5(af =0:25). The peculiar, non-NFW shape of the projected cumulative dwarf galaxy distribution in NGC 5044 within 350 kpc resembles the characteristic cumulative distribution of dark subhalos that are also known to be relatively young. Dynamical friction is unlikely to explain the apparent lack of group member galaxies at small radii in NGC 5044.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.