Diffuse Hot Gas in the NGC 4261 Group of Galaxies (original) (raw)

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Abstract

We have found diffuse X-ray gas in the group of galaxies containing the elliptical galaxy NGC 4261. This galaxy along with its associated companions are behind the Virgo cluster in the W-cloud. A recent analysis of the velocity structure in the Virgo region indicates that the W-cloud has ~30 members, most of which are low luminosity dwarfs. The hot X-ray emitting gas is centered about halfway between NGC 4261 and NGC 4264 and extends out to a radius of ~40' (620 kpc). The spectral data for the diffuse component are well fitted with a Raymond-Smith plasma model with a temperature of 0.85_-0.16_^+0.1^ keV and abundance < 0.08 times the solar value. Under the assumption that the diffuse gas is in hydrostatic equilibrium the total mass within 40' is 1.9 x 10^13^ M_sun_. We estimate that the total baryonic mass of the hot gas and the galaxies is 20%-34% of the total mass in the central 40' radius of this group. This group of galaxies contains NGC 4273 which exhibits a "bow shock" morphology similar to that of NGC 2276. This is thought to occur when the ram pressure from the intragroup gas significantly perturbs the interstellar medium in a late-type galaxy. We show that this is unlikely in this group.

Publication:

The Astrophysical Journal

Pub Date:

May 1995

DOI:

10.1086/175632

Bibcode:

1995ApJ...444..582D

Keywords: