Astronomy and Astrophysics – Astrophysics
Scientific paper
2001-03-19
Mon.Not.Roy.Astron.Soc. 325 (2001) 693
Astronomy and Astrophysics
Astrophysics
18 pages, 8 figures. Accepted for publication in MNRAS
Scientific paper
10.1046/j.1365-8711.2001.04490.x
We have derived the X-ray luminosities of a sample of galaxies in groups, making careful allowance for contaminating intragroup emission. The L_X:L_B and L_X:L_{FIR} relations of spiral galaxies in groups appear to be indistinguishable from those in other environments, however the elliptical galaxies fall into two distinct classes. The first class is central-dominant group galaxies which are very X-ray luminous, and may be the focus of group cooling flows. All other early-type galaxies in groups belong to the second class, which populates an almost constant band of L_X/L_B over the range 9.8 < log L_B < 11.3. The X-ray emission from these galaxies can be explained by a superposition of discrete galactic X-ray sources together with a contribution from hot gas lost by stars, which varies a great deal from galaxy to galaxy. In the region where the optical luminosity of the non-central group galaxies overlaps with the dominant galaxies, the dominant galaxies are over an order of magnitude more luminous in X-rays. We also compared these group galaxies with a sample of isolated early-type galaxies, and used previously published work to derive L_X:L_B relations as a function of environment. The non-dominant group galaxies have mean L_X/L_B ratios very similar to that of isolated galaxies, and we see no significant correlation between L_X/L_B and environment. We suggest that previous findings of a steep L_X:L_B relation for early-type galaxies result largely from the inclusion of group-dominant galaxies in samples.
Forbes Duncan A.
Helsdon Stephen F.
O'Sullivan Ewan
Ponman Trevor J.
No associations
LandOfFree
X-ray luminosities of galaxies in groups does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with X-ray luminosities of galaxies in groups, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and X-ray luminosities of galaxies in groups will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-189193