17 November 2008
Louise Edwards (IPAC)
"Line Emission in Cooling Flow Brightest Cluster Galaxies"
The Brightest Cluster Galaxy (BCG) is often found at the same
position as the peak of a cluster's X-ray surface brightness. In
cases where the cooling time of the X-ray gas is less than the Hubble
time, this massive cooling component may affect the activity in the
central galaxy. In an effort to pinpoint current or recent activity
in these systems, I will discuss the frequency of occurrence and
properties of optical line emission in nearby BCGs. Our study
examines the BCGs (and controls) in two large homogeneous datasets:
the NOAO Fundamental Plane Survey (NFP) and the Sloan Digital Sky
Survey Data Release 3 (SDSS). For those BCGs located in cooling flow
clusters and also within 50 kpc of the X-ray center, nearly 100% show
optical emission lines (compared to only ~15% in the control sample).
I will also discuss a complementary study of a selected subsample of
BCGs using integral field spectroscopy to explore the morphology,
kinematics and diagnostic line ratios of the central regions. The
physical origin of the emission lines is not described by a single
process: in some cases there are LINER-like line ratios, whereas in
others it is a composite of star formation and LINER-like activity.