Alastair Edge

   I am a Reader in Astronomy in the Extragalactic Astronomy group of the Department of Physics at Durham University. My research concentrates on clusters of galaxies from an X-ray prespective. Selecting clusters on the basis of their X-ray luminosity ensures that the objects are massive and well-relaxed. In many cases these clusters are relatively dense in their cores and the resulting strong X-ray emission causes all the thermal energy of the gas to be radiated away. This phenomenon is termed a "Cooling Flow". The clear and unescapable conclusion from the X-ray observations is that there is a substantial mass of gas that has cooled but relatively little of this 'sink' had been found before 2000.


   A color Hubble Space Telescope ACS image of the central galaxy in A2390. This central galaxy contains significant star formation. We have had a series of HST SNAPSHOT programs to determine the detailed optical mophology of a complete sample of high optical line luminosity systems and a control sample of optically dull central galaxies (see HST Programs 8301 and 8719). In total over 250 snapshots have or will soon be taken.


   Results have found that the cores of clusters have considerable masses of molecular gas and dust present. Work on IRAM and JCMT by myself has lead to the discovery of 17 central cluster galaxies with CO(1-0) detections (click on icon for A1068). These CO line detections imply 10^9--11.5 Msun of molecular gas at temperatures of 20-50K. We have also found a large number of similar galaxies with strong H2 vibration-rotation lines in the near-infrared from UKIRT observations. These observations indicate that there is an underlying correlation between the ionised gas (Balmer lines) and molecular gas (H2 and CO). We have since obtained more IRAM 30m observations of another 80 clusters resulting in over 50 CO detections, OVRO and PdBI interferometic imaging and most recently Herschel spectroscopy of 11 BCGs.


   Much of my work has been based on data from the ROSAT All-Sky Survey. From work with Harald Ebeling and Pat Henry (IfA, Hawaii), we have found a large sample (>140) distant (z>0.3) clusters from this sample (the MACS sample). This work is being extended to lower redshift to create a total sample of over 1500 X-ray selected clusters.

UKIDSS Deep eXtragalactic Survey

   I am the coordinator of the UKIDSS DXS survey that will cover 35 sq.deg. split over four fields to Jvega=22.3 and Kvega=20.8. The DXS is one of five UKIDSS surveys. The data complements the PanSTARRS Medium Deep Survey, SWIRE, SERVS and SCUBA-2 Cosmology surveys.

VLT FORS and VIMOS Survey of Southern BCGs

   I have managed to obtain VLT FORS spectroscopy of the BCGs in over 400 of the 452 REFLEX clusters. These spectra find over 30% of these BCGs exhibit some optical line emission, a strong indication that come cool gas is present. We then observed 72 of the strongest line emitting objects with the integral field unit of VIMOS to map the extent and dynamics of the lines. These observations are revealing many of these galaxies have rotating gas disks.


Last Modified: November 1st 2010. [Netscape 4.5]

This page owes a great deal to the efforts of Ian Smail whose home page I have ruthlessly ripped off ( look for yourself!).

Alastair Edge,
Department of Physics, University of Durham, South Road, Durham DH1 3LE
Tel: +44-191-334-3792 / FAX: +44-191-334-3645