Interstellar Medium in Galaxies
Evolution of the interstellar medium following a galaxy merger can be studied through :-
X-ray observations of the hot gas phase (using X-ray satellites such as ROSAT and XMM-Newton).
Radio (21 cm) observations of the cold gas phase (using mapping radio telescopes such as the VLA).
Submillimeter observations of molecular lines from ALMA array and IRAM 30m telescopes. See our Infrared and Submm observations.
Age indicators, since the last merger event, using morphological or spectral indicators of the age of a galaxy.

Here is a compilation of how the X-ray observations appear to change with estimated age since a merger, in ongoing mergers and post-merger galaxies The horizontal line represents the approximate stellar contribution in elliptical galaxies. See Sansom et al. 2006 for details of this work.



For our VLA observations see here


People who have been involved in this work are:

Anne Sansom UCLan
John Hibbard NRAO, Charlotesville, US
Francois Schweizer Carnegie Observatories, Pasadena, US
Duncan Forbes Swinburne
Ewan O'Sullivan Harvard-Smithsonian Centre for Astrophysics, US



Relevant publications:

Sansom A.E., Hibbard, J.E., Schweizer, F., 2000. In ASP conference series. Vol. 240. 'Gas and Galaxy Evolution'. Socorro, May 2000, J.E. Hibbard, M.P. Rupen, J.H. van Gorkom (eds). "Gas in Ellipticals with Fine Structure".

Sansom A.E., Hibbard, J.E., Schweizer, F., 2000. AJ 120, 1946 "The Cold and Hot Gas Content of Fine Structure E and S0 Galaxies".

Hibbard J.E., Sansom A.E., 2003, AJ, 125, 667 "A Search for HI in Five Ellipticals with Fine Structure".

Sansom A.E., O'Sullivan E., Forbes D.A., Proctor R.N., Davis D.S., 2006, MNRAS, 370, 1541 "X-ray observations of three young, early-type galaxies."

Sansom A.E., Glass D.H.W., et al., 2019, MNRAS, 482, 4617 "ALMA observations of massive molecular gas reservoirs in dusty early-type galaxies."