Late bursts of star formation in normal elliptical galaxies
By Jeremiah Ostriker (University of Columbia)
Wednesday 19 Jun
Place: Aula 507 (Pere Pascual)
We normally think of elliptical galaxies as massive, stellar systems which are quasi-spherical, filled with old stars and hot gas and essentially quiescent objects. Successful simulations find them made at high redshift, as relatively small objects which grow at early times from gas infall and at late times from accreting satellites. They are known to contain massive black holes of unknown origin. I will show cosmological simulations that are in accord with this and will also show new, very high resolution sims which indicate quite different phenomena. Matter ejected via normal stellar evolution (AGB stars and SN I) provides enough gas to cause cooling flows which lead to episodic formation of dense cold gas disks at the centers of normal ellipticals. These, in turn host formation of massive stars and also feed the central black hole. The disks are dramatic sources of IR and molecular emission. This leads to the commonly observed “E + A” phenomenon and many other dramatic observational events hosted by otherwise passive old galaxies.