Revealing the ISM of star-forming galaxies with GRB afterglow spectroscopy


Emission lines in X-ray spectra of clusters of galaxies reveal the presence of heavy elements in the diffuse hot plasma (ICM) in virial equilibrium in the dark matter potential well. Thanks to the X-ray satellites Chandra and XMM-Newton we are now able to measure with good accuracy the distribution and evolution of Iron up to redshift z åisebox-0.5ex 1.3. The capability of studying the chemical and thermodynamical properties of the ICM in high redshift clusters is an efficient tool to constrain the interaction processes between the cluster galaxies and the surrounding medium. We confirm that the ICM is already significantly enriched at a look-back time of 9 Gyr, and find that the Iron abundance change with redshift as (1+z)(̂-1.25), implying an increase of a factor of i̊sebox-0.5ex 2 with respect to z=1.3. This result can be explained by a prompt enrichment by star formation processes in massive ellipticals at z>2, followed by a slower release of enriched gas from disk galaxies into the ICM, associated to a morphological transition from disk to S0.

Nuovo Cimento B Serie