Metallicity Gradients in Cooling Flow Galaxies and Groups

Preprint
Publisher Website
Google Scholar
  • 19 January 2000
Abstract
Previous studies of the metallicities in the hot gas of galaxies and groups have reported conflicting results with most studies finding very sub-solar metallicities that disagree with standard theory. To investigate the possible role of metallicity gradients on these measurements we present deprojection analysis of the ROSAT PSPC data of 10 of the brightest cooling flow galaxies and groups. The PSPC allows for spatially resolved spectral analysis on a half-arcminute scale, and interesting constraints on both the temperatures and metallicities are possible because the ~1 keV temperatures of these systems are well matched to the bandpass of the PSPC. In 9 out of 10 systems we find clear evidence that the metallicity decreases with increasing radius: Z ~1 solar - (several) solar within the central radial bin (r < ~10 kpc) which decreases to Z ~0.5 solar at the largest radii examined (r ~50-100 kpc). The metallicities (and temperatures) are consistent with the average values for these systems that we obtained in our previous analyses of the ASCA data using multitemperature models which confirms that previous inferences of very sub-solar metallicities arise from the incorrect assumption of isothermal gas and not the presence of metallicity gradients. The metallicity profiles for these galaxies and groups are qualitatively consistent with the standard scenario where the gas is enriched by supernovae with rates and an initial mass function similar to the Milky Way and is diluted by mixing with primordial gas at large radii.

This publication has 0 references indexed in Scilit: