O, Ne, Mg, and Fe Abundances in Hot X-Ray-emitting Halos of Galaxy Clusters, Groups, and Giant Early-type Galaxies with XMM-Newton RGS Spectroscopy

Abstract: Chemical elements in the hot medium permeating early-type galaxies, groups, and clusters make them an excellent laboratory for studying metal enrichment and cycling processes in the largest scales of the universe. Here, we report the analysis by the XMM-Newton Reflection Grating Spectrometer of 14 early-type galaxies, including the well-known brightest cluster galaxies of Perseus, for instance. The spatial distribution of the O/Fe, Ne/Fe, and Mg/Fe ratios is generally flat at the central 60 arcsecond regions of each object, irrespective of whether or not a central Fe abundance drop has been reported. Common profiles between noble gas and normal metal suggest that the dust depletion process does not work predominantly in these systems. Therefore, observed abundance drops are possibly attributed to other origins, like systematics in the atomic codes. Giant systems of high gas mass-to-luminosity ratio tend to hold a hot gas ($\sim$ 2 keV) yielding the solar N/Fe, O/Fe, Ne/Fe, Mg/Fe, and Ni/Fe ratios. Contrarily, light systems at a subkiloelectronvolt temperature regime, including isolated or group-centered galaxies, generally exhibit super-solar N/Fe, Ni/Fe, Ne/O, and Mg/O ratios. We find that the latest supernova nucleosynthesis models fail to reproduce such a super-solar abundance pattern. Possible systematic uncertainties contributing to these high abundance ratios of cool objects are also discussed in tandem with the crucial role of future X-ray missions.