Line Emission and Star Formation in Brightest Cluster Galaxies in the ACCEPT and CLASH Samples
Abstract
We look at Brightest Cluster Galaxies (BCGs) from a heterogeneous but uniformly characterized sample, the Archive of Chandra Cluster Entropy Profile Tables (ACCEPT), of X-ray galaxy clusters from the Chandra X-ray telescope archive with published gas temperature, density, and entropy profiles. We use archival Galaxy Evolution Explorer (GALEX), Spitzer Space Telescope, and Two Micron All Sky Survey (2MASS) observations to assemble spectral energy distributions (SEDs) and colors for BCGs. We find that while the SEDs of some BCGs follow the expectation of red, dust-free old stellar populations, many exhibit signatures of recent star formation in the form of excess UV (38%) or mid-IR emission (43%), or both. These excesses are consistent with ongoing star formation activity in the BCG, star formation that appears to be enabled by the presence of high-density, X-ray-emitting intergalactic gas in the core of the cluster of galaxies. We further investigate galaxy clusters and BCGs which are part of the Cluster Lensing And Supernova survey with Hubble (CLASH) which are some of the most extreme clusters in ACCEPT. We present results for the Chandra X-ray reduction and analysis pipeline we are developing as well as narrow band Hα imaging and optical spectroscopy with the SOAR 4.1m telescope. We create surface brightness maps and temperature profiles from the Chandra X-ray data which indicate interesting regions near the cluster cores which show shock discontinuities with possible AGN bubbles and multi-phase gas in their cores. This hot, X-ray-emitting gas may provide the enhanced ambient pressure and some of the fuel to trigger star formation. This result is consistent with previous works that showed that BCGs in clusters with low central gas entropies host Hα emission-line nebulae and radio sources, while clusters with high central gas entropy exhibit none of these features.
- Publication:
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American Astronomical Society Meeting Abstracts #221
- Pub Date:
- January 2013
- Bibcode:
- 2013AAS...22130303H