The X-ray emission in post-merger ellipticals |
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Authors: | Ewan O'Sullivan Duncan A Forbes Trevor J Ponman |
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Institution: | School of Physics and Astronomy, University of Birmingham, Edgbaston, Birmingham B15 2TT;Astrophysics and Supercomputing, Swinburne University, Hawthorn, VIC 3122, Australia |
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Abstract: | The evolution in X-ray properties of early-type galaxies is largely unconstrained. In particular, little is known about how, and if, remnants of mergers generate hot gas haloes. Here we examine the relationship between X-ray luminosity and galaxy age for a sample of early-type galaxies. Comparing normalized X-ray luminosity to three different age indicators, we find that L X L B increases with age, suggesting an increase in X-ray halo mass with time after the last major star formation episode of a galaxy. The long-term nature of this trend, which appears to continue across the full age range of our sample, poses a challenge for many models of hot halo formation. We conclude that models involving a declining rate of type Ia supernovae, and a transition from outflow to inflow of the gas originally lost by galactic stars, offer the most promising explanation for the observed evolution in X-ray luminosity. |
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Keywords: | galaxies: elliptical and lenticular cD galaxies: evolution galaxies: interactions X-rays: galaxies |
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