Open AccessThe X‐ray emission in post‐merger ellipticals
Author(s) -
O'Sullivan Ewan,
Forbes Duncan A.,
Ponman Trevor J.
Publication year - 2001
Publication title -
monthly notices of the royal astronomical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 2.058
H-Index - 383
eISSN - 1365-2966
pISSN - 0035-8711
DOI - 10.1046/j.1365-8711.2001.04340.x
Subject(s) - physics , astrophysics , luminosity , galaxy , halo , supernova , astronomy , star formation , galaxy formation and evolution , stars , galactic halo
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.