The Hot Gas Exhaust of Starburst Engines in Mergers: Testing Models of
  Stellar Feedback and Star Formation Regulation
  Using archival data from the Chandra X-ray telescope, we have measured the
spatial extent of the hot interstellar gas in a sample of 49 nearby interacting
galaxy pairs, mergers, and merger remnants. For systems with SFR > 1 M(sun)/yr,
the volume and mass of hot gas are strongly and linearly correlated with the
star formation rate (SFR). This supports the idea that stellar/supernovae
feedback dominates the production of hot gas in these galaxies. We compared the
mass of X-ray-emitting hot gas Mx(gas) with the molecular and atomic hydrogen
interstellar gas masses in these galaxies (M(H2) and M(HI), respectively),
using published carbon monoxide and 21 cm HI measurements. Systems with higher
SFRs have larger Mx(gas)/(M(H2) + M(HI)) ratios on average, in agreement with
recent numerical simulations of star formation and feedback in merging
galaxies. The Mx(gas)/(M(H2) + M(HI)) ratio also increases with dust
temperature on average. The ratio Mx(gas)/SFR is anti-correlated with the IRAS
60 micron to 100 micron flux ratio and with the Spitzer 3.6 micron to 24
micron. These trends may be due to variations in the spatial density of young
stars, the stellar age, the ratio of young to old stars, the initial mass
function, and/or the efficiency of stellar feedback. Galaxies with low SFR (<1
M(sun)/yr) and high K band luminosities may have an excess of hot gas relative
to the relation for higher SFR galaxies, while galaxies with low K band
luminosities (and therefore low stellar masses) may have a deficiency in hot
gas, but our sample is not large enough for strong statistical significance.
