Chandra Survey of Nearby Highly Inclined Disc Galaxies - II: Correlation
  Analysis of Galactic Coronal Properties
  X-ray observations provide a key tool for exploring the properties of
galactic coronae and their formation processes. In an earlier paper, we have
presented a Chandra data analysis of the coronae of 53 nearby highly-inclined
disc galaxies. Here we study the correlation of the X-ray measurements with
other galaxy properties and compare the results with those obtained for
elliptical galaxies. A good correlation is present between the coronal
luminosity Lx and the SFR. But we find a better correlation between Lx and the
total SN mechanical energy input rate (ESN), including the expected
contribution from core collapsed (CC) and Ia SNe. The X-ray radiation
efficiency (eta=Lx/ESN) has a mean value of ~0.4% with an rms of ~0.5dex. eta
further correlates with MTF/M* (MTF is the baryon mass measured from the
rotation velocity and the Tully-Fisher relation, M* is the stellar mass
measured from the K-band luminosity) and the CC SN rate surface density (FSN,
in units of SN/yr/kpc^2), which can be characterized as: eta=0.41%MTF/M* and
eta=1.4%FSN^-0.3. These correlations reflect the roles played by the
gravitational mass and energetic feedback concentrations in determining eta.
The characteristic temperature of the corona shows little dependence on the
total or specific SFR, the cold gas content, or Lx. The coronae of disc
galaxies tend to be more X-ray luminous, hotter, and lower in Fe/O abundance
ratio than those of elliptical ones of similar masses. Early-type non-starburst
disc galaxies tend to be more Fe-rich, while starburst ones have a roughly
constant abundance ratio of Fe/O~0.36solar. Our results are consistent with the
coronal gas being mainly provided by stellar feedback in a mass range of
M*~10^{8.7-11}Msun. In addition, processes such as charge exchange at cool/hot
gas interfaces, as well as various environmental effects, are also needed to
explain the diversity of coronal properties.
