PhD Thesis (PDF) - Department of Astronomy - University of Virginia

sources could be a non-trivial source of emission in the inner effective radius.
Since this galaxy was bright enough to fit multiple annuli of unresolved emission
and there were indications of multiple temperatures of the diffuse gas, we attempted
to determine the radial dependence of gas temperature and abundance. We used eight
annuli, each with approximately 1000 net counts, out to a = 180 ′′ . In Table 3.2 rows
(11)–(18), we show the results of assuming the model was the sum of the resolved
point source model with its normalization free and a single-temperature gas MEKAL
model. Most of the fits produced reasonable χ 2 . Any radial changes in the abundance
are dwarfed by the errors of the fits, although the best-fit abundances were mainly
subsolar. On the other hand, it is clear that the first two annuli have a much lower
temperature, ∼0.85 keV, than the outer five annuli, ∼1.5 keV. The temperature of
the third annulus is between the two temperatures. These fits are in rough agreement
with the two-temperature model found within 1 effective radius, a < 55. ′′ 2; however,
the flux of the unresolved sources is smaller, and the temperature fit for the hotter
gas is larger when fitting the inner effective radius at once, as opposed to in multiple
annuli. The best-fit normalization of the power-law and MEKAL model suggest that
for a < 180 ′′ they both contribute approximately equally to the flux. Within 1aeff,
the diffuse gas is dominant by at least 2:1. From the best-fit fluxes of the annular
fits, we can estimate the X-ray luminosity (0.3–10 keV) to be ∼2.9 × 10 41 ergs s −1 in
gas and ∼2.4 × 10 41 ergs s −1 in unresolved sources for a < 180 ′′ . Around 30%–40%
of the gaseous luminosity comes from the cooler gas. The resolved 3 σ sources in the
entire field have an X-ray luminosity of ∼1.4 × 10 41 ergs s −1 . In a < 180 ′′ , this scales
to ∼0.4×10 41 ergs s −1 . Bolometric corrections increase the source luminosity by 44%
and the total gaseous luminosity by 28%.
107
Using the RC3 optical profile, a < 180 ′′ corresponds to ∼80% of the total optical