Temperature Profiles of Hot Gas In Early Type Galaxies
  Using the data products of the Chandra Galaxy Atlas (Kim et al. 2019a), we
have investigated the radial profiles of the hot gas temperature in 60 early
type galaxies. Considering the characteristic temperature and radius of the
peak, dip, and break (when scaled by the gas temperature and virial radius of
each galaxy), we propose a universal temperature profile of the hot halo in
ETGs. In this scheme, the hot gas temperature peaks at RMAX = 35 +/- 25 kpc (or
~0.04 RVIR) and declines both inward and outward. The temperature dips (or
breaks) at RMIN (or RBREAK) = 3 - 5 kpc (or ~0.006 RVIR). The mean slope
between RMIN (RBREAK) and RMAX is 0.3 +/- 0.1. Allowing for selection effects
and observational limits, we find that the universal temperature profile can
describe the temperature profiles of 72% (possibly up to 82%) of our ETG
sample. The remaining ETGs (18%) with irregular or monotonically declining
profiles do not fit the universal profile and require another explanation. The
temperature gradient inside RMIN (RBREAK) varies widely, indicating different
degrees of additional heating at small radii. Investigating the nature of the
hot core (HC with a negative gradient inside RMIN), we find that HC is most
clearly visible in small galaxies. Searching for potential clues associated
with stellar, AGN feedback, and gravitational heating, we find that HC may be
related to recent star formation. But we see no clear evidence that AGN
feedback and gravitational heating play any significant role for HC.
