Thermality and Heat Content of horizons from infinitesimal coordinate
  transformations
  Thermal properties of a static horizon, (like the entropy S, heat content TS
etc.) can be obtained either from the surface term of the Einstein-Hilbert
action or by evaluating the Noether charge, corresponding to the
diffeomorphisms generated by the timelike Killing vector field. We show that,
for a wide class of geometries, the same results can be obtained using the
vector field which produces an infinitesimal coordinate transformation between
two physically relevant reference frames, viz. the freely falling frame near
the horizon and the static, accelerated, frame. In particular, the
infinitesimal coordinate transformation from inertial coordinates to uniformly
accelerated frame can be used to obtain the heat content and entropy of the
Rindler horizon. This result offers insight into understanding the observer
dependent degrees of freedom which contribute to the entropy of null surfaces.
