Cosmological implications of the composite spectra of galactic X-ray
  binaries constructed using MAXI data
  We have investigated the long term average spectral properties of galactic
X-ray binaries in the energy range of 3-20 keV, using long term monitoring data
from MAXI -Gas Slit Camera (GSC). These long term average spectra are used to
construct separately the composite spectra of galactic High Mass X-ray binaries
(HMXBs) and Low Mass X-ray binaries (LMXBs). These composite spectra can be
described empirically with piece-wise power-law with three components. X-rays
from HMXBs are considered as important contributors to heating and ionization
of neutral hydrogen in the intergalactic medium during the Epoch of
Reionization. Using the above empirical form of the composite HMXB spectra
extrapolated to lower energies as an input, we have studied the impact of these
sources on the 21-cm signal using the outputs of N-body simulation and 1D
radiative transfer. The heating due to the composite spectrum is less patchy
compared to power-law spectrum with a spectral index $\alpha = 1.5$, used in
previous studies. The amplitude of the heating peak of large scale power
spectrum, when plotted as a function of the redshift, is less for the composite
spectrum.
