Broad-band spectral study of X-ray transient MAXI J1820+070 using Swift/XRT and NuSTAR. (arXiv:1907.01012v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Bharali_P/0/1/0/all/0/1">Priya Bharali</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chauhan_J/0/1/0/all/0/1">Jaiverdhan Chauhan</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Boruah_K/0/1/0/all/0/1">Kalyanee Boruah</a>
We report on a textit{NuSTAR} and textit{Swift}/XRT observation of the
newly discovered X-ray transient MAXI J1820+070. textit{Swift}/XRT and
textit{NuSTAR} have concurrently observed the newly detected source on 14
March 2018. We have simultaneously fitted the broad-band spectra obtained from
textit{Swift}/XRT and textit{NuSTAR}. The observed joint spectra in the
energy range 0.6–78.0 keV are well modeled with a weak disk black-body
emission, dominant thermal Comptonization and relativistic reflection fraction.
We have detected a fluorescent Iron-K$alpha$ line relativistically broadened,
and a Compton hump at $sim$ 30 keV. We constrain the inner disk radius as well
as the disk inclination angle and their values are found to be
4.1$^{+0.8}_{-0.6}$ R$_{ISCO}$ (where R$_{ISCO}equiv$ radius of the innermost
stable circular orbit) or 5.1$^{+1.0}_{-0.7}$ r$_{g}$ (where r$_{g}equiv$
gravitational radius) and 29.8$^{+3.0}_{-2.7}$ $^circ$ respectively. The best
fit broad-band spectra suggest that the source was in the hard state and
evolving. The source emission is best described by weak thermal emission along
with strong thermal Comptonization from a relatively cold, optically thick,
geometrically thin and ionized accretion disk. X-ray spectral modeling helps us
to understand the accretion and ejection properties in the vicinity of the
compact object.
We report on a textit{NuSTAR} and textit{Swift}/XRT observation of the
newly discovered X-ray transient MAXI J1820+070. textit{Swift}/XRT and
textit{NuSTAR} have concurrently observed the newly detected source on 14
March 2018. We have simultaneously fitted the broad-band spectra obtained from
textit{Swift}/XRT and textit{NuSTAR}. The observed joint spectra in the
energy range 0.6–78.0 keV are well modeled with a weak disk black-body
emission, dominant thermal Comptonization and relativistic reflection fraction.
We have detected a fluorescent Iron-K$alpha$ line relativistically broadened,
and a Compton hump at $sim$ 30 keV. We constrain the inner disk radius as well
as the disk inclination angle and their values are found to be
4.1$^{+0.8}_{-0.6}$ R$_{ISCO}$ (where R$_{ISCO}equiv$ radius of the innermost
stable circular orbit) or 5.1$^{+1.0}_{-0.7}$ r$_{g}$ (where r$_{g}equiv$
gravitational radius) and 29.8$^{+3.0}_{-2.7}$ $^circ$ respectively. The best
fit broad-band spectra suggest that the source was in the hard state and
evolving. The source emission is best described by weak thermal emission along
with strong thermal Comptonization from a relatively cold, optically thick,
geometrically thin and ionized accretion disk. X-ray spectral modeling helps us
to understand the accretion and ejection properties in the vicinity of the
compact object.
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