Broadband time-resolved spectroscopy of thermonuclear X-ray bursts from 4U 1636-536 using AstroSat. (arXiv:2109.14631v1 [astro-ph.HE])

Broadband time-resolved spectroscopy of thermonuclear X-ray bursts from 4U 1636-536 using AstroSat. (arXiv:2109.14631v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Kashyap_U/0/1/0/all/0/1">Unnati Kashyap</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ram_B/0/1/0/all/0/1">Biki Ram</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guver_T/0/1/0/all/0/1">Tolga Guver</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chakraborty_M/0/1/0/all/0/1">Manoneeta Chakraborty</a>

Broadband spectral studies of Type-I X-ray bursts can put strong constraints
on the physics of burst spectra as well as their interaction with the
environment. We present the results obtained from the broadband time-resolved
spectroscopy of 15 thermonuclear bursts detected simultaneously from the
neutron star atoll source 4U 1636-536 using LAXPC and SXT onboard AstroSat.
During the observations with AstroSat, the Low mass X-ray binary (LMXB) 4U
1636-536 is observed to show a modest spectral evolution within the island
state. The broadband burst spectra are observed to show an excess in addition
to the thermal emission from the neutron star surface near the peak of the
bursts. We investigate the interpretation of the excess observed near the peak
of the burst as re-emission/reprocessing of the photons by the accretion
disk/corona or scattering of the photons in the neutron star atmosphere or the
enhanced persistent emission due to Poynting-Robertson drag. This is the first
reported broadband simultaneous study of Type-I bursts using LAXPC and SXT
onboard AstroSat. This kind of study may provide a better understanding of the
burst-accretion interaction and how the bursts influence the overall accretion
process contributed by the accretion disk as well as the corona.

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