textit{AstroSat} and textit{MAXI} view of the Black Hole binary 4U 1630-472 during 2016 and 2018 Outbursts. (arXiv:2007.00928v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+B%2E_B/0/1/0/all/0/1">Blessy E. B.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Agrawal_V/0/1/0/all/0/1">V. K. Agrawal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+C%2E_R/0/1/0/all/0/1">Ramadevi M. C.</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Katoch_T/0/1/0/all/0/1">Tilak Katoch</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Antia_H/0/1/0/all/0/1">H. M. Antia</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mandal_S/0/1/0/all/0/1">Samir Mandal</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Nandi_A/0/1/0/all/0/1">Anuj Nandi</a>
We present an in-depth spectral and timing analysis of the Black Hole binary
4U 1630-472 during 2016 and 2018 outbursts as observed by textit{AstroSat} and
textit{MAXI}. The extensive coverage of the outbursts with textit{MAXI} is
used to obtain the Hardness Intensity Diagram (HID). The source follows a
`c’-shaped profile in agreement with earlier findings. Based on the HIDs of
previous outbursts, we attempt to track the evolution of the source during a
`super’-outburst and `mini’-outbursts. We model the broadband energy spectra
($0.7-20.0$ keV) of textit{AstroSat} observations of both outbursts using
phenomenological and physical models. No Keplerian disc signature is observed
at the beginning of 2016 outburst. However, the disc appears within a few hours
after which it remains prominent with temperature ($T_{in}$) $sim$ 1.3 keV and
increase in photon index ($Gamma$) from 1.8 to 2.0, whereas the source was at
a disc dominant state throughout the textit{AstroSat} campaign of 2018
outburst. Based on the HIDs and spectral properties, we classify the outbursts
into three different states – the `canonical’ hard and soft states along with
an intermediate state. Evolution of rms along different states is seen although
no Quasi-periodic Oscillations (QPOs) are detected. We fit the observed spectra
using a dynamical accretion model and estimate the accretion parameters. Mass
of the black hole is estimated using inner disc radius, bolometric luminosity
and two component flow model to be $3-9$ $M_{odot}$. Finally, we discuss the
possible implications of our findings.
We present an in-depth spectral and timing analysis of the Black Hole binary
4U 1630-472 during 2016 and 2018 outbursts as observed by textit{AstroSat} and
textit{MAXI}. The extensive coverage of the outbursts with textit{MAXI} is
used to obtain the Hardness Intensity Diagram (HID). The source follows a
`c’-shaped profile in agreement with earlier findings. Based on the HIDs of
previous outbursts, we attempt to track the evolution of the source during a
`super’-outburst and `mini’-outbursts. We model the broadband energy spectra
($0.7-20.0$ keV) of textit{AstroSat} observations of both outbursts using
phenomenological and physical models. No Keplerian disc signature is observed
at the beginning of 2016 outburst. However, the disc appears within a few hours
after which it remains prominent with temperature ($T_{in}$) $sim$ 1.3 keV and
increase in photon index ($Gamma$) from 1.8 to 2.0, whereas the source was at
a disc dominant state throughout the textit{AstroSat} campaign of 2018
outburst. Based on the HIDs and spectral properties, we classify the outbursts
into three different states – the `canonical’ hard and soft states along with
an intermediate state. Evolution of rms along different states is seen although
no Quasi-periodic Oscillations (QPOs) are detected. We fit the observed spectra
using a dynamical accretion model and estimate the accretion parameters. Mass
of the black hole is estimated using inner disc radius, bolometric luminosity
and two component flow model to be $3-9$ $M_{odot}$. Finally, we discuss the
possible implications of our findings.
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