Title:	AstroSat observation of the accreting millisecond X-ray pulsar SAX J1808.4–3658 during its 2019 outburst
Authors:	Sharma, Rahul Sanna, Andrea Beri, Aru
Keywords:	accretion accretion disks stars: neutron x-ray: binaries SAX J1808.4–3658
Issue Date:	1-Mar-2023
Publisher:	Oxford University Press
Citation:	Monthly Notices of the Royal Astronomical Society, 2023, Vol. 519, p3811
Abstract:	We report on the analysis of the AstroSat data set of the accreting millisecond X-ray pulsar SAX J1808.4–3658, obtained during its 2019 outburst. We found coherent pulsations at ∼401 Hz and an orbital solution consistent with previous studies. The 3–20 keV pulse profile can be well fitted with three harmonically related sinusoidal components with background-corrected fractional amplitudes of ∼3.5 per cent⁠, ∼1.2 per cent and ∼0.37 per cent for the fundamental, second and third harmonics, respectively. Our energy-resolved pulse profile evolution study indicates a strong energy dependence. We also observed a soft lag in the fundamental and hard lags during its harmonic. The broad-band spectrum of SAX J1808.4–3658 can be described well using a combination of the thermal emission component with kT ∼ 1 keV, a thermal Comptonization (Γ ∼ 1.67) from the hot corona and broad emission lines due to Fe.
Description:	Restricted Access. An open-access version is available at arXiv.org (one of the alternative locations)
URI:	http://hdl.handle.net/2289/8041
ISSN:	0035-8711 1365-2966 (Online)
Alternative Location:	https://ui.adsabs.harvard.edu/abs/2023MNRAS.519.3811S/abstract https://arxiv.org/abs/2212.10088 https://doi.org/10.1093/mnras/stac3779 https://inspirehep.net/literature/2616477
Copyright:	2022 The Author(s)
Appears in Collections:	Research Papers (A&A)

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