Discovery and Identification of MAXI J1621-501 as a Type I X-ray Burster with a Super-Orbital Period. (arXiv:1908.03590v1 [astro-ph.HE])

Discovery and Identification of MAXI J1621-501 as a Type I X-ray Burster with a Super-Orbital Period. (arXiv:1908.03590v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Gorgone_N/0/1/0/all/0/1">Nicholas M. Gorgone</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kouveliotou_C/0/1/0/all/0/1">Chryssa Kouveliotou</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Negoro_H/0/1/0/all/0/1">Hitoshi Negoro</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Wijers_R/0/1/0/all/0/1">Ralph A. M. J. Wijers</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bozzo_E/0/1/0/all/0/1">Enrico Bozzo</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Guiriec_S/0/1/0/all/0/1">Sylvain Guiriec</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bult_P/0/1/0/all/0/1">Peter Bult</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Huppenkothen_D/0/1/0/all/0/1">Daniela Huppenkothen</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+G%7Fog%7Fus_E/0/1/0/all/0/1">Ersin Gogus</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Bahramian_A/0/1/0/all/0/1">Arash Bahramian</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kennea_J/0/1/0/all/0/1">Jamie Kennea</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Linford_J/0/1/0/all/0/1">Justin D. Linford</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Miller_Jones_J/0/1/0/all/0/1">James Miller-Jones</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Baring_M/0/1/0/all/0/1">Matthew G. Baring</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Beniamini_P/0/1/0/all/0/1">Paz Beniamini</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Chakrabarty_D/0/1/0/all/0/1">Deepto Chakrabarty</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Granot_J/0/1/0/all/0/1">Jonathan Granot</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hailey_C/0/1/0/all/0/1">Charles Hailey</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Harrison_F/0/1/0/all/0/1">Fiona A. Harrison</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Hartmann_D/0/1/0/all/0/1">Dieter H. Hartmann</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Iwakiri_W/0/1/0/all/0/1">Wataru Iwakiri</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kaper_L/0/1/0/all/0/1">Lex Kaper</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Kara_E/0/1/0/all/0/1">Erin Kara</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Mazzola_S/0/1/0/all/0/1">Simona Mazzola</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Murata_K/0/1/0/all/0/1">Katsuhiro Murata</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Stern_D/0/1/0/all/0/1">Daniel Stern</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tomsick_J/0/1/0/all/0/1">John A. Tomsick</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Horst_A/0/1/0/all/0/1">Alexander J. van der Horst</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Younes_G/0/1/0/all/0/1">George A. Younes</a>

MAXI J1621-501 is the first Swift/XRT Deep Galactic Plane Survey transient
that was followed up with a multitude of space missions (NuSTAR, Swift,
Chandra, NICER, INTEGRAL, and MAXI) and ground-based observatories (Gemini,
IRSF, and ATCA). The source was discovered with MAXI on 2017 October 19 as a
new, unidentified transient. Further observations with NuSTAR revealed 2 Type I
X-ray bursts, identifying MAXI J1621-501 as a Low Mass X-ray Binary (LMXB) with
a neutron star primary. Overall, 24 Type I bursts were detected from the source
during a 15 month period. At energies below 10 keV, the source spectrum was
best fit with three components: an absorbed blackbody with kT = 2.3 keV, a
cutoff power law with index $Gamma{}$ = 0.7, and an emission line centered on
6.3 keV. Timing analysis of the X-ray persistent emission and burst data has
not revealed coherent pulsations from the source or an orbital period. We
identified, however, a super-orbital period $sim{}$78 days in the source X-ray
light curve. This period agrees very well with the theoretically predicted
radiative precession period of $sim{}$82 days. Thus, MAXI J1621-501 joins a
small group of sources characterized with super-orbital periods.

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