Broad-band analysis of X-ray pulsar 2S 1845$-$024. (arXiv:2110.06642v1 [astro-ph.HE])

Broad-band analysis of X-ray pulsar 2S 1845$-$024. (arXiv:2110.06642v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Nabizadeh_A/0/1/0/all/0/1">Armin Nabizadeh</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Tsygankov_S/0/1/0/all/0/1">Sergey S. Tsygankov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Molkov_S/0/1/0/all/0/1">Sergey V. Molkov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Karasev_D/0/1/0/all/0/1">Dmitri I. Karasev</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Ji_L/0/1/0/all/0/1">Long Ji</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Lutovinov_A/0/1/0/all/0/1">Alexander A. Lutovinov</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Poutanen_J/0/1/0/all/0/1">Juri Poutanen</a>

We present results of detailed investigation of the poorly studied X-ray
pulsar 2S 1845$-$024 based on the data obtained with $NuSTAR$ observatory
during the type I outburst in 2017. Neither pulse phase-averaged, nor
phase-resolved spectra of the source show evidence for a cyclotron absorption
feature. We also used the data obtained from other X-ray observatories
($Swift$, $XMM-Newton$ and $Chandra$) to study the spectral properties as a
function of orbital phase. The analysis revealed a high hydrogen column density
for the source reaching $sim$10$^{24}$ cm$^{-2}$ around the periastron. Using
high-quality $Chandra$ data we were able to obtain an accurate localization of
2S 1845$-$024 at R.A. = 18$^{h}$48$^{m}$16$^{s}$.8 and Dec. =
$-$2$^{circ}$25’25”.1 (J2000) that allowed us to use infrared (IR) data to
roughly classify the optical counterpart of the source as an OB supergiant at
the distance of $gtrsim$15 kpc.

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