Chandra-HETGS Characterization of an Outflowing Wind in the Accreting Millisecond Pulsar IGR J17591-2342

Journal
Date Issued
2019
Author(s)
Nowak, Michael A.
•
•
Jaisawal, Gaurava Kumar
•
Chenevez, Jérôme
•
Chaty, Sylvain
•
Fortin, Francis
•
Rodriguez, Jérôme
•
Wilms, Jörn
DOI
Abstract
An accreting millisecond X-ray pulsar, IGR J17591-2342 was discovered in 2018 August in scans of the Galactic bulge and center by the International Gamma-Ray Astrophysics Laboratory X-ray and gamma-ray observatory. It exhibited an unusual outburst profile with multiple peaks in the X-ray, as observed by several X-ray satellites over 3 months. Here we present observations of this source performed in the X-ray/gamma-ray and near-infrared domains and focus on a simultaneous observation performed with the Chandra High Energy Transmission Gratings Spectrometer (HETGS) and the Neutron Star Interior Composition Explorer (NICER). The HETGS provides high-resolution spectra of the Si edge region that yield clues as to the source’s distance and reveal evidence (at 99.999% significance) of an outflow with a velocity of 2800 km s-1. We demonstrate good agreement between the NICER and HETGS continua, provided that one properly accounts for the differing manners in which these instruments view the dust-scattering halo in the source’s foreground. Unusually, we find a possible set of Ca lines in the HETGS spectra (with significances ranging from 97.0% to 99.7%). We hypothesize that IGR J17591-2342 is a neutron star low-mass X-ray binary at the distance of the Galactic bulge or beyond that may have formed from the collapse of a white dwarf system in a rare, calcium-rich Type Ib supernova explosion.
Volume
874
Issue
1
Start page
69
Uri
Url
Issn Identifier
0004-637X
Ads BibCode
2019ApJ...874...69N
Rights
open.access
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