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The Orbital Parameters of the Eclipsing High-mass X-Ray Binary Pulsar IGR J16493–4348 from Pulsar Timing

Pearlman, Aaron B. and Coley, Joel B. and Corbet, Robin H. D. and Pottschmidt, Katja (2019) The Orbital Parameters of the Eclipsing High-mass X-Ray Binary Pulsar IGR J16493–4348 from Pulsar Timing. Astrophysical Journal, 873 (1). Art. No. 86. ISSN 1538-4357. http://resolver.caltech.edu/CaltechAUTHORS:20190307-081606911

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Abstract

IGR J16493–4348 is an eclipsing supergiant high-mass X-ray binary (sgHMXB), where accretion onto the compact object occurs via the radially outflowing stellar wind of its early B-type companion. We present an analysis of the system's X-ray variability and periodic modulation using pointed observations (2.5–25 keV) and Galactic bulge scans (2–10 keV) from the Rossi X-ray Timing Explorer (RXTE) Proportional Counter Array (PCA), along with Swift Burst Alert Telescope (BAT) 70-month snapshot (14–195 keV) and transient monitor (15–50 keV) observations. The orbital eclipse profiles from the PCA scan and BAT light curves are modeled using asymmetric and symmetric step and ramp functions. We obtain an improved orbital period measurement of 6.7828 ± 0.0004 days from an observed minus calculated (O–C) analysis of mid-eclipse times derived from the BAT transient monitor and PCA scan data. No evidence is found for the presence of a strong photoionization or accretion wake. We refine the superorbital period to 20.067 ± 0.009 days from the discrete Fourier transform (DFT) of the BAT transient monitor light curve. A pulse period of 1093.1036 ± 0.0004 s is measured from a pulsar timing analysis using pointed PCA observations spanning ~1.4 binary orbits. We present pulse times of arrival (ToAs), circular and eccentric timing models, and calculations of the system's Keplerian binary orbital parameters. We derive an X-ray mass function of f_x(M) = 13.2_(-2.5)^(+2.4) M_⊙ and find a spectral type of B0.5 Ia for the supergiant companion through constraints on the mass and radius of the donor. Measurements of the eclipse half-angle and additional parameters describing the system geometry are provided.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.3847/1538-4357/aaf001DOIArticle
https://arxiv.org/abs/1811.06543arXivDiscussion Paper
ORCID:
AuthorORCID
Pearlman, Aaron B.0000-0002-8912-0732
Coley, Joel B.0000-0001-7532-8359
Corbet, Robin H. D.0000-0002-3396-651X
Pottschmidt, Katja0000-0002-4656-6881
Additional Information:© 2019. The American Astronomical Society. Received 2018 July 11; revised 2018 October 11; accepted 2018 November 9; published 2019 March 7. We thank the referee for useful suggestions that helped us improve this paper. A. B. Pearlman acknowledges support by the Department of Defense (DoD) through the National Defense Science and Engineering Graduate (NDSEG) Fellowship Program and by the National Science Foundation (NSF) Graduate Research Fellowship under Grant No. DGE-1144469. This work was partially supported by NASA grant NNX15AI74G.
Group:Space Radiation Laboratory
Funders:
Funding AgencyGrant Number
National Defense Science and Engineering Graduate (NDSEG) FellowshipUNSPECIFIED
NSF Graduate Research FellowshipDGE-1144469
NASANNX15AI74G
Subject Keywords:pulsars: individual (IGR J16493–4348) – stars: neutron – X-rays: binaries – X-rays: stars
Record Number:CaltechAUTHORS:20190307-081606911
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20190307-081606911
Official Citation:Aaron B. Pearlman et al 2019 ApJ 873 86
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:93609
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:07 Mar 2019 17:04
Last Modified:25 Mar 2019 22:07

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