The First NuSTAR Observation of 4U 1538-522: Updated Orbital Ephemeris and a Strengthened Case for an Evolving Cyclotron Line Energy
Hemphill PB, Rothschild RE, Cheatham DM, Furst F, Kretschmar P, Kühnel M, Pottschmidt K, Staubert R, Wilms J, Wolff MT (2019)
Publication Status: Published
Publication Type: Journal article
Publication year: 2019
Journal
Publisher: IOP PUBLISHING LTD
Book Volume: 873
Article Number: ARTN 62
Journal Issue: 1
Abstract
We have performed a comprehensive spectral and timing analysis of the first NuSTAR observation of the high-mass X-ray binary 4U 1538-522. The observation covers the X-ray eclipse of the source, plus the eclipse ingress and egress. We use the new measurement of the mid-eclipse time to update the orbital parameters of the system and find marginally significant evolution in the orbital period, with (P) over dot(orb)/P-orb = (-0.95 +/- 0.37) x 10(-6) yr(-1). The cyclotron line energy is found to be approximately 1.2 keV higher than RXTE measurements from 1997 to 2003, in line with the increased energy observed by Suzaku in 2012 and strengthening the case for secular evolution of 4U 1538-522's CRSF. We additionally characterize the behavior of the iron fluorescence and emission lines and line-of-sight absorption as the source moves into and out of eclipse.
Authors with CRIS profile
Matthias Bissinger
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Jörn Wilms
Professur für Astronomie und Astrophysik
Involved external institutions
U.S. Naval Research Laboratory
United States (USA) (US)
Eberhard Karls Universität Tübingen
Germany (DE)
University of Maryland, Baltimore County (UMBC)
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
University of California, San Diego
United States (USA) (US)
Massachusetts Institute of Technology (MIT)
United States (USA) (US)
United States (USA) (US)
Eberhard Karls Universität Tübingen
Germany (DE)
University of Maryland, Baltimore County (UMBC)
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
University of California, San Diego
United States (USA) (US)
Massachusetts Institute of Technology (MIT)
United States (USA) (US)
How to cite
APA:
Hemphill, P.B., Rothschild, R.E., Cheatham, D.M., Furst, F., Kretschmar, P., Kühnel, M.,... Wolff, M.T. (2019). The First NuSTAR Observation of 4U 1538-522: Updated Orbital Ephemeris and a Strengthened Case for an Evolving Cyclotron Line Energy. Astrophysical Journal, 873(1). https://doi.org/10.3847/1538-4357/ab03d3
MLA:
Hemphill, Paul B., et al. "The First NuSTAR Observation of 4U 1538-522: Updated Orbital Ephemeris and a Strengthened Case for an Evolving Cyclotron Line Energy." Astrophysical Journal 873.1 (2019).
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