The First NuSTAR Observation of 4U 1538-522: Updated Orbital Ephemeris and a Strengthened Case for an Evolving Cyclotron Line Energy

Journal article


Publication Details

Author(s): Hemphill PB, Rothschild RE, Cheatham DM, Furst F, Kretschmar P, Kühnel M, Pottschmidt K, Staubert R, Wilms J, Wolff MT
Journal: Astrophysical Journal
Publisher: IOP PUBLISHING LTD
Publication year: 2019
Volume: 873
Journal issue: 1
ISSN: 0004-637X


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.


FAU Authors / FAU Editors

Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik


External institutions with authors

Eberhard Karls Universität Tübingen
European Space Astronomy Centre (ESAC)
Massachusetts Institute of Technology (MIT)
University of California, San Diego
University of Maryland, Baltimore County
U.S. Naval Research Laboratory


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://dx.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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Last updated on 2019-03-06 at 18:08