A TEST OF THE NATURE OF THE FE K LINE IN THE NEUTRON STAR LOW-MASS X-RAY BINARY SERPENS X-1

Journal Article · Wed Apr 20 04:00:00 EDT 2016 · Astrophysical Journal

DOI:https://doi.org/10.3847/0004-637X/821/2/105· OSTI ID:22663106

Chiang, Chia-Ying; Cackett, Edward M. ^[1]; Miller, Jon M. ^[2]; Barret, Didier ^[3]; Fabian, Andy C.; Parker, Michael L. ^[4]; D’Aì, Antonino ^[5]; Bhattacharyya, Sudip ^[6]; Burderi, Luciano ^[7]; Salvo, Tiziana Di; Iaria, Rosario ^[8]; Egron, Elise ^[9]; Homan, Jeroen ^[10]; Lin, Dacheng ^[11]

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1. Department of Physics and Astronomy, Wayne State University, 666 W. Hancock, Detroit, MI 48202 (United States)
2. Department of Astronomy, The University of Michigan, 500 Church Street, Ann Arbor, MI48109-1046 (United States)
3. Universite de Toulouse, UPS-OMP, Toulouse (France)
4. Institute of Astronomy, University of Cambridge, Madingley Road, Cambridge CB3 0HA (United Kingdom)
5. INAF-Istituto di Astrofisica Spaziale e Fisica Cosmica di Palermo, via U. La Malfa 153, I-90146 Palermo (Italy)
6. Department of Astronomy and Astrophysics, Tata Institute of Fundamental Research, Mumbai 400005 (India)
7. Dipartimento di Fisica, Università degli Studi di Cagliari, SP Monserrato-Sestu, KM 0.7, I-09042 Monserrato (Italy)
8. Dipartimento di Fisica e Chimica, Universitá di Palermo, via Archirafi 36, I-90123 Palermo (Italy)
9. INAF-Osservatorio Astronomico di Cagliari, via della Scienza 5, I-09047 Selargius (Italy)
10. MIT Kavli Institute for Astrophysics and Space Research, 77 Massachusetts Avenue 37-582D, Cambridge, MA 02139 (United States)
11. Space Science Center, University of New Hampshire, Durham, NH 03824 (United States)

Broad Fe K emission lines have been widely observed in the X-ray spectra of black hole systems as well as in neutron star systems. The intrinsically narrow Fe K fluorescent line is generally believed to be part of the reflection spectrum originating in an illuminated accretion disk which is broadened by strong relativistic effects. However, the nature of the lines in neutron star low-mass X-ray binaries (LMXBs) has been a matter of debate. We therefore obtained the longest, high-resolution X-ray spectrum of a neutron star LMXB to date with a 300 ks Chandra High Energy Transmission Grating Spectrometer (HETGS) observation of Serpens X-1. The observation was taken under the “continuous clocking” mode, and thus was free of photon pile-up effects. We carry out a systematic analysis and find that the blurred reflection model fits the Fe line of Serpens X-1 significantly better than a broad Gaussian component does, implying that the relativistic reflection scenario is much preferred. Chandra HETGS also provides a highest spectral resolution view of the Fe K region and we find no strong evidence for additional narrow lines.

• OSTI ID: 22663106
• Journal Information: Astrophysical Journal, Journal Name: Astrophysical Journal Journal Issue: 2 Vol. 821; ISSN ASJOAB; ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTRONOMY AND ASTROPHYSICS
ACCRETION DISKS
BINARY STARS
BLACK HOLES
FLUORESCENCE
MASS
NEUTRON STARS
PHOTONS
POWER TRANSMISSION
REFLECTION
RELATIVISTIC RANGE
RESOLUTION
SPECTROMETERS
X RADIATION
X-RAY SPECTRA