A COMPARISON OF BROAD IRON EMISSION LINES IN ARCHIVAL DATA OF NEUTRON STAR LOW-MASS X-RAY BINARIES

Journal Article · Fri Aug 10 00:00:00 EDT 2012 · Astrophysical Journal

DOI:https://doi.org/10.1088/0004-637X/755/1/27· OSTI ID:22039179

Cackett, Edward M ^[1]; Miller, Jon M ^[2]; Reis, Rubens C; Fabian, Andrew C ^[3]; Barret, Didier ^[4]

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1. Department of Physics and Astronomy, Wayne State University, 666 W. Hancock St, Detroit, MI 48201 (United States)
2. Department of Astronomy, University of Michigan, 500 Church St, Ann Arbor, MI 48109-1042 (United States)
3. Institute of Astronomy, University of Cambridge, Madingley Rd, Cambridge, CB3 0HA (United Kingdom)
4. Institut de Recherche en Astrophysique et Planetologie, 9, Avenue du Colonel Roche, BP 44346, F-31028 Toulouse Cedex 4 (France)

Relativistic X-ray disklines have been found in multiple neutron star low-mass X-ray binaries, in close analogy with black holes across the mass scale. These lines have tremendous diagnostic power and have been used to constrain stellar radii and magnetic fields, often finding values that are consistent with independent timing techniques. Here, we compare CCD-based data from Suzaku with Fe K line profiles from archival data taken with gas-based spectrometers. In general, we find good consistency between the gas-based line profiles from EXOSAT, BeppoSAX, and RXTE and the CCD data from Suzaku, demonstrating that the broad profiles seen are intrinsic to the line and not broad due to instrumental issues. However, we do find that when fitting with a Gaussian line profile, the width of the Gaussian can depend on the continuum model in instruments with low spectral resolution, though when the different models fit equally well the line widths generally agree. We also demonstrate that three BeppoSAX observations show evidence for asymmetric lines, with a relativistic diskline model providing a significantly better fit than a Gaussian. We test this by using the posterior predictive p-value method, and bootstrapping of the spectra to show that such deviations from a Gaussian are unlikely to be observed by chance.

• OSTI ID: 22039179
• Journal Information: Astrophysical Journal, Vol. 755, Issue 1; Other Information: Country of input: International Atomic Energy Agency (IAEA); ISSN 0004-637X
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
ACCRETION DISKS
ASTROPHYSICS
ASYMMETRY
BLACK HOLES
CHARGE-COUPLED DEVICES
COMPARATIVE EVALUATIONS
EMISSION SPECTRA
GAMMA ASTRONOMY
IRON
LINE WIDTHS
MAGNETIC FIELDS
MASS
NEUTRON STARS
PHOTON EMISSION
RELATIVISTIC RANGE
RESOLUTION
X RADIATION
X-RAY SPECTROMETERS