Evidence of a Broad Relativistic Iron Line from the Neutron Star Low-Mass X-ray Binary Serpens X-1

Abstract

We report on an analysis of XMM-Newton data from the neutron star low mass X-ray binary (LMXB) Serpens X-1 (Ser X-1). Spectral analysis of EPIC PN data indicates that the previously known broad iron K$\alpha$ emission line from this source has a significantly skewed structure with a moderately extended red wing. The asymmetric shape of the line is well described with the laor and diskline models in XSPEC and strongly supports an inner accretion disk origin of the line. To our knowledge this is the first strong evidence of a relativistic line in a neutron star LMXB. This finding suggests that the broad lines seen in other neutron star LMXBs likely originate from the inner disk as well. Detailed study of such lines opens up a new way to probe neutron star parameters and their strong gravitational fields. The red wing of the iron line from Ser X-1 is not as broad as that observed from some black hole systems. This is not unreasonable for a neutron star system, as the accretion disk has to terminate at or before the hard stellar surface. Finally, the inferred source inclination angle in the approximate range 40 degree to 60 degree is consistent with the lack of dips and eclipses from Ser X-1.

arXiv comment13 pages, 2 tables, 2 figures, published in ApJ Letters

References in corpus (15)

• Constraining Black Hole Spin Via X-ray Spectroscopy
• Fluorescent iron lines as a probe of astrophysical black hole systems
• XMM-EPIC observation of MCG-6-30-15: Direct evidence for the extraction of energy from aspinning black hole?
• The distances to Galactic low-mass X-ray binaries: consequences for black hole luminosities and kicks
• Evidence for Spin and Energy Extraction in a Galactic Black Hole Candidate: The XMM-Newton/EPIC-pn Spectrum of XTE J1650-500
• Suzaku observations of the hard X-ray variability of MCG-6-30-15: the effects of strong gravity around a Kerr black hole
• Resolving the Composite Fe K-alpha Emission Line in the Galactic Black Hole Cygnus X-1 with Chandra
• Constraints on Neutron Star Parameters from Burst Oscillation Light Curves of the Accreting Millisecond Pulsar XTE J1814-338
• Complex X-ray Absorption and the Fe Kalpha Profile in NGC 3516
• Revealing the High Energy Emission from the Obscured Seyfert Galaxy MCG -5-23-16 with Suzaku
• Simultaneous BeppoSAX and RXTE observations of the X-ray burst sources GX 3+1 and Ser X-1
• On the deep minimum state in the Seyfert galaxy MCG-6-30-15
• Broadening of the Iron emission line in MCG-6-30-15 by Comptonization
• The XMM-Newton/INTEGRAL monitoring campaign of IGR J16318-4848
• RXTE Observations of 1A 1744-361: Correlated Spectral and Timing Behavior

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