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http://hdl.handle.net/20.500.12386/30820
Title: | SPECTRAL CHANGES IN THE HYPERLUMINOUS PULSAR IN NGC 5907 AS A FUNCTION OF SUPER-ORBITAL PHASE | Authors: | Fürst, F. Walton, D. J. Stern, D. BACHETTI, Matteo Barret, D. Brightman, M. Harrison, F. A. Rana, V. |
Issue Date: | 2017 | Journal: | THE ASTROPHYSICAL JOURNAL | Number: | 834 | Issue: | 1 | First Page: | 77 | Abstract: | We present broadband, multi-epoch X-ray spectroscopy of the pulsating ultra-luminous X-ray source (ULX) in NGC 5907. Simultaneous XMM-Newton and NuSTAR data from 2014 are best described by a multicolor blackbody model with a temperature gradient as a function of accretion disk radius significantly flatter than expected for a standard thin accretion disk (T(r)\propto r-p, with p=0.608-0.012+0.014). Additionally, we detect a hard power-law tail at energies above 10 keV, which we interpret as being due to Comptonization. We compare this observation to archival XMM-Newton, Chandra, and NuSTAR data from 2003, 2012, and 2013, and investigate possible spectral changes as a function of phase over the 78-day super-orbital period of this source. We find that observations taken around phases 0.3-0.4 show very similar temperature profiles, even though the observed flux varies significantly, while one observation taken around phase 0 has a significantly steeper profile. We discuss these findings in light of the recent discovery that the compact object is a neutron star and show that precession of the accretion disk or the neutron star can self-consistently explain most observed phenomena. | URI: | http://hdl.handle.net/20.500.12386/30820 | URL: | https://iopscience.iop.org/article/10.3847/1538-4357/834/1/77 | ISSN: | 0004-637X | DOI: | 10.3847/1538-4357/834/1/77 | Bibcode ADS: | 2017ApJ...834...77F | Fulltext: | open |
Appears in Collections: | 1.01 Articoli in rivista |
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