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A strongly truncated inner accretion disk in the Rapid Burster

van de Eijnden, J. and Bagnoli, T. and Degenaar, N. and Lohfink, A. M. and Parker, M. L. and Zand, J. J. M. and Fabian, A. C. (2017) A strongly truncated inner accretion disk in the Rapid Burster. Monthly Notices of the Royal Astronomical Society: Letters, 466 (1). L98-L102. ISSN 1745-3925. doi:10.1093/mnrasl/slw244.

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The neutron star (NS) low-mass X-ray binary (LMXB) the Rapid Burster (RB; MXB 1730-335) uniquely shows both Type I and Type II X-ray bursts. The origin of the latter is ill-understood but has been linked to magnetospheric gating of the accretion flow. We present a spectral analysis of simultaneous Swift, NuSTARand XMM–Newton observations of the RB during its 2015 outburst. Although a broad Fe K line has been observed before, the high quality of our observations allows us to model this line using relativistic reflection models for the first time. We find that the disc is strongly truncated at 41.8^(+6.7)_(−5.3) gravitational radii (∼87 km), which supports magnetospheric Type II burst models and strongly disfavours models involving instabilities at the innermost stable circular orbit. Assuming that the RB magnetic field indeed truncates the disc, we find B = (6.2 ± 1.5) × 10^8 G, larger than typically inferred for NS LMXBs. In addition, we find a low inclination (i=29°±2°). Finally, we comment on the origin of the Comptonized and thermal components in the RB spectrum.

Item Type:Article
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URLURL TypeDescription Paper
Parker, M. L.0000-0002-8466-7317
Fabian, A. C.0000-0002-9378-4072
Additional Information:© 2016 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2016 December 1. Received 2016 November 28; in original form 2016 November 3. Published: 05 December 2016. We thank the referee for comments on this Letter. JvdE and ND are supported by a Vidi grant from the Netherlands Organization for Scientific Research (NWO) awarded to ND. ND also acknowledges support via a Marie Curie fellowship (FP-PEOPLE-2013-IEF-627148) from the European Commission. ACF, AL and MP are supported by Advanced Grant Feedback 340442 from the European Research Counsil (ERC). TB acknowledges support from NewCompStar (COST Action MP1304). JvdE and TB acknowledge the hospitality of the Institute of Astronomy in Cambridge, where this research was carried out. We are grateful to Fiona Harrison, Norbert Schartel, Neil Gehrels and the observation planners for making these Director's Discretionary Time observations possible.
Subject Keywords:accretion, accretion discs – stars: neutron – X-rays: binaries – X-rays: individual: MXB 1730-335
Issue or Number:1
Record Number:CaltechAUTHORS:20161209-150822081
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Official Citation:J. van den Eijnden, T. Bagnoli, N. Degenaar, A. M. Lohfink, M. L. Parker, J. J. M in ‘t Zand, A. C. Fabian; A strongly truncated inner accretion disc in the Rapid Burster, Monthly Notices of the Royal Astronomical Society: Letters, Volume 466, Issue 1, 21 March 2017, Pages L98–L102,
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:72697
Deposited By: Joy Painter
Deposited On:10 Dec 2016 02:07
Last Modified:11 Nov 2021 05:05

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