A precessing Be disc as a possible model for occultation events in GX 304-1

Kühnel M, Rothschild RE, Okazaki AT, Müller S, Pottschmidt K, Ballhausen R, Choi J, Kreykenbohm I, Fuerst F, Marcu-Cheatham DM, Hemphill P, Sagredo M, Kretschmar P, Martinez-Nunez S, Torrejon JM, Staubert R, Wilms J (2017)

Publication Status: Published

Publication Type: Journal article

Publication year: 2017

Journal

Publisher: OXFORD UNIV PRESS

Book Volume: 471

Pages Range: 1553-1564

Journal Issue: 2

DOI: 10.1093/mnras/stx1663

Abstract

We report on the RXTE detection of a sudden increase in the absorption column density, N-H, during the 2011 May outburst of GX 304-1. The NH increased up to similar to 16 x 10(22) atoms cm(-2), which is a factor of 3-4 larger than what is usually measured during the outbursts of GX 304-1 as covered by RXTE. Additionally, an increase in the variability of the hardness ratio as calculated from the energy resolved RXTE-Proportional Counter Array light curves is measured during this time range. We interpret these facts as an occultation event of the neutron star by material in the line of sight. Using a simple 3D model of an inclined and precessing Be disc around the Be-type companion, we are able to qualitatively explain the NH evolution over time. We are able to constrain the Be disc density to be of the order of 10(-11) g cm(-3). Our model strengthens the idea of inclined Be discs as origin of double-peaked outbursts as the derived geometry allows accretion twice per orbit under certain conditions.

Authors with CRIS profile

Involved external institutions

University of California, San Diego United States (USA) (US) University of Maryland, Baltimore County United States (USA) (US) Hokkaido University (Hokudai) / 北海道大学 Japan (JP) Harvard University United States (USA) (US) European Space Astronomy Centre (ESAC) Spain (ES) Eberhard Karls Universität Tübingen Germany (DE) University of Alicante / Universidad de Alicante / Universitat d'Alacant Spain (ES) Instituto de Física de Cantabria (IFCA) Spain (ES) Massachusetts Institute of Technology (MIT) United States (USA) (US)

How to cite

APA:

Kühnel, M., Rothschild, R.E., Okazaki, A.T., Müller, S., Pottschmidt, K., Ballhausen, R.,... Wilms, J. (2017). A precessing Be disc as a possible model for occultation events in GX 304-1. Monthly Notices of the Royal Astronomical Society, 471(2), 1553-1564. https://dx.doi.org/10.1093/mnras/stx1663

MLA:

Kühnel, Matthias, et al. "A precessing Be disc as a possible model for occultation events in GX 304-1." Monthly Notices of the Royal Astronomical Society 471.2 (2017): 1553-1564.

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