Outburst of GX 304-1 monitored with INTEGRAL: positive correlation between the cyclotron line energy and flux
Klochkov D, Doroshenko V, Santangelo A, Staubert R, Ferrigno C, Kretschmar P, Caballero I, Wilms J, Kreykenbohm I, Pottschmidt K, Rothschild RE, Wilson-Hodge CA, Puehlhofer G (2012)
Publication Status: Published
Publication Type: Journal article
Publication year: 2012
Journal
Publisher: EDP SCIENCES S A
Book Volume: 542
Article Number: ARTN L28
DOI: 10.1051/0004-6361/201219385
Abstract
Context. X-ray spectra of many accreting pulsars exhibit significant variations as a function of flux and thus of mass accretion rate. In some of these pulsars, the centroid energy of the cyclotron line(s), which characterizes the magnetic field strength at the site of the X-ray emission, has been found to vary systematically with flux.Aims. GX304-1 is a recently established cyclotron line source with a line energy around 50 keV. Since 2009, the pulsar shows regular outbursts with the peak flux exceeding one Crab. We analyze the INTEGRAL observations of the source during its outburst in January-February 2012.Methods. The observations covered almost the entire outburst, allowing us to measure the source's broad-band X-ray spectrum at different flux levels. We report on the variations in the spectral parameters with luminosity and focus on the variations in the cyclotron line.Results. The centroid energy of the line is found to be positively correlated with the luminosity. We interpret this result as a manifestation of the local sub-Eddington (sub-critical) accretion regime operating in the source.
Authors with CRIS profile
Jörn Wilms
Professur für Astronomie und Astrophysik
Ingo Kreykenbohm
Dr.Karl-Remeis-Sternwarte Bamberg, Astronomisches Institut
Involved external institutions
Eberhard Karls Universität Tübingen
Germany (DE)
University of Geneva / Université de Genève (UNIGE)
Switzerland (CH)
University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot
France (FR)
University of Maryland, Baltimore County
United States (USA) (US)
National Aeronautics and Space Administration (NASA)
United States (USA) (US)
University of California, San Diego
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
Germany (DE)
University of Geneva / Université de Genève (UNIGE)
Switzerland (CH)
University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot
France (FR)
University of Maryland, Baltimore County
United States (USA) (US)
National Aeronautics and Space Administration (NASA)
United States (USA) (US)
University of California, San Diego
United States (USA) (US)
European Space Astronomy Centre (ESAC)
Spain (ES)
How to cite
APA:
Klochkov, D., Doroshenko, V., Santangelo, A., Staubert, R., Ferrigno, C., Kretschmar, P.,... Puehlhofer, G. (2012). Outburst of GX 304-1 monitored with INTEGRAL: positive correlation between the cyclotron line energy and flux. Astronomy & Astrophysics, 542. https://dx.doi.org/10.1051/0004-6361/201219385
MLA:
Klochkov, D., et al. "Outburst of GX 304-1 monitored with INTEGRAL: positive correlation between the cyclotron line energy and flux." Astronomy & Astrophysics 542 (2012).
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