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A constant Cyclotron Line Energy in 4U 0115+634

Müller, S. and Ferrigno, C. and Kühnel, M. and Schönherr, G. and Becker, P. A. and Wolff, M. T. and Hertel, D. and Schwarm, F. W. and Grinberg, V. and Obst, M. and Caballero, I. and Pottschmidt, K. and Fürst, F. and Kreykenbohm, I. and Rothschild, R. E. and Hemphill, P. and Martínez-Núñez, S. and Torrejón, J. M. and Klochkov, D. and Staubert, R. and Wilms, J. (2012) A constant Cyclotron Line Energy in 4U 0115+634. In: An INTEGRAL view of the high-energy sky (the first 10 years) - 9th INTEGRAL Workshop and celebration of the 10th anniversary of the launch. Proceedings of Science. No.176. SISSA , Trieste, Italy, Art. No. 20.

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We present a study of RXTE and INTEGRAL spectra of the transient 3.6 s X-ray pulsar 4U 0115+634 taken during a giant outburst in 2008 March/April. The spectra can be almost equally well modeled by two different semi-empirical continuum models, modified by an Fe Kα fluorescence line, interstellar absorption, and cyclotron resonance scattering features (CRSFs) located at ∼10.7, 21.8, 35.5, 46.7, and 59.7 keV. One of these two models, the so called NPEX model, leads to an anticorrelation between the centroid energy of the fundamental CRSF E_0 and the X-ray flux F_X, in agreement with previous works. The other model, consisting of a simple exponentially cutoff power law modified by a Gaussian emission feature around 10 keV, however, leads to a constant value for E_0 for the observed fluxes and a comparatively narrow line shape. We show that the cyclotron line model component resulting from the NPEX fits rather contribute to the broadband continuum model. We conclude that the previously reported anticorrelation is probably due to an artifact of the particular modeling of the continuum.

Item Type:Book Section
Related URLs:
URLURL TypeDescription
Wolff, M. T.0000-0002-4013-5650
Grinberg, V.0000-0003-2538-0188
Pottschmidt, K.0000-0002-4656-6881
Fürst, F.0000-0003-0388-0560
Kreykenbohm, I.0000-0001-7335-1803
Hemphill, P.0000-0002-1676-6954
Wilms, J.0000-0003-2065-5410
Alternate Title:Boon and bane of studying the multiple cyclotron source 4U 0115+63
Additional Information:Copyright owned by the author(s) under the term of the Creative Commons Attribution-NonCommercial-ShareAlike. This research has been funded by the Bundesministerium für Wirtschaft und Technologie under Deutsches Zentrum für Luft- und Raumfahrt grants 50OR0808, 50OR0905, 50OR1113, and 50OR1007, and by the Deutscher Akademischer Austauschdienst. MTW is supported by the US Office of Naval Research. IC acknowledges financial support from the French Space Agency CNES through CNRS. SMN and JMT acknowledge support from the Spanish Ministerio de Ciencia, Tecnología e Innovación (MCINN) through grant AYA2010-15431 and the use of the computer facilities made available through the grant AIB2010DE-00057.
Group:Space Radiation Laboratory
Funding AgencyGrant Number
Bundesministerium für Wirtschaft und Technologie (BMWi)UNSPECIFIED
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OR0808
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OR0905
Deutsches Zentrum für Luft- und Raumfahrt (DLR)50OR1007
Deutscher Akademischer Austauschdienst (DAAD)UNSPECIFIED
Office of Naval Research (ONR)UNSPECIFIED
Centre National d'Études Spatiales (CNES)UNSPECIFIED
Centre National de la Recherche Scientifique (CNRS)UNSPECIFIED
Ministerio de Ciencia, Tecnología e Innovación (MCINN)AYA2010-15431
Ministerio de Ciencia, Tecnología e Innovación (MCINN)AIB2010DE-00057
Series Name:Proceedings of Science
Issue or Number:176
Record Number:CaltechAUTHORS:20180824-100033544
Persistent URL:
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89138
Deposited By: George Porter
Deposited On:28 Aug 2018 19:54
Last Modified:16 Nov 2021 00:32

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