DISTORTED CYCLOTRON LINE PROFILE IN CEP X-4 AS OBSERVED BY NuSTAR

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Details zur Publikation

Autor(en): Fuerst F, Pottschmidt K, Miyasaka H, Bhalerao V, Bachetti M, Boggs SE, Christensen FE, Craig WW, Grinberg V, Hailey CJ, Harrison FA, Kennea JA, Rahoui F, Stern D, Tendulkar SP, Tomsick JA, Walton DJ, Wilms J, Zhang WW
Zeitschrift: Astrophysical Journal Letters
Verlag: American Astronomical Society
Jahr der Veröffentlichung: 2015
Band: 806
ISSN: 2041-8205


Abstract

We present spectral analysis of Nuclear Spectroscopic Telescope Array and Swift observations of Cep X-4 during its outburst in 2014. We observed the source once during the peak of the outburst and once during the decay, finding good agreement in the spectral shape between the observations. We describe the continuum using a power law with a Fermi-Dirac cutoff at high energies. Cep X-4 has a very strong cyclotron resonant scattering feature (CRSF) around 30 keV. A simple absorption-like line with a Gaussian optical depth or a pseudo-Lorentzian profile both fail to describe the shape of the CRSF accurately, leaving significant deviations at the red side of the line. We characterize this asymmetry with a second absorption feature around 19 keV. The line energy of the CRSF, which is not influenced by the addition of this feature, shows a small but significant positive luminosity dependence. With luminosities between (1-6) x 10(36) erg s(-1), Cep X-4 is below the theoretical limit where such a correlation is expected. This behavior is similar to Vela X-1 and we discuss parallels between the two systems.


FAU-Autoren / FAU-Herausgeber

Wilms, Jörn Prof. Dr.
Professur für Astronomie und Astrophysik


Autor(en) der externen Einrichtung(en)
California Institute of Technology (Caltech)
Columbia University
European Southern Observatory (ESO)
INAF-Osservatorio Astronomico di Cagliari
Inter-University Centre for Astronomy and Astrophysics (IUCAA)
Massachusetts Institute of Technology (MIT)
National Aeronautics and Space Administration (NASA)
Pennsylvania State University (Penn State)
Technical University of Denmark / Danmarks Tekniske Universitet (DTU)
University of California, Berkeley
University of Maryland, Baltimore County


Zitierweisen

APA:
Fuerst, F., Pottschmidt, K., Miyasaka, H., Bhalerao, V., Bachetti, M., Boggs, S.E.,... Zhang, W.W. (2015). DISTORTED CYCLOTRON LINE PROFILE IN CEP X-4 AS OBSERVED BY NuSTAR. Astrophysical Journal Letters, 806. https://dx.doi.org/10.1088/2041-8205/806/2/L24

MLA:
Fuerst, F., et al. "DISTORTED CYCLOTRON LINE PROFILE IN CEP X-4 AS OBSERVED BY NuSTAR." Astrophysical Journal Letters 806 (2015).

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