Journal article

Publication Details

Author(s): Fuerst F, Nowak MA, Tomsick JA, Miller JM, Corbel S, Bachetti M, Boggs SE, Christensen FE, Craig WW, Fabian AC, Gandhi P, Grinberg V, Hailey CJ, Harrison FA, Kara E, Kennea JA, Madsen KK, Pottschmidt K, Stern D, Walton DJ, Wilms J, Zhang WW
Journal: Astrophysical Journal
Publication year: 2015
Volume: 808
Journal issue: 2
ISSN: 0004-637X
eISSN: 1538-4357


We present spectral analyses of five Nuclear Spectroscopic Telescope Array and Swift observations of GX 339-4 taken during a failed outburst during the summer of 2013. These observations cover Eddington luminosity fractions in the range approximate to 0.9%-6%. Throughout this outburst GX 339-4 stayed in the hard state and all five observations show similar X-ray spectra, with a hard power law with a photon index near 1.6, and significant contribution from reflection. Using simple reflection models we find unrealistically high iron abundances. Allowing for different photon indices for the continuum incident on the reflector relative to the underlying observed continuum results in a statistically better fit and reduced iron abundances. With a photon index around 1.3, the input power law on the reflector is significantly harder than that which is directly observed. We study the influence of different emissivity profiles and geometries and consistently find an improvement when using separate photon indices. The inferred inner accretion disk radius is strongly model dependent, but we do not find evidence for a truncation radius larger than 100 r(g) in any model. The data do not allow independent spin constraints, but the results are consistent with the literature (i.e., a > 0). Our best-fit models indicate an inclination angle in the range 40 degrees-60 degrees, consistent with limits on the orbital inclination but higher than reported in the literature using standard reflection models. The iron line around 6.4 keV is clearly broadened, and we detect a superimposed narrow core as well. This core originates from a fluorescent region outside the influence of the strong gravity of the black hole. Additionally, we discuss possible geometries.

FAU Authors / FAU Editors

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

External institutions with authors

California Institute of Technology (Caltech)
Columbia University
Durham University
Massachusetts Institute of Technology (MIT)
Pennsylvania State University (Penn State)
Technical University of Denmark / Danmarks Tekniske Universitet (DTU)
University of California, Berkeley
University of Cambridge
University of Maryland, Baltimore County
University of Michigan
University of Paris 7 - Denis Diderot / Université Paris VII Denis Diderot
University of Toulouse

How to cite

Fuerst, F., Nowak, M.A., Tomsick, J.A., Miller, J.M., Corbel, S., Bachetti, M.,... Zhang, W.W. (2015). THE COMPLEX ACCRETION GEOMETRY OF GX 339-4 AS SEEN BY NuSTAR AND SWIFT. Astrophysical Journal, 808(2).

Fuerst, F., et al. "THE COMPLEX ACCRETION GEOMETRY OF GX 339-4 AS SEEN BY NuSTAR AND SWIFT." Astrophysical Journal 808.2 (2015).


Last updated on 2019-23-08 at 08:32