EPJ Web of Conferences
Volume 64, 2014Physics at the Magnetospheric Boundary
|Number of page(s)||4|
|Section||Observations of Compact Objects (Part 1)|
|Published online||08 January 2014|
NuSTAR detection of 4s Hard X-ray Lags from the Accreting Pulsar GS 0834-430
1 Université de Toulouse; UPS-OMP; IRAP; Toulouse, France
2 CNRS; Institut de Recherche en Astrophysique et Planétologie ; 9 Av. colonel Roche, BP 44346, F-31028 Toulouse cedex 4, France
3 Cahill Center for Astronomy and Astrophysics, California Institute of Technology, Pasadena, CA 91125
4 Space Sciences Laboratory, University of California, Berkeley, CA 94720, USA
5 Kavli Institute for Astrophysics and Space Research, Massachusetts Institute of Technology, Cambridge, MA 02139
6 DTU Space, National Space Institute, Technical University of Denmark, Elektrovej 327, DK-2800 Lyngby, Denmark
7 Lawrence Livermore National Laboratory, Livermore, CA 94550, USA
8 Columbia Astrophysics Laboratory, Columbia University, New York, NY 10027, USA
9 Istituto di Astrofisica e Planetologia Spaziali, INAF, Via Fosso del Cavaliere 100, Roma I-00133, Italy
10 CRESST, UMBC, and NASA GSFC, Code 661, Greenbelt, MD 20771, USA
11 Jet Propulsion Laboratory, California Institute of Technology, Pasadena, CA 91109, USA
12 Dr. Karl-Remeis-Sternwarte and ECAP, Sternwartstr. 7, 96 049 Bamberg, Germany
13 NASA Goddard Space Flight Center, Greenbelt, MD 20771, USA
a e-mail: firstname.lastname@example.org
Published online: 8 January 2014
The NuSTAR hard X-ray telescope observed the transient Be/X-ray binary GS 0834–430 during its 2012 outburst. The source is detected between 3 – 79 keV with high statistical significance, and we were able to perform very accurate spectral and timing analysis. The phase-averaged spectrum is consistent with that observed in many other magnetized accreting pulsars. We fail to detect cyclotron resonance scattering features in either phase-averaged nor phase-resolved spectra that would allow us to constrain the pulsar’s magnetic field. We detect a pulse period of ~ 12:29 s in all energy bands. The pulse profile can be modeled with a double Gaussian and shows a strong and smooth hard lag of up to 0.3 cycles in phase, or about 4s between the pulse at ~ 3 and ≳ 30 keV. This is the first report of such a strong lag in high-mass X-ray binary (HMXB) pulsars. Previously reported lags have been significantly smaller in phase and restricted to low-energies (E<10 keV). We investigate the possible mechanisms that might produce such lags. We find the most likely explanation for this effect to be a complex beam geometry.
© Owned by the authors, published by EDP Sciences, 2014
This is an Open Access article distributed under the terms of the Creative Commons Attribution License 2.0, which permits unrestricted use, distribution, and reproduction in any medium, provided the original work is properly cited.
Current usage metrics show cumulative count of Article Views (full-text article views including HTML views, PDF and ePub downloads, according to the available data) and Abstracts Views on Vision4Press platform.
Data correspond to usage on the plateform after 2015. The current usage metrics is available 48-96 hours after online publication and is updated daily on week days.
Initial download of the metrics may take a while.