NuSTAR detection of 4s Hard X-ray Lags from the Accreting Pulsar GS 0834-430

Thumbnail Image

Files

epjconf_mag2013_06011.pdf (860.17 KB)

Links to Files

https://www.epj-conferences.org/articles/epjconf/abs/2014/01/epjconf_mag2013_06011/epjconf_mag2013_06011.html

Permanent Link

https://doi.org/10.1051/epjconf/20136406011
 http://hdl.handle.net/11603/29595

Collections

UMBC Center for Space Sciences and Technology (CSST) / Center for Research and Exploration in Space Sciences & Technology II (CRSST II)
UMBC Faculty Collection
UMBC Physics Department

Author/Creator

Author/Creator ORCID

https://orcid.org/0000-0002-4656-6881

Date

2014-01-08

Type of Work

conference papers and proceedings
Text

Department

Program

Citation of Original Publication

Bachetti, Matteo, Hiromasa Miyasaka, Fiona Harrison, Felix Fürst, Didier Barret, Eric C. Bellm, Steven E. Boggs, et al. “NuSTAR Detection of 4s Hard X-Ray Lags from the Accreting Pulsar GS 0834-430.” EPJ Web of Conferences 64 (2014): 06011. https://doi.org/10.1051/epjconf/20136406011.

Rights

This work was written as part of one of the author's official duties as an Employee of the United States Government and is therefore a work of the United States Government. In accordance with 17 U.S.C. 105, no copyright protection is available for such works under U.S. Law.
Public Domain Mark 1.0

Subjects

Abstract

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.