The Evolution of GX 339-4 in the Low-hard State as Seen by NuSTAR and Swift

Wang-Ji, Jingyi and Garcia, Javier A and Steiner, James F and Tomsick, John A and Harrison, Fiona A and Bambi, Cosimo and Petrucci, Pierre-Olivier and Ferreira, Jonathan and Chakravorty, Susmita and Clavel, Maica (2018) The Evolution of GX 339-4 in the Low-hard State as Seen by NuSTAR and Swift. In: ASTROPHYSICAL JOURNAL, 855 (1).

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Abstract

We analyze 11 Nuclear Spectroscopic Telescope Array and Swift observations of the black hole X-ray binary GX. 339-4. in the hard state, 6 of which were taken during the end of the 2015 outburst and 5 during a failed outburst in 2013. These observations cover luminosities from 0.5% to 5% of the Eddington luminosity. Implementing the most recent version of the reflection model relxillCp, we perform simultaneous spectral fits on both data sets to track the evolution of the properties in the accretion disk, including the inner edge radius, the ionization, and the temperature of the thermal emission. We also constrain the photon index and electron temperature of the primary source (the ``corona''). We observe a maximum truncation radius of 37 R-g in the preferred fit for the 2013 data set, and a marginal correlation between the level of truncation and luminosity. We also explore a self-consistent model under the framework of coronal Comptonization, and find consistent results regarding the disk truncation in the 2015 data, providing a more physical preferred fit for the 2013 observations.

Item Type:	Journal Article
Publication:	ASTROPHYSICAL JOURNAL
Publisher:	IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Additional Information:	Copyright of this article belong to IOP PUBLISHING LTD, TEMPLE CIRCUS, TEMPLE WAY, BRISTOL BS1 6BE, ENGLAND
Department/Centre:	Division of Physical & Mathematical Sciences > Physics
Date Deposited:	20 Aug 2018 14:48
Last Modified:	20 Aug 2018 14:48
URI:	http://eprints.iisc.ac.in/id/eprint/60455

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