Volume 551, March 2013
|Number of page(s)||4|
|Published online||11 February 2013|
INTEGRAL observations of Scorpius X-1: evidence for Comptonization up to 200 keV
Instituto Nacional de Pesquisas Espaciais – INPE Avenida dos Astronautas
São José dos Campos-SP,
e-mail: email@example.com; firstname.lastname@example.org; email@example.com
Received: 31 October 2012
Accepted: 22 January 2013
We have analyzed a long-term database for Sco X-1 obtained with the telescope IBIS onboard the INTEGRAL satellite in order to study the hard X-ray behavior of Sco X-1 from 20 up to 200 keV. Besides the data used for producing of the INTEGRAL catalog of sources, this is the longest (412 ks) database of IBIS on Sco X-1 up to date. The production of hard X-ray tails in low-mass X-ray binaries is still a matter of debate. Since most of the fits to the high-energy part of the spectra are done with powerlaw models, the physical mechanism for the hard X-ray tail production is unclear. The purpose of this study is to better constrain those possible mechanisms. Our main result shows a strong correlation between the fluxes in the thermal and nonthermal part of Sco X-1 spectra. We, thus, suggest that comptonization of lower energy photons is the mechanism for producing hard X-ray tails in Sco X-1.
Key words: radiation mechanisms: non-thermal / radiation mechanisms: thermal / techniques: image processing / stars: neutron / X-rays: binaries
© ESO, 2013
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