A jet model for Galactic black-hole X-ray sources: some constraining correlations

N. D. Kylafis; I. E. Papadakis; P. Reig; D. Giannios; G. G. Pooley

doi:doi:10.1051/0004-6361:20079159

Free access

Issue		A&A Volume 489, Number 2, October II 2008


Page(s)		481 - 487
Section		Astrophysical processes
DOI		http://dx.doi.org/10.1051/0004-6361:20079159
Published online		23 July 2008

A&A 489, 481-487 (2008)
DOI: 10.1051/0004-6361:20079159

A jet model for Galactic black-hole X-ray sources: some constraining correlations

N. D. Kylafis^{1, 2}, I. E. Papadakis^{1, 2}, P. Reig^{2, 1}, D. Giannios³, and G. G. Pooley⁴

¹ Physics Department, University of Crete, PO Box 2208, 710 03 Heraklion, Crete, Greece
e-mail: kylafis@physics.uoc.gr
² Foundation for Research and Technology-Hellas, PO Box 1527, 711 10 Heraklion, Crete, Greece
³ Max Planck Institute for Astrophysics, Box 1317, 85741 Garching, Germany
⁴ Astrophysics Group, Cavendish Laboratory, Madingley Road, Cambridge CB3 OHE, UK

Received 28 November 2007 / Accepted 11 July 2008

Abstract
Context. Some recent observational results impose significant constraints on all the models that have been proposed to explain the Galactic black-hole X-ray sources in the hard state. In particular, it has been found that during the hard state of Cyg X-1 the power-law photon number spectral index, $\Gamma$ , is correlated with the average time lag, $\langle t_{\rm lag}\rangle$ , between hard and soft X-rays. Furthermore, the peak frequencies of the four Lorentzians that fit the observed power spectra are correlated with both $\Gamma$ and $\langle t_{\rm lag}\rangle$ .
Aims. We have investigated whether our jet model can reproduce these correlations.
Methods. We performed Monte Carlo simulations of Compton upscattering of soft, accretion-disk photons in the jet and computed the time lag between hard and soft photons and the power-law index $\Gamma$ of the resulting photon number spectra.
Results. We demonstrate that our jet model naturally explains the above correlations, with no additional requirements and no additional parameters.

Key words: radiation mechanisms: non-thermal -- accretion, accretion disks -- black hole physics -- methods: statistical -- X-rays: binaries

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.