| P2: Spectral Variability and Timing of X-Ray Binaries: A Global Approach |
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1st PostDoc: Teo Muñoz-Darias
Time for 1st PostDoc project: Feb 2009 -Jan 2011
Experience Maximum 5 years research experience counted from date of Masters Degree, counted from the date of appointment. Either a PhD or at least 4 years of research experience from date of Masters Degree. By Masters Degree it is meant the degree that formally allows to start a doctorate either in the country where the degree was obtained or in the hst country. Nationality
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Galactic back holes in binary systems can accrete matter from the companion star. Close to the compact object, the accreting plasma emits in the X-ray band and can reach very high luminosities. This region located a few kilometers from a black hole constitutes an ideal laboratory for studying the effects of General Relativity in presence of a strong field. At the same time, it is important to study the properties of the accretion flow itself. Its different physical components and emission mechanisms are very complex and not yet fully understood. Moreover, there is a strong relation between the accretion properties and the ejection of powerful relativistic jets from the systems. In particular, the observed X-ray flux varies in a non-periodic fashion on very fast time scales, down to a few milliseconds. This complex fast time variability shows a marked dependence on the energy spectrum of the source, with transitions which can be as fast as a few seconds. The spectral dependence of this variability also changes markedly as a function of the energy spectrum, leading to a rather complex picture. This postdoc project will seek an improved understanding of these issues through the analysis of archival and new RXTE, INTEGRAL and Swift data for both black hole and neutron star X-ray binaries. Power-density spectra, phase-lag spectra and rms-weighed energy spectra will be produced and the structure and evolution of the different components will be studied as a function of the system’s spectral properties. A homogeneous analysis with both black-hole and neutron-star binaries will allow a comparison of the observational properties and advance our understanding of the full relation between spectral components and fast time variability. In addition, we will perform an unbiased search for high-frequency oscillations in black-hole binaries, which constitute the best approach for obtaining observational evidence for strong gravity effects. These oscillations do not obviously correspond to any of the main features in the variability of NS binaries. The detections will be studied in terms of timing and spectral properties and will provide a firm observational ground for the interpretation in terms of relativistic models.