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PhD position: Connection between accretion and jets in microquasars | Closing date: 2017-03-19 Contact: Prof. Andrzej A. Zdziarski |
Applications are invited for a PhD position at Nicholas Copernicus Astronomical Center of the Polish Academy of Sciences, Warsaw, Poland, to work with Prof. Andrzej A. Zdziarski. The abstract of the project is given below | ▸ more | The relationship between black-hole accretion flows and jets is one of major unsolved problems of contemporary astrophysics. Matter falling from large distances onto the black hole loses its angular momentum and forms a disc-like inflow with a complex structure. However, a part of that matter is channelled into narrow bipolar outflows, i.e., jets. Jets are formed around both supermassive black holes (in active galactic nuclei, quasars, blazars) and stellar-mass black holes in interacting binary systems (called microquasars). The subject of the thesis will be studies of phenomena taking place close to the black hole in the region of jet formation. The way jets are formed and their emission are still not well understood. In particular, it has been disputed whether X-ray emission of microquasars originates in the accretion flow or in the jets. A recent popular model has been the 'lamppost', a compact X-ray source located on the black-hole rotation axis, and thus forming the jet base. This model is so far relatively undeveloped, and the thesis work may include studies of its dynamics, ways it can be formed, and electron-positron pair production within it. The theoretical results will be then compared to observations, e.g., X-ray spectra, radio/X-ray correlations, variability power spectra, and time lags between different spectral bands. A major feature in the observed X-ray spectra is an Fe fluorescent line, around 6-7 keV, originating from re-emission of X-ray radiation striking the surrounding accretion disc. Relativistic distortion of the line due to gravity and motion around the black hole is then used to infer the extent of the disc and the spin of the black hole.
Further details about how to apply for this position can be found at the PhD studies website of CAMK (http://www.camk.edu.pl/en/phd/).
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