There is a studentship available to carry out a PhD at the Kapteyn Institute, University of Groningen, to do observational research on black holes (BH). The goal of the PhD project is to obtain robust measurements of BH spins, both for stellar-mass BHs in our Galaxy, and super-massive BHs at the center of active galactic nuclei (AGN). The PhD student will be supervised by Mariano Mendez.
Rationale: BHs are characterized by three quantities: Mass, spin, and charge. Only mass and spin are astrophysically interesting. This project focuses on the problem of measuring the BH spin. Spins are important for 3 reasons: (i) They are a direct consequence of the BH formation mechanism. (ii) The innermost stable circular orbit (ISCO) is 6 times closer to the BH, and hence effects of General Relativity are more extreme, in maximally spinning BHs than in non-rotating ones. (iii) The binding energy at the ISCO is 7 times larger for a maximally spinning BH than for a non-spinning one; current ideas about the way superluminal jets are powered, both in microquasars and AGN, appeal to accretion to, and energy extraction from, a fast spinning BH.
There are three ways to measure BH spins; one is based on timing, and two are based on spectroscopic measurements in the X-ray band. Both spectroscopic methods depend crucially on properly modelling the underlying continuum emission. Not enough attention has been paid to possible absorption by highly ionized gas that is known to be present in the vicinity of the BH. Here we will address this problem.
For this project, the PhD student will systematically analyze high-resolution X-ray spectra of a group of galactic and extragalactic BHs, taken with the Chandra and XMM-Newton observatories, accounting for the presence of this ionized absorber, and assessing how this gas affects the inferred BH spin.
Applications should be sent either by email or regular mail to the address below, and should include a curriculum vitae with a list of grades, a short (about 1-page long) summary of research interests and experience, and a short (about 1-page long) description of any previous research work (e.g., Bachelor and/or Master thesis), explaining the part carried out by the applicant, and
the relevance of the work in a larger context.
The applicant must arrange for two reference letters being sent separately to the same address. If English is not the native language of the applicant, the reference letters should include an assessment of the English level (written and oral) of the applicant.
Complete applications should arrive before or on 31 July 2007.
Additional information can be obtained from the address below.
prof. dr. Mariano Mendez
Kapteyn Astronomical Institute
University of Groningen
Postbus 800
9700 av Groningen
The Netherlands
Email: mariano@astro.rug.nl
Tel. +31-30-253 5839 (until 1 Sep 2007)
Tel. +31-50-363 4073 (from 1 Sep 2007)
Rationale: BHs are characterized by three quantities: Mass, spin, and charge. Only mass and spin are astrophysically interesting. This project focuses on the problem of measuring the BH spin. Spins are important for 3 reasons: (i) They are a direct consequence of the BH formation mechanism. (ii) The innermost stable circular orbit (ISCO) is 6 times closer to the BH, and hence effects of General Relativity are more extreme, in maximally spinning BHs than in non-rotating ones. (iii) The binding energy at the ISCO is 7 times larger for a maximally spinning BH than for a non-spinning one; current ideas about the way superluminal jets are powered, both in microquasars and AGN, appeal to accretion to, and energy extraction from, a fast spinning BH.
There are three ways to measure BH spins; one is based on timing, and two are based on spectroscopic measurements in the X-ray band. Both spectroscopic methods depend crucially on properly modelling the underlying continuum emission. Not enough attention has been paid to possible absorption by highly ionized gas that is known to be present in the vicinity of the BH. Here we will address this problem.
For this project, the PhD student will systematically analyze high-resolution X-ray spectra of a group of galactic and extragalactic BHs, taken with the Chandra and XMM-Newton observatories, accounting for the presence of this ionized absorber, and assessing how this gas affects the inferred BH spin.
Applications should be sent either by email or regular mail to the address below, and should include a curriculum vitae with a list of grades, a short (about 1-page long) summary of research interests and experience, and a short (about 1-page long) description of any previous research work (e.g., Bachelor and/or Master thesis), explaining the part carried out by the applicant, and
the relevance of the work in a larger context.
The applicant must arrange for two reference letters being sent separately to the same address. If English is not the native language of the applicant, the reference letters should include an assessment of the English level (written and oral) of the applicant.
Complete applications should arrive before or on 31 July 2007.
Additional information can be obtained from the address below.
prof. dr. Mariano Mendez
Kapteyn Astronomical Institute
University of Groningen
Postbus 800
9700 av Groningen
The Netherlands
Email: mariano@astro.rug.nl
Tel. +31-30-253 5839 (until 1 Sep 2007)
Tel. +31-50-363 4073 (from 1 Sep 2007)
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