QPOs in microquasars and Sgr A*: measuring the black hole spin

@article{41405,
   author = {Török, Gabriel},
   article_location = {WEINHEIM},
   article_number = {9},
   doi = {http://dx.doi.org/10.1002/asna.200510427},
   keywords = {black hole physics; X-ray variability},
   language = {eng},
   issn = {0004-6337},
   journal = {Astronomische Nachrichten},
   title = {QPOs in microquasars and Sgr A*: measuring the black hole spin},
   volume = {326},
   year = {2005}
}

TY  - JOUR
ID  - 41405
AU  - Török, Gabriel
PY  - 2005
TI  - QPOs in microquasars and Sgr A*: measuring the black hole spin
JF  - Astronomische Nachrichten
VL  - 326
IS  - 9
SP  - 856-860
EP  - 856-860
PB  - WILEY-V C H VERLAG GMBH
SN  - 00046337
KW  - black hole physics
KW  - X-ray variability
N2  - In all four microquasars which show double peak kHz QPOs, the ratio of the two frequencies is 3:2. This strongly supports the suggestion that twin peak kHz QPOs are due to a resonance between some modes of accretion disk oscillations. Here, we stress that fits to observations of the hypothetical resonances between vertical and radial epicyclic frequencies (particularly of the parametric resonance) give an accurate estimate of the spin for the three microquasars with known mass. Measurement of double peak QPOs frequencies in the Galaxy centre seems also to be consistent with the 3:2 ratio established by previous observations in microquasars, however the Sgr A* data are rather difficult for the same exact analysis. If confirmed, the 3:2 ratio of double peak QPOs in Sgr A* would be of a fundamental importance for the black hole accretion theory and the precise measurement could help to solve the question of QPOs nature.
ER  - 

TÖRÖK, Gabriel. QPOs in microquasars and Sgr A*: measuring the black hole spin. \textit{Astronomische Nachrichten}. WEINHEIM: WILEY-V C H VERLAG GMBH, 2005, vol.~326, No~9, p.~856-860. ISSN~0004-6337. Available from: https://dx.doi.org/10.1002/asna.200510427.