2015/07/10 by Sandip K. Chakrabarti, Chakrabarti, Sandip K., Santanu Mondal +3
Engineering · Physics and Astronomy · #Astrophysical Phenomena and Observations #FOS: Physical sciences #High Energy Astrophysical Phenomena (astro-ph.HE) #Mechanics and Biomechanics Studies
paper · pdf · doi:10.48550/arxiv.1507.02831
openalex publication_date 2015/07/10 · openalex created_date 2022/10/01 · openalex updated_date 2026/07/28
It has long been proposed that low frequency QPOs in stellar mass black holes\nor their equivalents in super massive black holes are results of resonances\nbetween infall and cooling time scales. We explicitly compute these two time\nscales in a generic situation to show that resonances are easily achieved.\nDuring an outburst of a transient black hole candidate (BHC), the accretion\nrate of the Keplerian disk as well as the geometry of the Comptonizing cloud\nchange very rapidly. During some period, resonance condition between the\ncooling time scale (predominantly by Comptonization) and the infall time scale\nof the Comptonizing cloud is roughly satisfied. This leads to low frequency\nquasi-periodic oscillations (LFQPOs) of the Compton cloud and the consequent\noscillation of hard X-rays. In this paper, we explicitly follow the BHC H\n1743-322 during its 2010 outburst. We compute Compton cooling time and infall\ntime on several days and show that QPOs take place when these two roughly agree\nwithin ~50%, i.e., the resonance condition is generally satisfied. We also\nconfirm that for the sharper LFQPOs (i.e., higher Q-factors) the ratio of two\ntime scales is very close to 1.\n