Institute of Astronomy

A New Method of Determining Black Hole Spin and Accretion Disk Properties for Supermassive and Stellar-mass Black Holes

SpeakerTalk DateTalk Series
Ruth Daly (Penn State)25 February 2021Institute of Astronomy Colloquia


Black hole systems, consisting of a black hole, accretion disk, and collimated outflow, will be discussed. Three samples of active galactic nuclei (AGN), including 756 AGN, and 102 measurements of four stellar-mass galactic black holes (GBHs) will be considered. General expressions will be derived and applied to obtain the black hole spin function, spin, and accretion disk magnetic field strength in dimensionless and physical units for each source. Relatively high spin values are obtained. The distributions of accretion disk magnetic field strengths for the three AGN samples are quite broad and have mean values of about 10 kG, while those for stellar-mass GBHs have mean values of about 100 MG. Reasonable agreement is found between spin values obtained here and published values obtained with a well-established method. Black hole spin and disk magnetic field strength demographics indicate that black hole spin functions, spins, and disk magnetic field strengths are similar for the AGN source types studied. Mass accretion rates are obtained in dimensionless and physical units using a new method. The results and implications of these studies will be discussed.


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