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ASD Colloquium Series



Black Hole Spin and Accretion Disk Magnetic Field Strengths for over 700 Sources
Ruth Daly (PSU & CCA)

Black hole systems, composed of a black hole, accretion disk, and collimated outflow, will be discussed. Three active galactic nucleus (AGN) samples including 753 AGNs and 102 measurements of four stellar-mass galactic black holes (GBHs) will be considered. General expressions for black hole spin functions and accretion disk magnetic field strengths 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 of about (0.6 - 1) are obtained for the sources. The distributions of accretion disk magnetic field strengths for the three AGN samples are quite broad and have mean values of about 104 G, while those for stellar-mass GBHs have mean values of about 108 G. Good agreement is found between spin values obtained here and published values obtained with well-established methods; comparisons for one GBH and six AGNs indicate that similar spin values are obtained with independent methods. Black hole spin and disk magnetic field strength demographics indicate that black hole spin functions and spins are similar for all of the source types studied, including GBHs and different categories of AGNs. The method applied here does not depend on any specific accretion disk emission model and does not depend on a specific model that relates jet beam power to compact radio luminosity; hence, the results obtained here can be used to constrain and study these models.

The Astrophysics Science Division colloquia occur on Tuesdays at 3:45 pm, with an opportunity to meet the speaker at 3:30 pm, in building 34, room W120A/B (unless otherwise noted).

Date January 28, 2020
Start/End Time 03:45 PM - 05:00 PM
Location B34, W120A/B
Contact Knicole Colon
Email Address
Event Type Seminars/Colloquia
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