# Black Hole Spin and Accretion Disk Magnetic Field Strength Estimates for more than 750 AGN and Multiple GBH

## TL;DR

This study estimates black hole spins and magnetic field strengths for over 750 AGN and 102 GBH, finding high spins and broad magnetic field distributions, with results consistent across different methods and source types.

## Contribution

The paper introduces a model-independent method to estimate black hole spin and magnetic field strength using theoretical considerations, applicable to diverse black hole systems.

## Key findings

- High spin values (0.6-1) for most sources.
- Magnetic field strengths average around 10^4 G for AGN and 10^8 G for GBH.
- Results agree with established methods and are consistent across source types.

## Abstract

Black hole systems, comprised of a black hole, accretion disk, and collimated outflow are studied here. Three AGN samples including 753 AGN, and 102 measurements of 4 GBH are studied. Applying the theoretical considerations described by Daly (2016), general expressions for the black hole spin function and accretion disk magnetic field strength are presented 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; spin functions indicate typical spin values of about (0.6 - 1) for the sources. The distribution of accretion disk magnetic field strengths for the three AGN samples are quite broad and have mean values of about $10^4$ G, while those for individual GBH have mean values of about $10^8$ G. Good agreement is found between spin values obtained here and published values obtained with well-established methods; comparisons for 1 GBH and 6 AGN indicate that similar spin values are obtained with independent methods. Black hole spin and disk magnetic field strength demographics are obtained and indicate that black hole spin functions and spins are similar for all of the source types studied including GBH and different categories of AGN. The method applied here does not depend upon any specific accretion disk emission model, and does not depend upon 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.