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Active galactic nuclei as scaled-up Galactic black holes
I M McHardy1, E Koerding, C Knigge
1School of Physics and Astronomy, The University, Southampton SO17 1BJ, UK. imh@astro.soton.ac.uk
Nature
|December 8, 2006
Summary
Active galactic nuclei (AGN) behave like scaled-up Galactic black hole systems. This finding, based on X-ray variations and optical emission lines, confirms that accretion processes are consistent across different black hole masses.
Area of Science:
- Astrophysics
- Black Hole Physics
- Cosmic Evolution
Background:
- A key question in astrophysics is whether active galactic nuclei (AGN) exhibit similar variability patterns to Galactic black hole systems when scaled by mass.
- X-ray emission, originating near black holes, is a crucial diagnostic for understanding their behavior.
Purpose of the Study:
- To determine if AGN are essentially scaled-up versions of Galactic black holes by comparing their X-ray variability timescales.
- To establish a physical link between the accretion processes in both types of black hole systems.
Main Methods:
- Analysis of characteristic timescales in X-ray variations from both AGN and Galactic black hole systems.
- Correction for accretion rate variations to enable direct comparison of timescales.
- Correlation analysis between optical emission line widths in AGN and their characteristic X-ray timescales.
Main Results:
- After accounting for accretion rate variations, X-ray variability timescales from AGN and Galactic black holes are found to be physically linked.
- The accretion process is demonstrated to be consistent for both small (Galactic) and large (AGN) black holes.
- A strong correlation is observed between the widths of optical emission lines in AGN and their characteristic X-ray timescales, supporting the linkage.
Conclusions:
- Active galactic nuclei (AGN) are confirmed to be scaled-up versions of Galactic black hole systems.
- The accretion physics governing small and supermassive black holes are fundamentally the same.
- This unified understanding allows for the study of AGN behavior on cosmological timescales by observing Galactic systems.
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