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Two Different Accretion Classes in Seyfert 1 Galaxies and QSOs.
The Astrophysical Journal
|October 27, 1999
Summary
Black hole accretion rates in Seyfert galaxies and QSOs correlate with X-ray spectral slopes. Two distinct classes, possibly advection-dominated accretion flow (ADAF) and thin disk accretion, are identified, confirmed by observations of galaxy 1H 0419-577.
Area of Science:
- Astrophysics
- High-energy astrophysics
Background:
- Central black hole masses in Seyfert galaxies and QSOs are measurable via broad emission lines and reverberation.
- Accretion rates are estimated using black hole mass and luminosity.
Purpose of the Study:
- To investigate the relationship between X-ray spectral slope and accretion rate in Seyfert galaxies and QSOs.
- To classify these objects based on their accretion properties.
Main Methods:
- Compiled a sample of Seyfert 1 galaxies and QSOs with known black hole masses, luminosities, and X-ray spectral slopes.
- Analyzed the correlation between X-ray spectral slope and accretion rate.
- Examined object distribution in the spectral index versus log(L_ion/L_Edd) plane.
Main Results:
- A strong correlation was found between X-ray spectral slope and accretion rate.
- Objects segregated into two distinct classes on the spectral index versus log(L_ion/L_Edd) plane.
- These classes potentially represent advection-dominated accretion flow (ADAF) and thin disk accretion.
Conclusions:
- The observed two-class distribution suggests different accretion flow modes in Seyfert galaxies and QSOs.
- Observations of the two-state galaxy 1H 0419-577 support these findings.
- Further spectral fitting with ADAF and thin disk models will refine this classification.