AGN accretion

AGN accretion is of research interest, studied through observing quasars, Seyfert galaxies, and radio galaxies. Observations show variations in characteristics between different AGNs as well as variations of an AGN over time. These are attributed to the material being accreted (the amount, type, and temperature), and some to our viewing angle. Some terms:

• alpha disk (aka thin disk, accreting material on the order of\ 10⁴-10⁷ K).
• advection dominated accretion flow (ADAF) (hotter material: can be MAD or SANE).
• standard and normal evolution (SANE).
• magnetically arrested disk (MAD).
• slim disk (like alpha disk, but super-Eddington accretion).
• cold disk accretion (accretion via alpha disk).
• hot disk accretion (means ADAF).

Some of these models can also apply to circumstellar disks.