Seyfert galaxies

Seen with visible light, these are fairly ordinary spiral galaxies. But they have unusual properties in their cores.

What is the energy source?

Recall that there is some evidence of a supermassive black hole at the center of our Galaxy. Let's look at what theory predicts for such an oject with its accretion disk.

Maybe there is a ``supermassive'' black hole at the center of a Seyfert Galaxy.

What we see is lots of energy that isn't from stars, coming from a small region, with fast moving gas. It all fits.

Suggested masses are 106 to 109 solar masses.

Energy production

Calculations indicate that accretion onto a black hole should be a pretty efficient energy source. Of the total energy m c2 of a mass m of gas, something like 10% would be radiated away. (The rest would go into increasing the mass of the black hole.) The black hole would have to eat 0.1 Msun per year to produce 1038 W of power (10 LMW).

Davison E. Soper, Institute of Theoretical Science, University of Oregon, Eugene OR 97403 USA