9
Different Views of the Accretion Disk
The
torus of gas and dust can block part of our view
•Seyfert
2 galaxies: Edge on view
Only gas well above and below disk is visible
See only “slow” gas Þ narrow emission lines
Only gas well above and below disk is visible
See only “slow” gas Þ narrow emission lines
•Seyfert
1 galaxies: Slightly tilted
view
Hot high velocity gas close to black hole is visible
High velocities Þ broad emission lines
Hot high velocity gas close to black hole is visible
High velocities Þ broad emission lines
•BL
Lac objects: Pole on view
Looking right down the jet at central region
Extremely bright – vary on time scales of hours
Looking right down the jet at central region
Extremely bright – vary on time scales of hours
•Quasars: Very active AGN at large distances
Can barely make out the galaxy surrounding them
Were apparently more common in distant past
Can barely make out the galaxy surrounding them
Were apparently more common in distant past
From our text: Horizons, by Seeds