Gas Disks and Supermassive Black Holes in Nearby Radio Galaxies

Gas Radial Velocity (km s -1 )
Gas Radial Velocity (km s -1 )
Gas Radial Velocity (km s -1 )
200
0
-200
-400
-600
200
0
-200
-400
-600
200
0
-200
-400
-600
NGC383 Central Slit: ∆v = 120 km s -1
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
-ve offset slit position
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
+ve offset slit position
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
Gas Radial Velocity (km s -1 )
Gas Radial Velocity (km s -1 )
200
0
-200
-400
-600
200
0
-200
-400
-600
NGC383 Central Slit: ∆v = 220 km s -1
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
-ve offset slit position
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
+ve offset slit position
-0.4 -0.2 0.0 0.2 0.4
Position along slit (arcsec)
Figure 4.25 The observed velocity profiles of NGC 383 for each of the three observed
slit positions: (left) offset by the velocity and slope calculated in §4.2.5 and (right)
with a velocity offset of 220 km s −1 , which provides a more meaningful fit (judged
by the author), extra power in the velocity field in the side slit position may result
from the nucleus lying off center across the width of the central slit. The velocities
are shown shaded according to the relative signal-to-noise of each spectrum, formal
errors from the fit are also indicated (see Chapter 3). The three solid lines show
model velocity profiles for no black hole, a 1 × 10 8 M⊙ black hole and a 9 × 10 8 M⊙
(the steeper lines from models with the greatest black hole mass). See text for details
of the models. The dashed vertical lines give a rough approximation of the radius of
influence of a black hole based on the mass estimate from the M• − σ relation and
the size of the random motions observed.
Gas Radial Velocity (km s -1 )
200
0
-200
-400
-600
212