Authors: Alister W. Graham
Abstract:
The residuals about the standard Mbh-σ relation
correlate with the effective radius, absolute magnitude, and Sersic
index of the host bulge — although, it is noted here that the
elliptical galaxies do not partake in such correlations. Moreover, it
is revealed that barred galaxies (with their relatively small, faint,
and low stellar concentration bulges) can deviate from the
Mbh-σ relation by δ(log Mbh) ≈ -0.5
to -1.0 dex (their σ values are too large) and generate much of
the aforementioned correlations. Removal of the seven barred galaxies
from the Tremaine et al. set of 31 galaxies gives a ``barless
Mbh-σ'' relation with an intrinsic scatter of 0.17
dex (cf. 0.27 dex for the 31 galaxies) and a total scatter of 0.25 dex
(cf. 0.34 dex for the 31 galaxies). The introduction of a third
parameter does not reduce the scatter. Furthermore, removal of the
barred galaxies, or all the disk galaxies, from an expanded and
updated set of 40 galaxies with direct black hole mass measurements
gives a consistent result, such that
log(Mbh/Msun) = (8.25±0.05) + (3.68±0.25)log
[σ/200 km s-1].
The (barless) σ-L relation for
galaxies with black hole mass measurements is found to be consistent
with that from the SDSS sample of early-type galaxies. In addition
the barless Mbh-σ relation, the Mbh-L
relation, and the Mbh-n relation are shown to yield SMBH
masses less than 2-4 x 109 Msun.