For refcode 1998MNRAS.295..933G: Retrieve 36 NED objects in this reference. Please click here for ADS abstract
NED Abstract
Copyright by Royal Astronomical Society.
1998MNRAS.295..933G
Some effects of galaxy structure and dynamics on the Fundamental
Plane  II. A VirgoFornax distance modulus
Alister W. Graham
Accepted 1997 December 1. Received 1997 November 12; in original form
1997 June 5
ABSTRACT
The influence of broken structural homology, and the implied broken
dynamical homology, is examined for the Fundamental Plane (FP). Requiring
a symmetrical treatment of the FP variables, a bisector method of linear
regression was applied, in three dimensions, to derive the best FP. A
bootstrapping procedure has been used to estimate the uncertainties
associated with the slope of the FP. For 25 E and S0 Virgo galaxies, the
`standard' FP, constructed using R^1/4^ model parameters for the
effective radii (R_e,4_) and the mean surface brightness within this
radius ({SIGMA}_e,4_) and using central velocity dispersion (CVD)
measurements ({sigma}_0_), gave a relation described by
R_e,4_ is proportional to {sigma}_0_^1.10+/0.14^{SIGMA}_e,4_^0.55+/
0.009^. Using Sersic R^1/n^ lightprofile model parameters and the
projected infiniteaperture velocity dispersion ({sigma}_tot,n_), derived
from application of the Jeans equation to the observed intensity
profiles, gave an `improved' FP described by the relation R_e,n_ is
proportional to {sigma}_tot,n_^1.37+/0.16{SIGMA}_e,n_^0.76+/0.05^.
This result, based on independent data, supports the previous finding by
Graham & Colless that assumptions of structural and dynamical homology
are partly responsible for the departure of the observed FP from the
plane expected by the virial theorem, which predicts R is proportional to
{sigma}^2^{SIGMA}^1^. Upon removal of the known S0 galaxies from the
sample of Virgo galaxies, the above planes were observed to change to
R_e,4_ is proportional to {sigma}_0_^1.19+/0.21^{SIGMA}_e,4_^0.60+/
.11^ and R_e,n_ is proportional to {sigma}_tot,n_^1.72+/
0.24^{SIGMA}_e,n_^0.74+/0.09. The perpendicular rms residuals about
these planes are 0.084 and 0.050 dex, respectively.
The Fornax cluster was similarly treated, although removal of the S0
galaxies left a sample of only seven ellipticals that had published CVD
measurements. Treating the range of structural and dynamical profiles
present in this sample produced a FP given by the relation R_e,n_ is
proportional to {sigma}_tot,n_^2.03+/0.78{SIGMA}_e,n_^1.07+/0.30^, in
tantalizing agreement with the plane expected from the virial theorem,
but with discouragingly large errors caused by the small sample size.
Similarly to Virgo, the perpendicular rms residual about this plane is
0.050 dex.
The FP was also constructed with the purpose of using it as a distance
indicator, achieved by minimizing the distancedependent quantity log R
against the distanceindependent quantities {SIGMA} and log {sigma}. A
VirgoFornax distance modulus was computed using WorkingHotelling
confidence bands. The `standard' FP parameters gave a value of 0.45+/
0.16 mag, whereas the `improved' FP parameters gave a value of 0.25 +/
0.12 mag. However, a full treatment of the uncertainties on the FP
slopes, derived through a bootstrapping procedure of the three
dimensional FP data set, revealed that the analytical expressions for the
uncertainties on the estimated distance moduli given above should be
increased by a factor of ~5.
Key words: galaxies: elliptical and lenticular, cD  galaxies:
fundamental parameters  galaxies: kinematics and dynamics  galaxies:
structure  distance scale.
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