Issue |
A&A
Volume 410, Number 2, November I 2003
|
|
---|---|---|
Page(s) | 445 - 459 | |
Section | Cosmology (including clusters of galaxies) | |
DOI | https://doi.org/10.1051/0004-6361:20031296 | |
Published online | 17 November 2003 |
Distance to the Centaurus cluster and its subcomponents from surface brightness fluctuations*
1
Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
2
Departamento de Astronomía y Astrofísica, P. Universidad Católica, Casilla 104, Santiago 22, Chile
Corresponding author: S. Mieske, smieske@astro.puc.cl
Received:
19
May
2003
Accepted:
28
July
2003
We present I-band Surface Brightness Fluctuations (SBF) measurements for 15 early
type galaxies (3 giants, 12 dwarfs) in the central
region of the Centaurus cluster, based on deep photometric data in 7 fields obtained
with VLT FORS1 and with very good seeing.
From the SBF-distances to our sample galaxies we determine the distance of the
Centaurus cluster to be 41.3 ± 2.1 Mpc (33.08 ± 0.11 mag). This places
the Centaurus cluster at about the same distance as the “Great Attractor”.
We find a distance
difference of 0.27 ± 0.34 mag between the two subcomponents Cen 30 and Cen 45,
ruling out that both components
are separated by their
Hubble flow distance.
A distance difference of 0.48 ± 0.21 mag is found between
the central galaxies NGC 4696 (Cen 30) and NGC 4709 (Cen 45) of both components, supported by the different
turn-over magnitudes of their respective globular cluster systems. This suggests that
Cen 45 is falling into but has not yet reached Cen 30, supporting the idea of a large scale filament along the line
of sight towards Centaurus (Churazov et al. [CITE]). 83.0 ± 8.3 km s
Mpc-1
is obtained for
our Cen 30 sample
taking into account the peculiar motion of the Local Group into the direction of the Centaurus cluster.
This value of H0 corresponds to a much smaller Hubble flow distortion in the
direction of Centaurus than determined
by Tonry et al. ([CITE]), implying that the GA mass estimate
by Tonry et al. may be too high and/or that the Centaurus cluster falls into the GA almost
perpendicularly to the line of sight.
As our mean single measurement error is very
close to the measured distance scatter of the investigated galaxies, we can only derive an
upper limit of ±10 Mpc radial extension for the Centaurus cluster,
corresponding to a five times larger radial than tangential extension.
No evidence for an infall pattern into the Great Attractor is found within the uncertainties
for the 11 galaxies
with measured redshifts.
Key words: galaxies: clusters: individual: Centaurus cluster / galaxies: distances and redshift / techniques: photometric
© ESO, 2003
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