Astronomy and Astrophysics, volume 438, 103-119 (2005/7-4)
The distance to Hydra and Centaurus from surface brightness fluctuations: Consequences for the Great Attractor model.
MIESKE S., HILKER M. and INFANTE L.
Abstract (from CDS):
We present I-band Surface Brightness Fluctuation (SBF) measurements for 16 early-type galaxies (3 giants, 13 dwarfs) in the central region of the Hydra cluster, based on deep photometric data in 7 fields obtained with VLT FORS1. From the SBF-distances to the galaxies in our sample we estimate the distance of the Hydra cluster to be 41.2±1.4Mpc ((m-M)=33.07±0.07mag). Based on an improved correction for fluctuations from undetected point sources, we revise the SBF-distance to the Centaurus cluster from Mieske & Hilker (2003A&A...410..445M
) upwards by 10% to 45.3±2.0Mpc ((m-M)=33.28±0.09mag). The relative distance modulus of the two clusters then is (m-M)Cen
=0.21 ±0.11mag. With H0
=72±4km/s/Mpc, we estimate a positive peculiar velocity of 1225±235km/s for Hydra and 210±295km/s for the Cen30 component of Centaurus. Allowing for a thermal velocity dispersion of 200km/s, this rules out a common peculiar flow velocity for both clusters at 98% confidence. We find that the 9x1015
``Great Attractor'' at a distance of ≃45Mpc can explain the observed peculiar velocities if shifted about 15° towards the Hydra cluster position. Our results are inconsistent at 94% confidence with a scenario where the Centaurus cluster is identical to the GA. In order to better restrict partially degenerate Great Attractor parameters like its mass and distance, a recalculation of the local flow model with updated distance information over a larger area than covered by us would be needed.
galaxies: clusters: individual: Hydra cluster - cosmology: large scale structure of Universe - galaxies: kinematics and dynamics - galaxies: distances and redshift - techniques: photometric
Tables 2, 4: numbering 'NNN' is not used in SIMBAD (numbering of the line in the [CZ2003] catalogue).
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