The distance to Hydra and Centaurus from surface brightness fluctuations: Consequences for the Great Attractor model

Free access article

Issue		A&A Volume 438, Number 1, July IV 2005


Page(s)		103 - 119
Section		Extragalactic astronomy
DOI		http://dx.doi.org/10.1051/0004-6361:20041583

A&A 438, 103-119 (2005)
DOI: 10.1051/0004-6361:20041583

The distance to Hydra and Centaurus from surface brightness fluctuations: Consequences for the Great Attractor model

S. Mieske^{1, 2}, M. Hilker¹ and L. Infante²

¹ Sternwarte der Universität Bonn, Auf dem Hügel 71, 53121 Bonn, Germany
e-mail: smieske@astro.uni-bonn.de
² Departamento de Astronomía y Astrofísica, P. Universidad Católica, Casilla 104, Santiago 22, Chile

(Received 2 July 2004 / Accepted 29 March 2005)

Abstract
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 $\pm$ 1.4 Mpc ((m-M)=33.07 $\pm$ 0.07 mag). Based on an improved correction for fluctuations from undetected point sources, we revise the SBF-distance to the Centaurus cluster from Mieske & Hilker (2003, A&A, 410, 455) upwards by 10% to 45.3 $\pm$ 2.0 Mpc ((m-M)=33.28 $\pm$ 0.09 mag). The relative distance modulus of the two clusters then is $(m-M)_{\rm Cen}-(m-M)_{\rm Hyd}=0.21 \pm 0.11$ mag. With $H_{\rm0}=$ 72 $\pm$ 4 km s^-1 Mpc^-1, we estimate a positive peculiar velocity of 1225 $\pm$ 235 km s^-1 for Hydra and 210 $\pm$ 295 km s^-1 for the Cen30 component of Centaurus. Allowing for a thermal velocity dispersion of 200 km s^-1, this rules out a common peculiar flow velocity for both clusters at 98% confidence. We find that the $9\times 10^{15}\; M_{\odot}$ "Great Attractor" at a distance of $\simeq$ 45 Mpc can explain the observed peculiar velocities if shifted about 15 $\degr$ 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.

Key words: galaxies: clusters: individual: Hydra cluster -- cosmology: large scale structure of Universe -- galaxies: kinematics and dynamics -- galaxies: distances and redshift -- techniques: photometric

SIMBAD Objects

What is OpenURL?

The OpenURL standard is a protocol for transmission of metadata describing the resource that you wish to access. An OpenURL link contains article metadata and directs it to the OpenURL server of your choice. The OpenURL server can provide access to the resource and also offer complementary services (specific search engine, export of references...). The OpenURL link can be generated by different means.

If your librarian has set up your subscription with an OpenURL resolver, OpenURL links appear automatically on the abstract pages.
You can define your own OpenURL resolver with your EDPS Account. In this case your choice will be given priority over that of your library.
You can use an add-on for your browser (Firefox or I.E.) to display OpenURL links on a page (see http://www.openly.com/openurlref/). You should disable this module if you wish to use the OpenURL server that you or your library have defined.