Morphology of the local volume

M. Kerscher¹ and A. Tikhonov²

¹ Mathematisches Institut, Ludwig-Maximilians-Universität, Theresienstrasse 39, 80333 München, Germany e-mail: kerscher@math.lmu.de
² Saint-Petersburg State University, Russian Federation e-mail: avtikh@gmail.com

Received: 20 April 2009
Accepted: 21 October 2009

Abstract

To study the global morphology of the galaxy distribution in our local neighbourhood we calculate the Minkowski functionals for a sequence of volume limited samples within a sphere of 8 Mpc centred on our galaxy. The well known strong clustering of the galaxies and the dominance of voids and coherent structures on larger scales is clearly visible in the Minkowski functionals. The morphology of the galaxy distribution changes with the limiting absolute magnitude. The samples, encompassing the more luminous galaxies, show emptier voids and more pronounced coherent structures. Indeed there is a prominent peak in the luminosity function of isolated galaxies for M_B≈ -14, which at least partly explains these morphological changes. We compare our date with halo samples from a ΛCDM simulation. Special care was taken to reproduce the observed local neighbourhood as well as the observed luminosity function in these mock samples. All in all the mock samples render the global morphology of the galaxy distribution quite well. However, the detailed morphological analysis reveals that real galaxies cluster stronger, the observed voids are emptier and the structures are more pronounced compared to the mock samples from the ΛCDM simulation.