Site Map
Contacts
Follow us on Facebook Follow us on Twitter YouTube channel
Centro de Astrofísica da Universidade do Porto

The VIMOS-VLT Deep Survey: Evolution in the Halo Occupation Number since z ∼ 1

U. Abbas, S. de la Torre, O. Le Fèvre, L. Guzzo, C. Marinoni, B. Meneux, A. Pollo, G. Zamorani, D. Bottini, B. Garilli, V. Le Brun, D. Maccagni, R. Scaramella, M. Scodeggio, L. Tresse, G. Vettolani, A. Zanichelli, C. Adami, S. Arnouts, S. Bardelli, M. Bolzonella, A. Cappi, S. Charlot, P. Ciliegi, T. Contini, S. Foucaud, P. Franzetti, I. Gavignaud, O. Ilbert, A. Iovino, F. Lamareille, H. J. McCracken, B. Marano, A. Mazure, R. Merighi, S. Paltani, R. Pellò, L. Pozzetti, M. Radovich, D. Vergani, E. Zucca, M. Bondi, A. Bongiorno, J. Brinchmann, O. Cucciati, L. de Ravel, L. Gregorini, E. Pérez-Montero, Y. Mellier, P. Merluzzi

Abstract
We model the evolution of the mean galaxy occupation of dark-matter halos over the range 0.1 < z < 1.3, using the data from the VIMOS-VLT Deep Survey (VVDS). The galaxy projected correlation function wp(rp) was computed for a set of luminosity-limited subsamples and fits to its shape were obtained using two variants of halo occupation distribution (HOD) models. These provide us with a set of best-fitting parameters, from which we obtain the average mass of a halo and average number of galaxies per halo. We find that after accounting for the evolution in luminosity and assuming that we are largely following the same population, the underlying dark matter halo shows a growth in mass with decreasing redshift as expected in a hierarchical structure formation scenario. Using two different HOD models, we see that the halo mass grows by 90 % over the redshift interval z=[0.5,1.0]. This is the first time the evolution in halo mass at high redshifts has been obtained from a single data survey and it follows the simple form seen in N-body simulations with M(z) = M0e-βz, and β = 1.3±0.30. This provides evidence for a rapid accretion phase of massive halos having a present-day mass M0 ∼ 1013.5h-1M, with a m > 0.1M0 merger event occuring between redshifts of 0.5 and 1.0. Futhermore, we find that more luminous galaxies are found to occupy more massive halos irrespectively of the redshift. Finally, the average number of galaxies per halo shows little increase from redshift z∼ 1.0 to z∼ 0.5, with a sharp increase by a factor ∼3 from z∼ 0.5 to z∼ 0.1, likely due to the dynamical friction of subhalos within their host halos.

Keywords
methods: statistical - galaxies: high-redshift - large-scale structure of universe

Notes
Based on data obtained with the European Southern Observatory Very Large Telescope, Paranal, Chile, program 070.A-9007(A), and on data obtained at the Canada-France-Hawaii-Telescope, operated by the CNRS of France, CNRC in Canada and the University of Hawaii.

Monthly Notices of the Royal Astronomical Society
Volume 406, Page 1306
August 2010

>> PDF>> ADS>> DOI

Institute of Astrophysics and Space Sciences

Institute of Astrophysics and Space Sciences (IA) is a new but long anticipated research infrastructure with a national dimension. It embodies a bold but feasible vision for the development of Astronomy, Astrophysics and Space Sciences in Portugal, taking full advantage and fully realizing the potential created by the national membership of the European Space Agency (ESA) and the European Southern Observatory (ESO). IA resulted from the merging the two most prominent research units in the field in Portugal: the Centre for Astrophysics of the University of Porto (CAUP) and the Center for Astronomy and Astrophysics of the University of Lisbon (CAAUL). It currently hosts more than two-thirds of all active researchers working in Space Sciences in Portugal, and is responsible for an even greater fraction of the national productivity in international ISI journals in the area of Space Sciences. This is the scientific area with the highest relative impact factor (1.65 times above the international average) and the field with the highest average number of citations per article for Portugal.

Proceed on CAUP's website|Go to IA website