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

The 2dF QSO Redshift Survey- XV. Correlation analysis of redshift-space distortions

J. da Ângela, P. J. Outram, T. Shanks, B. J. Boyle, S. M. Croom, N. S. Loaring, L. Miller, R. J. Smith

Abstract
We analyse the redshift-space (z-space) distortions of quasi-stellar object (QSO) clustering in the 2-degree field instrument (2dF) QSO Redshift Survey (2QZ). To interpret the z-space correlation function, ξ(σ, π), we require an accurate model for the QSO real-space correlation function, ξ(r). Although a single power-law ξ(r) ~r model fits the projected correlation function [wp(σ)] at small scales, it implies somewhat too shallow a slope for both wp(σ) and the z-space correlation function, ξ(s), at larger scales (>~20h-1Mpc). Motivated by the form for ξ(r) seen in the 2dF Galaxy Redshift Survey (2dFGRS) and in standard Λ cold dark matter (CDM) predictions, we use a double power-law model for ξ(r), which gives a good fit to ξ(s) and wp(σ). The model is parametrized by a slope of γ= 1.45 for 1 < r < 10h-1Mpc and γ= 2.30 for 10 < r < 40h-1Mpc. As found for the 2dFGRS, the value of β determined from the ratio of ξ(s)/ξ(r) depends sensitively on the form of ξ(r) assumed. With our double power-law form for ξ(r), we measure β(z= 1.4) = 0.32+0.09-0.11. Assuming the same model for ξ(r), we then analyse the z-space distortions in the 2QZ ξ(σ, π) and put constraints on the values of Ω0m and β(z= 1.4), using an improved version of the method of Hoyle et al. The constraints we derive are Ω0m= 0.35+0.19-0.13, β(z= 1.4) = 0.50+0.13-0.15, in agreement with our ξ(s)/ξ(r) results at the ~1σ level.

Monthly Notices of the Royal Astronomical Society
Volume 360, Page 1040
July 2005

>> PDF>> ADS

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