Galaxy clustering using photometric redshifts

TL;DR

This study analyzes galaxy clustering evolution over a broad redshift range using photometric redshifts, revealing stable correlation function parameters and increasing bias with redshift, based on a large galaxy sample.

Contribution

First comprehensive analysis of galaxy two-point correlation function evolution at z > 1.5 using photometric redshifts over a large dataset.

Findings

Correlation function parameters are stable across redshifts.

Bias factor increases from 1.1-1.2 locally to 3-3.5 at high redshift.

Luminous galaxies have steeper correlation slopes.

Abstract

We investigate the evolution of the galaxy two point correlation function (CF) over a wide redshift range, 0.2 < z < 3. For the first time the systematic analysis covers the redshifts above 1 - 1.5. The catalogue of ~250000 galaxies with i+ < 25 and known photometric redshifts in the Subaru Deep field is used. The galaxies are divided into three luminosity classes and several distance/redshift bins. First, the 2D CF is determined for each luminosity class and distance bin. Calculations are based on the quantitative differences between the surface distributions of galaxy pairs with comparable and distinctly different photometric redshifts. The power law approximation for the CF is used. A limited accuracy of photometric redshifts as compared to the spectroscopic ones has been examined and taken into account. Then, the 3D functions for all the selected luminosities and distances are calculated. The power-law parameters of the CF, the slope and the correlation length, are determined. Both parameters do not show strong variations over the whole investigated redshift range. The slope of the luminous galaxies appears to be consistently steeper than that for the fainter ones. The linear bias factor, b(z), grows systematically with redshift; assuming the local normalization b(0) = 1.1-1.2, the bias reaches 3 - 3.5 at the high redshift limit.