Galaxy And Mass Assembly (GAMA): colour and luminositydependent clustering from calibrated photometric redshifts
Abstract
We measure the twopoint angular correlation function of a sample of 4289 223 galaxies with r < 19.4 mag from the Sloan Digital Sky Survey (SDSS) as a function of photometric redshift, absolute magnitude and colour down to M_{r}  5 log h = 14 mag. Photometric redshifts are estimated from ugriz model magnitudes and two Petrosian radii using the artificial neural network package ANNz, taking advantage of the Galaxy And Mass Assembly (GAMA) spectroscopic sample as our training set. These photometric redshifts are then used to determine absolute magnitudes and colours. For all our samples, we estimate the underlying redshift and absolute magnitude distributions using Monte Carlo resampling. These redshift distributions are used in Limber's equation to obtain spatial correlation function parameters from powerlaw fits to the angular correlation function. We confirm an increase in clustering strength for subL* red galaxies compared with ∼L* red galaxies at small scales in all redshift bins, whereas for the blue population the correlation length is almost independent of luminosity for ∼L* galaxies and fainter. A linear relation between relative bias and log luminosity is found to hold down to luminosities L ∼ 0.03L*. We find that the redshift dependence of the bias of the L* population can be described by the passive evolution model of Tegmark & Peebles. A visual inspection of a random sample from our r < 19.4 sample of SDSS galaxies reveals that about 10 per cent are spurious, with a higher contamination rate towards very faint absolute magnitudes due to overdeblended nearby galaxies. We correct for this contamination in our clustering analysis.
 Publication:

Monthly Notices of the Royal Astronomical Society
 Pub Date:
 September 2012
 DOI:
 10.1111/j.13652966.2012.21434.x
 arXiv:
 arXiv:1206.0943
 Bibcode:
 2012MNRAS.425.1527C
 Keywords:

 techniques: photometric;
 surveys;
 galaxies: distances and redshifts;
 galaxies: statistics;
 largescale structure of Universe;
 Astrophysics  Cosmology and Nongalactic Astrophysics
 EPrint:
 23 pages, 19 figures and 7 tables, MNRAS, in press