MegaZ-LRG: a photometric redshift catalogue of one million SDSS luminous red galaxies

ABSTRACT We estimate the constraining power of Javalambre-Physics of the Accelerated Universe Astrophysical Survey (J-PAS) for parameters of an interacting dark energy (DE) cosmology. The survey is expected to map several millions of luminous red galaxies, emission line galaxies, and quasars in an area of thousands of square degrees in the northern sky with precise photometric redshift measurements. Forecasts for the DESI and Euclid surveys are also evaluated and compared to J-PAS. Using the Fisher matrix approach, we find that J-PAS can place constraints on the interaction parameter comparable to those from DESI, with an absolute uncertainty of about 0.02, when the interaction term is proportional to the dark matter energy density, and almost as good, of about 0.01, when the interaction is proportional to the DE density. For the equation of state of DE, the constraints from J-PAS are slightly better in the two cases (uncertainties 0.04–0.05 against 0.05–0.07 around the fiducial value −1). Both surveys stay behind Euclid but follow it closely, imposing comparable constraints in all specific cases considered.

Download Full-text

A comparison of six photometric redshift methods applied to 1.5 million luminous red galaxies

Monthly Notices of the Royal Astronomical Society ◽

10.1111/j.1365-2966.2011.19375.x ◽

2011 ◽

Vol 417 (3) ◽

pp. 1891-1903 ◽

Cited By ~ 59

Author(s):

F. B. Abdalla ◽

M. Banerji ◽

O. Lahav ◽

V. Rashkov

Keyword(s):

Photometric Redshift ◽

Luminous Red Galaxies ◽

Red Galaxies

Download Full-text

The Clustering of DESI-like Luminous Red Galaxies Using Photometric Redshifts

Monthly Notices of the Royal Astronomical Society ◽

10.1093/mnras/staa3764 ◽

2020 ◽

Author(s):

Rongpu Zhou ◽

Jeffrey A Newman ◽

Yao-Yuan Mao ◽

Aaron Meisner ◽

John Moustakas ◽

...

Keyword(s):

Large Scale ◽

Model Fit ◽

Photometric Redshifts ◽

Photometric Redshift ◽

New Methods ◽

Luminous Red Galaxies ◽

A New Technique ◽

Red Galaxies ◽

Halo Occupation Distribution ◽

Best Fit

Abstract We present measurements of the redshift-dependent clustering of a DESI-like luminous red galaxy (LRG) sample selected from the Legacy Survey imaging dataset, and use the halo occupation distribution (HOD) framework to fit the clustering signal. The photometric LRG sample in this study contains 2.7 million objects over the redshift range of 0.4 < z < 0.9 over 5655 sq. degrees. We have developed new photometric redshift (photo-z) estimates using the Legacy Survey DECam and WISE photometry, with σNMAD = 0.02 precision for LRGs. We compute the projected correlation function using new methods that maximize signal-to-noise while incorporating redshift uncertainties. We present a novel algorithm for dividing irregular survey geometries into equal-area patches for jackknife resampling. For a 5-parameter HOD model fit using the MultiDark halo catalog, we find that there is little evolution in HOD parameters except at the highest-redshifts. The inferred large-scale structure bias is largely consistent with constant clustering amplitude over time. In an appendix, we explore limitations of MCMC fitting using stochastic likelihood estimates resulting from applying HOD methods to N-body catalogs, and present a new technique for finding best-fit parameters in this situation. Accompanying this paper we have released the PRLS (Photometric Redshifts for the Legacy Surveys) catalog of photo-z’s obtained by applying the methods used in this work to the full Legacy Survey Data Release 8 dataset. This catalog provides accurate photometric redshifts for objects with z < 21 over more than 16,000 square degrees of sky.

Download Full-text