2017/07/04 by Shadab Alam, Rupert A. C. Croft, Shirley Ho +2 · 1 citation
Physics and Astronomy · #Astronomy #Astrophysics #Cosmology and Gravitation Theories #Galaxies: Formation, Evolution, Phenomena #Galaxy #Gamma-ray bursts and supernovae #Photometry (optics) #Physics #Redshift #Redshift survey #Sky #Stars #astro-ph.CO #astro-ph.GA #gr-qc #physics.pop-ph
paper · pdf · doi:10.1093/mnras/stx1684
11 pages, 8 figures, published in MNRAS, see link for a combined video summary of this and three other related papers posted today: https://youtu.be/nESs6jsXBCs . An elementary introduction to gravitational redshift is here: https://youtu.be/6tbCk_4Tk10
openalex publication_date 2017/07/04 · arxiv created 2017/09/22 · arxiv updated 2017/09/25 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/06
In a galaxy redshift survey, the objects to be targeted for spectra are selected from a photometrically observed sample. The observed magnitudes and colours of galaxies in this parent sample will be affected by their peculiar velocities, through relativistic Doppler and relativistic beaming effects. In this paper, we compute the resulting expected changes in galaxy photometry. The magnitudes of the relativistic effects are a function of redshift, stellar mass, galaxy velocity and velocity direction. We focus on the CMASS sample from the Sloan Digital Sky Survey (SDSS) and Baryon Oscillation Spectroscopic Survey (BOSS), which is selected on the basis of colour and magnitude. We find that 0.10 per cent of the sample (∼585 galaxies) has been scattered into the targeted region of colour–magnitude space by relativistic effects, and conversely 0.09 per cent of the sample (∼532 galaxies) has been scattered out. Observational consequences of these effects include an asymmetry in clustering statistics, which we explore in a companion paper. Here, we compute a set of weights that can be used to remove the effect of modulations introduced into the density field inferred from a galaxy sample. We conclude by investigating the possible effects of these relativistic modulation on large-scale clustering of the galaxy sample.