Probing the Cosmological Principle with the CSST Photometric Survey

TL;DR

This study forecasts the detection of the kinematic dipole in galaxy distribution using the CSST photometric survey, providing a test for the cosmological principle by comparing large-scale structure with CMB measurements.

Contribution

It presents a method to reconstruct the kinematic dipole from mock galaxy counts and forecasts its detection significance with the upcoming CSST survey.

Findings

Detection of the dipole at 3 sigma confidence level.

Increased significance to 4 sigma using high-redshift data.

Provides a consistency check between CMB and large-scale structure dipoles.

Abstract

The cosmological principle states that our Universe is statistically homogeneous and isotropic at large scales. However, due to the relative motion of the Solar System, an additional kinematic dipole can be detected in the distribution of galaxies, which should be consistent with the dipole observed in the cosmic microwave background temperature. In this paper, we forecast the mock number count maps from the China Space Station Telescope photometric survey to reconstruct the kinematic dipole. Using the whole photometric mock data, we obtain a positive evidence for the dipole signal detection at 3 sigma confidence level, and the significance would be increased to 4 sigma when we only use the high-redshift samples with z = 1.8 to 4. This result can provide a good consistency check between the kinematic dipoles measured in the CMB and that from the large scale structure, which can help us to verify the basic cosmological principle.