Probing the rest-frame of the Universe with near-IR cosmic infrared background

TL;DR

This paper proposes a new method to measure the kinematic nature of the near-IR cosmic infrared background dipole, helping to distinguish between primordial and kinematic contributions to the CMB dipole using upcoming space surveys.

Contribution

It introduces a technique to accurately measure the near-IR CIB dipole by reconstructing galaxy light from resolved galaxies in future wide surveys, isolating the kinematic component.

Findings

The method can achieve high S/N measurements of the CIB dipole in upcoming surveys.

It enables differentiation between primordial and kinematic dipole contributions.

The approach accounts for galaxy clustering and foreground emissions.

Abstract

While the cosmic microwave background (CMB) dipole is largely assumed entirely kinematic, there appears evidence that a part of it is primordial. Such possibility arises in models implying a tilt, interpreted as a dark flow, across the observable Universe. The kinematic nature of the entire CMB dipole can be probed using the dipole of cosmic backgrounds from galaxies after the last scattering. The near-IR cosmic infrared background (CIB) spectral energy distribution leads to an amplified dipole compared to the CMB. The CIB dipole is affected by galaxy clustering, decreasing with fainter, more distant galaxies, and by Solar System emissions and Galactic dust, which dominate the net CIB cosmological dipole in the optical/near-IR. We propose a technique that enables an accurate measurement of the kinematic near-IR CIB dipole. The CIB, effectively the integrated galaxy light (IGL), would be reconstructed from resolved galaxies in the forthcoming space-borne wide surveys covering four bands 0.9 to 2.5 micron. The galaxies will be sub-selected from the identified magnitude range where the dipole component from galaxy clustering is below the expected kinematic dipole. Using this technique the dipole can be measured in each of the bands at the statistical signal-to-noise S/N>50--100 with the forthcoming Euclid and Roman surveys, isolating CMB dipole's kinematic nature.