# High significance detection of the tSZ effect relativistic corrections

## TL;DR

This paper reports the first high-significance detection of relativistic corrections to the tSZ effect, confirming its potential as a probe for galaxy cluster temperatures through spectral distortion analysis.

## Contribution

The study provides the first high-significance (5.3 sigma) detection of relativistic tSZ corrections using large galaxy cluster samples and spectral analysis.

## Key findings

- Detected relativistic tSZ corrections at 5.3 sigma significance.
- Confirmed consistency between tSZ spectral distortions and X-ray temperatures.
- Demonstrated tSZ spectral law as a tool for measuring galaxy cluster temperatures.

## Abstract

The thermal Sunyaev-Zel'dovich (tSZ) effect is produced by the interaction of cosmic microwave background (CMB) photons with the hot (a few keV) and diffuse gas of electrons inside galaxy clusters integrated along the line of sight. This effect produces a distortion of CMB blackbody emission law. This distortion law depends on the electronic temperature of the intra-cluster hot gas, $T_{e}$, through the so-called tSZ relativistic corrections. In this work, we have performed a statistical analysis of the tSZ spectral distortion on large galaxy cluster samples. We performed a stacking analysis for several electronic temperature bins, using both spectroscopic measurements of X-ray temperatures and a scaling relation between X-ray luminosities and electronic temperatures. We report the first high significance detection of the relativistic tSZ at a significance of 5.3 $\sigma$. We also demonstrate that the observed tSZ relativistic corrections are consistent with X-ray deduced temperatures. This measurement of the tSZ spectral law demonstrates that tSZ effect spectral distorsion can be used as a probe to measure galaxy cluster temperatures.