Measurement of the thermal Sunyaev-Zel'dovich effect around cosmic voids

TL;DR

This study detects the thermal Sunyaev-Zel'dovich effect around cosmic voids, indicating they are under-pressured, and compares the findings with models to understand the underlying physics.

Contribution

First detection of the tSZ effect around cosmic voids, providing insights into their pressure profiles and environmental effects.

Findings

Void regions are under-pressured relative to the cosmic mean.

Measured tSZ signal amplitude is slightly lower than model predictions.

Detection significance is 3.4 sigma.

Abstract

We stack maps of the thermal Sunyaev-Zel'dovich effect produced by the Planck Collaboration around the centers of cosmic voids defined by the distribution of galaxies in the CMASS sample of the Baryon Oscillation Spectroscopic Survey, scaled by the void effective radii. We report a first detection of the associated cross-correlation at the $3.4\sigma$ level: voids are under-pressured relative to the cosmic mean. We compare the measured Compton-$y$ profile around voids with a model based solely on the spatial modulation of halo abundance with environmental density. The amplitude of the detected signal is marginally lower than predicted by an overall amplitude $\alpha_v=0.67\pm0.2$. We discuss the possible interpretations of this measurement in terms of modelling uncertainties, excess pressure in low-mass halos, or non-local heating mechanisms.