Planck ISW-lensing likelihood and the CMB temperature

TL;DR

This paper introduces a new Planck likelihood for CMB lensing and temperature cross-correlation, enabling improved constraints on the ISW effect and the CMB background temperature using Planck data.

Contribution

It presents the first public Planck likelihood for ISW-lensing cross-correlation, enhancing cosmological parameter constraints from CMB data.

Findings

Constrained the CMB background temperature using the new likelihood.

Demonstrated the likelihood's effectiveness in breaking geometric degeneracy.

Improved cosmological constraints compared to previous methods.

Abstract

We present a new Planck CMB lensing-CMB temperature cross-correlation likelihood that can be used to constrain cosmology via the Integrated Sachs-Wolfe (ISW) effect. CMB lensing is an excellent tracer of ISW, and we use the latest PR4 Planck data maps and lensing reconstruction to produce the first public Planck likelihood to constrain this signal. We demonstrate the likelihood by constraining the CMB background temperature from Planck data alone, where the ISW-lensing cross-correlation is a powerful way to break the geometric degeneracy, substantially improving constraints from the CMB and lensing power spectra alone.