# Temperature and density dependent cooling function for H$_2$ with updated H$_2$/H collisional rates

## TL;DR

This paper presents updated calculations of the H$_2$ cooling function considering new collisional data and reactive pathways, crucial for understanding thermal processes in early Universe and low-metallicity environments.

## Contribution

It introduces a novel H$_2$ cooling function based on recent collisional data, explicitly including reactive pathways at low temperatures.

## Key findings

- Deviations from previous cooling function calculations.
- A multivariate fit for cooling rates depending on temperature and density.
- Enhanced understanding of gas thermal evolution in primordial environments.

## Abstract

The energy transfer among the components in a gas determines its fate. Especially at low temperatures, inelastic collisions drive the cooling and the heating mechanisms. In the early Universe as well as in zero- or low- metallicity environments the major contribution comes from the collisions among atomic and molecular hydrogen, also in its deuterated version. The present work shows some updated calculations of the H$_2$ cooling function based on novel collisional data which explicitely take into account the reactive pathway at low temperatures. Deviations from previous calculations are discussed and a multivariate data analysis is performed to provide a fit depending on both the gas temperature and the density of the gas.