# Radial Variations of the Volume- and Surface-Star Formation Laws in the Galaxy

## TL;DR

This study investigates how the star formation laws vary with galactic radius in the Milky Way, revealing that both the law's slope and efficiency change systematically from the inner to outer galaxy.

## Contribution

It provides the first detailed analysis of radial variations in the volume- and surface-star formation laws within our galaxy using 3D gas and star formation data.

## Key findings

- The star formation law's index is flatter in the inner galaxy.
- The star formation coefficient is higher in the inner galaxy and decreases outward.
- A mutual anti-correlation exists between the law's index and coefficient.

## Abstract

Variation of the volume- and surface-Schmidt laws (star-formation or SF law) with the galacto-centric distance R was investigated using 3D distributions of HII regions, HI, and molecular (H_2) gases in the Milky Way. Both the power-law index and SF coefficient were found to be variable with R. The index is flatter in the inner disc than in the outer Galaxy, and the coefficient is larger in the inner disc, decreasing steeply outward. There is also a mutual anti-correlation between the index and SF coefficient, and the SF law can be expressed by a single-parameter function of the SF coefficient. The variable SF law is discussed in relation to the self-regulation star formation.