Description
Firmly establishing the conversion of gas into stars within molecular clouds is central to understanding how galaxies build up their stellar populations. The efficiency and rate of star formation depend strongly on the properties of molecular clouds, especially their mass and density. While current models capture broad trends, many clouds within and beyond our Galaxy show deviations from the expected relations between star-formation rate and gas density. A major challenge in improving star-formation models is the large uncertainty in measuring molecular cloud masses. Traditional probes of gas density, such as dust or molecular line emission, often yield inconsistent results depending on local environmental conditions. This limits our ability to test star formation models with confidence. In this talk, we will show how the inner 200 parsecs of the Milky Way, the Central Molecular Zone (CMZ), is a natural laboratory to address this problem. It contains some of the largest and most dense molecular clouds in the Galaxy, often under a broad range of physical conditions. Its proximity to Earth also allows for high-resolution observations and the detection of weak high-energy gamma-ray and neutrino signals produced when cosmic rays interact with interstellar gas. Since the cosmic ray distribution in the CMZ is well constrained by gamma-ray data, neutrino emission provides an independent and unbiased probe of the gas density. This can be used to calibrate traditional gas tracers and reduce their systematic uncertainties, enabling more robust and reliable tests of star formation models, both within our Galaxy and beyond.
