Death of the Immortal Molecular Cloud: Resolution Dependence of the Gas-Star Formation Relation Rules out Decoupling by Stellar Drift

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Main Authors: Kruijssen, J. M. Diederik, Chevance, Mélanie, Longmore, Steven N., Ginsburg, Adam, Ramambason, Lise, Romanelli, Andrea
Format: Preprint
Published: 2024
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author Kruijssen, J. M. Diederik
Chevance, Mélanie
Longmore, Steven N.
Ginsburg, Adam
Ramambason, Lise
Romanelli, Andrea
author_facet Kruijssen, J. M. Diederik
Chevance, Mélanie
Longmore, Steven N.
Ginsburg, Adam
Ramambason, Lise
Romanelli, Andrea
contents Recent observations have demonstrated that giant molecular clouds (GMCs) are short-lived entities, surviving for the order of a dynamical time before turning a few percent of their mass into stars and dispersing, leaving behind an isolated young stellar population. The key question has been whether this GMC dispersal actually marks a point of GMC destruction by stellar feedback from the new-born stars, or if GMCs might be `immortal' and only dynamically decouple from their nascent stars due to stellar drift. We address this question in six nearby galaxies, by quantifying how the gas-star formation relation depends on the spatial scale for scales between the GMC diameter and the GMC separation length, i.e. the scales where an excess of GMCs would be expected to be found in the stellar drift scenario. Our analysis reveals a consistent dearth of GMCs near young stellar populations regardless of the spatial scale, discounting the notion of `immortal' GMCs that decouple from their nascent stars through stellar drift. Instead, our findings demonstrate that stellar feedback destroys most GMCs at the end of their lifecycle. Employing a variety of statistical techniques to test both hypotheses, we find that the probability that stellar feedback concludes the GMC lifecycle is about 2,000 times higher than the probability that stellar drift separates GMCs and young stellar regions. This observation strengthens the emerging picture that galaxies consist of dynamic building blocks undergoing vigorous, feedback-driven lifecycles that collectively regulate star formation and drive the baryon cycle within galaxies.
format Preprint
id arxiv_https___arxiv_org_abs_2404_14495
institution arXiv
publishDate 2024
record_format arxiv
spellingShingle Death of the Immortal Molecular Cloud: Resolution Dependence of the Gas-Star Formation Relation Rules out Decoupling by Stellar Drift
Kruijssen, J. M. Diederik
Chevance, Mélanie
Longmore, Steven N.
Ginsburg, Adam
Ramambason, Lise
Romanelli, Andrea
Astrophysics of Galaxies
Recent observations have demonstrated that giant molecular clouds (GMCs) are short-lived entities, surviving for the order of a dynamical time before turning a few percent of their mass into stars and dispersing, leaving behind an isolated young stellar population. The key question has been whether this GMC dispersal actually marks a point of GMC destruction by stellar feedback from the new-born stars, or if GMCs might be `immortal' and only dynamically decouple from their nascent stars due to stellar drift. We address this question in six nearby galaxies, by quantifying how the gas-star formation relation depends on the spatial scale for scales between the GMC diameter and the GMC separation length, i.e. the scales where an excess of GMCs would be expected to be found in the stellar drift scenario. Our analysis reveals a consistent dearth of GMCs near young stellar populations regardless of the spatial scale, discounting the notion of `immortal' GMCs that decouple from their nascent stars through stellar drift. Instead, our findings demonstrate that stellar feedback destroys most GMCs at the end of their lifecycle. Employing a variety of statistical techniques to test both hypotheses, we find that the probability that stellar feedback concludes the GMC lifecycle is about 2,000 times higher than the probability that stellar drift separates GMCs and young stellar regions. This observation strengthens the emerging picture that galaxies consist of dynamic building blocks undergoing vigorous, feedback-driven lifecycles that collectively regulate star formation and drive the baryon cycle within galaxies.
title Death of the Immortal Molecular Cloud: Resolution Dependence of the Gas-Star Formation Relation Rules out Decoupling by Stellar Drift
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2404.14495