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An uncertainty principle for star formation - I. Why galactic star formation relations break down below a certain spatial scale

Kruijssen, JMD and Longmore, SN (2014) An uncertainty principle for star formation - I. Why galactic star formation relations break down below a certain spatial scale. MONTHLY NOTICES OF THE ROYAL ASTRONOMICAL SOCIETY, 439 (4). pp. 3239-3252. ISSN 0035-8711

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Abstract

Galactic scaling relations between the (surface densities of) the gas mass and the star formation (SF) rate are known to develop substantial scatter or even change form when considered below a certain spatial scale. We quantify how this behaviour should be expected due to the incomplete statistical sampling of independent star-forming regions. Other included limiting factors are the incomplete sampling of SF tracers from the stellar initial mass function and the spatial drift between gas and stars. We present a simple uncertainty principle for SF, which can be used to predict and interpret the failure of galactic SF relations on small spatial scales. This uncertainty principle explains how the scatter of SF relations depends on the spatial scale and predicts a scale-dependent bias of the gas depletion time-scale when centring an aperture on gas or SF tracer peaks. We show how the scatter and bias are sensitive to the physical size and time-scales involved in the SF process (such as its duration or the molecular cloud lifetime), and illustrate how our formalism provides a powerful tool to constrain these largely unknown quantities. Thanks to its general form, the uncertainty principle can also be applied to other astrophysical systems, e.g. addressing the time evolution of star-forming cores, protoplanetary discs or galaxies and their nuclei.

Item Type: Article
Additional Information: This is a pre-copyedited, author-produced PDF of an article accepted for publication in Monthly Notices of the Royal Astronomical Society following peer review. The version of record "An uncertainty principle for star formation - I. Why galactic star formation relations break down below a certain spatial scale" is available online at http://dx.doi.org/10.1093/mnras/stu098
Uncontrolled Keywords: 0201 Astronomical And Space Sciences
Subjects: Q Science > QB Astronomy
Divisions: Astrophysics Research Institute
Publisher: OXFORD UNIV PRESS
Related URLs:
Date Deposited: 08 Jun 2016 07:47
Last Modified: 08 Jun 2016 07:47
DOI or Identification number: 10.1093/mnras/stu098
URI: http://researchonline.ljmu.ac.uk/id/eprint/3729

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