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Mapping the core mass function to the initial mass function

Guszejnov, Dávid and Hopkins, Philip F. (2015) Mapping the core mass function to the initial mass function. Monthly Notices of the Royal Astronomical Society, 450 (4). pp. 4137-4149. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20151002-124114892

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Abstract

It has been shown that fragmentation within self-gravitating, turbulent molecular clouds (‘turbulent fragmentation’) can naturally explain the observed properties of protostellar cores, including the core mass function (CMF). Here, we extend recently developed analytic models for turbulent fragmentation to follow the time-dependent hierarchical fragmentation of self-gravitating cores, until they reach effectively infinite density (and form stars). We show that turbulent fragmentation robustly predicts two key features of the initial mass function (IMF). First, a high-mass power-law scaling very close to the Salpeter slope, which is a generic consequence of the scale-free nature of turbulence and self-gravity. We predict the IMF slope (−2.3) is slightly steeper than the CMF slope (−2.1), owing to the slower collapse and easier fragmentation of large cores. Secondly, a turnover mass, which is set by a combination of the CMF turnover mass (a couple solar masses, determined by the ‘sonic scale’ of galactic turbulence, and so weakly dependent on galaxy properties), and the equation of state (EOS). A ‘soft’ EOS with polytropic index γ < 1.0 predicts that the IMF slope becomes ‘shallow’ below the sonic scale, but fails to produce the full turnover observed. An EOS, which becomes ‘stiff’ at sufficiently low surface densities Σgas ∼ 5000 M_⊙ pc^(−2), and/or models, where each collapsing core is able to heat and effectively stiffen the EOS of a modest mass (∼0.02 M_⊙) of surrounding gas, are able to reproduce the observed turnover. Such features are likely a consequence of more detailed chemistry and radiative feedback.


Item Type:Article
Related URLs:
URLURL TypeDescription
http://dx.doi.org/10.1093/mnras/stv872DOIArticle
http://mnras.oxfordjournals.org/content/450/4/4137PublisherArticle
http://arxiv.org/abs/1411.2979arXivDiscussion Paper
ORCID:
AuthorORCID
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2015 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2015 April 17. Received 2015 April 2. In original form 2014 November 11. First published online May 20, 2015. We thank Ralf Klessen and Mark Krumholz for inspirational conversations throughout the development of this work. Support for PFH and DG was provided by the Gordon and Betty Moore Foundation through Grant 776 to the Caltech Moore Center for Theoretical Cosmology and Physics, an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant 1411920. Numerical calculations were run on the Caltech computer cluster ‘Zwicky’ (NSF MRI award PHY-0960291) and allocation TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF.
Group:TAPIR, Moore Center for Theoretical Cosmology and Physics
Funders:
Funding AgencyGrant Number
Gordon and Betty Moore Foundation776
Alfred P. Sloan FoundationUNSPECIFIED
NASANNX14AH35G
NSFAST-1411920
NSFPHY-0960291
NSFTG-AST130039
Subject Keywords:stars formation; galaxies: active; galaxies: evolution; galaxies: formation; cosmology: theory
Record Number:CaltechAUTHORS:20151002-124114892
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20151002-124114892
Official Citation:Dávid Guszejnov and Philip F. Hopkins Mapping the core mass function to the initial mass function MNRAS (July 11, 2015) Vol. 450 4137-4149 doi:10.1093/mnras/stv872 First published online May 20, 2015
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:60724
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:02 Oct 2015 20:00
Last Modified:17 Aug 2017 19:46

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