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Isothermal Fragmentation: Is there a low-mass cut-off?

Guszejnov, Dávid and Hopkins, Philip F. and Grudić, Michael Y. and Krumholz, Mark R. and Federrath, Christoph (2018) Isothermal Fragmentation: Is there a low-mass cut-off? Monthly Notices of the Royal Astronomical Society, 480 (1). pp. 182-191. ISSN 0035-8711. http://resolver.caltech.edu/CaltechAUTHORS:20180913-133203850

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Abstract

The evolution of self-gravitating clouds of isothermal gas forms the basis of many star formation theories. Therefore it is important to know under what conditions such a cloud will undergo monolithic collapse into a single, massive object, or will fragment into a spectrum of smaller ones. And if it fragments, do initial conditions (e.g. Jeans mass, sonic mass) influence the mass function of the fragments, as predicted by many theories of star formation? In this paper we show that the relevant parameter separating monolithic collapse from fragmentation is not the Mach number of the initial turbulence (as suspected by many), but the infall Mach number M_(infall) ∼ √GM/(Rc^2_s ), equivalent to the number of Jeans masses in the initial cloud NJ. We also show that fragmenting clouds produce a power-law mass function with slopes close to the expected -2 (i.e. equal mass in all logarithmic mass intervals). However, the low-mass cut-off of this mass function is entirely numerical; the initial properties of the cloud have no effect on it. In other words, if M_(infall) ≫ 1, fragmentation proceeds without limit to masses much smaller than the initial Jeans mass.


Item Type:Article
Related URLs:
URLURL TypeDescription
https://doi.org/10.1093/mnras/sty1847DOIArticle
https://arxiv.org/abs/1804.08574arXivDiscussion Paper
ORCID:
AuthorORCID
Guszejnov, Dávid0000-0001-5541-3150
Hopkins, Philip F.0000-0003-3729-1684
Additional Information:© 2018 The Author(s) Published by Oxford University Press on behalf of the Royal Astronomical Society. This article is published and distributed under the terms of the Oxford University Press, Standard Journals Publication Model (https://academic.oup.com/journals/pages/about_us/legal/notices) Accepted 2018 July 6. Received 2018 July 5; in original form 2018 April 23. Support for PFH, MYG ,and DG was provided by an Alfred P. Sloan Research Fellowship, NASA ATP Grant NNX14AH35G, and NSF Collaborative Research Grant #1411920 and CAREER grant #1455342. Numerical calculations were run on the Caltech compute clusters ‘Zwicky’ (NSF MRI award # PHY-0960291) and ‘Wheeler’ and allocation TG-AST130039 granted by the Extreme Science and Engineering Discovery Environment (XSEDE) supported by the NSF. Parts of this research were supported by the Australian Research Council Centre of Excellence for All Sky Astrophysics in 3 Dimensions (ASTRO 3D), through project number CE170100013. CF acknowledges funding provided by the Australian Research Council’s Discovery Projects (grants DP150104329 and DP170100603), the ANU Futures Scheme, and the Australia-Germany Joint Research Cooperation Scheme (UA-DAAD).
Group:TAPIR
Funders:
Funding AgencyGrant Number
Alfred P. Sloan FoundationUNSPECIFIED
NASANNX14AH35G
NSFAST-1411920
NSFAST-1455342
NSFPHY-0960291
NSFTG-AST130039
Australian Research CouncilCE170100013
Australian Research CouncilDP150104329
Australian Research CouncilDP170100603
Australian National UniversityUNSPECIFIED
Australia-Germany Joint Research Cooperation Scheme (UA-DAAD)UNSPECIFIED
Subject Keywords:hydrodynamics, turbulence, stars: formation, cosmology: theory
Record Number:CaltechAUTHORS:20180913-133203850
Persistent URL:http://resolver.caltech.edu/CaltechAUTHORS:20180913-133203850
Official Citation:Dávid Guszejnov, Philip F Hopkins, Michael Y Grudić, Mark R Krumholz, Christoph Federrath; Isothermal Fragmentation: Is there a low-mass cut-off?, Monthly Notices of the Royal Astronomical Society, Volume 480, Issue 1, 11 October 2018, Pages 182–191, https://doi.org/10.1093/mnras/sty1847
Usage Policy:No commercial reproduction, distribution, display or performance rights in this work are provided.
ID Code:89624
Collection:CaltechAUTHORS
Deposited By: George Porter
Deposited On:13 Sep 2018 22:46
Last Modified:06 Feb 2019 18:43

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