Modeling The Pollution Of Pristine Gas In The Early Universe

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dc.contributor.utaustinauthorScalo, Johnen_US
dc.creatorPan, Lubin B.en_US
dc.creatorScannapieco, Evanen_US
dc.creatorScalo, Johnen_US
dc.date.accessioned2016-04-28T19:35:17Z
dc.date.available2016-04-28T19:35:17Z
dc.date.issued2013-10en
dc.description.abstractWe conduct a comprehensive theoretical and numerical investigation of the pollution of pristine gas in turbulent flows, designed to provide useful new tools for modeling the evolution of the first generation of stars. The properties of such Population III (Pop III) stars are thought to be very different than those of later stellar generations, because cooling is dramatically different in gas with a metallicity below a critical value Z(c), which lies between similar to 10(-6) and similar to 10(-3) Z(circle dot). The critical value is much smaller than the typical overall average metallicity, < Z >, and therefore the mixing efficiency of the pristine gas in the interstellar medium plays a crucial role in determining the transition from Pop III to normal star formation. The small critical value, Z(c), corresponds to the far left tail of the probability distribution function (PDF) of the metal abundance. Based on closure models for the PDF formulation of turbulent mixing, we derive evolution equations for the fraction of gas, P, lying below Z(c), in statistically homogeneous compressible turbulence. Our simulation data show that the evolution of the pristine fraction P can be well approximated by a generalized "self-convolution" model, which predicts that (P) over dot = -(n/tau(con))P(1 - P-1/n), where n is a measure of the locality of the mixing or PDF convolution events and the convolution timescale tau(con) is determined by the rate at which turbulence stretches the pollutants. Carrying out a suite of numerical simulations with turbulent Mach numbers ranging from M = 0.9 to 6.2, we are able to provide accurate fits to n and tau(con) as a function of M, Z(c)/< Z >, and the length scale, L-p, at which pollutants are added to the flow. For pristine fractions above P = 0.9, mixing occurs only in the regions surrounding blobs of pollutants, such that n = 1. For smaller values of P, n is larger as the mixing process becomes more global. We show how these results can be used to construct one-zone models for the evolution of Pop III stars in a single high-redshift galaxy, as well as subgrid models for tracking the evolution of the first stars in large cosmological numerical simulations.en_US
dc.description.departmentAstronomyen_US
dc.description.sponsorshipNASA NNX09AD106en_US
dc.description.sponsorshipAstrobiology Institute 08-NAI5-0018en_US
dc.description.sponsorshipNational Science Foundation AST 11-03608en_US
dc.description.sponsorshipDOE ASC/Alliancesen_US
dc.identifierdoi:10.15781/T2SZ4C
dc.identifier.Filename2013_10_modelingpollution.pdfen_US
dc.identifier.citationPan, Liubin, Evan Scannapieco, and Jon Scalo. "Modeling the Pollution of Pristine Gas in the Early Universe." The Astrophysical Journal, Vol. 775, No. 2 (Oct., 2013): 111.en_US
dc.identifier.doi10.1088/0004-637x/775/2/111en_US
dc.identifier.issn0004-637Xen_US
dc.identifier.urihttp://hdl.handle.net/2152/34828
dc.language.isoEnglishen_US
dc.relation.ispartofen_US
dc.relation.ispartofserialAstrophysical Journalen_US
dc.rightsAdministrative deposit of works to Texas ScholarWorks: This works author(s) is or was a University faculty member, student or staff member; this article is already available through open access or the publisher allows a PDF version of the article to be freely posted online. The library makes the deposit as a matter of fair use (for scholarly, educational, and research purposes), and to preserve the work and further secure public access to the works of the University.en_US
dc.rights.restrictionOpenen_US
dc.subjectdark ages, reionization, first starsen_US
dc.subjectevolutionen_US
dc.subjectgalaxies:en_US
dc.subjecthigh-redshiften_US
dc.subjectism: abundancesen_US
dc.subjectstars: population iiien_US
dc.subjectturbulenceen_US
dc.subjectlarge-eddy-simulationen_US
dc.subjectpopulation-iii starsen_US
dc.subjectturbulent reacting flowsen_US
dc.subjectinitial mass functionen_US
dc.subjectsubgrid-scale-modelen_US
dc.subjectextremely metal-pooren_US
dc.subjectgalactic 1st starsen_US
dc.subjectly-alpha emittersen_US
dc.subjectcompressible turbulenceen_US
dc.subjectinterstellar-mediumen_US
dc.subjectastronomy & astrophysicsen_US
dc.titleModeling The Pollution Of Pristine Gas In The Early Universeen_US
dc.typeArticleen_US

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