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dc.contributor.authorZonoozi, Akram Hasani
dc.contributor.authorLieberz, Patrick
dc.contributor.authorBanik, Indranil
dc.contributor.authorHaghi, Hosein
dc.contributor.authorKroupa, Pavel
dc.identifier.citationZonoozi , A H , Lieberz , P , Banik , I , Haghi , H & Kroupa , P 2021 , ' The Kennicutt-Schmidt law and the main sequence of galaxies in Newtonian and Milgromian dynamics ' , Monthly Notices of the Royal Astronomical Society , vol. 506 , no. 4 , pp. 5468-5478 .
dc.identifier.otherORCID: /0000-0002-4123-7325/work/106397613
dc.descriptionFunding: Supported in part by Fondazione Cassa di Risparmio in Bologna, Project: “Biologia e clinica delle gravi insufficienze d’organo”, year 1999.en
dc.description.abstractThe Kennicutt-Schmidt law is an empirical relation between the star formation rate surface density (ΣSFR) and the gas surface density (Σgas) in disc galaxies. The relation has a power-law form ΣSFR ∝ Σgasn. Assuming that star formation results from gravitational collapse of the interstellar medium, ΣSFR can be determined by dividing Σgas by the local free-fall time tff. The formulation of tff yields the relation between ΣSFR and Σgas, assuming that a constant fraction (ΣSFE) of gas is converted into stars every tff. This is done here for the first time using Milgromian dynamics (MOND). Using linear stability analysis of a uniformly rotating thin disc, it is possible to determine the size of a collapsing perturbation within it. This lets us evaluate the sizes and masses of clouds (and their tff) as a function of Σgas and the rotation curve. We analytically derive the relation ΣSFR ∝ Σgasn both in Newtonian and Milgromian dynamics, finding that n = 1.4. The difference between the two cases is a change only to the constant pre-factor, resulting in increased ΣSFR of up to 25 per cent using MOND in the central regions of dwarf galaxies. Due to the enhanced role of disc self-gravity, star formation extends out to larger galactocentric radii than in Newtonian gravity, with the clouds being larger. In MOND, a nearly exact representation of the present-day main sequence of galaxies is obtained if ϵSFE = constant ≈ 1.1 per cent. We also show that empirically found correction terms to the Kennicutt-Schmidt law are included in the here presented relations. Furthermore, we determine that if star formation is possible, then the temperature only affects ΣSFR by at most a factor of √2.
dc.relation.ispartofMonthly Notices of the Royal Astronomical Societyen
dc.subjectGalaxies: ISMen
dc.subjectGalaxies: Star formationen
dc.subjectGalaxies: Statisticsen
dc.subjectGalaxy: Discen
dc.subjectQB Astronomyen
dc.subjectQC Physicsen
dc.subjectSpace and Planetary Scienceen
dc.subjectAstronomy and Astrophysicsen
dc.titleThe Kennicutt-Schmidt law and the main sequence of galaxies in Newtonian and Milgromian dynamicsen
dc.typeJournal articleen
dc.contributor.institutionUniversity of St Andrews. School of Physics and Astronomyen
dc.description.statusPeer revieweden

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