Top-heavy integrated galactic stellar initial mass functions IGIMFs in starbursts - Astrophysics > Cosmology and Nongalactic AstrophysicsReport as inadecuate




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Abstract: Star formation rates SFR larger than 1000 Msun- yr are observed in extremestar bursts. This leads to the formation of star clusters with masses > 10^6Msun in which crowding of the pre-stellar cores may lead to a change of thestellar initial mass function IMF. Indeed, the large mass-to-light ratios ofultra-compact dwarf galaxies and recent results on globular clusters suggestthe IMF to become top-heavy with increasing star-forming density. We explorethe implications of top-heavy IMFs in these very massive and compact systemsfor the integrated galactic initial mass function IGIMF, which is thegalaxy-wide IMF, in dependence of the star-formation rate of galaxies. Theresulting IGIMFs can have slopes, alpha 3, for stars more massive than about 1Msun between 1.5 and the Salpeter slope of 2.3 for an embedded cluster massfunction ECMF slope beta of 2.0, but only if the ECMF has no low-massclusters in galaxies with major starbursts. Alternatively, beta would have todecrease with increasing SFR >10 Msun- yr such that galaxies with majorstarbursts have a top-heavy ECMF. The resulting IGIMFs are within the range ofobservationally deduced IMF variations with redshift.



Author: Carsten Weidner, Pavel Kroupa, Jan Pflamm-Altenburg

Source: https://arxiv.org/







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