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arXiv · 1410.5229

Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies at z ~ 1.4

A. Gargiulo·P. Saracco·M. Longhetti·S. Tamburri·I. Lonoce·F. Ciocca
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Abstract

This paper aims at understanding if the normalization of the stellar initial mass function (IMF) of massive early-type galaxies (ETGs) varies with cosmic time and/or with mean stellar mass density Sigma (M*/2\pi Re^2). For this purpose we collected a sample of 18 dense (Sigma>2500 M_sun/pc^2) ETGs at 1.2 = 1.4 follow the same IMF-sigma_e trend of typical local ETGs, but with a lower mass-normalization. Nonetheless, once the IMF-sigma_e trend we have found for high-z dense ETGs is compared with that of local ETGs with similar Sigma and sigma_e, they turn out to be consistent. The similarity between the IMF-sigma_e trends of dense high-z and low-z ETGs over 9 Gyr of evolution and their lower mass-normalization with respect to the mean value of local ETGs suggest that, independently on formation redshift, the physical conditions characterizing the formation of a dense spheroid lead to a mass spectrum of new formed stars with an higher ratio of high- to low-mass stars with respect to the IMF of normal local ETGs.

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A. Gargiulo, P. Saracco, M. Longhetti, S. Tamburri, I. Lonoce, F. Ciocca. 2014-10-20. Lower mass normalization of the stellar initial mass function for dense massive early-type galaxies at z ~ 1.4. https://doi.org/10.1051/0004-6361/201424235

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