Connection between dynamically derived initial mass function normalization and stellar population parameters

Richard M. McDermid, Michele Cappellari, Katherine Alatalo, Estelle Bayet, Leo Blitz, Maxime Bois, Frédéric Bournaud, Martin Bureau, Alison F. Crocker, Roger L. Davies, Timothy A. Davis, P. T. De Zeeuw, Pierre Alain Duc, Eric Emsellem, Sadegh Khochfar, Davor Krajnović, Harald Kuntschner, Raffaella Morganti, Thorsten Naab, Tom Oosterloo & 5 others Marc Sarzi, Nicholas Scott, Paolo Serra, Anne Marie Weijmans, Lisa M. Young

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Abstract

We report on empirical trends between the dynamically determined stellar initial mass function (IMF) and stellar population properties for a complete, volume-limited sample of 260 early-type galaxies from the ATLAS3D project. We study trends between our dynamically derived IMF normalization αdyn ≡ (M/L)stars/(M/L)Salp and absorption line strengths, and interpret these via single stellar population-equivalent ages, abundance ratios (measured as [α/Fe]), and total metallicity, [Z/H]. We find that old and alpha-enhanced galaxies tend to have on average heavier (Salpeter-like) mass normalization of the IMF, but stellar population does not appear to be a good predictor of the IMF, with a large range of αdyn at a given population parameter. As a result, we find weak αdyn-[α/Fe] and αdyn -Age correlations and no significant αdyn -[Z/H] correlation. The observed trends appear significantly weaker than those reported in studies that measure the IMF normalization via the low-mass star demographics inferred through stellar spectral analysis.

Original languageEnglish
Article numberL37
Pages (from-to)1-5
Number of pages5
JournalAstrophysical Journal Letters
Volume792
Issue number2
DOIs
Publication statusPublished - 10 Sep 2014

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Bibliographical note

Copyright The American Astronomical Society. First published in Astrophysical journal letters, volume 792, number 2, article L37. The original publication is available at http://doi.org/10.1088/2041-8205/792/2/L37, published by IOP Publishing. Version archived for private and non-commercial use with the permission of the author/s and according to publisher conditions. For further rights please contact the publisher.

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