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The MASSIVE survey - III. Molecular gas and a broken Tully-Fisher relation in the most massive early-type galaxies

Davis, Timothy A,, Greene, Jenny, Ma, Chung-Pei, Pandya, Viraj, Blakeslee, John P., McConnell, Nicholas and Thomas, Jens 2016. The MASSIVE survey - III. Molecular gas and a broken Tully-Fisher relation in the most massive early-type galaxies. Monthly Notices of the Royal Astronomical Society 455 (1) , pp. 214-226. 10.1093/mnras/stv2313

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Abstract

In this work, we present CO(1–0) and CO(2–1) observations of a pilot sample of 15 early-type galaxies (ETGs) drawn from the MASSIVE galaxy survey, a volume-limited integral-field spectroscopic study of the most massive ETGs (M* ≳ 1011.5 M⊙) within 108 Mpc. These objects were selected because they showed signs of an interstellar medium and/or star formation. A large amount of gas (>2 × 108 M⊙) is present in 10 out of 15 objects, and these galaxies have gas fractions higher than expected based on extrapolation from lower mass samples. We tentatively interpret this as evidence that stellar mass-loss and hot halo cooling may be starting to play a role in fuelling the most massive galaxies. These MASSIVE ETGs seem to have lower star formation efficiencies (SFE = SFR/MH2) than spiral galaxies, but the SFEs derived are consistent with being drawn from the same distribution found in other lower mass ETG samples. This suggests that the SFE is not simply a function of stellar mass, but that local, internal processes are more important for regulating star formation. Finally, we used the CO line profiles to investigate the high-mass end of the Tully–Fisher relation (TFR). We find that there is a break in the slope of the TFR for ETGs at high masses (consistent with previous studies). The strength of this break correlates with the stellar velocity dispersion of the host galaxies, suggesting it is caused by additional baryonic mass being present in the centre of massive ETGs. We speculate on the root cause of this change and its implications for galaxy formation theories.

Item Type: Article
Date Type: Publication
Status: Published
Schools: Physics and Astronomy
Subjects: Q Science > QB Astronomy
Publisher: Oxford University Press
ISSN: 0035-8711
Funders: STFC
Date of First Compliant Deposit: 30 March 2016
Date of Acceptance: 2 October 2015
Last Modified: 18 Oct 2019 23:29
URI: http://orca.cf.ac.uk/id/eprint/80370

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