The ATLAS3D project – III. A census of the stellar angular momentum within the effective radius of early-type galaxies: unveiling the distribution of Fast and Slow Rotators

Дата и время публикации : 2011-02-22T10:23:01Z

Авторы публикации и институты :
Eric Emsellem
Michele Cappellari
Davor Krajnović
Katherine Alatalo
Leo Blitz
Maxime Bois
Frédéric Bournaud
Martin Bureau
Roger L. Davies
Timothy A. Davis
P. T. de Zeeuw
Sadegh Khochfar
Harald Kuntschner
Pierre-Yves Lablanche
Richard M. McDermid
Raffaella Morganti
Thorsten Naab
Tom Oosterloo
Marc Sarzi
Nicholas Scott
Paolo Serra
Glenn van de Ven
Anne-Marie Weijmans
Lisa M. Young

Ссылка на журнал-издание: Ссылка на журнал-издание не найдена
Коментарии к cтатье: 28 pages, 23 figures, LaTeX. Accepted for publication in MNRAS. High resolution version can be found on http://purl.com/atlas3d
Первичная категория: astro-ph.CO

Все категории : astro-ph.CO

Краткий обзор статьи: We provide a census of the apparent stellar angular momentum within 1 Re of a volume-limited sample of 260 early-type galaxies (ETGs) in the nearby Universe, using integral-field spectroscopy obtained in the course of the ATLAS3D project. We exploit the LambdaR parameter to characterise the existence of two families of ETGs: Slow Rotators which exhibit complex stellar velocity fields and often include stellar kinematically Distinct Cores (KDCs), and Fast Rotators which have regular velocity fields. Our complete sample of 260 ETGs leads to a new criterion to disentangle Fast and Slow Rotators which now includes a dependency on the apparent ellipticity (Epsilon). It separates the two classes significantly better than the previous prescription, and than a criterion based on V/Sigma: Slow Rotators and Fast Rotators have LambdaR lower and larger than kFSxSQRT(Epsilon), respectively, where kFS=0.31 for measurements made within 1 Re. We show that the vast majority of early-type galaxies are Fast Rotators: these have regular stellar rotation, with aligned photometric and kinematic axes (Paper II, Krajnovic et al. 2011}, include discs and often bars and represent 86% (224/260) of all early-type galaxies in the volume-limited ATLAS3D sample. Fast Rotators span the full range of apparent ellipticities from 0 to 0.85, and we suggest that they cover intrinsic ellipticities from about 0.35 to 0.85, the most flattened having morphologies consistent with spiral galaxies. Only a small fraction of ETGs are Slow Rotators representing 14% (36/260) of the ATLAS3D sample of ETGs. Of all Slow Rotators, 11% (4/36) exhibit two counter-rotating stellar disc-like components and are rather low mass objects (Mdyn<10^10.5 M_Sun). All other Slow Rotators (32/36) appear relatively round on the sky (Epsilon_e<0.4), tend to be massive (Mdyn>10^10.5 M_Sun), and often (17/32) exhibit KDCs.

Category: Physics