TY - JOUR
T1 - The ATLAS(3D) project - XXIV. The intrinsic shape distribution of early-type galaxies
AU - Weijmans, Anne Marie
AU - De Zeeuw, P. T.
AU - Emsellem, Eric
AU - Krajnović, Davor
AU - Lablanche, Pierre Yves
AU - Alatalo, Katherine
AU - Blitz, Leo
AU - Bois, Maxime
AU - Bournaud, Frédéric
AU - Bureau, Martin
AU - Cappellari, Michele
AU - Crocker, Alison F.
AU - Davies, Roger L.
AU - Davis, Timothy A.
AU - Duc, Pierre Alain
AU - Khochfar, Sadegh
AU - Kuntschner, Harald
AU - McDermid, Richard M.
AU - Morganti, Raffaella
AU - Naab, Thorsten
AU - Oosterloo, Tom
AU - Sarzi, Marc
AU - Scott, Nicholas
AU - Serra, Paolo
AU - Kleijn, Gijs Verdoes
AU - Young, Lisa M.
PY - 2014/3/19
Y1 - 2014/3/19
N2 - We use the ATLAS3D sample to perform a study of the intrinsic shapes of early-type galaxies, taking advantage of the available combined photometric and kinematic data. Based on our ellipticity measurements from the Sloan Digital Sky Survey Data Release 7, and additional imaging from the Isaac Newton Telescope, we first invert the shape distribution of fast and slow rotators under the assumption of axisymmetry. The so-obtained intrinsic shape distribution for the fast rotators can be described with a Gaussian with a mean flattening of q = 0.25 and standard deviation σq = 0.14, and an additional tail towards rounder shapes. The slow rotators are much rounder, and are well described with a Gaussian with mean q = 0.63 and σq = 0.09. We then checked that our results were consistent when applying a different and independent method to obtain intrinsic shape distributions, by fitting the observed ellipticity distributions directly using Gaussian parametrizations for the intrinsic axis ratios. Although both fast and slow rotators are identified as early-type galaxies in morphological studies, and in many previous shape studies are therefore grouped together, their shape distributions are significantly different, hinting at different formation scenarios. The intrinsic shape distribution of the fast rotators shows similarities with the spiral galaxy population. Including the observed kinematic misalignment in our intrinsic shape study shows that the fast rotators are predominantly axisymmetric, with only very little room for triaxiality. For the slow rotators though there are very strong indications that they are (mildly) triaxial.
AB - We use the ATLAS3D sample to perform a study of the intrinsic shapes of early-type galaxies, taking advantage of the available combined photometric and kinematic data. Based on our ellipticity measurements from the Sloan Digital Sky Survey Data Release 7, and additional imaging from the Isaac Newton Telescope, we first invert the shape distribution of fast and slow rotators under the assumption of axisymmetry. The so-obtained intrinsic shape distribution for the fast rotators can be described with a Gaussian with a mean flattening of q = 0.25 and standard deviation σq = 0.14, and an additional tail towards rounder shapes. The slow rotators are much rounder, and are well described with a Gaussian with mean q = 0.63 and σq = 0.09. We then checked that our results were consistent when applying a different and independent method to obtain intrinsic shape distributions, by fitting the observed ellipticity distributions directly using Gaussian parametrizations for the intrinsic axis ratios. Although both fast and slow rotators are identified as early-type galaxies in morphological studies, and in many previous shape studies are therefore grouped together, their shape distributions are significantly different, hinting at different formation scenarios. The intrinsic shape distribution of the fast rotators shows similarities with the spiral galaxy population. Including the observed kinematic misalignment in our intrinsic shape study shows that the fast rotators are predominantly axisymmetric, with only very little room for triaxiality. For the slow rotators though there are very strong indications that they are (mildly) triaxial.
KW - Elliptical and lenticular, cD- galaxies
KW - Galaxies
KW - Structure
UR - http://www.scopus.com/inward/record.url?scp=84919492160&partnerID=8YFLogxK
U2 - 10.1093/mnras/stu1603
DO - 10.1093/mnras/stu1603
M3 - Article
SN - 0035-8711
VL - 444
SP - 3340
EP - 3356
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -