TY - JOUR
T1 - SDSS-IV MaNGA
T2 - Stellar angular momentum of about 2300 galaxies: Unveiling the bimodality of massive galaxy properties
AU - Graham, Mark T.
AU - Cappellari, Michele
AU - Li, Hongyu
AU - Mao, Shude
AU - Bershady, Matthew A.
AU - Bizyaev, Dmitry
AU - Brinkmann, Jonathan
AU - Brownstein, Joel R.
AU - Bundy, Kevin
AU - Drory, Niv
AU - Law, David R.
AU - Pan, Kaike
AU - Thomas, Daniel
AU - Wake, David A.
AU - Weijmans, Anne Marie
AU - Westfall, Kyle B.
AU - Yan, Renbin
N1 - Publisher Copyright:
© The Author(s) 2018.
PY - 2018
Y1 - 2018
N2 - We measure λRe, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ϵ, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the Mapping Nearby Galaxies at Apache Point Observatory survey, the largest such sample to date.We use the (λRe, ϵ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λRe measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λRe . Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λRe, ϵ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λRe and ϵ < 0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90° in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing aboveM= 2 × 1011M⊙ where a significant number of high-mass fast rotators also exist.
AB - We measure λRe, a proxy for galaxy specific stellar angular momentum within one effective radius, and the ellipticity, ϵ, for about 2300 galaxies of all morphological types observed with integral field spectroscopy as part of the Mapping Nearby Galaxies at Apache Point Observatory survey, the largest such sample to date.We use the (λRe, ϵ) diagram to separate early-type galaxies into fast and slow rotators. We also visually classify each galaxy according to its optical morphology and two-dimensional stellar velocity field. Comparing these classifications to quantitative λRe measurements reveals tight relationships between angular momentum and galaxy structure. In order to account for atmospheric seeing, we use realistic models of galaxy kinematics to derive a general approximate analytic correction for λRe . Thanks to the size of the sample and the large number of massive galaxies, we unambiguously detect a clear bimodality in the (λRe, ϵ) diagram which may result from fundamental differences in galaxy assembly history. There is a sharp secondary density peak inside the region of the diagram with low λRe and ϵ < 0.4, previously suggested as the definition for slow rotators. Most of these galaxies are visually classified as non-regular rotators and have high velocity dispersion. The intrinsic bimodality must be stronger, as it tends to be smoothed by noise and inclination. The large sample of slow rotators allows us for the first time to unveil a secondary peak at ±90° in their distribution of the misalignments between the photometric and kinematic position angles. We confirm that genuine slow rotators start appearing aboveM= 2 × 1011M⊙ where a significant number of high-mass fast rotators also exist.
KW - Galaxies: elliptical and lenticular, cD- galaxies: evolution
KW - Galaxies: formation
KW - Galaxies: kinematics and dynamics
KW - Galaxies: spiral
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U2 - 10.1093/mnras/sty504
DO - 10.1093/mnras/sty504
M3 - Article
AN - SCOPUS:85084842697
SN - 0035-8711
VL - 477
SP - 4711
EP - 4737
JO - Monthly Notices of the Royal Astronomical Society
JF - Monthly Notices of the Royal Astronomical Society
IS - 4
ER -