TY - JOUR
T1 - The stellar orbit distribution in present-day galaxies inferred from the CALIFA survey
AU - Zhu, Ling
AU - Ven, Glenn Van De
AU - Bosch, Remco Van Den
AU - Rix, Hans Walter
AU - Lyubenova, Mariya
AU - Falcón-Barroso, Jesús
AU - Martig, Marie
AU - Mao, Shude
AU - Xu, Dandan
AU - Jin, Yunpeng
AU - Obreja, Aura
AU - Grand, Robert J.J.
AU - Dutton, Aaron A.
AU - Macciò, Andrea V.
AU - Gómez, Facundo A.
AU - Walcher, Jakob C.
AU - García-Benito, Rubén
AU - Zibetti, Stefano
AU - Sánchez, Sebastian F.
PY - 2018/3/1
Y1 - 2018/3/1
N2 - Galaxy formation entails the hierarchical assembly of mass, along with the condensation of baryons and the ensuing, self-regulating star formation 1,2 . The stars form a collisionless system whose orbit distribution retains dynamical memory that can constrain a galaxy's formation history 3 . The orbits dominated by ordered rotation, with near-maximum circularity λ z ≈ 1, are called kinematically cold, and the orbits dominated by random motion, with low circularity λ z ≈ 0, are kinematically hot. The fraction of stars on 'cold' orbits, compared with the fraction on 'hot' orbits, speaks directly to the quiescence or violence of the galaxies' formation histories 4,5 . Here we present such orbit distributions, derived from stellar kinematic maps through orbit-based modelling for a well-defined, large sample of 300 nearby galaxies. The sample, drawn from the CALIFA survey 6, includes the main morphological galaxy types and spans a total stellar mass range from 108.7 to 1011.9 solar masses. Our analysis derives the orbit-circularity distribution as a function of galaxy mass and its volume-averaged total distribution. We find that across most of the considered mass range and across morphological types, there are more stars on 'warm' orbits defined as 0.25 ≤ λ z ≤ 0.8 than on either 'cold' or 'hot' orbits. This orbit-based 'Hubble diagram' provides a benchmark for galaxy formation simulations in a cosmological context.
AB - Galaxy formation entails the hierarchical assembly of mass, along with the condensation of baryons and the ensuing, self-regulating star formation 1,2 . The stars form a collisionless system whose orbit distribution retains dynamical memory that can constrain a galaxy's formation history 3 . The orbits dominated by ordered rotation, with near-maximum circularity λ z ≈ 1, are called kinematically cold, and the orbits dominated by random motion, with low circularity λ z ≈ 0, are kinematically hot. The fraction of stars on 'cold' orbits, compared with the fraction on 'hot' orbits, speaks directly to the quiescence or violence of the galaxies' formation histories 4,5 . Here we present such orbit distributions, derived from stellar kinematic maps through orbit-based modelling for a well-defined, large sample of 300 nearby galaxies. The sample, drawn from the CALIFA survey 6, includes the main morphological galaxy types and spans a total stellar mass range from 108.7 to 1011.9 solar masses. Our analysis derives the orbit-circularity distribution as a function of galaxy mass and its volume-averaged total distribution. We find that across most of the considered mass range and across morphological types, there are more stars on 'warm' orbits defined as 0.25 ≤ λ z ≤ 0.8 than on either 'cold' or 'hot' orbits. This orbit-based 'Hubble diagram' provides a benchmark for galaxy formation simulations in a cosmological context.
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U2 - 10.1038/s41550-017-0348-1
DO - 10.1038/s41550-017-0348-1
M3 - Article
AN - SCOPUS:85042698787
VL - 2
SP - 233
EP - 238
JO - Nature Astronomy
JF - Nature Astronomy
SN - 2397-3366
IS - 3
ER -