A relation between the characteristic stellar ages of galaxies and their intrinsic shapes

• Published in: Nature Astronomy
• Main Authors: van de Sande, J., Scott, Nicholas, Bland-Hawthorn, J., Brough, Sarah, Bryant, J. J., Colless, Matthew, Cortese, L., Croom, Scott M., D'Eugenio, Francesco, Foster, Caroline, Goodwin, Michael, Konstantopoulos, I. S., Medling, Anne, Sharp, Rob
• Format: Article in Journal/Newspaper
• Language: English
• Published: Nature Publishing Group
• Subjects: sami
• Online Access: http://hdl.handle.net/1885/205941; https://doi.org/10.1038/s41550-018-0436-x; https://openresearch-repository.anu.edu.au/bitstream/1885/205941/3/jvds_sami_vsp_arxiv.pdf.jpg

Stellar population and stellar kinematic studies provide unique but complementary insights into how galaxies build-up their stellar mass and angular momentum1,2,3. A galaxy's mean stellar age reveals when stars were formed, but provides little constraint on how the galaxy's mass was assembled. Resolved stellar dynamics4 trace the change in angular momentum due to mergers, but major mergers tend to obscure the effect of earlier interactions5. With the rise of large multi-object integral field spectroscopic surveys, such as SAMI6 and MaNGA7, and single-object integral field spectroscopic surveys (for example, ATLAS3D (ref. 8), CALIFA9, MASSIVE10), it is now feasible to connect a galaxy′s star formation and merger history on the same resolved physical scales, over a large range in galaxy mass, morphology and environment4,11,12. Using the SAMI Galaxy Survey, here we present a combined study of spatially resolved stellar kinematics and global stellar populations. We find a strong correlation of stellar population age with location in the (V/σ, ϵe) diagram that links the ratio of ordered rotation to random motions in a galaxy to its observed ellipticity. For the large majority of galaxies that are oblate rotating spheroids, we find that characteristic stellar age follows the intrinsic ellipticity of galaxies remarkably well. The SAMI Galaxy Survey is based on observations made at the Anglo-Australian Telescope. The Sydney–Australian Astronomical Observatory Multi-object Integral field spectrograph (SAMI) was developed jointly by the University of Sydney and the Australian Astronomical Observatory. The SAMI input catalogue is based on data taken from the Sloan Digital Sky Survey, the GAMA Survey and the VST ATLAS Survey. The SAMI Galaxy Survey is funded by the Australian Research Council Centre of Excellence for All-sky Astrophysics (CAASTRO), through project number CE110001020, and other participating institutions. Parts of this research were conducted by the Australian Research Council Centre of Excellence for ...