Please use this identifier to cite or link to this item: http://hdl.handle.net/1959.3/1845

Download PDF (Author's final draft) (Adobe Acrobat PDF, -1 bytes)

Title

Structural evolution in elliptical galaxies: the age-shape relation

Author(s)

Ryden, Barbara S.;  Forbes, Duncan A.;  Terlevich, Ale

Abstract

We test the hypothesis that the apparent axial ratio of an elliptical galaxy is correlated with the age of its stellar population. We find that old ellipticals (with estimated ages t>7.5 Gyr) are rounder on average than younger ellipticals. The statistical significance of this shape difference is greatest at small radii; a Kolmogorov–Smirnov test comparing the axial ratios of the two populations at R=Re/16 yields a statistical significance greater than 99.96 per cent. The relation between age and apparent shape is linked to the core/power-law surface brightness profile dichotomy. Core ellipticals have older stellar populations, on average, than power-law ellipticals and are rounder in their inner regions. Our findings are consistent with a scenario in which power-law ellipticals are formed in gas-rich mergers, while core ellipticals form in dissipationless mergers, with cores formed and maintained by the influence of a binary black hole.

Publication type

Journal article

Research centre

Swinburne University of Technology. Centre for Astrophysics and Supercomputing

Source

Monthly Notices of the Royal Astronomical Society, Vol. 326, no. 3 (Sep 2001), pp. 1141-1148

Publication year

2001

Keyword(s)

Elliptical and lenticular galaxies;  Galactic evolution;  Galactic structure;  Photometry

Publisher

Blackwell Publishing

ISSN

0035-8711

Publisher URL

http://dx.doi.org/doi:10.1046/j.1365-8711.2001.04673.x

Copyright

Copyright © 2001 Royal Astronomical Society. Author's final draft reproduced here in accordance with the copyright policy of the publisher.

Full text

Peer reviewed