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Dissecting simulated disc galaxies – I. The structure of mono-age populations
- Source :
- Monthly Notices of the Royal Astronomical Society. 442:2474-2486
- Publication Year :
- 2014
- Publisher :
- Oxford University Press (OUP), 2014.
-
Abstract
- We study seven simulated disc galaxies, three with a quiescent merger history, and four with mergers in their last 9 Gyr of evolution. We compare their structure at z=0 by decomposing them into "mono-age populations" (MAPs) of stars within 500 Myr age bins. All studied galaxies undergo a phase of merging activity at high redshift, so that stars older than 9 Gyr are found in a centrally concentrated component, while younger stars are mostly found in discs. We find that most MAPs have simple exponential radial and vertical density profiles, with a scale-height that typically increases with age. Because a large range of merger histories can create populations with simple structures, this suggests that the simplicity of the structure of mono-abundance populations observed in the Milky Way by Bovy et al. (2012b,c) is not necessarily a direct indicator of a quiescent history for the Milky Way. Similarly, the anti-correlation between scale-length and scale-height does not necessarily imply a merger-free history. However, mergers produce discontinuities between thin and thick disc components, and jumps in the age-velocity relation. The absence of a structural discontinuity between thin and thick disc observed in the Milky Way would seem to be a good indicator that no merger with a mass ratio larger than 1:15-1:10 occurred in the last 9 Gyr. Mergers at higher redshift might nevertheless be necessary to produce the thickest, hottest components of the Milky Way's disc.<br />15 pages, 13 figures. Accepted for publication in MNRAS
- Subjects :
- Physics
Milky Way
FOS: Physical sciences
Astronomy
Astronomy and Astrophysics
Astrophysics::Cosmology and Extragalactic Astrophysics
Astrophysics
Galaxy merger
Disc galaxy
Astrophysics - Astrophysics of Galaxies
Galaxy
Redshift
Stars
Thin disk
Space and Planetary Science
Astrophysics of Galaxies (astro-ph.GA)
Astrophysics::Earth and Planetary Astrophysics
Disc
Astrophysics::Galaxy Astrophysics
Subjects
Details
- ISSN :
- 13652966 and 00358711
- Volume :
- 442
- Database :
- OpenAIRE
- Journal :
- Monthly Notices of the Royal Astronomical Society
- Accession number :
- edsair.doi.dedup.....77a7f31214af4c8e88bb5b458c855376