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SUMMARY: Stellar haloes as probes of galaxy evolution - Payel Das (Univers
 ity of Oxford)
DTSTART:20160629T121500Z
DTEND:20160629T124500Z
UID:TALK66589@talks.cam.ac.uk
CONTACT:Paula Jofre
DESCRIPTION:Halo stars may have formed in situ\, been flung out from furth
 er in\, or accreted from neighbouring systems. The particular combination 
 of processes is embedded in the phase-space and metallicity distributions 
 of the stars\, and therefore they serve as fossils of the halo's formation
  history. I will present models of the haloes of nearby massive elliptical
  galaxies and our own Galaxy\, using a range of methods to constrain the d
 ark matter mass\, the structure of stellar orbits\, and examine age and me
 tallicity gradients. We find a strong correlation between the dark matter 
 mass and the density of the local environment\, and evidence for generally
  radial orbits\, both consistent with an accretion scenario for halo forma
 tion. Higher ages and metallicities are clearly more concentrated in actio
 n space\, where actions are constants of motion such as angular momentum. 
 This favours a scenario where more massive systems with older and metal-ri
 cher stars penetrate the gravitational potential of the central system mor
 e deeply. However the gradients manifest in real space only as a negligibl
 e metallicity gradient (~-0.001 dex/kpc) and a weak age gradient (~-0.02 G
 yr/kpc).
LOCATION:Sackler Lecture Theatre\, IoA
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