Thick Disk Formation . Chris Brook, Hugo Martel, Vincent Veilleux Université Laval . Brad Gibson Swinburne University, Melbourne, Australia . Daisuke Kawata Carnegie Observatory . Introduction. -review our knowledge of thick disks
Chris Brook, Hugo Martel, Vincent Veilleux
Swinburne University, Melbourne, Australia
□ dwarf spheroidal stars
Shetrone et al 2001, 2003
Geisler et al 2004
Venn et al. 2004
Kinematics, metal abundances and ages support the hypothesis it is a distinct component
photometric observations(Dalcanton & Bernstein `02)
GCD+: Details of the Code
Traced the merger histories.
Brook, Kawata, Martel Gibson, Bailin, submittedto ApJ
x z=0: Schwarzkopf & Dettmarr (`00)
o z~1: Reshetnikov, Dettmar & Combes (`03)
Enhance star formation and infall of pre-enriched gas satisfy nicely the criteria set by Kim Venn.
Halo: Robertson et al. `05
Thin 4.1 kpc
Thick 2.6 kpc
Thin~ 0.5 kpc
Thick~ 1.2 kpc
scenario 2well supportedby Galactic observations (Quillen & Garret 2001; Wyse 2000; Gilmore et al. 2002; Freeman & Bland-Hawthorn 2002; Feltzing et al. 2003).
scenario 3 also has contemporary support from observations and simulations (Abadi et al. `03, Helmi et al. `05, Yoachim & Dalcanton `05, but see poster #60 Brooks & Governato, metallicity?)
Thick disk formation during the high redshift epoch of multiple mergers of gas rich building blocks is consistent with observations of the Milky Way and extra-galactic thick disks.
Thick disk and thin disk material are spatially well separated at high redshift
Support hierarchical models
Decoupled cores, counter-rotating disks
Two accretion events
Thick Disk: chemical abundance evidence suggest seperate formation from thin disk
(although ongoing research req’d)
Early heating of thin disk most accepted model (e.g. Freeman & Bland-Hawthorn 2000)
Recent observations suggest that old, metal rich thick disks are prevalent (perhaps even ubiquitous) in disk galaxies.
Our work suggests thick disk formed through chaotic merging of gas rich “building blocks” at high redshift.