Download - The Local Group
The Local Group35 - 40 members
M31, and its satellites (red)
Milky Way, and its satellites (blue)
Isolated dwarfs (blue)
THE LOCAL GROUP
Mass Length Time
Stellar Archaeology and Galaxy Genesis
● LR kinematic and general metallicity measures of main Galactic structures
● detailed HR abundances of these to trace chemical development over time
● LR analysis of surviving nearby galaxies and streams
● exploit synergy with GAIA to break degeneracies
Mike Irwin
DE + DM + VM
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Credit: Matthias Steinmetz
age in Gyr
mass
fra
ctio
nAbadi, Navarro, Steinmetz & Eke 2003
Fine structure of simulated galaxies
thin
dis
kth
ick
dis
ksp
hero
id
Galaxy substructure and satellite accretion
38 30 23
Bullock & Johnston 2005
300 x 300 kpc
CDM modelspredict large-scalesubtructure in Lgalaxies like M31 and MW
*
Near-field cosmology - some key questions
● where are the missing satellites?● are dark matter profiles universal?● what is the extent nature and spatial
distribution of dark matter?● how were the Galaxy and M31 constructed?
are they typical disk galaxies?● what was the role of accretion in the
formation of the halo, disk, bulge?● what was the detailed chemical enrichment
history of the stellar components?
Galactic Science
clusters galaxies
singlestellar componentsno DM ?
mulitplestellarcomponentsDM ?
missing satellites ??
AndXIAndXII
AndXIII
Belokurov et al. 2006
AndXIV
AndXVAndXVI
Missing satellites & Halo DM lumpiness
Pal5 : Odenkirchen et al (2003)
An accretion into the MW disk?
● Heliocentric distance:
– TRGB: 7.2 ± 0.3 kpc
● 4-10 Gyr population
● σ=12km/s
(Martin et al 2004, 2005,Bellazzini et al. 2005)
DA
RT
Canis-Major and the Monoceros Ring
DA
RT
Galactic Science
● chemo-dynamic structure of Galactic components - interface between disk, bulge/bar, halo - ancient dissolved and surviving substructures
● fossil record of chemical evolution of stellar pops - chemical signature of ancient accretions - properties of metal-poor popIII stars
● evolutionary history of stellar components - IMF, SFH, tagging the chemical development - the role of star clusters
● linking the Bulge to the high Z universe ● detailed chemo-dynamics of surviving satellites
What do you need - I ?
● wide field well calibrated imaging optical -> NIR
● north: SDSS ugriz, WFCAM UKIDSS zyJHK● south: Skymapper, VST, CTIO 4m DES, VISTA ● all-sky: 2MASS calibration and pathfinder● GAIA: proper motions and parallaxes ● large area stellar spectroscopy (million stars)● automate majority of processing and analysis
=> logg, Teff, vel, [m/H]
What do you need - II ?
● large telescope with a wide fov eg. degrees diam
● 1000-4000 fibres to exploit target surface density
● survey selected regions totalling ~1000 sq deg● larger systematic survey find new structures● LR -> Mgb 4800-5500A and CaT 8150-8850A
vels to < 10 km/s; [Fe/H] to 0.1-0.2 dex; limited chemical tagging e.g. [alpha/Fe] ?
● synergy with GAIA => LR to ~V=20 => full 6D kinematic phase space information
GA substructure with LAMOST +
• dsphs and “dark” satellites eg. UMaI, UmaII ......
• tidal streams eg. GCs; dSphs; orphan streams
• open clusters and unbound debris
• known halo/disk sub-structures eg. Triang-And-Perseus; Sgr stream; Hercules-Aquila cloud; Arcturus group .......
• outer disk eg. warp -v- Canis Major edge of, outer spiral arm structure
DA
RT
LAMOST and GA competition
Summary
● large area spectroscopic studies of nearby galaxies are needed to test cosmological predictions on low-mass scales– nature and distribution of dark
matter– detailed formation history of galaxies
● GAIA will revolutionise this field, but will lack detailed chemical information, as well as accurate radial velocities