Title: Galaxy formation and evolution with a GSMT:
1- Galaxy formation and evolution with a GSMT
- The z0 fossil record
- 17 March, 2003
2Current Landscape
- The star formation, chemical evolution and
dynamical histories of the Galaxy have been
largely (though not completely) pieced together
from studies of the kinematics and abundances of
field stars and clusters. - Starting with 4m-based photometry and now with 8
and 10m high-dispersion spectroscopy similar
studies have been extended to the Milky Way dwarf
galaxy complement.
3Color-magnitude Studies of Star-Formation
Histories
Fornax Carina
4Current Landscape
- The star-formation histories of the Galaxys dSph
have proven to be surprisingly diverse and so-far
unexplained. - To date, beyond the Local Group inferences about
SFH and chemical evolution history have been
based on integrated spectroscopy and photometry. - 8/10m AO-based studies in their infancy.
5The role of a 30m
- Extend fossil record studies of resolved
stellar populations to 15Mpc. - Vastly larger samples across full Hubble
Sequence. - Environments ranging from field to Virgo
Cluster-like density (core of the Coma I group).
6 The Big Questions
- What are the star formation histories for M31
M81 and their dwarf complements? - Did star formation commence simultaneously
throughout the Local Group? - What are the key factors that govern dwarf galaxy
star formation episodes? - What are the complete chemical enrichment
histories of Local Group galaxies? - Fe/alpha/r-process compared to Galaxy. Inferences
for IMF and feedback differences
7Big Questions cont.
- Directly measured star formation histories of
giant elliptical galaxies. - Is there a significant population of young stars
in giant elliptical galaxies? (JWST?) - Detailed mix of elements with different
nucleosynthetic origins in a gE
8Big Questions cont.
- Did star formation commence at the same time
throughout the volume of space to Virgo? - Cosmic variance in SFH as a function of Hubble
type/environment - z0 population census is crucial for matching
populations at larger z
9The role of a 30m Analysis Techniques
- Establish distance scale to Virgo Cluster to 10
via RR Lyrae,TRGB observations - CMD studies
- Main-sequence turnoff ages
- Fe/H and Fe/H spread from RGB morphology
- Horizontal branch morphology inferences for ages
- R5000 to 50000 spectroscopic studies
- Kinematics
- Detailed chemical compositions
10MSTO (10Gyr) V HB V RGB tip V
Absolute 4.5 0.8 -1
M31 28.8 25.1 22.3
M81 32.3 28.5 27.8
NGC 3379 34.5 30.8 29
Virgo 36 32.3 30.5
11MSTO (10Gyr) V/I/K HB level V/I/K RGB tip V/I/K
Absolute 4.5/3.8/3.2 0.8/0/-1.2 -1/-4/-7.5
M31 28.8/28.1/27.5 25.1/24.3/23.1 22.3/20.3/16.8
M81 32.3/31.5/30.9 28.5/27.8/26.6 27.8/24.8/20.3
NGC 3379 34.5/33.8/33.2 30.8/30/28.8 29/26/22.5
Virgo 36/35.2/34.7 32.3/31.5/30.3 30.5/27.5/24
What you shade in a table like this depends
strongly on MCAO performance
1230m
M81 Group
M31 Group
10m
4m
Galactic dSph
I15 20 25
30
Nearby GGC
Old MSTO magnitude
13Useful type of plot?
14 Relevant numbers to collect
- Sample sizes broken down by Hubble Type as a
function of distance (easy) - S/N vs science for different studies (easy)
- Surface brightness/crowding limits and effects
(hard). Olsen/Rigout work is an important
contribution.
Good MCAO simulations are crucial to this area
15Capabilities requirements list
- Instrumentation
- R40000 optical/Near-IR spectroscopy
- MCAO/ modest-field JHK photometry
- AO
- PSF stability/strehl requirements require
simulations - Lambda regimes
- B through K
16What might be missing from current discussions?
Slide from November 2002 - are we getting
anywhere?
- Real simulations
- Crowding
- Effects of realistic PSF for AO photometry and
spectroscopy - Tools required for using diagnostics in the
near-IR (CMD/abundances) - most of the gains will
require AO with moderate or better strehl --
likely only possible longward of 1 micron for the
next few decades) - Young stellar populations
17Would you build an ELT to do this?
- Perhaps not. 8/10m AO will make excellent
progress throughout the Local Group and probably
out the the M81 Group. - Will we learn fundamentally new things extending
to the 10Mpc groups and Virgo? - If an ELT is there, these are excellent areas and
excellent astronomy will be available. - MSTO photometry throughout Local Group and
stellar pops in a gE may be the greatest
potential - Sub-mas astrometry of faint objects