Galaxy formation and evolution with a GSMT: - PowerPoint PPT Presentation

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Galaxy formation and evolution with a GSMT:

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Environments ranging from field to Virgo Cluster-like density (core of the Coma I group) ... fundamentally new things extending to the 10Mpc groups and Virgo? ... – PowerPoint PPT presentation

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Title: Galaxy formation and evolution with a GSMT:


1
  • Galaxy formation and evolution with a GSMT
  • The z0 fossil record
  • 17 March, 2003

2
Current 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.

3
Color-magnitude Studies of Star-Formation
Histories
Fornax Carina
4
Current 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.

5
The 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

7
Big 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

8
Big 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

9
The 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

10
MSTO (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
11
MSTO (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
12
30m
M81 Group
M31 Group
10m
4m
Galactic dSph
I15 20 25
30
Nearby GGC
Old MSTO magnitude
13
Useful 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
15
Capabilities 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

16
What 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

17
Would 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
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