Title: Towards Constraining the Physical Properties of High Redshift Galaxies
1Towards Constraining the Physical Properties of
High Redshift Galaxies
- Romeel Davé
- Kristian Finlator
- Ben D. Oppenheimer
- University of Arizona
2What are the physical properties of
reionization-epoch galaxies?
- Direct constraints from spectra Too faint.
- Obtain from models that reproduce bulk
properties Many parameters, few objects. - SED-fit photometry Many uncertainties.
- Stellar populations
- Extinction
- Star formation history
- Can we place constraints on galaxy formation
models from photometry of individual galaxies?
3Rest-UV Luminosity Fcn
- Gadget-2 hydro sims with metal cooling 8-64
Mpc/h volumes - UVLF seems to indicate some SF suppression
required Outflows? - But constraints are weak Dust? Cosmology?
(n0.95, s80.75)
4Physical Properties Generic Predictions
- SFR ? M Cold accretion.
- Highly biased clustered Can reionize local
infall region by z9. - Enriched to gt1/30 Z? M-Z slope in place ltlt1
metal-free SF. - Can we test such predictions generically?
RD, Finlator, Oppenheimer 06
5Photometry of Simulated Galaxies
- Photometry from sims SFH (t,Z) ? BC03 w/Chabrier
IMF. - Straightforward to find sim galaxies that
reproduce Abell 2218 KESR photometry. - Turn this around What constraints on models from
photometry?
RD, Finlator, Oppenheimer 06
6Constraints from Photometry
- Ability to match photometry is fairly generic
Independent of outflow, cosmology. - Cant constrain total SF from this need UVLF.
- BUT Matching photo-metry yields fairly robust
physical properties!
Finlator, RD, Oppenheimer 06
7SPOC Physical Properties from Observed Photometry
- Use simulated galaxies SFH as a prior on SED
fitting. - Obtain predicted probability distributions of
AV, Z, Age, SFR, M, z. - Goal Test simulated SFHs.
Finlator, RD, Oppenheimer 06
8Comparison with Traditional SED Fitting
- Sims provide tighter constraints than simple
assumed SFHs ? Non-trivial prediction! - Need spectra to test.
- For now, can provide constraints from
physically-motivated hierarchical galaxy
formation model.
Finlator, RD, Oppenheimer 06
9Simulated SFH Rising
- Why are predicted properties robust?
- Hydro simulations generically predict
constantly-rising SFHs. - This is the basic prediction we can test with
SPOC.
Finlator, RD, Oppenheimer 06
10Simulations Work Mostly
- Six zgt5.5 objects with IRAC data.
- Good fits (?n2lt1) obtained for most objects.
- Exceptions GLARE (bursting?), HCM6A (high
Ha?). - Best-fit simulated galaxies are fairly massive,
have older stars, always show a 4000Ã… break.
log M9.3
log M8.7
log M10.1
log M10.1
log M9.2
log M9.4
Finlator, RD, Oppenheimer 06
11Summary
- To understand high-z galaxy formation we need
- Halo mass Clustering.
- Star formation rate dist Rest-UV LF.
- Stellar mass dist Rest optical LF.
- Star formation history Photometry.
- Generally, hydro simulations can reproduce
current observations of both UVLF and SFH. - SPOC provides way to test simulated SFHs against
individual galaxies with photometric data
identifies deviating systems (bursts? AGN?). - Makes predictions that will be tested with JWST.
- SPOC model libraries available upon request.
12Bursty SFHs SFR-M
- Tight SFR-M relation stringently tested.
- Mostly, simulations pass test Can fit data,
with tighter constraints than simple SFHs. - But for GLARE3001, high SFR/low M fits better
Bursting?
Finlator, RD, Oppenheimer 06