Simulations of Simulations of Reionization-Epoch Reionization-Epoch

GalaxiesGalaxies

Romeel Davé (Arizona)Romeel Davé (Arizona)

Kristian FinlatorKristian Finlator, Ben D. , Ben D. OppenheimerOppenheimer

Galaxies at Galaxies at z>6: Why?z>6: Why?

Responsible for Responsible for reionizing the reionizing the universe.universe.

Test early galaxy Test early galaxy formation models.formation models.

Now observed!Now observed! What are their What are their

physical properties?physical properties? What constraints do What constraints do

they place on they place on models?models?

Movie by N. Gnedin

z~7 arc in Abell 2218Kneib et al 2004

Cosmological Hydro SimulationsCosmological Hydro Simulations Gadget-2 (PM-Tree-eSPH), with new Gadget-2 (PM-Tree-eSPH), with new momentum-driven windmomentum-driven wind

models + metal-line cooling (no Hmodels + metal-line cooling (no H22).). Reproduces observed IGM metals at z~2-5Reproduces observed IGM metals at z~2-5 (Oppenheimer & RD 06) (Oppenheimer & RD 06)

2x2562x25633 runs, runs, CDM, [CDM, [8,16,32,648,16,32,64]h]h-1-1Mpc, various outflows.Mpc, various outflows. No radiative transfer, No radiative transfer, uniform HM01uniform HM01 (QG01) reionizes @ z~9. (QG01) reionizes @ z~9. Feedback cycle tracked self-consistently; geometry critical.Feedback cycle tracked self-consistently; geometry critical.

Movie by B. Oppenheimer3 Mpc/h comoving

Rest-UV Luminosity FunctionsRest-UV Luminosity Functions nwnw: no winds; : no winds; cwcw: “constant” winds, v: “constant” winds, vww=484 km/s =484 km/s

(Springel & Hernquist 2003); (Springel & Hernquist 2003); mzw/vzwmzw/vzw: momentum-: momentum-driven winds, vdriven winds, vww (from local starbursts; Martin 2005). (from local starbursts; Martin 2005).

Matches rest-UV LF at z~4-6; Matches rest-UV LF at z~4-6; steep slopesteep slope @ faint-end! @ faint-end! Overcooling @ z~6: Overcooling @ z~6: Large suppressionLarge suppression of SF needed at of SF needed at

early times, across all masses.early times, across all masses.

GOODS B-dropoutsBouwens et al 06

RD, Finlator, Oppenheimer 06

Stellar Mass buildupStellar Mass buildup Despite large suppression, Despite large suppression, stellar stellar

mass builds up quicklymass builds up quickly.. At z=7, space density of MAt z=7, space density of M**>10>101010MM

objects ~ SDSS LRG’s today.objects ~ SDSS LRG’s today. Halos masses ~100MHalos masses ~100M**~~101099-10-101212MM

Atomic line cooling dominates. Atomic line cooling dominates. Tight M*-SFRTight M*-SFR relation driven by relation driven by

cold-mode accretion (Keres etal cold-mode accretion (Keres etal 05).05).

RD, Finlator, Oppenheimer 06

~JWSTdepth

Galaxies Self-Reionize EarlyGalaxies Self-Reionize Early Lots of SF Lots of SF lots of lots of

ionizing photonsionizing photons Stromgren sphere overlap Stromgren sphere overlap

as a function of Mas a function of M**: : Percolation at z»9 for Percolation at z»9 for MM**<10<1099MM..

Combined with large vCombined with large vcirccirc Rad Xfer not critical for Rad Xfer not critical for studying 6<z<9 galaxies.studying 6<z<9 galaxies.

RD, Finlator, Oppenheimer 06

Zahn et al 2006

Galaxies Self-Enrich QuicklyGalaxies Self-Enrich Quickly ……despite strong outflows that enrich IGM.despite strong outflows that enrich IGM. Typical Typical ~0.1-0.3Z~0.1-0.3Z @ z~6, @ z~6, veryvery little evolution with z. little evolution with z. MM**-Z rel’n evolves slowly to z~2, -Z rel’n evolves slowly to z~2, agrees with Erb etal 06agrees with Erb etal 06.. Very little “metal free” SFVery little “metal free” SF (Z<10 (Z<10-3-3ZZ); bulk of IMF normal. ); bulk of IMF normal.

RD, Finlator, Oppenheimer 06

Points: Erb etal 06 z~2Line: SDSS z~0

Case Study: Abell 2218 KESRCase Study: Abell 2218 KESR z~6.7z~6.7 galaxy well-fit galaxy well-fit

by simulated, by simulated, independent of independent of outflows/cosmology.outflows/cosmology.

This galaxy is This galaxy is typical:typical: M M** and SFR and SFR fall exactly on fall exactly on simulation’s tight Msimulation’s tight M**--SFR correlation.SFR correlation.

Star formation Star formation history best history best characterized by characterized by steady risesteady rise; NOT ; NOT constant, decaying, constant, decaying, or single-burst; yet or single-burst; yet all models fit with all models fit with 22<1.<1.

Finlator, RD, Oppenheimer 06

SPOC: Physical Constraints from SPOC: Physical Constraints from Simulated GalaxiesSimulated Galaxies

SPOC: Bayesian SPOC: Bayesian engine to engine to constrain constrain physical parameters physical parameters from photometric from photometric datadata by comparison by comparison with simulated with simulated sample.sample.

Provides Provides tighter tighter constraintsconstraints than “toy than “toy model” SFHs model” SFHs because simulated because simulated SFHs are ~self-SFHs are ~self-similar.similar.

Also Also tests modeltests model: If : If “prior” is wrong, no “prior” is wrong, no good fit obtained!good fit obtained!

Finlator, RD, Oppenheimer 06

Constraining z~6 GalaxiesConstraining z~6 Galaxies 6 observed objects have 6 observed objects have MM**~10~109-10 9-10 MM, SFR~2-50 M, SFR~2-50 M/yr./yr. All well-fit by simulated galaxies All well-fit by simulated galaxies exceptexcept GLARE#3001; GLARE#3001;

this one poorly fit by ALL models, seems “bursty”.this one poorly fit by ALL models, seems “bursty”. SPOC SPOC identifies outlier objectsidentifies outlier objects that critically test models. that critically test models.

Finlator, RD, Oppenheimer 06

2~3

2~8

SummarySummary Galaxies at 6<z<9 are fundamentally Galaxies at 6<z<9 are fundamentally

similar to lower-z systems: Massive, similar to lower-z systems: Massive, SFRSFRM*, enriched to >~0.1ZM*, enriched to >~0.1Z, live in , live in reionized regions by z~9.reionized regions by z~9.

Simulations can match observed luminosity Simulations can match observed luminosity function if feedback heavily suppresses star function if feedback heavily suppresses star formation by z~6.formation by z~6.

Mass-metallicity relation evolves very Mass-metallicity relation evolves very slowly, and even at z~9 there is little slowly, and even at z~9 there is little Population III star formation.Population III star formation.

Individual observed galaxies are Individual observed galaxies are straightforwardly accommodated in straightforwardly accommodated in simulations, and in turn models be used to simulations, and in turn models be used to constrain physical parameters using SPOC.constrain physical parameters using SPOC.