Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

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Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA

Transcript of Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Page 1: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Galaxies and Quasars in the Epoch of Reionization

Yuexing LiKeck Fellow

Harvard-CfA

Page 2: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Main Collaborators

• Thoeretical: Lars Hernquist (CfA), Volker Springel (MPA),

Tiziana Di Matteo (CMU), Tom Abel (Stanford)

• Observational: Giovanni Fazio (CfA), Xiaohui Fan (Arizona)

Page 3: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Cosmic Hisotryrecombination

Cosmic Dark Ages: no light no star, no quasar; IGM: HIFirst light: the first galaxies and quasars in the universeEpoch of reionization: radiation from the first objects lit up and ionize IGM : HI HII reionization completed, the universe is transparent and the dark ages ended

today

Courtesy: George Djorgovski

Page 4: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Fan+01,03,04,06Schneider+03,05,07Willott+07 ….Giavalisco+04Bouwens+06, 07Thompson+05, 06Iye+06, Yan+06 ….Brandt+02Shemmer+06 Bertoldi+03, Carilli+04Beelen+06, Jiang+06Maiolino+04, Wang+07 …Schady+08 Fynbo+08 …

Courtesy: Edo Berger

HSTChandraSpitzerSDSSSubaruSWIFTGLASTMAMBO….

Exciting Era for High-z Objects

Presence of SMBH in quasars, MBH~109 M⊙

Presence of large stellar component in galaxies, Mstar > 1011 M ⊙ at z>6

Presence of copious dust Mdust~108 M⊙ in

these objects

Page 5: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Questions & MythsI: Can such massive objects form so early in the

LCDM cosmology?– myth: there is a “cut-off” at z~5 (Efstathiou & Rees 88)– myth: exotic mechanisms required, e.g., super-Eddington accretion

(Volonteri & Rees 05, 06); supermassive BH seeds (Bromm & Loeb 03, Haiman 04, Dijstra+08)

II: How do they grow and evolve?– myth: z~6 quasars have “undersized” host galaxies (Walter+2003)– myth: SMBH – host correlations don’t hold at high z

III: What are their contributions to IR emission and reionization?– myth: all FIR comes from star heating (Bertoldi+2003, Carilli+2004)– myth: quasars don’t contribute to reionization (e.g., Gnedin+04)

Page 6: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Modeling Galaxies & QSOs• Physics to account for close link between galaxy formation

and BH growth– SMBH - host correlations (e.g, Magorrian+98, Gebhardt+00,

Ferrarese+00, Tremaine+02…)– Similarity between cosmic SFH & quasar evolution (e.g., Madau+95,

Shaver+96)

• Hydrodynamic simulations to follow evolution of quasar activity and host galaxy– Large-scale structure formation– Galactic-scale gasdynamics, SF, BH growth– Feedback from both stars and BHs

• Radiative transfer calculations to track interaction between photons and ISM /IGM– Radiation from stars & BHs– Scattering, extinction of ISM & reemission by dust– Evolution of SEDs, colors, luminosities, AGN contamination

Page 7: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

GADGET2 (Springel 05)

+ART2

(Li et al 08A)

(All-wavelength Radiative Transfer with Adaptive Refinement Tree)

Formation, evolution & multi-band properties of galaxies & quasars

CARTCosmological All-wavelength Radiative Transfer

Page 8: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

• Multi-scale simulations with GADGET2 (Springel 05)

– N-body cosmological simulation in 3 Gpc3

– Identify halos of interest at z=0– Zoom in & re-simulate the halo region with higher res. – Merging history extracted– Re-simulate the merger tree hydrodynamically

• Self-regulated BH growth model (DiMatteo et al. 05)

– Bondi accretion under Eddington limit– Feedback by BHs in thermal energy coupled to gas

I: Quasar Formation - MIMZoom: HR-region ~60 h-1Mpc, 4003

X (h-1 Mpc)

Y (

h-1

Mp

c)

Zoom-in sims

Page 9: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

• Merger tree with 7 major mergers z~14-7• Idealized galaxy using MMW model with properties (Mvir,

Rvir, Cvir) scaled with z (Mo+98)• BH seeds from remnants of PopIII stars (Abel+02, Bromm

& Larson04, Yoshida+06, 08), M=200 M ⊙ at z=30• BH binary merge when separation below resolution:

– At high-z, the potential well is deeper because galaxies are more compact

– BH binary merge rapidly in gaseous environment (Escala+04,05)– Gravitational recoil may eject BH if Vkick > Vesc, Vkick ~100 – 475 km/s

(e.g., Gonzalez+07, Campanelli+07)– Maximum Vkick < 200 km/s in gas-rich galaxy mergers (Bogdanovic+07)– Our halos have Vesc > 300 km/s

Formation of a z~6 QSO from Hierarchical Mergers

G1G2

G3

G4

G5

G6G7 G8

7.7x1012 M⊙

Page 10: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.
Page 11: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Age of Universe (Gyr)

Redshift z

• <SFR> ~ 103 M⊙/yr, at z>8, drops to ~100 M⊙/yr at z~6.5 heavy metal enrichment at z>10

• Indiv. BH grows via gas accretion, total system grows collectively

• System evolves from starburst quasar

• Merger remnant MBH ~ 2*109 M⊙ , M* ~ 1012 M ⊙ Magorrian relation

Li et al 07

Co-evolution of SMBHs and Host

Page 12: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

• 3-D Monte Carlo RT code ART2 treats radiative equilibrium calculate dust emission self-consistently (Bjorkman & Wood 01)

• Adaptive grid (Jonsson06) cover large dynamical range, capture inhomogeneous density distribution

• Multi-phase ISM model (McKee & Ostriker 77) + GMC scaling relations (Larson 1981)

• Supernova-origin dust model dust in young, high-z objects (e.g., Maiolino+04, Todini & Ferrara 01)

II: Multi-band Properties - ART2

rest (m)

Opa

city

(cm

2 /g)

X (kpc)

Y (

kpc)

Page 13: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Evolution of SEDs

obs (m)Li et al 08A

post-QSO

starburst-like

quasar-like

Page 14: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Origin of Thermal Emission

• Quasar system evolves from cold --> warm

• In peak quasar phase, radiation /heating is dominated by AGN

• Starbusts and quasars have different IR-optical-Xray correlations

LFIR

SF

RLi et al 08

Lx (L⊙)

L FIR

(L ⊙

)

LB (L⊙)

L FIR

(L ⊙

)

Li et al 08B, in prep

Redshift z

LIR

(L

sun

)F

25u

m/F

60u

m

Li et al 08

Page 15: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

• SPH cosmological simulations with BHs• They form in massive halos in overdense

regions• They are highly clustered• May provide patchy ionization of HI• SMBH -- host correlations hold

III. Galaxies & Quasars in Cosmological Volume

quasar

galaxy

Li et al. 08C, in prep

starsY

(h-1

Mpc

)

X (h-1 Mpc)

BH

Log

Ifra

c

X (h-1 Mpc)Li et al 09, in prep

Page 16: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

Summary

• CART is a powerful approach to study the formation, evolution, and multi-band properties of galaxies and quasars.

• Luminous z~6 quasars can form in the LCDM cosmology hierarchical mergers of gas-rich proto-galaxies, with BH accretion under Eddington limit.

• Galaxy progenitors of these quasars are strong starbursts, providing important contribution to metal enrichment & dust production.

• Early galaxies and quasars form in highly overdense region, highly clustered patchy reionization

Page 17: Galaxies and Quasars in the Epoch of Reionization Yuexing Li Keck Fellow Harvard-CfA.

• Birth place: massive halos in overdense region– Clustering, cross correlations of galaxies and quasars– Lensing

• Triggering mechanism: hierarchical merger– Morphology, pairs, CO maps– MBH -- relation– Merger rate

• Evolutionary path: Starburst --> quasar– Star formation history, evolved stellar components, mass functions– Metal enrichment, molecular gas, dust

• Thermal emission: stars --> AGN– SFR indicators– IR - optical relations

• End product: SMBH -- host correlations– MBH -- Mhost relation

Predictions & Observational Tests