Title: Galaxies and Quasars in the Epoch of Reionization
1Galaxies and Quasars in the Epoch of Reionization
- Yuexing Li
- Keck Fellow
- Harvard-CfA
2Main Collaborators
- Thoeretical Lars Hernquist (CfA),
Volker Springel (MPA),
Tiziana Di Matteo (CMU), Tom Abel
(Stanford) - Observational Giovanni Fazio (CfA),
Xiaohui Fan (Arizona)
3Cosmic Hisotry
- Cosmic Dark Ages no light
- no star, no quasar IGM HI
- First light the first galaxies
- and quasars in the universe
- Epoch 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
4Exciting Era for High-z Objects
Fan01,03,04,06 Schneider03,05,07 Willott07
. Giavalisco04 Bouwens06, 07 Thompson05,
06 Iye06, Yan06 . Brandt02 Shemmer06
Bertoldi03, Carilli04 Beelen06,
Jiang06 Maiolino04, Wang07 Schady08
Fynbo08
Presence of large stellar component in galaxies,
Mstar gt 1011 M? at zgt6
Presence of SMBH in quasars, MBH109 M?
Presence of copious dust Mdust108 M? in these
objects
5Questions Myths
- I Can such massive objects form so early in the
LCDM cosmology? - myth there is a cut-off at z5 (Efstathiou
Rees 88) - myth exotic mechanisms required, e.g.,
super-Eddington accretion (Volonteri Rees 05,
06) supermassive BH seeds (Bromm Loeb 03,
Haiman 04, Dijstra08) - II How do they grow and evolve?
- myth z6 quasars have undersized host galaxies
(Walter2003) - myth SMBH host correlations dont hold at high
z - III What are their contributions to IR emission
and reionization? - myth all FIR comes from star heating
(Bertoldi2003, Carilli2004) - myth quasars dont contribute to reionization
(e.g., Gnedin04)
6Modeling Galaxies QSOs
- Physics to account for close link between galaxy
formation and BH growth - SMBH - host correlations (e.g, Magorrian98,
Gebhardt00, Ferrarese00, Tremaine02) - Similarity between cosmic SFH quasar evolution
(e.g., Madau95, Shaver96) - 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
7GADGET2 (Springel 05)ART2 (Li et al
08A)(All-wavelength Radiative Transfer with
Adaptive Refinement Tree)
CARTCosmological All-wavelength Radiative
Transfer
Formation, evolution multi-band properties of
galaxies quasars
8I Quasar Formation - MIM
- Multi-scale simulations with GADGET2 (Springel
05) - N-body cosmological simulation in 3 Gpc3
- Identify halos of interest at z0
- 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
9Formation of a z6 QSO from Hierarchical Mergers
- Merger tree with 7 major mergers z14-7
- Idealized galaxy using MMW model with properties
(Mvir, Rvir, Cvir) scaled with z (Mo98) - BH seeds from remnants of PopIII stars (Abel02,
Bromm Larson04, Yoshida06, 08), M200 M? at
z30 - 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
(Escala04,05) - Gravitational recoil may eject BH if Vkick gt
Vesc, Vkick 100 475 km/s (e.g., Gonzalez07,
Campanelli07) - Maximum Vkick lt 200 km/s in gas-rich galaxy
mergers (Bogdanovic07) - Our halos have Vesc gt 300 km/s
10(No Transcript)
11Co-evolution of SMBHs and Host
Age of Universe (Gyr)
- ltSFRgt 103 M?/yr, at zgt8, drops to 100 M?/yr at
z6.5 ? heavy metal enrichment at zgt10 - Indiv. BH grows via gas accretion, total system
grows collectively - System evolves from starburst ? quasar
- Merger remnant MBH 2109 M? , M 1012 M? ?
Magorrian relation
Redshift z
Li et al 07
12II Multi-band Properties - ART2
- 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., Maiolino04, Todini
Ferrara 01)
13Evolution of SEDs
14Origin of Thermal Emission
- Quasar system evolves from cold --gt warm
- In peak quasar phase, radiation /heating is
dominated by AGN - Starbusts and quasars have different
IR-optical-Xray correlations
15III. Galaxies Quasars in Cosmological Volume
- 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
16Summary
- CART is a powerful approach to study the
formation, evolution, and multi-band properties
of galaxies and quasars. - Luminous z6 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
17Predictions Observational Tests
- 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 --gt quasar
- Star formation history, evolved stellar
components, mass functions - Metal enrichment, molecular gas, dust
- Thermal emission stars --gt AGN
- SFR indicators
- IR - optical relations
- End product SMBH -- host correlations
- MBH -- Mhost relation