Transcript Formation of the Most Distant & Luminous Quasars

Formation & evolution of
galaxies and quasars at z~6
Yuexing Li
Harvard / CfA
Collaborators
• CfA: Lars Hernquist, T.J. Cox, Phil Hopkins, Matt McQuinn,
Giovanni Fazzio, Doug Finkbeiner, Matias Zaldarriaga
• Tiziana DiMatteo (UCM), Liang Gao, Adrian Jenkins (Durham),
Brant Robertson, Andrew Zentner (Chicago), Volker Springel
(MPA), Naoki Yoshida (Nagoya)
• Arizona: Xiaohui Fan, Linhua Jiang, Desika Narayanan
References
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Li, Hernquist et al. (2006A, astro-ph/0608190), Formation
Li, Hernquist et al. (2006B, in preparation), IR properties
Li, McQuinn et al. (2006C, in preparation), HII regions
Narayanan, Li et al. (2006, ApJ submitted), CO emission
A brief cosmic history
recombination
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 object lit up and ionize
IGM : HI  HII
 reionization completed,
the universe is transparent and
the dark ages ended
today
Courtesy: X. Fan, G. Djorgovski
High-z galaxies & quasars
as cosmology probes
• First generation of galaxies and quasars
• Star formation and metal enrichment in
the early universe
• Formation and growth of early supermassive black holes
• Role of quasars /BH feedback in galaxy
evolution
• Epoch of reionization
An exiciting hi-z Universe thanks
to HST, Spitzer, Sloan…
Ferguson+00
Dickinson+04
Giavalisco+04
Bunker+04
Bouwens+04
Stavelli+04
Mobasher+05
Yan+06
Bouwens+06
Iye+06
….
Fan+01,03,04,06
…
A census of high-z quasars
• z>4: >1000 known
• z>5: >60
• z>6: 13 (12 SDSS
discoveries)
• SDSS i-dropout Survey:
– 7000 deg2 at zAB<20
– 23 luminous quasars at
5.7<z<6.4
• Highest redshift:
z=6.43, SDSS J1148+5251
Fan et al 03, 06
Quasars at z~6
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End of reionization
Bright, Lbol ~ 1013-14 L⊙
Rare, ~1 Gpc-3
Massive, MBH~109 M⊙,Mhalo ~
1013 M⊙
(Becker+01, White03, Fan+04)
CO
SDSS J1148+5251
optical
radio
radio
Walter et al 04
1kpc
Fan et al 03
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•
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Bertoldi et al 03
Bertoldi et al 03
Lbol ~1014 L⊙ (Barth+03)
MBH ~3x109 M⊙ (Willot+03)
LFIR ~1013 L⊙ (Carilli+04)
SFR ~103 M⊙/yr (Bertoldi+03)
MCO ~5x109 M⊙ (Walter+04)
Mdust ~7x108 M⊙ (Beelen+06)
Heavy metal enrichment
(Barth+03,Maiolino+05,Becker+06)
CII
Maiolino et al 05
Fe
Barth et al 03
Challenges
• Can such massive objects form so early in the
LCDM cosmology?
• How do BHs grow? At constant or superEddington accretion rate?
• Where does the quasar halo originate? What
are the initial conditions?
• What is the nature of the progenitors? Do they
grow /evolve coevally with SMBHs?
• How does BH feedback affect the hosts?
• What are the reionization sources?
Formation of galaxies & QSOs
• Account for BH growth, quasar activity and
host galaxy properties
• Galaxy formation and growth in hierarchical
cosmology
• BH growth in context of galaxy formation
• Context of large-scale structure formation &
galactic-scale gasdynamics, SF, BH growth,
feedback
Close link between
galaxy formation & BH growth
• Observations:
– M- correaltion
– Similarity btw cosmic SFH
& quasar evolution
• Theorectical models BH
growth is regulated by
feedback (Silk & Rees98, Wyithe
& Loeb03, TiMatteo et al 05)
– Blow out of gas once BH
reachs critical mass
• BHs may play important
roles in galaxy formation
• Feeback by AGN may – Solve the cooling flow
riddle in galaxy clusters
– Explain the clusterscaling relations
– Explain why ellipticals
are so gas-poor & red
– Metal enrichment of IGM
by quasar-driven winds
– Help to reionize and
surpress star formation in
small galaxies
Our approach
• Multi-scale simulations with GADGET2 (Springel 06)
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N-body cosmological simulation in 3 Gpc3
Largest halo at z=0 identified
Resimulate the halo region with zoom-in
Merging history prior to z=6 extracted
Resimulate the merger tree with real galaxies scaled
appropriately with z
• Self-regulated BH growth model (DiMatteo et al. 05)
– Bondi accretion under Eddington limit
– Feedback by BHs in thermal energy coupled to gas
Cosmological Simulations
Parent sim: 1000 h-1Mpc, 4003
WMAP1
WMAP3
Zoom-in re-simulations
Parent sim: 1000 h-1Mpc, 4003
Zoom: HR-region ~60 h-1Mpc, 4003
Merger tree of quasar halo
• FoF is employed to
construct the
merging history of
the quasar halo
• Merger tree of the
halo 7.7x1012 M⊙ at
z~6 is then followed
with hydrodynamical
resimulation with
real galaxies
A vigorous merging history
QuickTime™ and a
YUV420 codec decompressor
are needed to see this picture.
Evolution of quasar host
• Early on
-- galaxies interact
violently, blue,
starbursting
-- quasar is heavily
obscured.
• When galaxies
coalesce
-- accretion peaks
-- quasar becomes
optically visible as
feedback blows out
gas.
• Later times
-- SF & AR quenched,
--> reddened &
aging spheroid.
Starburst progenitors
• SFR varies highly,
mean ~ 103 M⊙/yr,
peak ~104 M⊙/yr at
z~9, drops to ~100
M⊙/yr at z~6.5
• Observational
estimate ~103 M⊙/yr
at z~6.4 assuming
LFIR dominated by
young stars
--> AGN contamination
Early metal enrichment
• Metal enrichment
starts at z>14
• Become supersolar at z~12
• Consistent with
metallicity derived
from CO (Walter et al
03), Fe emission
(Barth et al 03) & CII
line (Maiolino et al 05)
observations.
BH growth
• AR peaks at z~6.5
when galaxies
coalesce.
• AR varies highly
depends on strength of
interaction & feedback.
• Only a portion of
lifetime accretes at
Eddington rate
--> constant or superEddington accretion not
neccessary
Redshift z
Correlation btw BH & galaxies
• At z~6.5 peak of quasar
phase, Mbh ~ 2x109 M⊙ ,
M* ~ 1012 M⊙
 Magorrian relation
 Coeval growth of BH &
stellar spheroid through
mergers
 Time-independent, only
depend on formation of
galaxy & BH and feedback
• Ambiguous inferences
from observations
(Walter+04, Peng+06,
Shields+06…)
Age of Universe (Gyr)
Quasar lightcurves
• System is intrinsic
bright as ULIRG
• Starburst dominates
before quasar
phase
• At z~6.5, quasar
light dominates
--> phase transition
from starburst to
quasar (Norman &
Fan+03
Scoville88, Sanders88)
Redshift z
IR Calculations
rest (m)
Evolution of SEDs
Cold ULIRG --> warm ULIRG
(Sanders+96)
rest (m)
HII regions from stars vs. BHs
BH
Log Ifrac
Y (Mpc/h)
stars
X (Mpc/h)
X (Mpc/h)
CO excitation & morphology
Narayanan+06
• CO (J=6-5) excitation reproduces Bertoldi et al 03.
• CO (J=3-2) morphology agree with Walter et al 03, show multiple
peaks --> merger origin
• CO emission shows multiple components ~300 km/s as observed,
FWHM ~ 1500 km/s --> a broader line likely unresolved in obs.
• MCO~2x109M⊙, Mdyn~1012 M⊙, >> 5x1010 M⊙ estimated (Walter et al
04).
 BH & stellar bulge form coevally
Summary
• Our model simultaneously accounts for BHs growth,
quasar activity & host galaxy properties, successfully
reproduces the observed properties of
SDSSJ1148+5251 in the LCDM cosmology.
– Both BHs and host galaxies build up through
hierarchical mergers.
– BHs accrete gas under Eddington limit in a selfregulated manner owing to feedback.
• Our model should provide a viable mechanism for
other luminous quasars, no exotic process is needed.
Predictions
• The quasar host obeys the Magorrian
relation.
• The system evolves from cold ULIRG -> warm ULIRG as quasar grow stronger
• Quasar progenitors are strong
starburst galaxies, providing important
contribution to metal enrichment, and
reionization.
On-going & future work
• Can we see them?
– Detectability of these high-z QSOs &
galaxies
• How many are there?
– Abundance, luminosity function &
clustering of these objects at z>6
• What are the sources for reionization?
– Contributions from quasars & galaxies
…