Transcript Probing Cosmic Evolution with the Most Distant Quasars Xiaohui Fan University of Arizona Apr 18, 2010 Collaborators: Jiang, Carilli, Kurk, Rix, Strauss, Vestergaard, Walter, Wang Background: 46,420

Probing Cosmic Evolution with
the Most Distant Quasars
Xiaohui Fan
University of Arizona
Apr 18, 2010
Collaborators: Jiang, Carilli, Kurk, Rix, Strauss,
Vestergaard, Walter, Wang
Background: 46,420 Quasars from the SDSS Data Release Three
46,420 Quasars from the SDSS Data Release Three
5
Ly forest
3
Ly
2
CIV
redshift
CIII
MgII
FeII
1
FeII
OIII
H
0
4000 A
wavelength
9000 A
Almost 50 Years Ago:
First Quasar: 3C 273 by Maarten
Schmidt
Quest to the Highest Redshift
Quest to the Highest Redshift
090423
080913
050904
000131
GRBs
970228
30 at z>6
60 at z>5.5
>100 at z>5
z~6: Crucial Transition in
quasar evolution
• Evolution of quasar density and accretion rate:
– Formation of the first billion solar mass BHs?
• Dust-free quasars
– Connection to the earliest galaxies?
• Gas and star formation in host galaxies
– Evolution of M-σ relation?
• Evolution of IGM neutral fraction
– End of reionization epoch?
Theorists Tell us
• These luminous z~6 quasars:
– The most massive system in early
Universe
– Living in the densest environment
– BH accreting at Eddington
– Host galaxies have ULIRG properties
with maximum starburst
Li et al. 2007
Quasar Evolution at z~6
•
•
•
Strong density evolution
– Density declines by a factor of ~40
from between z~2.5 and z~6
Black hole mass measurements
– MBH~109-10 Msun
– Mhalo ~ 1012-13 Msun
– rare, 5-6 sigma peaks at z~6
(density of 1 per Gpc3)
Quasars accreting at maximum rate
– Quasar luminosity consistent with
Eddington limit
Low-z
z~6
Fan et al. 2006, 2010
Puzzle 1:
Are there luminous quasars at z>>7
• Black Holes do not grow arbitrarily fast
– Accretion onto BHs dicitated by Eddington Limit
– E-folding time of maximum supermassive BH growth: 40 Myr
– At z=7: age of the universe: 800 Myr = maximum 20 e-folding
• Billion solar mass BH at z>7
• Non-stop, maximum accretion from 100 solar mass BHs at
z=15 (collapse of first stars in the Universe)
• Theoretically difficult for formation of z>7 billion solar
mass BHs
• What if we find them:
– Direct collapse of “intermediate” mass BHs?
– More efficient accretion model “super-Eddington”?
Puzzle 2: non-evolution of quasar (black hole) emission
z~6 composite
Low-z composite
Ly a
NV
Ly a forest
OI
SiIV
XF et al. 2010
•
•
•
Jiang, XF et al. 2008
Rapid chemical enrichment in quasar vicinity
Quasar env has supersolar metallicity : no metallicity evolution
High-z quasars are old, not yet first quasars, and live in metally enriched env
similar to centers of massive galaxies
When did the first quasar form?
Dust: emitting
in infrared
radiation from X-ray to radio as a result of black hole
accretion and growth
Disappearance of Dust Torus at z~6?
typical
J0005
3.5m
4.8m
5.6m 8.0m 16m
24m
• quasars with no hot dust
• Spitzer SEDs consistent
with disk continuum only
• No similar objects known
at low-z
• no enough time to form
hot dust tori? Or formed in
metal-free environment?
Jiang, XF et al. 2010
Epoch of first quasars?
Dust/Bolometric
Dust-free quasars:
Dust/Bolometric
• Only at the highest redshift
• With the smallest BH mass
• First generation supermassive
BHs from metal-free environment?
• How are they related to PopIII?
BH mass
Jiang, XF et al. 2010
High-redshift quasars live in the center of star-forming galaxies
CO
•
J1148 (z=6.42) - Spatially resolved CO and [CII]
emissions:
– Size: ~1.5 kpc
– Star formation rate of: ~1000 Msunyr-1kpc-2
• theoretically close to maximum star
formation rate ?
• Gas supply exhaused over a few tdyn
– Similar SF intensity to the brightest local
starburst (Arp 200) but 100 times larger!
1kpc
Walter et al. 2004
J1148 (z=6.42):
•CO line width ~300 km/s
•Dynamical mass
~1011Msun?
•BH formed earlier than
completion of galaxy
assembly?
Walter et al. 2009
reionization
Two Key Constraints:
1. WMAP 5-yr: zreion=11+/-3
2. IGM transmission: zreion > 6
From Avi Loeb
First detection of Gunn-Peterson Effect
Evolution of Lyman Absorptions at z=5-6
transparent
opaque
z = 0.15
Accelerated Evolution at z>5.7
•
(1+z)11
•
(1+z)4.5
Optical depth evolution accelerated
– z<5.7:  ~ (1+z)4.5
– z>5.7:  ~ (1+z)>11
– > Order of magnitude increase in
neutral fraction of the IGM
 End of Reionization
Dispersion of optical depth also
increased
– Some line of sight have dark
troughs as early as z~5.7
– But detectable flux in ~50% case
at z>6
–
XF et al. 2006
End of reionization is not
uniform, but with large scatter
Beyond Gunn-Peterson Optical Depth:
HII Region Sizes
zem
•
•
•
•
Gunn-Peterson test saturates at z>6
Size of HII region
Rs ~ (LQ tQ / fHI )1/3
HII region size decreases by ~ 3 from z=5.7 to 6.4
Best estimate: fHI ~ a few percent at z~6
Can be applied to higher z and fHI with lower S/N
data
Model uncertainties due to radiative transfer
Carilli et al. 2010
HII region size
•
•
z
Probing Reionization History
WMAP
Roads ahead
• Luminous quasars probe the evolution of the most
massive systems in the early universe
• Important changes were happening at z~6-7
– Timescale constraints on billion solar mass BH growth
– Evidence of youngest quasar structure
– End of reionization epoch with order of magnitude (or more?)
increase in IGM neutral fraction
– Discovery (or lack of ) z~7 quasars might reveal new surprises
– Requires new generation of large IR sky surveys
• Quasars and GRBs are complimentary probes to the peak
of reionization epoch
– GRB probes pristine, low mass galaxies and can reach high-z
faster