Detection of integrated Sachs-Wolfe effect by
cross-correlation of the
cosmic microwave background
and
radio galaxies
Collaborators:
Ue-Li Pen (CITA)
K-W Ng(IoP, AS)
中
央
研 Guo Chin Liu
究
院
2007/12/20@NTHU
Hubble Diagram with 42 High-Redshift Supernovae
Something is missing for
the “cosmological principle”
based Friedmann universe.
Standard candle?
Evolution of SN Ia is small.
D. Branch et al. 2001
Perlmutter et al. 1998
m+k+=1
Microwave Sky from WMAP
CMB contains richest
information of our universe.
Expansion rate
Age of universe
Inflation model
Content of universe
Geometry of universe
Thermal history (reionization)
……………
Statistics of CMB Sky
Geometry of our universe
ISW effect
Observation of CMB
first peak alone does
not guarantee the
existence of dark energy.
1. We are living in low
density universe, i.e.,
m0.3.
Allen et al. 2002
Carlberg et al. 1997
2. Hubble constant is not
so small, for example,
from SZ clusters
measurement, H0=6070
Reese et al. 2002
Udomprasert et al 2004.
m+k+=1
Spergal et al. 2007
Astronomical Observation for Dark Energy
Need to be sensitive on
1. Geometry of universe (distance vs. redshift relation)
2. Structure formation
Current used observations
1. Supernova type Ia : probe the geometry of universe
Caution: assuming uniform intrinsic luminosity
2. CMB : good constraint on small curvature
Caution : no time evolution data
3. Large scale structure : evolution of geometry of universe and
growth factor D(z)
Caution: depend on CDM model for structure formation
Other possibilities
Dark energy couples with cold dark matter : Changing
matter power spectrum
S. Lee, G. Liu & K. Ng PRD 2006
Coupling with CMB photons: Producing parity odd
term in CMB polarization power spectra
G. Liu, S. Lee & K. Ng PRL 2006
The physical quantity to be determined:
Equation of state w(z)=p/
Cosmological constant: w=-1
Quintessence : wQ: w0, w0+(1-a)w1, oscillating….
a. Assume flat universe and const. w
w=-1.05+0.15-0.2
Knop et al.2004 (SN)
b. time evolution w=w0+ (1-a)w1
w0=-1.146+0.176-0.178
w1=0.6+0.622-0.652 --no dark energy perturbation
w0=-1.118+0.152-0.147
w1=0.499+0.453-0.498 -- with dark energy perturbation
G-B Zhao et al. 2006(SN+CMB+galaxy clustering)
CDM explains observation data very well
Inhomogeneity
Dark energy
Cosmological
constant
Cosmologists are often in error, but never in doubt
Lev Landau
Future observation
Weak lensing: Size of distortion image depends on
distance traveled and growth factor
BAO: Baryon Acoustic Oscillation is sensitive to dark
energy through its effect on the angular-diameter
distance vs. redshift relation and through its effect on
the time evolution of the expansion rate.
Clusters observation: growth rate and geometry of
universe
1. Joint Efficient Dark-Energy Investigation
(JEDI)
* SN Ia 0<z<2
* BAO 10-100 M galaxies, 1000-10000
deg^2
* Weak lensing 1000-10000 deg^2
2. SuperNova Acceleration Probe (SNAP)
*SN Ia 0<z<1.7
*Weal lensing
Second Hint from CMB
ISW effect (late)I
1. If the potential decays between the time a photon falls into
a potential well and when it climbs out it gets a boost in
temperature of due to the differential gravitational redshift
and due to an accompanying contraction of the wavelength
2. No ISW effect in matter dominate epoch.
3. The dark energy dominating on late epoch creates the
temperatures anisotropies on large scales.
E=|1-2|
2
1
T/T=-2  d d/d
ISW effect II
1. Signature of dark energy
2. Probe of evolution of structure
3. Sensitive on large scale
(horizon)
4. Difficult to detect
Try to look for correlation of CMB with matter
Cross correlation of CMB with matter in local
universe Proposed by Crittenden & Turok (1996)
Density fluctuation
Form structures
CMB gains energy
Possible tracers
1. NRAO VLA Sky Survey (NVSS)
2. Hard X-ray background (HEAO-1)
3. Sloan Digital Sky Survey (SDSS)
4. Two Micron All Sky Survey Extended Source Catalogue
(2MASS XSC)
Contribution to Signal from different Redshift
Crittenden & Turok PRL 1996
First detection of the cross-correlation
Correlating CMB sky to
hard X-rays (HEAO-1) and
radio galaxy (NVSS)
wiNiwjTj/wiwj
3 sigma detection for hard
X-rays and 2.5 sigma for
radio galaxy
Boughn & Crittenden, nature, 2004
Contamination
1. Sunyaev-Zeldovich Effect: anisotropies generated through
the inverse Compton scattering with free e- correlates with
the galaxy itself.
On small scales
2. Emission from the radio galaxy
Emission at f<few tens GHz contaminates the microwave
sky.
On small scales
3. Primary CMB itself: △T(ISW) < 30% of △T(total)
Details of this work I
1. We work at harmonic space
SZ and radio emission is
ignorable.
Low correlation between
each mode
2. ClNT=<aNlmaT*lm>
△T/T()=aTlmYlm()
3. Using NVSS as matter
distribution tracer.
4. Healpix software is used for
visualization and calculating
alm
NVSS data
1. 1.4GHz , 82% sky coverage (>-40)
2. Sensitivity 2.5 mJy contains 1.8 million sources
3. Typical luminosity function models indicate 0z2 distribution
Detail II
41GHz
61GHz
T
T
Q
Q
U
U
Result I
CMB anisotropies & polarization on large scales
CMB last scattering surface
△TSW, z=1100
Generate P. for l>100
△Treion, z=10
Generate P for l < 30~50
△TISW, z<2
Dark energy dominates
Observer
Correction by the information of polarization
At large scales T=TSW + Tre + TISW
E(no ISW) =aT(no ISW) + n
<TE> = a <TT>
<EE>=a2<TT> + n2
T(ISW) =T – E/a * WF
WF=a2<TT>/<EE>
Result II
Discussion & Summary
1. Working in harmonics space, signal with 2-sigma is detected
in l~ 10-20. Though it is smaller than detection in real space,
statistically it gives same information.
2. Primary CMB is the dominated noise in this cross-correlation.
Using polarization information, we can filter out part of it.
3. It suppress the noise about 17%, 3% and 8.7% in band power
l=3, 7 and 15. Give a better constrain on dark energy model.