1. Detection of integrated Sachs-Wolfe effect by cross-correlation of the
cosmic microwave background
and
radio galaxies
中央研究院
Guo Chin Liu
Collaborators:
Ue-Li Pen (CITA)
K-W Ng(IoP, AS)

2. 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

3. 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)
……………

4. Statistics of CMB Sky
Geometry of our universe
ISW effect

5. Observation of CMB first peak alone does not guarantee the existence of dark energy.
We are living in low density universe, i.e., m Allen et al Carlberg et al. 1997
Hubble constant is not so small, for example, from SZ clusters measurement, H0= Reese et al Udomprasert et al 2004.
m+k+=1
Spergal et al. 2007

6. Astronomical Observation for Dark Energy
Need to be sensitive on
Geometry of universe (distance vs. redshift relation)
2. Structure formation
Current used observations
Supernova type Ia : probe the geometry of universe Caution: assuming uniform intrinsic luminosity
CMB : good constraint on small curvature Caution : no time evolution data
Large scale structure : evolution of geometry of universe and growth factor D(z) Caution: depend on CDM model for structure formation

7. 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

8. 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= Knop et al.2004 (SN)
b. time evolution w=w0+ (1-a)w1 w0=
w1= no dark energy perturbation
w0=
w1= with dark energy perturbation G-B Zhao et al. 2006(SN+CMB+galaxy clustering)
CDM explains observation data very well

9. Inhomogeneity
Dark energy
Cosmological constant

10. Cosmologists are often in error, but never in doubt 　Lev Landau

11. 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

12. Joint Efficient Dark-Energy Investigation (JEDI). SN Ia 0<z<2
Joint Efficient Dark-Energy Investigation (JEDI) * SN Ia 0<z<2 * BAO M galaxies, deg^2 * Weak lensing deg^2
SuperNova Acceleration Probe (SNAP) *SN Ia 0<z<1.7 *Weal lensing

14. Second Hint from CMB ISW effect (late)I
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
No ISW effect in matter dominate epoch.
The dark energy dominating on late epoch creates the temperatures anisotropies on large scales. 1 2
E=|1-2|
T/T=-2  d d/d

15. Try to look for correlation of CMB with matter
ISW effect II
Signature of dark energy
Probe of evolution of structure
Sensitive on large scale (horizon)
Difficult to detect
Try to look for correlation of CMB with matter

16. Cross correlation of CMB with matter in local universe Proposed by Crittenden & Turok (1996)
Density fluctuation
CMB gains energy
Form structures
Possible tracers
NRAO VLA Sky Survey (NVSS)
Hard X-ray background (HEAO-1)
Sloan Digital Sky Survey (SDSS)
Two Micron All Sky Survey Extended Source Catalogue (2MASS XSC)

17. Contribution to Signal from different Redshift
Crittenden & Turok PRL 1996

18. 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

19. Contamination
Sunyaev-Zeldovich Effect: anisotropies generated through the inverse Compton scattering with free e- correlates with the galaxy itself. On small scales
Emission from the radio galaxy Emission at f<few tens GHz contaminates the microwave sky. On small scales
Primary CMB itself: △T(ISW) < 30% of △T(total)

20. Details of this work I
We work at harmonic space SZ and radio emission is ignorable. Low correlation between each mode
ClNT=<aNlmaT*lm> △T/T()=aTlmYlm()
Using NVSS as matter distribution tracer.
Healpix software is used for visualization and calculating alm

21. 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

22. Detail II
41GHz
61GHz T T Q Q U U

23. Result I

24. 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

25. 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>

26. Result II

27. Discussion & Summary
Working in harmonics space, signal with 2-sigma is detected in l~ Though it is smaller than detection in real space, statistically it gives same information.
Primary CMB is the dominated noise in this cross-correlation. Using polarization information, we can filter out part of it.
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.