1. Cosmological parameters with radio galaxies
Oleg Verkhodanov
Special astrophysical observator
Nizhnij Arkhyz

2. Radio cosmology
Dark ages

3. Radio galaxies -
galaxies with radio power mostly due to nucleus activity
Power of emission is up to 10^48 erg/s

4. What are the radio galaxies ?

5. Cygnus A E-galaxy m=16 z = 0.057, theta~2' (80 kpc),
v = 0.02c, P= 3x10^44 erg/s

6. Centaurus A (NGC 5128)
P = 10^42 erg/s,
d = 12 kpc

7. Virgo A
(NGC 4486, M87)
cD-galaxy
20'' (1.5 kpc) optical jet

8. Radio galaxies identified with gE or cD galaxies
and should be visible in optics and radio waves from very beginning (z<~6)

9. 2 basic morphological types of RG
Fanaroff – Riley I
Fanaroff – Riley II

10. Unified model

11. Continuum radio galaxy spectra
alpha
S~nu
Steep spectrum:
alpha<-0.5

12. Radio galaxies as Universe reference point
The most distant radio galaxy: z=5.19
(van Breugel et al., 1999)

13. Distribution of radio galaxies for Cambridge catalogs
(Cruz et al., 2007)

14. Cosmology with radio galaxies
a) “size – redshift” (standard rod)
b) “luminosity – redshift” (standard candle)
c) ''Log N – Log S'' (“source number – flux density”)
d) Gravitational lensing
e) Clustering and large stellar structure forming
f) Age of stellar systems
g) Black hole formation at high redshift
h) Dark matter search in halos
What is good ? (probably, we know)
1) Universe expands, accelerating;
2) There are CMB radiation and its angular fluctuations;
3) elements in Universe.

15. Radio galaxies and large scale structure

16. ''Size – redshift'' diagram for radio sources and CMB
(Jackson, Janneta, 2006)

17. Gravitational lenses
Einstein ring
(RC ) B

18. Source counts: Log N – Log S
FR II:
1) FRII & QSR, alp<-0.5
2) QSR with flat Sp
3) RG, BL Lac,
FR I:
6) BL Lac, 
7) Starburst galaxies
(Jackson, Wall, 1999)

19. “Big Trio” Program
RATAN-600
VLA
BTA

20. “Big Trio” program
1) Radio sources of the “Cold” survey ( >10 mJy at 7.6 cm)
2) Steep radio spectrum (synchrotron) selection
3) VLA (radio): morphology selection (FR II)
4) 6m telescope (optics): identification, BVRI-photometry, spectrosopy (redshift)
5) Age estimation

21. “Big Trio” program

23. Age of radio galaxies

24. Giant elliptical galaxies with old stellar population ==> photometrical study and existance at very high z ~4 (Pipino & Mantteucci, 2004).
selection of distant gE (z>0.5) with radio galaxies ==> by radio astronomical methods (Pedani, 2003).

25. Estimation of stellar and galaxy age
by thermal nuclear reactions -
independent test for Universe expansion

26. Sample of 220 objects with 3 subsamples:
(1) Famous radio galaxies FR II (1<z<4):
initially 300 RGs (NED) ---> resulting 30 FRII
(2) RGs of FR II from the “Cold” survey
(“Big Trio”: Parijskij et al., ),
(3) Elliptical galaxies from clusters (Stanford, 2002) (0.1<z<1.3)

27. (Verkhodanov, Parijskij, Starobinsky, 2005)
Approximation of t(z) with integral curve and detection of H_o и Omega_Lambda
(Verkhodanov, Parijskij, Starobinsky, 2005)
Sample binning dz=0.2 и dz=0.3
Take maximum in each bin

28. Two models of synthetic spectra

29. Age [Myr]
Redshift z
Age [Myr]
Redshift z

30. Possible errors
metalicity: error ~100 Myr (Jimenez, Loeb, 2002)
initial mass function has low influence (Bolzonella et al., 2001),
error in galaxy type detection,
incomplete sample: robust detection
Bootstrap method:
mutiplication coefficient 100, variation of H_o ~ 10%

31. Model dz Om_mOm_L H_o epsilon
SED [Myr]
GISSEL
GISSEL
PEGASE
PEGASE
H_o = 72 +/ Om_L = 0.8 +/- 0.1,
not exelent, but satisfys the model

32. What is further ? 2) Combining different methods
1) Select ALL the distant RGs and typical close gEs
2) Combining different methods

33. z = 4.514 (Kopylov et al., 2006) The 2nd RG by z, the 1st RG by power
among RGs, z>4

34. Thank you for hospitality !