1. 03/000 Cosmologic astrometry Australian Government Geoscience Australia Yonsei University, Seoul 18 October 2010

2. Geoscience Australia 18 October 2010

3. The concept Geoscience Australia 18 October 2010 B   B = 10000 km,  = 0.03 cos  sec

4. ICRF2 defining sources 18 October 2010

5. ICRF1 → ICRF2 1995 → 2010 total number of objects 608 → 3414 number of defining sources 212 → 295 formal error σ(0) = 60 µas → 7 µas “inflated” error σ = 250 µas → 41 µas Geoscience Australia 18 October 2010

6. Astrometry of stars (~2000 years) ↓ Astrometry of quasars Geoscience Australia 18 October 2010 no structure huge variable structure

7. ICRF source instability (structure) Geoscience Australia 18 October 2010

8. Instability of the ICRF sources (2201+315) Geoscience Australia 18 October 2010

9. Instability of ICRF sources ( 2201+315, in sky plane, 2001-2004) Geoscience Australia 18 October 2010 Kellermann et al. (2004) Position angle of the brightest jet ~ 158º Geodetic VLBI: Position angle ~ 148º apparent proper motion ~ 0.6 mas/year

10. 2145+067 18 October 2010

11. Change of position of a celestial object approximated by linear trend Geoscience Australia 18 October 2010 Definition of proper motion

12. 2145+067 18 October 2010

13. The apparent motions look random The systematic has been searched since (Gwinn, Eubanks et al. 1997; MacMillan 2003) Geoscience Australia 18 October 2010

14. Apparent motion 18 October 2010

15. FK5 → ICRF2 1988 → 2010 position accuracy 0”.019= 19000 µas → 41 µas apparent motion accuracy 700 µas/year → 10-100 µas/year Geoscience Australia 18 October 2010

16. Assumption (1995) “The reference radio sources have no measurable proper motion [ at the level of precision achieved by 1995 ]” Geoscience Australia 18 October 2010

17. Possible reasons of the assumption violation 1. Secular aberration drift (Bastian, 1995; Sovers et al., 1998, Klioner, 2003) 18 October 2010 2. Hubble constant anisotropy (Kristian and Sachs, 1966) 3. Primordial gravitational waves (Kristian and Sachs, 1966; Pyne et al., 1996) 4. Motion of the Solar system with respect CMB Kardashev (1986), Sovers et al (1998) <14 µas/year (Galaxy M81)

18. Directed towards the centre of Galaxy (RA= 270º, DE = -30º) a = V²/R Geoscience Australia 18 October 2010 1. Centrifugal acceleration due to rotation of the Solar system around the Galaxy center

19. Geoscience Australia 18 October 2010 1. Centrifugal acceleration due to rotation of the Solar system around the Galaxy center

20. Geoscience Australia 18 October 2010 1. Centrifugal acceleration due to rotation of the Solar system around the Galaxy center V a V a

21. Geoscience Australia 18 October 2010 1. All quasars are attracted by the Galactic centre

22. Geoscience Australia 18 October 2010 1. Centrifugal acceleration due to rotation of the Solar system Volatile!

23. 2 и 3 18 October 2010 Proper motion in the expanding Universe (Kristian and Sachs, 1966) “Observations in cosmology”

24. 2. The Hubble law 18 October 2010 The Earth H - the Hubble constant It is supposed to be isotropic for all directions on the sky

25. 2. Hubble constant anisotropy 18 October 2010 - generalised Hubble expansion

26. 18 October 2010 The Hubble law Anisotropic Hubble expansion and non- zero systematic 2. Hubble constant anisotropy

27. 3. Primordial gravitational waves (Kristian and Sachs, 1966) 18 October 2010 σ – “Shear” ω - rotation E – Electric-type gravitational waves H – Magnetic-type gravitational waves

28. 18 October 2010 Gwinn et al (1997) – power density of gravitational waves 3. Primordial gravitational waves

29. Only three reasons are considered Geoscience Australia 18 October 2010 1. Dipole systematic 2. Rotation (no physics yet) 3. Gravitational waves and Hubble constant anisotropy

30. Proper motion model 18 October 2010 rotation Magnetic-type Gravitational waves Electric-type gravitational waves or Hubble constant anisotropy dipole

31. Proper motion model 18 October 2010 dipole rotation

32. 18 October 2010 Systematic effect in apparent motion

33. This is not effect of intrinsic structure! Geoscience Australia 18 October 2010

34. ~ 5000 24-hour sessions since 1980 ~ 6 million delays ~ 3000 sources Software CALC/SOLVE (S.Lambert, A.-M. Gontier; Paris Observatory) Geoscience Australia 18 October 2010 Global solution

35. Proper motion model 18 October 2010 dipole rotation

36. Dipole effect in apparent proper motion 18 October 2010 α = 266º +/-8º δ= -18º+/- 18º A = 5.8 +/- 1.4 μas

37. 18 October 2010 Quadrupole effect in apparent proper motion

38. 18 October 2010

39. Quadrupole effect in apparent proper motion – component E(2,1)

40. 18 October 2010 Quadrupole effect in apparent proper motion – component E(2,0)

41. Geoscience Australia 18 October 2010 Main results - Quadrupole systematic is marginal A = 3.5 +/- 0.9 μas Energy density of primordial gravitational waves Too much uncertainty!!!

42. - Galactocentric acceleration Geoscience Australia 18 October 2010 Dipole effect α = 266º +/-8º δ = -18º+/- 18º A = 5.8 +/- 1.4 μas Main results First direct identification of Galactocenrtic acceleration of the Solar system barycentre

43. Geoscience Australia 18 October 2010 Main results Problems for ICRS definition Assumption (1995) “The reference radio sources have no measurable proper motion [at the level of precision achieved by 1995]” The secular acceleration drift (dipole effect) is not taken into account by the current ICRS definition/assumption

44. Question 18 October 2010 If proper motion are real, then the reference axes are not fixed by the positions of the defining sources! How to deal with the non-zero proper motion???

45. Conclusion Secular aberration drift has been found. Fundamental astrometry has a strong cosmologic component Geodetic VLBI is able to measure apparent motion of several thousand reference radio sources and promote some fundamental discoveries about the Universe Attract more resources (funds, grants, students) and public/media attention 18 October 2010

46. Suggestion Modify the IVS observational program to obtain about 3000 proper motion by 2020 (instead of 700). This number increases very slowly, from ~500 in 2001 to ~700 in 2010. Just because existing IVS observational programs target on the well- known sources with long observational history. New sources are observed rarely. To organize a dedicated astrometric program in the southern hemisphere. New AuScope network + New Zealand dish + Asia-Pacific network + Kokee. 18 October 2010

47. Thank you! 18 October 2010