1 COSMIC POLARIZATION ROTATION & COSMOLOGICAL MODELS AND Detectability of Primordial G-Waves Wei-Tou Ni Wei-Tou Ni Center for Gravitation and Cosmology, Purple M ountain Observatory, Chinese Academy of Scienc es, Nanjing, CHINA National Astronomical Observatories, Chinese A cademy of Sciences, Beijing, CHINA
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1 COSMIC POLARIZATION ROTATION & COSMOLOGICAL MODELS AND Detectability of Primordial G-Waves Wei-Tou Ni Center for Gravitation and Cosmology, Purple Mountain.
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ed the polarization of the cosmic background. With the pseudoscalar-photon interaction , the p
olarization anisotropy is shifted relative to the temperature anisotropy.
In 2003, WMAP found that the polarization and temperature are correlated to 10σ. This gives a constraint of 10-1 rad or 6 degrees of the cosmic polarization rotation angleΔφ.
Change of Polarization due to Change of Polarization due to Cosmic PropagationCosmic Propagation
The effect of φ in (2) is to change the phase of two different circular polarizations of electromagnetic-wave propagation in gravitation field and gives polarization rotation for linearly polarized light.[6-8]
Polarization observations of radio galaxies put a limit of Δφ ≤ 1 over cosmological distance.[9-14]
Further observations to test and measure Δφ to 10-6 is promising. The natural coupling strength φ is of order 1. However, the
isotropy of our observable universe to 10-5 may leads to a change (ξ)Δφ of φ over cosmological distance scale 10-5 smaller. Hence, observations to test and measure Δφ to 10-6 are needed.
Electomagnetic Wave Propagation and Polarization Electomagnetic Wave Propagation and Polarization EPEP
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T. P. Krisher, {\sl Phys. Rev}. D {\bf 44}, R2211 (1991).
Pseudoscalar-Photon Interaction and Astrophysical/Cosmic Pseudoscalar-Photon Interaction and Astrophysical/Cosmic Polarization Rotation Polarization Rotation ΔΔθθ (= (=ΔΔφφ)) of Electromagnetic Wave of Electromagnetic Wave
PropagationPropagation
W.-T. Ni, A Nonmetric Theory of Gravity, preprint, Montana State University, Bozeman, Montana, USA (1973), http://gravity5.phys.nthu.edu.tw.
S. M. Carroll, G. B. Field, R. Jackiw, {\sl Phys. Rev}. D {\bf 41}, 1231 (1990). S. M. Carroll and G. B. Field, {\sl Phys. Rev}. D {\bf 43}, 3789 (1991). B. Nodland and J. P. Ralston, {\sl Phys. Rev. Lett}. {\bf 78}, 3043 (1997). J. F. C. Wardle, R. A. Perley, and M. H. Cohen, {\sl Phys. Rev. Lett.} {\bf 79}, 1
801 (1997). D. J. Eisenstein and E. F. Bunn, {\sl Phys. Rev. Lett.} {\bf 79}, 1957 (1997). S. M. Carroll and G. B. Field, {\sl Phys. Rev. Lett.} {\bf 79}, 2394 (1997). T. J. Loredo, E. A. Flanagan, and I. M. Wasserman, {\sl Phys, Rev.} {\bf D 56},
7507 (1997). S. M. Carroll, {\sl Phys. Rev. Lett.} {\bf 81}, 3067 (1998). A. Lue, L. Wang, and M. Kamionkowski, Phys. Rev. Lett. {\bf 83}, 1506 (1999).
Space contribution to the local polarization rotation Space contribution to the local polarization rotation angle -- [μΣ13angle -- [μΣ13φ,φ,μμΔΔxμ] = |▽xμ] = |▽φφ| cos | cos θθ ΔΔx0. The time x0. The time contribution is contribution is φ,0φ,0 ΔΔx0. The total contribution is (|x0. The total contribution is (|
▽▽φφ| cos | cos θθ + + φ,0φ,0) ) ΔΔx0. x0. ( (ΔΔx0x0 > 0) > 0)
Intergrated:φ(2) - φ(1)φ(2) - φ(1)1: a point at the 1: a point at the decoupling epochdecoupling epoch2: observation 2: observation pointpoint
Variations and FluctuationsVariations and Fluctuations
rotationφ(2) - φ(1)rotationφ(2) - φ(1) δδφ(2) - φ(2) - δδφ(1): φ(1): δδφ(2) variations and fluctuations at φ(2) variations and fluctuations at
the last scattering surface of thethe last scattering surface of the decoupling epoch; decoupling epoch; δδφ(1), at present observation φ(1), at present observation
point, fixedpoint, fixed <[<[δδφ(2) - φ(2) - δδφ(1)]^2> variance of fluctuation φ(1)]^2> variance of fluctuation ~ ~
[coupling[couplingξ × 10^(-5)]^2 × 10^(-5)]^2 The coupling depends on various cosmological The coupling depends on various cosmological
COSMOLOGICAL INTERPRETATION, Komatsu et al., arXiv:0803.0547v2 [astro-ph] 17 Oct 2008
The power spectra of TB and EB correlations constrain a parity-violating interaction, which rotates the polarization angle and converts E to B. The polarization angle could not be rotated more than −5.9◦ < α < 2.4◦ (95% CL) between the decoupling and the present epoch. I.e. -30 ± 73 mrad (2σ)
Pseudoscalar-photon interaction is proportional to the gradient of the pseudoscalar field. From phenomenological point of view, this gradient could be neutrino number asymmetry, other density current, or a constant vector. In these situations, Lorentz invariance or CPT may effectively be violated.
Probing neutrino number asymmetry Better accuracy in CMB polarization observation is expe
cted from PLANCK mission to be launched this year. A dedicated CMB polarization observer in the future would probe this fundamental issue more deeply.
The Gravitational Wave Background from The Gravitational Wave Background from Cosmological Compact BinariesCosmological Compact Binaries
Alison J. Farmer and E. S. Phinney (Mon. Not. RAS [2003])Alison J. Farmer and E. S. Phinney (Mon. Not. RAS [2003])
Optimistic (upper dotted), fiducial (Model A, lower solid line) and pessimistic (lower dotted) extragalactic backgrounds plotted against the LISA (dashed) single-arm Michelson combination sensitivity curve. The‘unresolved’ Galactic close WD–WD spectrum from Nelemans et al. (2001c) is plotted (with signals from binaries resolved by LISA removed), as well as an extrapolated total, in which resolved binaries are restored, as well as an approximation to the GalacticMS–MS signal at low frequencies.
LISALISA LISA consists of a fleet of 3 spacecraft 20º behind earth in solar orbit keeping a triangular configuration of nearly equal sides (5 × 106 km). Mapping the space-time outside super-massive black holes by measuring the capture of compact objects set the LISA requirement sensitivity between 10-2-10-3 Hz. To measure the properties of massive black hole binaries also requires good sensitivity down at least to 10-4 Hz. (2017)
Super-ASTROD (1Super-ASTROD (1stst TAMA Meeting1996) TAMA Meeting1996)W.-T. Ni, “ASTROD and gravitational waves” in W.-T. Ni, “ASTROD and gravitational waves” in Gravitational WGravitational W
ave Detectionave Detection, , edited by K. Tsubono, M.-K. Fujimoto and K. Kuroda edited by K. Tsubono, M.-K. Fujimoto and K. Kuroda
(Universal Academy Press, Tokyo, Japan, 1997), pp. 117-129.(Universal Academy Press, Tokyo, Japan, 1997), pp. 117-129.
With the advance of laser technology and the development of space interferometry, one can envisage a 15 W (or more) compact laser power and 2-3 fold increase in pointing ability.
With these developments, one can increase the distance from 2 AU for ASTROD to 10 AU (2×5 AU) and the spacecraft would be in orbits similar to Jupiter's. Four spacecraft would be ideal for a dedicated gravitational-wave mission (Super-ASTROD).
Primordial GW and Super-ASTRODPrimordial GW and Super-ASTROD
For detection of primordial GWs in space. One may go to frequencies lower or higher than LISA/ASTROD bandwidth where there are potentially less foreground astrophysical sources to mask detection.
DECIGO and Big Bang Observer look for gravitational waves in the higher range
Super-ASTROD look for gravitational waves in the lower range. Super-ASTROD (ASTROD III) : 3-5 spacecraft with 5 AU
orbits together with an Earth-Sun L1/L2 spacecraft and ground optical stations to probe primordial gravitational-waves with frequencies 0.1 μHz - 1 mHz and to map the outer solar system.
Sensitivity to Primordial GWSensitivity to Primordial GW
The minimum detectable intensity of a stochastic GW background is proportional to detector noise spectral power density S_n(f) times frequency to the third power
with the same strain sensitivity, lower frequency detectors have an f ^(-3)-advantage over the higher frequency detectors.
compared to LISA, ASTROD has 27,000 times (30^3) better sensitivity due to this reason, while Super-ASTROD has an additional 125 (5^3) times better sensitivity.
Polarization as a tool to test cosmological models and to look into (gravitational) axion and possible dark energy pseudoscalar, CPT, Neutrino Asymmetry, etc.
Primordial gravitational waves may possibly be detected by ASTROD/Super-ASTROD and DECIGO/Big Bang Observer