Large-scale alignment of optical polarizations from distant QSOs using coordinate-invariant statistics

Abstract

We introduce several coordinate-invariant statistical procedures in order to test for alignment of polarizations of electromagnetic radiation from astrophysical sources. A large-scale alignment of optical polarizations from distant quasi-stellar objects (QSOs) has recently been observed by Hutsemékers and collaborators. The new statistical procedures are based on comparing polarizations at different angular coordinates by making a parallel transport. The results of these statistical procedures continue to support the existence of the large-scale alignment effect in the QSO optical polarization data. The alignment is found to be much more pronounced in the data sample with low degrees of polarization, p 2 per cent. This suggests that the alignment may be attributed to some propagation effect. The distance scale over which the alignment effect is dominant is found to be of order 1 Gpc. We also find that a very large-scale alignment is present in the large-redshift, z 1, data sample. In fact, the data sample with z 1 appears to be aligned over the entire celestial sphere. This alignment is seen independent of the degree of polarization of the sources. We discuss possible physical effects, such as extinction and pseudoscalar-photon mixing, which may be responsible for the observations.

Generating intrinsic dipole anisotropy in the large scale structures

“…We solve the Eqns (7)(8)(9)(10)(11)(12) by use of standard techniques [20]. The results for the long wavelength mode being both subhorizon and superhorizon during present time are standard results of the text.…”

“…While u 2 = 1/3 during radiation domination, it is zero during matter domination. The solutions for superhorizon mode potentials of Eqn (12) shows that the potential is effectively constant and equal to the initial value at each epoch. We calculate the values of the density contrast in different component by making use of the curvature perturbation, ζ( r), which remains constant.…”

“…Radio polarizations from radio galaxies show large scale dipole pattern [9]. The optical polarization of quasars also show alignment over length scales of Gpc [10][11][12]. Interestingly, the quadrupole-octupole alignment axis [1], the radio polarization dipole axis [9], the two point correlation in the optical polarization data [12] all align quite close to the CMB dipole axis [3].…”

Mapping extreme-scale alignments of quasar polarization vectors

“…A weakness of the tests used in Paper I was their dependency upon the coordinate system. Jain et al (2004) −4 we used up to 10 5 simulations. Significance levels are given in Fig.…”

Quasar polarization with ultralight (pseudo-)scalars

“…It was found and confirmed that the quasar polarization vectors are not randomly oriented as naturally expected, but appear concentrated around one preferential direction on very large spatial scales [11][12][13][14]. The polarization vectors appear coherently aligned over huge (∼ Gpc) regions of the sky located at both low (z ∼ 0.5) and high (z ∼ 1.5) redshifts and characterized by different preferred directions of the quasar polarization.…”