Measuring spectral distortions of the cosmic microwave background (CMB) is attracting considerable attention as a probe of high energy particle physics in the cosmological context, since PIXIE and PRISM have recently been proposed. In this paper, CMB distortions due to resonant
The 21 cm signatures induced by moving cosmic string loops are investigated. Moving cosmic string loops seed filamentary nonlinear objects. We analytically evaluate the differential 21 cm brightness temperature from these objects. We show that the br
ightness temperature reaches 200 mK for a loop whose tension is about the current upper limit, $Gmusim10^{-7}$. We also calculate the angular power spectrum, assuming scaling in loop distribution. We find that the angular power spectrum for $Gmu>10^{-8}$ at $z=30$ or $Gmu>10^{-10}$ at $z=20$ can dominate the spectrum of the primordial density fluctuations. Finally we show that a future SKA-like observation has the potential to detect the power spectrum due to loops with $Gmu=10^{-8}$ at $z=20$.
TeV blazars offer an exciting prospect for discovering cosmological magnetic fields and for probing high energy processes, including CP violation, in the early universe. We propose a method for reconstructing both the non-helical and the helical magn
etic field correlators using observations of cascade photons from TeV blazars.
We study diffusion damping of acoustic waves in the photon-baryon fluid due to cosmic strings, and calculate the induced $mu$- and $y$-type spectral distortions of the cosmic microwave background. For cosmic strings with tension within current bounds
, their contribution to the spectral distortions is subdominant compared to the distortions from primordial density perturbations.
The cosmic microwave background (CMB) polarisation and the 21 cm line fluctuations are powerful probes of cosmological reionisation. We study how the cross-correlation between the CMB polarisation (E-modes) and the 21 cm line fluctuations can be used
to gain further understanding of the reionisation history, within the framework of inhomogeneous reionisation. Since the E-mode polarisation reflects the amplitude of the quadrupole component of the CMB temperature fluctuations, the angular power spectrum of the cross-correlation exhibits oscillations at all multipoles. The first peak of the power spectrum appears at the scale corresponding to the quadrupole at the redshift that is probed by the 21 cm line fluctuations. The peak reaches its maximum value in redshift when the average ionisation fraction of the universe is about half. On the other hand, on small scales, there is a damping that depends on the duration of reionisation. Thus, the cross-correlation between the CMB polarisation and the 21 cm line fluctuations has the potential to constrain accurately the epoch and the duration of reionisation.
