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Abstract:

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 primordial inflation explorer (PIXIE) and polarized radiation imaging and spectroscopy mission (PRISM) have recently been proposed. In this paper, CMB distortions due to resonant conversions between CMB photons and light axionlike particles (ALPs) are investigated, motivated by the string axiverse scenario which suggests the presence of a plenitude of light axion particles. The distortions due to resonant conversions have a frequency-independent shape, in contrast to μ and y distortions. Therefore, one can distinguish the distortions due to resonant conversions from μ and y distortions. Since these resonant conversions depend on the strength of primordial magnetic fields, constraints on CMB distortions can provide an upper limit on the product of the photon-ALP coupling constant g and the comoving strength of primordial magnetic fields B. Potentially feasible constraints from PIXIE/PRISM can set a limit gBâ‰210-16 GeV-1 nG for ALP mass mφâ‰210-14 eV. Although this result is not a direct constraint on g and B, it is significantly tighter than the product of the current upper limits on g and B. © 2013 American Physical Society.

Abstract:

We outline the prospects for performing pioneering radio weak gravitational lensing analyses using observations from a potential forthcoming JVLA Sky Survey program. A large-scale survey with the JVLA can offer interesting and unique opportunities for performing weak lensing studies in the radio band, a field which has until now been the preserve of optical telescopes. In particular, the JVLA has the capacity for large, deep radio surveys with relatively high angular resolution, which are the key characteristics required for a successful weak lensing study. We highlight the potential advantages and unique aspects of performing weak lensing in the radio band. In particular, the inclusion of continuum polarisation information can greatly reduce noise in weak lensing reconstructions and can also remove the effects of intrinsic galaxy alignments, the key astrophysical systematic effect that limits weak lensing at all wavelengths. We identify a VLASS "deep fields" program (total area ~10-20 square degs), to be conducted at L-band and with high-resolution (A-array configuration), as the optimal survey strategy from the point of view of weak lensing science. Such a survey will build on the unique strengths of the JVLA and will remain unsurpassed in terms of its combination of resolution and sensitivity until the advent of the Square Kilometre Array. We identify the best fields on the JVLA-accessible sky from the point of view of overlapping with existing deep optical and near infra-red data which will provide crucial redshift information and facilitate a host of additional compelling multi-wavelength science.