Speaker
Description
The presence of magnetic fields has been inferred in extragalactic spaces like voids, and astrophysical mechanisms are unable to explain the magnitude of these fields. This hints towards cosmological magnetic fields of primordial origin, that are amplified by the astrophysical dynamo effect.
As future surveys and telescopes provide higher precision measurements of CMB, LSS and EoR; we are expected to constrain the strength of these Primordial Magnetic fields (PMFs), if not detect them. However, addition of PMFs leads to effects that differ from the standard $\Lambda$-CDM predictions on which our inferences are based.
One important effect of PMFs is on recombination and the CMB. The presence of PMFs leads to additional clumping in the pre-recombination plasma, accelerating the recombination process. As a result, the inferred angular diameter distance to last scattering increases, and our inference of cosmological parameters changes. For example, the measured $H_0$ increases in a universe with PMFs, likely alleviating the Hubble tension.
The CMB photons scatter with neutral H (and He) atoms post recombination, prolonging last scattering. Since this effect is based on well-understood physics, it provides a robust probe of the ionization history and the last scattering surface. Thus, measuring Rayleigh scattering of the CMB would help constrain the ionization history and indirectly constrain PMFs.
My project deals with combining both effects and presenting realistic estimates of the constraints obtainable from CMB observations from the Simons Observatory, CCAT Observatory, and Planck Collaboration.
| Other topic / keywords: | Rayleigh Scattering |
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