Exploring scalar-photon interactions in energetic astrophysical events

Scalar fields like dilaton appear in quantum field theory (QFT) due to scale symmetry breaking. Their appeal also extends to modified theories of gravity, like $F(R)$ gravity, Horva Lifshitz gravity etc. In unified theories they make their appearance through compactification of the extra dimension. Apart from resolving the issues of compactification scale and size, the particles of their fields can also turn out to be excellent candidate to solve the dark energy (DE) and dark matter (DM) problem of the universe. In this work we study their mixing dynamics with photons in a magnetized media, by incorporating the effect of parity violating part of the photon polarization tensor, evaluated in a finite density magnetized media. This piece, though in general is odd in the external magnetic field strength $eB$; in this work we however have retained terms to $O$($eB$). We are able to demonstrate in this work that, in magnetized medium a dilatonic scalar field $(\phi)$ can excite the two transverse degrees of freedom (DOF) of the photons. One due to direct coupling and the other indirectly through the parity violating term originating due to magnetized medium effects. This results in the mixing dynamics being governed by, $3\times 3$ mixing matrices. This mixing results in making the underlying media optically active. In this work we focus on the spectro-polarimetric imprints of these particles, on the spectra of the electromagnetic (EM) fields of Gamma Ray Bursters (GRB). Focusing on a range of parameters (i.e., magnetic field strength, plasma frequency $(\omega_{p})$, size of the magnetized volume, coupling strength to photons and their mass) we make an attempt to point out how space-borne detectors should be designed to optimise their detection possibility.

Ankur Chaubey, Manoj K. Jaiswal, Avijit K. Ganguly · 2020