Electromagnetic Radiation from Binary Stars Mediated by Ultralight Scalar

TL;DR

This paper investigates electromagnetic radiation from eccentric binary stars with scalar charges, analyzing how scalar-photon coupling influences observable signals and constraining model parameters using pulsar data.

Contribution

It provides a detailed calculation of scalar-mediated electromagnetic radiation in binary systems, including orbital frequency effects and observational constraints.

Findings

Scalar radiation is suppressed below the scalar mass threshold.

Scalar-photon coupling constraints are derived from pulsar binary data.

Extensions to quadrupole order and hyperbolic orbits are discussed.

Abstract

We present the electromagnetic (EM) dipole radiation flux from an eccentric Keplerian binary endowed with scalar charges, in the presence of scalar-photon coupling $\phi A_\mu A^\mu$ or $\phi F_{\mu\nu}F^{\mu\nu}$. The scalar radiation is suppressed for orbital frequency below the scalar mass, while the scalar-mediated indirect EM radiation survives. We examine the constraints imposed on the scalar-photon and scalar-charge couplings by the current observational data of pulsar binaries, in case that the scalar charge is given by the muon number. The general extensions of the calculation to the quadrupole order and hyperbolic orbit are also discussed.