Constraints on electrophilic scalar coupling from rotating magnetized stars and effects of cosmic neutrino background

TL;DR

This paper investigates how ultralight electrophilic scalar fields around magnetized stars can produce observable effects, constraining their coupling to electrons through astrophysical observations, and discusses how cosmic neutrino backgrounds influence these limits.

Contribution

It introduces a novel method to constrain scalar-electron couplings using astrophysical data from pulsars and binary systems, considering effects of cosmic neutrino backgrounds.

Findings

Orbital decay measurements set the strongest constraints on scalar-electron coupling.

Cosmic neutrino backgrounds can weaken the constraints on scalar interactions.

Enhanced magnetic fields and faster spins in compact objects could improve future bounds.

Abstract

An ultralight electrophilic scalar field can produce a long-range Yukawa-like spatial profile around a rotating, magnetized star when coupled to the constant number density of electrons in either the magnetosphere or the star itself. This long-range scalar field generates an effective scalar charge in the star or its magnetosphere, leading to a long-range force between two compact stars in a binary system. The electrophilic scalar can also radiate from isolated pulsars or double pulsar binary systems. Using the Crab pulsar and PSR J0737-3039A/B as test cases, we derive constraints on the scalar-electron coupling by analyzing observations of long-range force, orbital period decay in binary systems, and pulsar spin-down rates. Among these, the most stringent limits on the coupling are obtained from the orbital period decay. However, these constraints can be significantly reduced if the scalar interacts with the pervasive cosmic neutrino background. Enhancing experimental sensitivity and studying compact objects with stronger magnetic fields and higher angular velocities could further strengthen these bounds.