Constraining Axions with ZTF J1901+1458

TL;DR

This paper proposes using highly magnetic white dwarfs like ZTF J1901+1458 as new astrophysical targets to detect axions produced in stellar interiors, potentially surpassing current experimental bounds.

Contribution

It introduces a novel method of constraining axion-nucleon coupling via X-ray observations of magnetic white dwarfs, expanding the search beyond helioscope experiments.

Findings

A 100 ks NuSTAR observation could improve existing axion coupling bounds.

White dwarfs with strong magnetic fields are viable targets for axion detection.

The method could surpass current and future helioscope constraints.

Abstract

The axion-nucleon coupling enables the production of axions through the decay of excited ${}^{57}\textrm{Fe}$ isotopes, and axions produced in the Sun through this process are often a target of helioscope searches. We show for the first time that hot, highly magnetic white dwarfs such as ZTF J1901+1458 are a viable target to search for the X-ray signature of axions that were produced by the ${}^{57}\textrm{Fe}$ transition in the core and then converted to photons in the magnetosphere. We calculate that a 100 ks observation of ZTF J1901+1458 with NuSTAR would constrain the coupling of axions to nucleons and photons at a level below the bounds of both current and future planned helioscopes.