Signatures of mirror stars

David Curtin,Jack Setford

doi:10.1007/jhep03(2020)041

Abstract

Motivated by theories of Neutral Naturalness, we argue that Mirror Stars are a generic possibility in any hidden sector with analogues of Standard Model (SM) electromagnetism and nuclear physics. We show that if there exists a tiny kinetic mixing between the dark photon and the SM photon, Mirror Stars capture SM matter from the interstellar medium, which accumulates in the core of the Mirror Star and radiates in the visible spectrum. This signature is similar to, but in most cases much fainter than, ordinary white dwarfs. We also show for the first time that in the presence of captured SM matter, a fraction of dark photons from the core of the Mirror Star convert directly to SM photons, which leads to an X-ray signal that represents a direct probe of the properties of the Mirror Star core. These two signatures together are a highly distinctive, smoking gun signature of Mirror Stars. We show that Mirror Stars could be discovered in both optical and X-ray searches up to approximately 100-1000 light years away, for a range of well-motivated values of the kinetic mixing parameter.

Highlights

With the conspicuous absence of new physics at colliders to date, the hierarchy problem remains as problematic and urgent as ever
Motivated by theories of Neutral Naturalness, we argue that Mirror Stars are a generic possibility in any hidden sector with analogues of Standard Model (SM) electromagnetism and nuclear physics
We show for the first time that in the presence of captured SM matter, a fraction of dark photons from the core of the Mirror Star convert directly to SM photons, which leads to an X-ray signal that represents a direct probe of the properties of the Mirror Star core

Summary

Introduction

With the conspicuous absence of new physics at colliders to date, the hierarchy problem remains as problematic and urgent as ever. Dark Matter (DM) searches have yet to bear fruit; most constraints on dark matter models generally assume a simplistic dark sector in which all of the dark matter is comprised of a single species. Appealing though this possibility is, it is not clear that it is the most well-motivated scenario. If the dark sector is related to the Standard Model (SM) by any kind of symmetry, which would be the case if the new physics is connected to the hierarchy problem as in the Minimal Twin Higgs [6], the complexity of the Standard Model itself might motivate a non-minimal dark sector. Understanding the possible signatures of Dark Complexity is an important and timely challenge

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Conclusion