On the possibility of observable signatures of leptonium from astrophysical sources

TL;DR

This paper explores the theoretical possibility of detecting signatures of true muonium and true tauonium atoms formed in astrophysical environments, despite their short lifetimes, by calculating their production rates and potential observable signals.

Contribution

It provides the first detailed calculations of formation probabilities and observable signatures of muonium and tauonium in astrophysical sources, considering their production, decay, and detection prospects.

Findings

Potential observable X-ray and gamma-ray signatures from accretion disks around stellar black holes.

Calculated formation probabilities of muonium and tauonium in high-energy astrophysical environments.

Estimated fluxes suggest current observatories could detect these signatures.

Abstract

The formation of Ps in our Galaxy is well measured, and has led to important and unanswered questions on the origin of the positrons. In principle it should be possible to form analogous systems from mu and tau leptons, viz. true muonium and true tauonium. However the probability of formation for these systems is greatly reduced due to the intrinsically short lifetimes of the mu and tau leptons. Likewise, the decay of the atoms is hastened by the high probability of the constituent particles decaying. Nevertheless, if sufficient numbers of mu and tau pairs are produced in high energy astrophysical environments there may be significant production of true muonium and true tauonium, despite the small probabilities. This paper addresses this possibility. We have calculated the pair production spectra of mu and tau leptons from photon-photon annihilation and electron-positron annihilation in astrophysical environments. We have computed the cross-sections for radiative recombination and direct annihilation of the pairs, and the decay constants for the various allowable decays, and the wavelengths and energies of the recombination and annihilation signatures. In this way we have calculated the probabilities for the formation of true muonium and true tauonium, and the branching ratios for the various observable signatures. We have estimated the expected fluxes from accretion discs around microquasars and active galactic nuclei, and from interactions of jets with clouds and stars. We find that accretion discs around stellar mass black holes in our own Galaxy should have observable signatures at X-ray and gamma-ray energies that are in principle observable with current observatories.