Axion Gamma-Ray Signatures from Quark Matter in Neutron Stars and Gravitational Wave Comparisons

Abstract

We present a theoretical model for detecting axions from neutron stars in a QCD phase of quark matter. The axions would be produced from a quark-antiquark pair $u\bar{u}$ or $d\bar{d}$, in loop(s) involving gluons. The chiral anomaly of QCD and the spontaneously broken symmetry are invoked to explain the non-conservation of the axion current. From the coupling form factors, the axion emissivities ${\epsilon }_a$ can be derived, from which fluxes can be determined. We predict a photon flux, which may be detectable by Fermi LAT, and limits on the QCD mass $m_a$. In this model, axions decay to gamma rays in a 2-photon vertex. We may determine the expected fluxes from the theoretical emissivity. The sensitivity curve from the Fermi Large Area Telescope (Fermi LAT) would allow axion mass constraints for neutron stars as low as $m_a\le 10^{-14}$ eV 95$\%C.L.$. Axions could thus be detectable in gamma rays for neutron stars as distant as 100 kpc. A signal from LIGO GWS 170817 could be placed from the NS-NS merger, which gives an upper limit of $m_a\le 10^{-10}$ eV.

References in corpus (21)

• Strange Quark Matter and Compact Stars
• Detection of a Gamma-Ray Source in the Galactic Center Consistent with Extended Emission from Dark Matter Annihilation and Concentrated Astrophysical Emission
• New Observables for Direct Detection of Axion Dark Matter
• Strong bound on canonical ultra-light axion dark matter from the Lyman-alpha forest
• The phase diagram of neutral quark matter: Self-consistent treatment of quark masses
• Dimming Supernovae without Cosmic Acceleration
• Hints of the existence of Axion-Like-Particles from the gamma-ray spectra of cosmological sources
• SN 1987A Gamma-Ray Limits on the Conversion of Pseudoscalars
• Search for Spatially Extended Fermi-LAT Sources Using Two Years of Data
• Solar neutrino limit on axions and keV-mass bosons
• New cosmological mass limit on thermal relic axions
• Hardening of TeV gamma spectrum of AGNs in galaxy clusters by conversions of photons into axion-like particles
• Extra dimensions, SN1987a, and nucleon-nucleon scattering data
• Axion searches with the EDELWEISS-II experiment
• Two-Loop QCD Corrections to the Heavy Quark Form Factors: Anomaly Contributions
• Hidden Markov model tracking of continuous gravitational waves from a neutron star with wandering spin
• Constraints on Axions and Axionlike Particles from Fermi Large Area Telescope Observations of Neutron Stars
• The phase diagram of neutral quark matter: The effect of neutrino trapping
• New constraints for heavy axion-like particles from supernovae
• Quark matter in neutron stars
• Electromagnetic signal of the QCD phase transition in neutron star mergers