PeV neutrons as origin of separated SS433 TeV signals

TL;DR

SS433 exhibits distant, disconnected TeV gamma-ray twins whose origin remains puzzling. The authors propose that a past century eruption produced a collimated beam of tens PeV neutrons via photo-nuclear Delta-resonance in a UV photon bath, with neutrons beta-decaying in flight to tens of TeV electrons that upscatter ambient infrared photons to TeV gamma rays. Key quantitative links include the Delta-resonance energy condition $E_\gamma = \frac{(m_\Delta)^2}{2 E_p}$, neutron flight lengths $L_n \approx 75\,\text{ly}\left(\frac{E_n}{25\,\text{PeV}}\right)$, and Larmor-radius-based collimation for protons and electrons, which together reproduce the observed separation and brightness of the TeV tracks. If correct, this scenario connects SS433 to broader high-energy phenomena such as UHECRs and neutrino astronomy, while suggesting observational tests in other microquasars and upcoming gamma-ray surveys.

Abstract

The SS433, a well-known binary system with an internal black hole, have shown since half a century, an inner (a few year light distances) twin precessing jets spirals. These beams are made by tidal forces while stripping mass from large stellar companion feeding an inner BH accretion disk and an orthogonal accelerating twin jet. From it, the radio, X gamma jet emission. A couple of years ago H.E.S.S telescope as well as HAWC and LHAASO array detectors, discovered also the surprising signature of an unexpected far twin separated gamma beam at tens TeV energy. At a hundred light years distances from its central source. We suggest that it is the legacy of a past rare eruption, a century ago, of tens PeV (10^16 eV) relativistic twin neutron beams. Their beta decay in flight at far distances, into proton, neutrino and in particular into tens TeV electrons, could feed the observed TeV gamma traces. They are originated by the same secondary tens TeV electrons emitting hard gamma, by Inverse Compton Scattering onto interstellar infrared photons.

Figures (2)

• Figure 1: Above an artist's impression of the SS 433 system, showing the jets (blue) and the surrounding W50 (red): the jets travel undetected for a distance of about 75 ly before suddenly reappearing as bright sources of non-thermal emission (X-rays and gamma rays) as observed by H.E.S.S., HAWC and LHAASO inside the nebula long before generated by a supernova. A view of the SS433 spiral jet at a millimetre wavelength is shown in the inset, taken by the radio telescope array ALMA. Below hess2024acceleration the image of the H.E.S.S. data with the additional contour of the radio radiation. The image of the collimated two-TeV gamma-ray beams, separated at a distance between 75 and 150 ly, is very puzzling. It inspired present PeV neutron beam model.
• Figure 2: A rough scale schematic of the inner binary system SS433: an accretion disk on a celestial body and a companion star of comparable mass, both nominally ten solar masses, at their respective Kepler circular distances. The radii of the star and, in particular, of the accretion disk are approximate for a complete view only, but could be slightly or significantly larger. We show here the explosive stage, occurred possibly a century ago, when a Nova-like event offered the necessary luminosity to allow tens PeV proton coversion into tens PeV neutron beam.