A new lepto-hadronic model applied to the first simultaneous multiwavelength data set for Cygnus X–1

Abstract

Cygnus X–1 is the first Galactic source confirmed to host an accreting black hole. It has been detected across the entire electromagnetic spectrum from radio to GeV $\rm {\gamma }$-rays. The source’s radio through mid-infrared radiation is thought to originate from the relativistic jets. The observed high degree of linear polarisation in the MeV X-rays suggests that the relativistic jets dominate in this regime as well, whereas a hot accretion flow dominates the soft X-ray band. The origin of the GeV non-thermal emission is still debated, with both leptonic and hadronic scenarios deemed to be viable. In this work, we present results from a new semi-analytical, multi-zone jet model applied to the broad-band spectral energy distribution of Cygnus X–1 for both leptonic and hadronic scenarios. We try to break this degeneracy by fitting the first-ever high-quality, simultaneous multiwavelength data set obtained from the CHOCBOX campaign (Cygnus X–1 Hard state Observations of a Complete Binary Orbit in X-rays). Our model parameterises dynamical properties, such as the jet velocity profile, the magnetic field, and the energy density. Moreover, the model combines these dynamical properties with a self-consistent radiative transfer calculation including secondary cascades, both of leptonic and hadronic origin. We conclude that sensitive TeV $\rm {\gamma }$-ray telescopes like Cherenkov Telescope Array (CTA) will definitively answer the question of whether hadronic processes occur inside the relativistic jets of Cygnus X–1.

Black-hole X-ray binaries in the new era of multi-messenger astronomy

“…The rest of the depicted data are the Fermi/LAT data from [20] and the 7 yr upper limits of the MAGIC collaboration [22]. [14]. We see that the two different physical processes contribute to different parts of the neutrino spectrum.…”

“…To examine how likely is BHXBs to contribute to the low-energy part of the CR spectrum, we study the spectral energy distribution (SED) up to the TeV -rays, connecting it to the neutrino counterpart emitted by such sources. Based on the semi-analytical, multi-zone, leptonic jet model of [13], we developed a new lepto-hadronic jet model that takes into account the proton-proton (pp) and proton-photon (p ) interactions to produce -rays via the neutral pion decay [14]. We…”

“…We examine the first-ever simultaneous radio-to-X-ray spectrum of the prototypical high-mass BHXB Cyg X-1obtained by the CHOXBOX campaign (Cyg X-1 Hard state Observations of a Complete Binary Orbit in X-rays; [14]). By finding the statistically best fit of this spectrum we can predict the -ray emission and the neutrino flux.…”

“…BHXBs as multi-messengers D. Kantzas The predicted spectral energy distribution of Cyg X-1 in the GeV-to-TeV energy band. The physical jet parameters are those of [14]. We also include here the 5 yr upper limits set by the HAWC collaboration while the jets of Cyg X-1 were quenched (the so-called soft state) just for comparison [21].…”

Simulations of Neutrino and Gamma-Ray Production from Relativistic Black-Hole Microquasar Jets

“…The most well-studied microquasar systems include the Galactic X-ray binaries SS 433, Cyg X-1, Cyg X-3, and so forth. [20][21][22], while from the extragalactic systems we mention the LMC X-1, LMC X-3 located in the neighbouring galaxy of the Large Magellanic Cloud [23], and the Messier X-7 in the Messier 33 galaxy [24]. Their respective relativistic jets are emission sources in various wavelength bands and high-energy neutrinos.…”