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 gamma-rays. The source's radio through mid-infrared radiation is thought to originate from the relativistic jets. The observed high degree of linear polarization 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, multizone 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 parametrizes 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 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.
- Publication:
-
Monthly Notices of the Royal Astronomical Society
- Pub Date:
- January 2021
- DOI:
- 10.1093/mnras/staa3349
- arXiv:
- arXiv:2010.08501
- Bibcode:
- 2021MNRAS.500.2112K
- Keywords:
-
- acceleration of particles;
- radiation mechanisms: non-thermal;
- X-rays: individual: Cyg X-1;
- Astrophysics - High Energy Astrophysical Phenomena
- E-Print:
- 16 pages, 4 figures, accepted for publication in MNRAS