Modelling the high-energy emission from gamma-ray binaries using numerical relativistic hydrodynamics

Abstract

Detailed modeling of the high-energy emission from gamma-ray binaries has been propounded as a path to pulsar wind physics. Fulfilling this ambition requires a coherent model of the flow and its emission in the region where the pulsar wind interacts with the stellar wind of its companion. We developed a code that follows the evolution and emission of electrons in the shocked pulsar wind based on inputs from a relativistic hydrodynamical simulation. The code is used to model the well-documented spectral energy distribution and orbital modulations from LS 5039. The pulsar wind is fully confined by a bow shock and a back shock. The particles are distributed into a narrow Maxwellian, emitting mostly GeV photons, and a power law radiating very efficiently over a broad energy range from X-rays to TeV gamma rays. Most of the emission arises from the apex of the bow shock. Doppler boosting shapes the X-ray and VHE lightcurves, constraining the system inclination to $i\approx 35^{\mathrm{o}}$. There is a tension between the hard VHE spectrum and the level of X-ray to MeV emission, which requires differing magnetic field intensities that are hard to achieve with a constant magnetisation $\sigma$ and Lorentz factor ${\Gamma }_p$ of the pulsar wind. Our best compromise implies $\sigma \approx 1$ and ${\Gamma }_p\approx 5\times 10^3$, respectively higher and lower than the typical values in pulsar wind nebulae. The high value of $\sigma$ derived here, where the wind is confined close to the pulsar, supports the classical picture that has pulsar winds highly magnetised at launch. However, such magnetisations will require further investigations to be based on relativistic MHD simulations.

18 pages, 12 figures, under review with A&A (appendix with movies could not be uploaded to ArXiV)

References in corpus (16)

• Gamma-ray binaries: pulsars in disguise ?
• Simulated synchrotron emission from Pulsar Wind Nebulae
• Understanding the Very High-Energy Emission from Microquasars
• Modeling interaction of relativistic and nonrelativistic winds in binary system PSR 1259-63/SS2883. I.Hydrodynamical limit
• On the formation of TeV radiation in LS 5039
• The modulation of the gamma-ray emission from the binary LS 5039
• Propagation of very high energy gamma-rays inside massive binaries LS 5039 and LSI +61 303
• Unraveling the high-energy emission components of gamma-ray binaries
• Three-dimensional hydrodynamic simulations of asymmetric pulsar wind bow shocks
• Orbital evolution of colliding star and pulsar winds in 2D and 3D; effects of: dimensionality, EoS, resolution, and grid size
• Non-thermal emission from secondary pairs in close TeV binary systems
• Spectral signature of a free pulsar wind in the gamma-ray binaries LS 5039 and LSI +61$\degr$303
• INTEGRAL observation of hard X-ray variability of the TeV binary LS5039 / RX J1826.2-1450
• High-energy emissions from the gamma-ray binary LS 5039
• Probing the Pulsar Wind in the gamma-ray Binary System PSR B1259-63/SS 2883
• Simulations of an inhomogeneous stellar wind interacting with a pulsar wind in a binary system

Cited by in corpus (46)

• Transitional millisecond pulsars
• Constraining Relativistic Bow Shock Properties in Rotation-Powered Millisecond Pulsar Binaries
• 3D dynamics and morphology of bow-shock Pulsar Wind Nebulae
• Sign of hard X-ray pulsation from the gamma-ray binary system LS 5039
• X-ray Through Very-High-Energy Intrabinary Shock Emission from Black Widows and Redbacks
• The Synchrotron Emission Pattern of IntraBinary Shocks
• Discovery of the Galactic High-Mass Gamma-ray Binary 4FGL J1405.1-6119
• Mass-loading of bow shock pulsar wind nebulae
• Sizing up the population of gamma-ray binaries
• Modelling Jets, Tori and Flares in Pulsar Wind Nebulae
• Relativistic fluid modelling of gamma-ray binaries. I. The model
• Light curve and SED modeling of the gamma-ray binary 1FGL J1018.6$-$5856: constraints on the orbital geometry and relativistic flow
• Overview of non-transient gamma-ray binaries and prospects for the Cherenkov Telescope Array
• Modelling the multi-wavelength emissions from PSR B1259-63/LS 2883: the effects of the stellar disc on shock radiations
• A hydrodynamics-informed, radiation model for HESS J0632$+$057 from radio to gamma rays
• Relativistic fluid modelling of gamma-ray binaries. II. Application to LS 5039
• Investigation of the energy dependence of the orbital light curve in LS 5039
• A dynamical and radiation semi-analytical model of pulsar-star colliding winds along the orbit: Application to LS 5039
• Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind
• The Intrabinary Shock and Companion Star of Redback Pulsar J2215+5135
• Radio absorption in high-mass gamma-ray binaries
• NuSTAR and Parkes observations of the transitional millisecond pulsar binary XSS J12270-4859 in the rotation-powered state
• Formation of periodic FRB in binary systems with eccentricity
• Modeling the effects of clumpy winds in the high-energy light curves of γ-ray binaries
• X-ray and gamma-ray orbital variability from the gamma-ray binary HESS J1832-093
• Nonthermal emission from high-mass microquasar jets affected by orbital motion
• Broad-Band High-Energy Emission of the Gamma-ray Binary System LS 5039: Spectral and Temporal Features using NuSTAR and Fermi Observations
• NuSTAR Hard X-ray Observation of the Gamma-ray Binary Candidate HESS J1832-093
• Multidimensional relativistic MHD simulations of Pulsar Wind Nebulae: dynamics and emission
• Probing the Properties of the Pulsar Wind in the Gamma-Ray Binary HESS J0632+057 with NuSTAR and VERITAS Observations
• Properties of a hypothetical cold pulsar wind in LS~5039
• Multi-Wavelength Observation Campaign of the TeV Gamma-Ray Binary HESS J0632+057 with NuSTAR, VERITAS, MDM, and Swift
• Phase-resolved hard X-ray emission of the high-mass binary LS 5039: a spectral hardening above 50 keV detected with INTEGRAL
• Investigation of the broadband emission of the gamma-ray binary HESS J0632+057 using an intrabinary shock model
• The major role of eccentricity in the evolution of colliding pulsar-stellar winds
• Polarization study of gamma-ray binary
• High-Resolution Simulations of LS 5039
• Unveiling properties of the non-thermal X-ray production in the gamma-ray binary LS 5039 using the long-term pattern of its fast X-ray variability
• Relativistic astrospheres of gamma-ray binaries: modeling of non-thermal processes
• Modeling the High-energy Emission from the Gamma-ray Binary 1FGL J1018.6-5856
• HAWC Search for High-Mass Microquasars
• A diagnostic on the orbital spectrum of LS 5039 with Fermi-LAT
• How many VHE gamma-ray binaries with young pulsars can be observed?
• INTEGRAL View of TeV Sources: A Legacy for the CTA Project
• Particle Acceleration in Colliding Flows: Binary Star Winds and Other Double-Shock Structures
• Orbital Phase-resolved Analysis of X-ray and Gamma-ray Observations of the High-Mass Gamma-ray Binary 4FGL J1405.1-6119