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
arXiv:2303.12587 · doi:10.3847/1538-4357/acc175
Abstract
Gamma-ray binary systems, a subclass of high-mass X-ray binaries, show non-thermal emissions from radio to TeV. While efficient electron acceleration is considered to take place in them, the nature of the acceleration mechanism and the physical environments in these systems have been a long-standing question. In this work, we report on long-term recurrent patterns in the short-term variability of the soft X-ray emission of LS 5039, one of the brightest gamma-ray binary systems. The Neutron star Interior Composition Explorer (NICER) observed LS 5039 four times from 2018 to 2021. By comparing them with the previous Suzaku and NuSTAR long-exposure observations, we studied the long-term evolution of the orbital light curve in the soft X-ray band. Although the observations by NICER and Suzaku are separated by 14 years, i.e., more than 10^3 orbits, the orbital light curves show remarkable consistency after calculating their running averages with a window width 70 ks. Furthermore, all of the light curves show short-term variability with a time scale of 10 ks. Since the column density did not vary when the flux changed abruptly, such a short-term variability seems to be an intrinsic feature of the X-ray emission. We propose that the short-term variability is caused by clumps (or inhomogeneities) of the companion star wind impacting the X-ray production site. The observed time scale matches well with the lifetime of the clumps interacting with the pulsar wind and the dynamical time scale of the relativistic intrabinary shock in the pulsar wind scenario.
arXiv comment17 pages, 13 figures, accepted for publication in ApJ
References in corpus (44)
- Design Concepts for the Cherenkov Telescope Array
- Variable Very High Energy Gamma-ray Emission from the Microquasar LS I +61 303
- Discovery of the Binary Pulsar PSR B1259-63 in Very-High-Energy Gamma Rays around Periastron with H.E.S.S
- Discovery of very high energy gamma-rays associated with an X-ray binary
- Discovery of a High-Energy Gamma-Ray-Emitting Persistent Microquasar
- Gamma-ray binaries and related systems
- Gamma-ray binaries: pulsars in disguise ?
- Theory of high-energy emission from the pulsar/Be-star system PSR 125963 I: radiation mechanisms and interaction geometry
- A possible black hole in the gamma-ray microquasar LS 5039
- An Empirical Background Model for the NICER X-ray Timing Instrument
- Orbital, precessional and flaring variability of Cygnus X-1
- VERITAS Observations of the gamma-Ray Binary LS I +61 303
- 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
- Inverse Compton Emission of TeV Gamma Rays from PSR B1259-63
- The Orbits of the Gamma-ray Binaries LS I +61 303 and LS 5039
- TeV lightcurve of PSR B1259-63/SS2883
- Study of the Spectral and Temporal Characteristics of X-Ray Emission of the Gamma-Ray Binary LS 5039 with Suzaku
- Long term variability of Cygnus X-1 V. State definitions with all sky monitors
- Simulations of stellar/pulsar wind interaction along one full orbit
- Microquasar LS 5039: a TeV gamma-ray emitter and a potential TeV neutrino source
- Orbital X-Ray Variability of the Microquasar LS 5039
- A magnetar-like event from LS I +61 303 and its nature as a gamma-ray binary
- Modelling the high-energy emission from gamma-ray binaries using numerical relativistic hydrodynamics
- Unraveling the high-energy emission components of gamma-ray binaries
- The gamma-ray binary LS 5039: mass and orbit constraints from MOST observations
- Spectral energy distribution of the gamma-ray microquasar LS 5039
- The Low X-Ray State of LS 5039 / RX J1826.2-1450
- Sign of hard X-ray pulsation from the gamma-ray binary system LS 5039
- Exploring the connection between the stellar wind and the non-thermal emission in LS 5039
- Large-scale flow dynamics and radiation in pulsar gamma-ray binaries
- HD 259440: The Proposed Optical Counterpart of the gamma-ray Binary HESS J0632+057
- Long-term Stability of Non-thermal X-ray Modulation in the Gamma-ray Binary LS 5039
- NuSTAR observation of LS 5039
- LS 5039 - the counterpart of the unidentified MeV source GRO J1823-12
- High-energy emissions from the gamma-ray binary LS 5039
- Simulations of an inhomogeneous stellar wind interacting with a pulsar wind in a binary system
- Investigation of the energy dependence of the orbital light curve in LS 5039
- Non-thermal radiation from a pulsar wind interacting with an inhomogeneous stellar wind
- Clumpy stellar winds and high-energy emission in high-mass binaries hosting a young pulsar
- Modeling the effects of clumpy winds in the high-energy light curves of γ-ray binaries
- Evolution of the extended X-ray emission from the PSR B1259-63/LS 2883 binary in the 2014-2017 binary cycle
- Broad-Band High-Energy Emission of the Gamma-ray Binary System LS 5039: Spectral and Temporal Features using NuSTAR and Fermi Observations
- Phase-resolved hard X-ray emission of the high-mass binary LS 5039: a spectral hardening above 50 keV detected with INTEGRAL