Magnetic field analysis of the bow and terminal shock of the SS 433 jet

Sakemi, Haruka; Machida, Mami; Akahori, Takuya; Nakanishi, Hiroyuki; Akamatsu, Hiroki; Kurahara, Kohei; Farnes, J. S.

doi:10.1093/pasj/psy003

Cited by 15 publications

(13 citation statements)

References 26 publications

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“…The previous work [12] and this work used the same radio data introduced by Farnes et al (2017) [11]. However, this current paper extends our analysis.…”

Section: Observationsupporting

confidence: 63%

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Faraday Tomography of the SS433 Jet Termination Region

et al. 2018

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A jet termination region provides us with useful information about how a jet interacts with the interstellar medium. Identifying the strength and orientation of magnetic fields at the terminal is crucially important to understanding the mechanism of cosmic-ray acceleration. In this article, we report results of our Faraday-tomography analysis of the eastern region of the radio nebula W50, where a jet from the microquasar SS433 seems to terminate. We apply QU-fitting, a method of Faraday-tomography, to data from the Australia Telescope Compact Array (ATCA) at 1.3–3.0 GHz. In the analysis, we distinguish multiple polarized sources along the line of sight. We identify Galactic emission candidates at Faraday depths around 0 rad m−2 and 300 rad m−2. The Galactic emission around 0 rad m−2 is possibly located in front of W50. We also find emission from W50 with Faraday depths between φ = −112 to 228 rad m−2.

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“…The previous work [12] and this work used the same radio data introduced by Farnes et al (2017) [11]. However, this current paper extends our analysis.…”

Section: Observationsupporting

confidence: 63%

“…Sakemi et al (2018) carried out a detailed polarization analysis of the eastern region of W50 using the ATCA dataset [12]. They found a well-aligned magnetic field along the terminal shock and suggested the possibility of a spiral magnetic field that may be associated with the helical structure.…”

Section: Introductionmentioning

confidence: 99%

Faraday Tomography of the SS433 Jet Termination Region

et al. 2018

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“…When a poloidal field exists, toroidal fields may coil around the surface of the cocoon. Such a helical magnetic field has been found at the Eastern edge of W50, behind the terminal shock of the SS433 jet [11].…”

Section: Jet Dynamicsmentioning

confidence: 77%

“…The magnetic fields in the jets are amplified by the compression at the secondary terminal shock, and the magnetic fields are stored between the cocoon and the shocked-ambient gas. These coiling magnetic fields have been observed using polarization analysis at radio wavelengths in W50/SS433 eastern ear [11].…”

Section: Discussionmentioning

confidence: 97%

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Two-Temperature Magnetohydrodynamics Simulations of Propagation of Semi-Relativistic Jets

et al. 2019

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In astrophysical jets observed in active galactic nuclei and in microquasars, the energy exchange rate by Coulomb collision is insufficient for thermal equilibrium between ions and electrons. Therefore, it is necessary to consider the difference between the ion temperature and the electron temperature. We present the results of two-temperature magnetohydrodynamics(MHD) simulations to demonstrate the effects of Coulomb coupling. It is assumed that the thermal dissipation heats only ions. We find that the ion and electron temperatures are separated through shocks. Since the ion entropy is increased by energy dissipation at shocks and the Coulomb collisions are inefficient, electron temperature becomes about 10 times lower than the ion temperature in the hotspot ahead of the jet terminal shock. In the cocoon, electron temperature decreases by gas mixing between high temperature cocoon gas and low temperature shocked-ambient gas even when we neglect radiative cooling, but electrons can be heated through collisions with ions. Radiation intensity maps are produced by post processing numerical results. Distributions of the thermal bremsstrahlung radiation computed from electron temperature have bright filament and cavity around the jet terminal shock.propagation of light supersonic jets, which exhibited the basic structures of jets such as a bow shock, a terminal shock (a reverse shock), internal shocks, and a cocoon. Recently, jet propagation and its feedback to inter cluster medium has been studied in realistic environments of galaxy cluster by Guo et al. [6,7]. The spacial variation of the propagation velocity of the jet has been reported by analytical methods (e.g., [8,9]) and by numerical simulations (e.g., [10]).The magnetic field structure of jets has been studied using polarized radiation. Faraday tomography have revealed that jets in 3C273 and SS433/W50 [11,12] have a helical magnetic field. The effects of magnetic fields on the jet dynamics have been examined for both non-relativistic and relativistic jets assuming axisymmetry [13][14][15]. In three-dimensional calculations, jets develop current-driven kink instability (m = 1) [16,17]. In addition, some studies compared numerical results with observations [18][19][20].Previous studies, however, did not focus on thermal non-equilibrium between ions and electrons in optically thin plasmas. When the relaxation time of ions and electrons by Coulomb collisions is longer than the dynamical time, the electron temperature can be lower than the ion temperature partly because electrons are cooled by radiation, and partly because shock waves primarily heat ions. Therefore, the electron temperature becomes lower than the ion temperature under such circumstances [21,22]. Such a two-temperature plasma has been studied extensively in the context of optically thin hot accretion flows in galactic black hole candidates (Shapiro, Lightman and Eardley [23]) and in the jet launching region in low luminosity active galactic nucleis (AGNs). Ressler et al. [24] and Sadowski et al. [2...

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Mildly relativistic collisionless shock formed by magnetic piston

et al. 2020

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By using particle-in-cell simulations, we study the collision of two plasma flows with one of them carrying a magnetic field. Ion interpenetration results in the formation of a magnetic piston with the magnetic field compression proportional to the density ratio of the colliding plasmas. The counterpropagating ions in the nonmagnetized plasma upstream from the piston excite the ion Weibel instability, which turns into magnetic turbulence. The thickness of the piston increases with time, and it turns into a reverse magnetized shock after less than one ion gyro period. In front of the piston, the time needed to decrease the nonmagnetized ion anisotropy using the magnetic turbulence is much larger than the ion gyroperiod in the piston. Consequently, particles are reflected by the piston, which acts as a wall initiating a transient phase. After several ion periods, the formation of this electromagnetic forward shock is, then, accelerated by the piston, and at large timescale, the dissipation of energy is eventually mediated only by the Weibel turbulence. We report here a new configuration of shocks, where a reverse magnetized and a forward electromagnetic shock coexist separated by a tangential discontinuity. Particle acceleration and heating in the two shock structures and relevance of this scenario of collisionless shock formation to laboratory experiments and astrophysical conditions are discussed.

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Magnetic field analysis of the bow and terminal shock of the SS 433 jet

Cited by 15 publications

References 26 publications

Faraday Tomography of the SS433 Jet Termination Region

Faraday Tomography of the SS433 Jet Termination Region

Two-Temperature Magnetohydrodynamics Simulations of Propagation of Semi-Relativistic Jets

Mildly relativistic collisionless shock formed by magnetic piston

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