W 50 and SS 433

Abstract

Context. The Galactic microquasar SS 433 launches oppositely-directed jets at speeds approximately a quarter of the speed of light. These appear to have punched through and beyond the supposed supernova remnant shell W 50. The problems with this interpretation are: (i) The precessing jets have somehow been collimated before reaching the shell; (ii) Without deceleration, only recently launched jets would have reached no further; and (iii) Certain features in the lobes are moving slowly or are stationary.Aims. Hydrodynamic computations have demonstrated that for at least one set of parameters describing the ambient medium, jets that diverge and precess are both decelerated and collimated; the conformation of W 50 could then have been sculpted by the jets of SS 433. However, the parameters adopted for density and pressure in these computations are not consistent with observations of jets at a few years old; nor do they represent conditions within a supernova remnant. Our aim is to investigate whether the computations already performed can be scaled to a realistic W 50. Methods. We find simple and physically based scaling relations. The distance to collimation varies inversely with the square root of the pressure of the ambient medium and the speed with which the head of a collimated jet propagates scales with the square root of the temperature. We extrapolate the results of the hydrodynamic computations to lower densities and pressures.Results. The jets of SS 433, launched into an ambient medium of pressure ∼ 10 −9 erg cm −3 and temperature ∼ 10 8 K, within a supernova remnant, could be responsible for the characteristics of W 50. The precessing jets are collimated within ∼ 10 pc and the head of the resulting cylindrical jet propagates slowly.Conclusions. The problems of relating W 50 to SS 433 may now be solved.

Acceleration and transport of relativistic electrons in the jets of the microquasar SS 433

“…S11). This electron injection timescale is consistent with previous dynamical estimates for the age of the W 50/SS 433 complex, which range between 10,000 and 100,000 years ( 19 , 20 ). Our simulation evolves the electron population numerically in discrete time steps.…”

“…There is no single model that has yet reproduced all the observational features of SS 433 ( 19 , 41 ). Although simulations can account for the observed difference in opening angle between the inner and outer jets owing to the action of the ambient medium ( 20 , 42 , 43 ), this process would take place near the binary and does not result in the observed sharp transitions or shocks at 25 to 30 pc. The mirrored reappearance of the jets at this distance implies that the determination of this radius has a physical cause, although there is no further observational evidence to indicate that this location is unusual.…”

“…The outer jets terminate ~100 pc from the black hole ( 14 ), where they deform the surrounding radio nebula (known as W 50 or SNR G039.7-02.0), which is thought to be the supernova remnant associated with the formation of the compact object in SS 433 ( 18 ). The morphology of W 50 indicates that the opening angle of the outer jets is considerably smaller than the 20° precession angle of the inner jets ( 19 ); the origin of this discrepancy is unknown ( 20 ). The lack of apparent change in the measured positions of radio filaments in the jet termination regions over a 33-year period provides an upper limit on their velocity of <0.023 c ( 21 , 22 ), although it is unclear whether the radio filaments trace the jets’ flow.…”

Multiwavelength Emission from Galactic Jets: The Case of the Microquasar SS433

“…In our calculation, we have used v z = 0.26c, which is determined at the jet base (Margon & Anderson 1989;Eikenberry et al 2001). The bulk velocity in the knot region is less certain from observations, but possibly be smaller than 0.26c because knots are located at large distances from the core (Goodall et al 2011a,b;Monceau-Baroux et al 2014Panferov 2014Panferov , 2017Bowler & Keppens 2018). The primarily effect of adopting a smaller bulk velocity would be flattening of the spectrum, because the transition from advection-dominated regime to fast cooling regime would occur at lower energy.…”

Chance Coincidences between Black Hole Low-mass X-Ray Binaries and Supernova Remnants

“…Binary BHs may exist in SNRs, and evidence has accumulated (e.g., the morphology of the SNR shell appears to be directly affected by the observed jets) that SS 433 is a high-mass BH X-ray binary located in an SNR (Clark & Murdin 1978;Margon 1984;Bowler & Keppens 2018;Cherepashchuk et al 2020). However, there are relatively few BHs known in high-mass X-ray binaries, while there are a number of BHs in low-mass X-ray binaries (LMXBs).…”