Chandra saw a “superluminal” jet in a binary system

X-ray space telescope “Chandra” was able to track the motion of the plasma in the relativistic jets that responsible black hole in a binary system MAXI J1820+070. It turned out that the apparent velocity of one of the jets one and a half times the speed of light is due to the fact that the plasma moves in the direction of the observer. The obtained data allow to understand how such jets are formed and interact with the interstellar medium. Preprint published on the portal, briefly about it it is told on the website of the Observatory.

Astrophysical jet flows, such as jets or bipolar outflowsare observed in various objects, such as x-ray binaries, cataclysmic variables, young stellar objects or active galactic nuclei. The formation and evolution of such flows, and their relationship with the processes of accretion are still poorly understood, in particular, it is interesting how the jets interact with the interstellar medium.

System MAXI J1820+070 (or ASASSN-18ey) was discovered in the optical range 6 March 2018 from the ground survey ASAS-SN, and in five days she saw the x-ray telescope MAXI (Monitor of All-sky X-ray Image), mounted on the ISS. It is a x-ray binary system, located at a distance of about ten thousand light-years from Earth and contains a black hole with a mass of about eight solar masses and a normal star with a mass about half the mass of the Sun. Further observations, including in the radio using the VLA and MeerKAT, showed that the black hole is in the active state, surrounded by the accretion disc and generates jets and in July 2018 and August 2019 on the system was registered with two flashes of radiation.

A team of astronomers led by Espinasse Mathilde (Mathilde Espinasse) from the University of Paris published the results of the analysis of observations of MAXI J1820+070 at the space telescope “Chandra” in the period from November 2018 to may 2019. Scholars interested in the properties of the jets and the traces of their interaction with the environment.

Data collected by “Chandra” made it possible to see the movement of the plasma in the two relativistic jets that are faced with the environment that led to their gradual deceleration. During these collisions formed shock waves responsible for electron acceleration to energies more than ten teraelectronvolt. Speed North of the jet relative to the observer is estimated at 0,61 the speed of light and South — 1.59 the speed of light. This illusion of superluminal motion is explained by the fact that the plasma in the southern jet moving towards the observer, and on the North from him. The actual velocity of the plasma in both jets is estimated at more than 0.8 of the speed of light. It is noted that the minimum internal energy stored in the jet is several orders of magnitude greater than the energy released during the flares in the radio, seen in 2018. This suggests that a large part of the energy transfer particles in the jets are not converted to radiation, and is allocated in the interaction with the environment. It is expected that new observations of MAXI J1820+070 will allow us to better understand the further evolution of the jets.

Earlier we talked about how the jet of the active galaxy curved a bridge between merging clusters of galaxies as the Telescope event horizon got the most detailed image of the jet of the blazar 3C 279 and that heated the plasma in the jets of SS 433 microquasar.

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