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Abstract

We present an analysis of the X-ray data obtained in the period of flaring activity of SS 433 in July and August 2018, during which the brightest radio flares over the entire history of its observations were detected at frequencies 2–5 GHz based on data from the RATAN-600 radio telescope. The Swift/XRT and NICER space observatory data were obtained immediately during the radio flares within the program of Target of Opportunity (ToO) observations. The Chandra/HETGS observations and the additional quasi-simultaneous NICER calibration observations were carried out in the active phase of the system between the radio intensity peaks. We show that during the peak radio fluxes the emission lines of the relativistic jets are detected with confidence in the X-ray spectrum, while their basic parameters remain stable, which can serve as evidence for the absence of significant violations in the jet collimation and acceleration mechanisms. At the same time, the X-ray intensity of the jets at these moments drops by a factor of 4–5 and is restored to its normal values within ∼10 days. Anomalous deviations of the jet line positions from the predictions of the kinematic model were found in the period of activity and during the radio flares. Our modeling of the Chandra spectra using the emission model of baryonic jets in SS 433 point to rapid changes in the structure of the wind from the supercritical disk that partially blocks the emission from the hottest regions of the jets. The set of these factors points to a possible connection of the emergence of radio flares and active states of SS 433 with perturbations in the rate of mass transfer and outflow in the system.