Diagnostics of Parameters for the X-ray Jets of SS 433 from High-Resolution Chandra Spectroscopy

TL;DR

This study analyzes high-resolution Chandra X-ray spectra of SS 433 to determine jet parameters and models the broadband spectrum, revealing the jet's physical properties and the necessity of an additional hard X-ray component.

Contribution

It provides a systematic analysis of jet parameters using a multitemperature emission model and characterizes the hard X-ray component in SS 433's spectrum.

Findings

Jet parameters such as velocity, opening angle, and temperature were derived.

An additional hard X-ray component above 3 keV is necessary for spectral fitting.

The hard component is consistent with emission from a hot, absorbed extension of the jets.

Abstract

The X-ray spectrum of the Galactic microquasar SS 433 contains a rich set of emission lines of highly ionized atoms of heavy elements whose significant Doppler shift leaves no doubt that they are produced in collimated relativistic jets of outflowing material. We have performed a systematic analysis of the high-resolution X-ray spectra obtained by the Chandra observatory to determine the parameters of the jets within the multitemperature model of their emission that self-consistently predicts the source's line and continuum spectrum. The spectrum of SS 433 at energies below 3 keV is shown to be statistically satisfactorily described by the jet emission model, while the introduction of an additional hard component is required above 3 keV. We summarize the jet parameters (bulk velocity, opening angle, kinetic luminosity, base temperature, and relative elemental abundances) derived by fitting the data below 3 keV and describe the revealed degeneracies and systematic effects due to the presence of an additional component. Using the derived parameters, we show that the hard component is compatible with the emission from the hot (up to 40 keV) extension of the visible part of the jets moderately absorbed ($N_H \sim 2 \times 10^{23}$ cm$^{-2}$) in the cold-wind material. The combined X-ray emission model constructed in this way allows the broadband spectrum of SS 433 to be described self-consistently.