Structure and Magnetic Fields in the Precessing Jet System SS 433 II. Intrinsic Brightness of the Jets

TL;DR

This study uses VLA imaging to analyze the intrinsic brightness and evolution of SS 433's radio jets, revealing their similarity when accounting for age and complex decay behaviors over time.

Contribution

It provides a detailed analysis of the intrinsic brightness distribution of SS 433's jets, accounting for Doppler effects, and characterizes their brightness evolution over time.

Findings

Jets are intrinsically similar when compared at equal emission age.

Jet brightness decay follows exponential functions in certain age ranges.

Intrinsic brightness remains constant between approximately 60 and 150 days.

Abstract

Deep Very Large Array imaging of the binary X-ray source SS 433, sometimes classified as a microquasar, has been used to study the intrinsic brightness distribution and evolution of its radio jets. The intrinsic brightness of the jets as a function of age at emission of the jet material tau is recovered by removal of the Doppler boosting and projection effects. We find that intrinsically the two jets are remarkably similar when compared for equal tau, and that they are best described by Doppler boosting of the form D^{2+alpha}, as expected for continuous jets. The intrinsic brightnesses of the jets as functions of age behave in complex ways. In the age range 60 < tau < 150 days, the jet decays are best represented by exponential functions of tau, but linear or power law functions are not statistically excluded. This is followed by a region out to tau ~ 250 days during which the intrinsic brightness is essentially constant. At later times the jet decay can be fit roughly as exponential or power law functions of tau.