The hypersoft state of Cygnus X-3 - A key to jet quenching in X-ray binaries?

TL;DR

This study investigates the hypersoft state of Cygnus X-3, revealing that jet production is suppressed during this phase, which supports the concept of jet quenching in X-ray binaries through multiwavelength observations.

Contribution

The paper provides multiwavelength evidence that jet activity is significantly diminished or turned off during the hypersoft state of Cygnus X-3, illustrating jet quenching in soft states.

Findings

Jet production is suppressed during the hypersoft state.

The wind refills the region near the black hole when jets are quenched.

Spectral and timing properties support jet quenching scenario.

Abstract

Cygnus X-3 is a unique microquasar in the Galaxy hosting a Wolf-Rayet companion orbiting a compact object that most likely is a low-mass black hole. The unique source properties are likely due to the interaction of the compact object with the heavy stellar wind of the companion. In this paper, we concentrate on a very specific period of time prior to the massive outbursts observed from the source. During this period, Cygnus X-3 is in a so-called hypersoft state, where the radio and hard X-ray fluxes are found to be at their lowest values (or non-detected), the soft X-ray flux is at its highest values, and sporadic gamma-ray emission is observed. We will utilize multiwavelength observations in order to study the nature of the hypersoft state. We observed Cygnus X-3 during the hypersoft state with Swift and NuSTAR in the X-rays and SMA, AMI-LA, and RATAN-600 in the radio. We also considered X-ray monitoring data from MAXI and $\gamma$-ray monitoring data from AGILE and Fermi. We found that the spectra and timing properties of the multiwavelength observations can be explained by a scenario where the jet production is turned off or highly diminished in the hypersoft state and the missing jet pressure allows the wind to refill the region close to the black hole. The results provide proof of actual jet quenching in soft states of X-ray binaries.