The 2006 Radio Outburst of a Microquasar Cyg X-3: Observation and Data

TL;DR

This paper reports multi-frequency radio observations of a 2006 outburst of the microquasar Cyg X-3, revealing rapid variability, a stable core, and no jet structure at high resolution, enhancing understanding of microquasar activity.

Contribution

It provides detailed multi-frequency and VLBI observations of Cyg X-3's 2006 outburst, highlighting the source's variability and core stability with no jet detection.

Findings

Successive flares exceeding 1 Jy observed after activity quench

Higher frequency bands show shorter variability timescales

VLBI imaging reveals a stable core with rapid flux variations

Abstract

We present the results of the multi-frequency observations of radio outburst of the microquasar Cyg X-3 in February and March 2006 with the Nobeyama 45-m telescope, the Nobeyama Millimeter Array, and the Yamaguchi 32-m telescope. Since the prediction of a flare by RATAN-600, the source has been monitored from Jan 27 (UT) with these radio telescopes. At the eighteenth day after the quench of the activity, successive flares exceeding 1 Jy were observed successfully. The time scale of the variability in the active phase is presumably shorter in higher frequency bands. We also present the result of a follow-up VLBI observation at 8.4 GHz with the Japanese VLBI Network (JVN) 2.6 days after the first rise. The VLBI image exhibits a single core with a size of <8 mas (80 AU). The observed image was almost stable, although the core showed rapid variation in flux density. No jet structure was seen at a sensitivity of $T_b = 7.5\times 10^5$ K.