TUBITAK Destekli Projelerden Çıkan Yayınlar Topluluğu
Published January 1, 2017 | Version v1
Journal article Open

Single-dish and VLBI observations of Cygnus X-3 during the 2016 giant flare episode

Creators

  • 1. Osservatorio Astron Cagliari, INAF, Via Sci 5, I-09047 Selargius, Italy
  • 2. Ist Radio Astron Bologna, INAF, Via P Gobetti 101, I-40129 Bologna, Italy
  • 3. Observ Yebes IGN, CNTRAG, Apartado 148, E-19080 Yebes, Guadalajara, Spain
  • 4. Ist Radioastron, INAF, Sez Noto, I-96017 Noto, Italy
  • 5. Nicolaus Copernicus Univ, Fac Phys Astron & Informat, Ctr Astron, Grudziadzka 5, PL-87100 Torun, Poland
  • 6. Chalmers Univ Technol, Onsala Space Observ, Dept Earth & Space Sci, SE-43992 Onsala, Sweden

Description

In 2016 September, the microquasar Cygnus X-3 underwent a giant radio flare, which was monitored for 6 d with the Medicina Radio Astronomical Station and the Sardinia Radio Telescope. Long observations were performed in order to follow the evolution of the flare on an hourly scale, covering six frequency ranges from 1.5 to 25.6 GHz. The radio emission reached a maximum of 13.2 +/- 0.7 Jy at 7.2 GHz and 10 +/- 1 Jy at 18.6 GHz. Rapid flux variations were observed at high radio frequencies at the peak of the flare, together with rapid evolution of the spectral index: a steepened from 0.3 to 0.6 (with S-nu alpha nu(-alpha)) within 5 h. This is the first time that such fast variations are observed, giving support to the evolution from optically thick to optically thin plasmons in expansion moving outward from the core. Based on the Italian network (Noto, Medicina and SRT) and extended to the European antennas (Torun, Yebes, Onsala), very long baseline interferometry (VLBI) observations were triggered at 22 GHz on five different occasions, four times prior to the giant flare, and once during its decay phase. Flux variations of 2 h duration were recorded during the first session. They correspond to a mini-flare that occurred close to the core 10 d before the onset of the giant flare. From the latest VLBI observation we infer that 4 d after the flare peak the jet emission was extended over 30 mas.

Files

bib-27f32dcb-11af-4cb2-a4df-98665bdd15a6.txt

Files (432 Bytes)

Name Size Download all
md5:7da097a8567b10d9434f5124d45cf7a5
432 Bytes Preview Download