Rapid rise in the radio synchrotron emission from the recurrent nova system V745 Sco
ATel #5962; N. G. Kantharia (NCRA-TIFR), Nirupam Roy (MPIfR), G. C. Anupama (IIA), D. P. K. Banerjee (PRL), N. M. Ashok (PRL), Prasun Dutta (IISERB), T. P. Prabhu (IIA), Abhishek Johri (NCRA-TIFR)
on 10 Mar 2014; 05:20 UT
Credential Certification: Nimisha Kantharia (ngk@ncra.tifr.res.in)
We report the detection of radio synchrotron emission
from the nova system V745 Sco. While no radio emission was detected on
9 and 18 February 2014, we detect an unresolved source coincident with the
recurrent nova system V745 Sco on 5 March 2014 at 610 MHz
using GMRT. This is about 26 days since
its reported outburst on 6.6 February 2014 (AAVSO Special Notice 380, CBET 3803).
The evolution of the non-thermal synchrotron emission at 610 MHz is given below:
| Date | t-t0 (days) | 3 sigma limit/flux density (mJy) |
| 9 February | ~2 | < 0.55 |
| 18 February | ~11 | < 0.45 |
| 5 March | ~26 | 6.91(0.13) |
| 6 March | ~27 | 6.78(0.17) |
We also detect radio emission at 240 MHz of strength 4.3 (0.9) mJy on 6 March 2014.
The radio emission between 240 and 610 MHz, detected in the simultaneous
observations on 6 March 2014, has a spectral index of 0.49 (nu^{alpha}).
This indicates that the emission at 240 MHz is rising.
The thermal radio emission has been reported by Rupen et al. (ATel 5884) and
the X-ray emission lines from the blast wave of V745 Sco have also been recently detected
by Drake et al. (ATel 5920). The NIR observations infer the presence of shocked gas,
outburst energies higher than the outbursts of other symbiotic nova systems
such as RS Oph and V407 Cyg, and a large mass for the white dwarf
making it a possible progenitor system of a SN 1a (Banerjee et al. 2014, arXiv:1403.0651v2).
It certainly is an interesting system to study the evolution of the synchrotron radio emission.
We plan to continue monitoring this system with GMRT at low radio frequencies which
is an excellent tracer of the radio synchrotron emission generated due to the shock interaction
with the ambient material.
We thank the Centre Director, NCRA for allocating DDT time on GMRT and
the staff of the GMRT who made these observations possible. The GMRT is operated by the
National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research (NCRA-TIFR).
