Low radio frequency observations of T Pyx
ATel #4452; Nirupam Roy (NRAO), N. G. Kantharia (NCRA-TIFR), L. Chomiuk (Michigan State Univ./NRAO), T. Nelson (Univ. Minnesota), G. C. Anupama (IIA), M. F. Bode (Liverpool JMU), S. P. S. Eyres (Univ. Central Lancashire), T. J. O'Brien (Univ. Manchester), T. P. Prabhu (IIA)
on 4 Oct 2012; 20:05 UT
Credential Certification: Nirupam Roy (nroy@nrao.edu)
Subjects: Radio, Binary, Cataclysmic Variable, Nova, Transient, Variables
We report the results of target of opportunity observations at 610 MHz of the recurrent nova T Pyx (CBET #2700, IAUC #9205) using the Giant Metrewave Radio telescope (GMRT). This nova has been subjected to a multiwavelength monitoring campaign as reported by several observers in ATels #3285, #3549, #3647, #3707 and #3782. This current outburst has been detected and extensively studied at high radio frequencies (> 1 GHz) as well (ATels #3310, #3318 and #3679). The GMRT 610 MHz observations were carried out using allotted Director's Discretionary Time on 2012 March 18 and 2012 September 16 (i.e., 339 and 521 days respectively from the reported outburst on 2011 April 14). No radio source was detected at the nova coordinates (R.A. = 9h04m41s.52 +/- 0s.01, Decl. = -32d22'47".5 +/- 0".2, equinox 2000.0) down to 3-sigma flux density limits of 225 and 160 microJy on days 339 and 521 respectively. Combining these with high radio frequency detections with the VLA at similar epochs (private communication, EVLA nova team), it appears that the low frequency upper limit on day 339 is consistent with a spectral index of 1.5, and the radio emission from T Pyx is therefore indicated to be predominantly optically thick thermal with negligible non-thermal contribution at this epoch.
We thank the staff of the GMRT who made these observations possible. GMRT is operated by the National Centre for Radio Astrophysics of the Tata Institute of Fundamental Research.