http://arxiv.org/abs/1706.08896
We propose a new method to detect off-pulse (unpulsed and/or continuous) emission from pulsars, using the intensity modulations associated with interstellar scintillation. Our technique involves obtaining the dynamic spectra, separately for on-pulse window and off-pulse region, with time and frequency resolutions to properly sample the intensity variations due to scintillation, and then estimating their mutual correlation as a measure of off-pulse emission, if any. We describe and illustrate the essential details of this technique with the help of observation of PSR B0329+54 at frequencies 730 and 810 MHz, made with the Green Bank Telescope and present upper limits for the off-pulse intensity at the two frequencies. We also discuss advantages of this method over earlier approaches to detect off-pulse emission. In particular, we point out how certain non-idealities inherent to measurement set-ups could potentially affect estimations in earlier approaches, and argue that the present technique is immune to such non-idealities. We verify both of the above situations with relevant simulations. We expect this technique to pave way for extensive investigations of off-pulse emission with the help of even existing dynamic spectral data on pulsars and of course with more sensitive long-duration data from new observations.
K. Ravi and A. Deshpande
Wed, 28 Jun 17
-41/62
Comments: 20 pages, 8 figures, submitted to ApJ