Abstract Details
| Name: Krishnakumar M.A Affiliation: Radio Astronomy Centre, NCRA-TIFR, Ooty Conference ID: ASI2015_833 Title : Scatter broadening measurements of 124 pulsars at 327 MHz Authors and Co-Authors : Mitra, D Naidu, A Joshi, B.C Manoharan, P.K NCRA-TIFR, Pune. Abstract Type : Poster Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : Pulsar signals are affected by the fluctuations of the electron density in the Interstellar medium. These fluctuations give rise to random variations in the refractive index of the medium. The pulsar signal traverses through such irregularities and gets scattered in the process. This essentially broadens the otherwise narrow pulse with an exponential decay which has a characteristic timescale $\tau_{sc}$, known as the scatter broadening time. Measurements of such pulse broadening timescales can be used to probe the morphology of the interstellar medium in the pulsar line of sights. For a Kolmogorov distribution of irregularities, $\tau_{sc}$ scales as $C^{2}_{n_e}\nu^{-4.4} DM^{2.2}$, where $C^{2}_{n_e}$ is the scattering strength in the line of sight to the pulsar, DM is the dispersion measure of the pulsar and $\nu$ is the observing frequency. Hence, the pulse broadening due to scattering will dominate the intrinsic pulse width evolution at meter wavelengths for $DM > 100$ pc/cc. In this study, we present such measurements of $\tau_{sc}$ for 124 pulsars at 327 MHz, observed using the upgraded Ooty Radio Telescope (ORT). These pulsars lie in the DM range of 37 -- 503 pc/cc and declination ($\delta$) range of $-$57$^{\circ} < \delta< 60^{\circ}$. New $\tau_{sc}$ estimates for 58 pulsars are presented for the first time, increasing the sample of all such measurements by about 40\% at 327 MHz. Using all available $\tau_{sc}$ measurements in the literature, we investigate the dependence of $\tau_{sc}$ on DM. Our measurements, together with previously reported values for $\tau_{sc}$, affirm that the ionised interstellar medium upto 3 kpc is consistent with Kolmogorov spectrum, while it deviates significantly beyond this distance. |