Abstract Details
| Name: Devansh Agarwal Affiliation: IISER-Thiruvananthapuram Conference ID: ASI2016_819 Title : Multi-frequency profile evolution of Millisecond Pulsars Authors and Co-Authors : Devansh Agarwal (IISER-Thiruvananthapuram), Kishalay De (IISc-Bangalore) and Yashwant Gupta (NCRA-TIFR, Pune) Abstract Type : Poster Abstract Category : Stars, The Milky Way Galaxy and its neighbours Abstract : Though Millisecond Pulsars (MSPs) differ significantly from normal pulsars in periods, period derivatives, magnetic field strengths and evolutionary history, there are interesting comparisons in their emission properties. In particular, it is instructive to compare pulse profiles and their evolution with observing frequency. Kramer et al. (1998) did the first and to date the most comprehensive study of the frequency evolution of MSPs with a sample of 18 objects. However, very low-frequency observations were not included in this study. The high sensitivity of the GMRT at low frequencies makes it the ideal instrument to probe aspects of millisecond pulsar emission in this regime, and extend the existing database of MSP profiles to lower frequencies. We present results from a comprehensive study of 40 MSPs to investigate the frequency evolution of their profiles. We used existing data from the GMRT, along with the newly developed coherent dedispersion pipeline, to observe these MSPs at 2 to 4 frequency bands and constructed their average profiles. Subsequently, the average profiles were collated with existing profiles available in the EPN pulsar database and the literature, to assemble an extensive data set of MSP profiles over a broad range of frequencies. The profiles were aligned, normalised, and stacked for comparison. To quantifying the evolution of profiles with observing frequency, their widths ($w_{50}$) and peak to peak component separation (for multi-component) MSPs were calculated as a function of radio frequency. The standard radius to frequency mapping model (Cordes 1978) for normal pulsars describes that the profiles become wider, and separation between individual emission components increases. In this paper, we show that the RFM model does not apply very significantly to MSPs. We show few cases where the component separation increases (or increases and then saturates) with increasing frequency. Such deviations might be able to reveal interesting facts about the emission mechanism of these pulsars, and we discuss possible implications of these. |