Abstract Details

Name: Devojyoti Kansabanik
Affiliation: National Center for Radio Astrophysics
Conference ID: ASI2020_260
Title : Investigation of eclipse mechanism for Black Widow Pulsar J1544+4937
Authors and Co-Authors : Devojyoti Kansabanik, Bhaswati Bhattacharyya
Abstract Type : Poster
Abstract Category : Stars, ISM and Galaxy
Abstract : We will present results from multi-frequency investigation of eclipse mechanism of a black widow (BW) millisecond pulsar (MSP) PSR J1544+4937, which was discovered with the GMRT. Black widow binary systems where pulsar wind evaporates the companion are believed as one of the way to form isolated MSPs. PSR J1544+4937, like most other BW MSPs, exhibit long eclipses around companion's superior conjunction (~13% of its orbit, larger than the companion's Roche lobe), since pulsar emission is obscured by the material blown from the companion, which is no longer gravitationally bound to the companion. Frequency dependent eclipsing with a frequency onset of eclipsing between 339-591 MHz is reported for PSR J1544+4937 in a previous study. Equipped with simultaneous dual frequency observations at 300-500 MHz and 650-850 MHz using the upgraded GMRT (uGMRT), we determined a precise frequency onset of 345 ±5 MHz. Frequency onset determined by us is order of magnitude more precise than that is known for any other BW pulsar with frequency dependent eclipsing. In addition, we generated spectra of the eclipse phase which was hitherto unexplored for any other BW system. With the aid of more precise frequency onset and the spectra of the eclipse phase we performed a detailed investigation of the possible eclipse mechanisms that can satisfy the constrains from the observations. While modelling eclipse phase spectra; following Thomson et al 1994 we conclude that eclipsing is caused by cyclotron-synchrotron absorption of pulsed emission by the intra-binary material. In addition to the main eclipse we observed some additional short duration eclipses at various orbital phases, indicating variable intra-binary medium. Frequency onset of the short eclipse are observed to be different than the main eclipse and vary between eclipses. Future plan to extend this study for investigation of the eclipse mechanism for other BW pulsars will be presented.