| Name: Keerthi Prabhu Shirodkar |
| Affiliation: CHRIST (Deemed to be University) |
| Conference ID: ASI2026_841 |
| Title: A model for the transient scintillation of B1508+55 |
| Abstract Type: Poster |
| Abstract Category: Stars, Interstellar Medium, and Astrochemistry in Milky Way |
| Author(s) and Co-Author(s) with Affiliation: Keerthi Prabhu Shirodkar(CHRIST (Deemed to be University), Bengaluru - 560029, India), Visweshwar Ram Marthi(NCRA-TIFR, Pune - 411007, India), Ashley Stock(Swinburne University of Technology, Hawthorn - VIC 3122, Australia) |
| Abstract: Interstellar scintillation of compact sources, such as pulsars, precisely probes the small-scale electron density structures in the ionised interstellar medium. PSR B1508+55 is a system known to host two screens, with their scattering axes aligned mutually orthogonally. The closer screen (S1) at 127 pc is known to have structures that refract radiation at low radio frequencies (< 150 MHz), which manifest as echoes of the main pulse. Consequently, it exhibits strong scattering coinciding with the line-of-sight crossing of these echoes. Recently, in addition to cessation of strong scattering, we observed episodic scintillation in the Band 3 and Band 4 observations with uGMRT taken in 2023, suggesting the presence of strongly scattering structures in a screen (S2) located at 1940 pc. However, the transient nature of such a scattering event remains poorly understood. The observations reveal a more diffuse, fuzzy feature instead of the typical parallel stripe-like features in the secondary spectrum of scintillation. We propose a preliminary model describing the low modulation observed between episodes of modest scattering within a few minutes, speculating that these effects are caused by the combined effect of the interplay between the scattering on the two screens, mainly on S2, causing this rapid modulation. Our model suggests a range of scales for the structures on S2, in line with expectations, and can explain the observed effects satisfactorily. We also test this model by simulating this unique system that seems to be exhibiting exotic behaviour compared to other systems with similar screen orientation and distance. |
