| Name: Aman Kaushik |
| Affiliation: Tata Institute of Fundamental Research |
| Conference ID: ASI2026_361 |
| Title: Characterizing SMC pulsar SXP 46.6 |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Aman Kaushik(Tata Institute of Fundamental Research, Mumbai - 400005, India), Sayantan Bhattacharya(Tata Institute of Fundamental Research, Mumbai - 400005, India), Sudip Bhattacharyya(Tata Institute of Fundamental Research, Mumbai - 400005, India) |
| Abstract: Be/X-ray binaries (BeXRBs) represent a major subclass of high-mass X-ray binaries (HMXBs) where the companion star is a B-type star with a circumstellar decretion disk. These systems are characterized by regular X-ray outbursts linked to the interaction between the neutron star (NS) and the Be star’s disk at periastron. The NS, typically in a wide and eccentric orbit, accretes material as it passes through the dense equatorial disk of the Be star, giving rise to Type I outbursts near periastron. The pulsar SXP 46.6, originally discovered with the Rossi X-ray Timing Explorer (RXTE) in 1997, is one such BeXRB in the Small Magellanic Cloud (SMC). Here, we characterize SXP 46.6 using NuSTAR observations conducted in 2017. We observe that the spin period (P ) of this neutron star has
decreased from its discovered value of 46.6 s to a value of 45.984(1) s, indicating a spin-up at the rate of ˙P = −1.13 × 10^(−9) s s−1. This spin-up rate is used to calculate a high pulsar magnetic field value of 2.25 × 10^(13) G. This calculation also provides a low magnetic field value, which we rule out here by constraining the inner accretion disk radius to be less than the radius of the innermost stable circular orbit. The pulse profile shows a double-peaked structure in soft, hard, and broad X-ray bands which hints towards a pencil beam emission from two antipodal hot spots on the neutron star surface. We also perform spin phase-resolved spectroscopy for the first time, revealing spectral variations across different phases of the pulsar’s rotation. These results offer new insights into the long-term spin evolution and emission properties of SXP 46.6. (The article has been published in PRD: https://doi.org/10.1103/lwq4-8jz8) |
