| Name: CHANDRA KUMAR CHANDRAVANSHI |
| Affiliation: Pandit Ravishankar Shukla University Raipur |
| Conference ID: ASI2026_982 |
| Title: Multi-epoch X-ray Spectral and Timing Study of the Be/X-ray Binary SMC X-2 |
| Abstract Type: Poster |
| Abstract Category: High Energy Phenomena, Fundamental Physics and Astronomy |
| Author(s) and Co-Author(s) with Affiliation: Chandra Kumar Chandravanshi(S.o.S. in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur-492010, India), Pravat Dangal(St. Joseph’s College, Darjeeling 734104, India), Nand Kumar Chakradhari(S.o.S. in Physics and Astrophysics, Pt. Ravishankar Shukla University, Raipur-492010, India) |
| Abstract: SMC X-2 is a transient Be/X-ray binary pulsar in the Small Magellanic Cloud that has exhibited multiple giant (Type II) outbursts over the last few decades, reaching super-Eddington luminosities. These episodes provide an excellent opportunity to investigate accretion processes and emission geometry in strongly magnetized neutron stars. We present a comprehensive multi-epoch X-ray timing and spectral study of SMC X-2 using archival observations from RXTE, Swift/XRT, XMM–Newton, NuSTAR, NICER, and AstroSat, covering its major outbursts in 2000, 2015, and 2022.
Timing analysis confirms coherent pulsations with a spin period of ~2.37 s across all epochs. Energy-resolved pulse profiles show a clear luminosity-dependent evolution, transitioning from a single-peaked structure at lower luminosities to a double-peaked morphology at higher luminosities. This behavior is consistent with a change in emission geometry from a pencil-beam to a fan-beam pattern as the accretion rate increases. The pulsed fraction is found to increase with both energy and luminosity.
Broadband spectral modeling shows a hard Comptonized continuum along with a soft thermal component and iron fluorescence emission. An absorption-like feature detected in the hard X-ray band, around ~27 keV, is interpreted as a cyclotron resonance scattering feature, implying a neutron star magnetic field of the order of 10¹² G. The centroid energy of this feature tends to fluctuate within 25 to 31.5 keV, with indications of a luminosity-dependent energy shift. |
