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arXiv · 2410.17307

Monitoring Observations of SMC X-1's Excursions (MOOSE) III: X-ray Spectroscopy of a Warped, Precessing Accretion Disc

Rawan Karam·Kristen C. Dage·Bailey E. Tetarenko·McKinley C. Brumback·Daryl Haggard·Arash Bahramian·Chin-Ping Hu·Joey Neilsen·Diego Altamirano·Wasundara Athukoralalage·Philip A. Charles·William I. Clarkson·Ryan C. Hickox·Jamie Kennea
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Abstract

The MOOSE (Monitoring Observations of SMC X-1 Excursions) program uses the Neutron Star Interior Composition Explorer Mission (NICER) to monitor the high mass X-ray binary SMC X-1 during its superorbital period excursions. Here we perform X-ray spectral analyses of 26 NICER observations of SMC X-1, taken at the tail-end of the excursion between 2021-04-01 and 2022-01-05. We use a single spectral model to fit spectra observed in high, intermediate and low states, using a combination of a partial covering fraction model, a black-body disc, and a power-law component. We find that the partial covering fraction varies significantly with the superorbital state during superorbital excursion. Our findings suggest that the low/high state in SMC X-1 is caused by a very high obscuration of the accretion disk.

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Rawan Karam, Kristen C. Dage, Bailey E. Tetarenko, McKinley C. Brumback, Daryl Haggard, Arash Bahramian, Chin-Ping Hu, Joey Neilsen, Diego Altamirano, Wasundara Athukoralalage, Philip A. Charles, William I. Clarkson, Ryan C. Hickox, Jamie Kennea. 2024-10-22. Monitoring Observations of SMC X-1's Excursions (MOOSE) III: X-ray Spectroscopy of a Warped, Precessing Accretion Disc. https://arxiv.org/abs/2410.17307

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