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Evaluating Spectral Models and the X-ray States of Neutron-Star X-ray Transients

Dacheng Lin·Ronald A. Remillard·Jeroen Homan
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Abstract

We propose a hybrid model to fit the X-ray spectra of atoll-type X-ray transients in the soft and hard states. This model uniquely produces luminosity tracks that are proportional to T^4 for both the accretion disk and boundary layer. The model also indicates low Comptonization levels for the soft state, gaining a similarity to black holes in the relationship between Comptonization level and the strength of integrated rms variability in the power density spectrum. The boundary layer appears small, with a surface area that is roughly constant across soft and hard states. This result may suggestion that the NS radius is smaller than its inner-most stable circular orbit.

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Dacheng Lin, Ronald A. Remillard, Jeroen Homan. 2007-06-22. Evaluating Spectral Models and the X-ray States of Neutron-Star X-ray Transients. https://doi.org/10.1086/521181

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