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Is the Lack of Pulsations in Low Mass X-Ray Binaries due to Comptonizing Coronae?

Ersin Gogus·M. Ali Alpar·Marat Gilfanov
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Abstract

The spin periods of the neutron stars in most Low Mass X-ray Binary (LMXB) systems still remain undetected. One of the models to explain the absence of coherent pulsations has been the suppression of the beamed signal by Compton scattering of X-ray photons by electrons in a surrounding corona. We point out that simultaneously with wiping out the pulsation signal, such a corona will upscatter (pulsating or not) X-ray emission originating at and/or near the surface of the neutron star leading to appearance of a hard tail of Comptonized radiation in the source spectrum. We analyze the hard X-ray spectra of a selected set of LMXBs and demonstrate that the optical depth of the corona is not likely to be large enough to cause the pulsations to disappear.

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Ersin Gogus, M. Ali Alpar, Marat Gilfanov. 2006-12-22. Is the Lack of Pulsations in Low Mass X-Ray Binaries due to Comptonizing Coronae?. https://doi.org/10.1086/512028

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