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X--Ray Spectra from Neutron Stars Accreting at Low Rates

Luca Zampieri·Roberto Turolla·Silvia Zane·Aldo Treves
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Abstract

The spectral properties of X--ray radiation produced in a static atmosphere around a neutron star accreting at very low rates are investigated. Previous results by Alme \& Wilson (1973) are extended to the range $10^{-7}\leq L/L_{Edd}\leq 10^{-3}$ to include the typical luminosities, $L\sim 10^{31}-10^{32} \ {\rm ergs\, s^{-1}}$, expected from isolated neutron stars accreting the interstellar medium. The emergent spectra show an overall hardening with respect to the blackbody at the neutron star effective temperature in addition to a significant excess over the Wien tail. The relevance of present results in connection with the observability of low--luminosity X--ray sources is briefly discussed.

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Luca Zampieri, Roberto Turolla, Silvia Zane, Aldo Treves. 1994-07-22. X--Ray Spectra from Neutron Stars Accreting at Low Rates. https://doi.org/10.1086/175223

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