Model Atmospheres of Hot Neutron Stars

Model Atmospheres of Hot Neutron Stars

Agnieszka Majczyna, Jerzy Madej, Agata Różańska, Mirosław Należyty

We demonstrated here that X-ray spectral observations of the WFI detector of the Athena mission can constrain the equation of state of superdense matter of a neutron star. The Athena mission is planned to be launched in 2031. We applied here our continuum fitting method and determined mass and radius of the spherical, non-rotating neutron star. Model spectra of a hot neutron star were calculated using the atmosphere code ATM24. Next, those models were fitted to the simulated spectrum of the neutron star calculated for Athena’s WFI detector, using the satellite calibration files. Our analysis shows the high precision of our method and demonstrates the need for a fast detector onboard of Athena. We calculated a large grid of theoretical spectra with various parameters, effective temperature and surface gravity and a hydrogen-helium-iron composition of solar proportion. Model spectra were fitted to the simulated spectrum of a neutron star. We obtained very precise mass and radius values with errors equal to 9% for mass and 8% for radius within the 2σ confidence error.

Proceedings of the Polish Astronomical Society, vol. 10, 210-212 (2020)

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