Simulations of GX 301-2

TITLE: Low ionization plasma diagnostics in the wide binary GX 301-2.

GX 301-2 is a wide binary with an orbital period of 41.5 d. Its pulsar has a rather slow spin period of 696 s. Because of the wide orbit there is there is probably no significant disc accretion but accretion from a strong wind from its very early type B-star companion. The median X-ray luminosity is log L$_x \sim$ 36.4 at a distance of 1.8 kpc, depending on the separation of the neutron star and the main star. ASCA detected 6 K_alpha lines identified with neutral matter or low (I) ionization states (Mg-K_alpha at 1.254 keV, Si-K_alpha at 1.740 keV, S-K_alpha at 2.307 keV, Ar-K_alpha at 2.956 keV, Ca-K_alpha at 3.688 keV and Fe-K_alpha at 6.391 keV). The SIS0 + SIS1 spectrum also indicated a Fe-K absorption edge at 7.2 keV. From the HETG spectra we hope to test accreting wind models in the neutral matter domain, and probe the circumstellar matter in wide binary systems.

Figure 1: The photon spectrum obtained from ASCA (Pravdo et al. 1985). Besides a 0.8 keV Raymond-Smith stellar component it contains two intrinsically absorbed powerlaws plus several cool emission lines.

Figure 2: First order MEG spectrum obstained from a 40 ks exposure using the MARX simulator. This is the minimal exposure time that allows to observe and resolve most of the emission from the hot (0.8 keV) thermal plasma as well as the cool flourescent emission of Mg, Si, S, Ar, Ca, and Fe.

More to come...soon....

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