X-ray binaries with neutron stars at different accretion stages. (arXiv:1811.02842v1 [astro-ph.HE])

X-ray binaries with neutron stars at different accretion stages. (arXiv:1811.02842v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Postnov_K/0/1/0/all/0/1">Konstantin Postnov</a> (SAI MSU), <a href="http://arxiv.org/find/astro-ph/1/au:+Kuranov_A/0/1/0/all/0/1">Aleksandre Kuranov</a> (SAI MSU), <a href="http://arxiv.org/find/astro-ph/1/au:+Yungelson_L/0/1/0/all/0/1">Lev Yungelson</a> (INASAN RAS)

Different accretion regimes onto magnetized NSs in HMXBs are considered:
wind-fed supersonic (Bondi) regime at high accretion rates $dot Mgtrsim
4times 10^{16}$~[g s$^{-1}$] , subsonic settling regime at lower $dot M$ and
supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs
in HMXBs reach equilibrium spin periods $P^*$ proportional to binary orbital
period $P_b$. At supercritical accretion stage, the system may appear as a
pulsating ULX. Population synthesis of Galactic HMXBs using standard
assumptions on the binary evolution and NS formation is presented. Comparison
of the model $P^*$ — $P_b$ (the Corbet diagram), $P^*$ — $L_x$ and $P_b$ —
$L_x$ distributions with those for the observed HMXBs (including Be X-ray
binaries) and pulsating ULXs suggests the importance of the reduction of $P^*$
in non-circular orbits, explaining the location of Be X-ray binaries in the
model Corbet diagram, and the universal parameters of pulsating ULXs depending
only on the NS magnetic fields.

Different accretion regimes onto magnetized NSs in HMXBs are considered:
wind-fed supersonic (Bondi) regime at high accretion rates $dot Mgtrsim
4times 10^{16}$~[g s$^{-1}$] , subsonic settling regime at lower $dot M$ and
supercritical disc accretion during Roche lobe overflow. In wind-fed stage, NSs
in HMXBs reach equilibrium spin periods $P^*$ proportional to binary orbital
period $P_b$. At supercritical accretion stage, the system may appear as a
pulsating ULX. Population synthesis of Galactic HMXBs using standard
assumptions on the binary evolution and NS formation is presented. Comparison
of the model $P^*$ — $P_b$ (the Corbet diagram), $P^*$ — $L_x$ and $P_b$ —
$L_x$ distributions with those for the observed HMXBs (including Be X-ray
binaries) and pulsating ULXs suggests the importance of the reduction of $P^*$
in non-circular orbits, explaining the location of Be X-ray binaries in the
model Corbet diagram, and the universal parameters of pulsating ULXs depending
only on the NS magnetic fields.

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