# Two-dimensional Radiation-hydrodynamic Model for Supercritical Disk Accretion Flows onto Neutron Stars - Astrophysics

Two-dimensional Radiation-hydrodynamic Model for Supercritical Disk Accretion Flows onto Neutron Stars - Astrophysics - Descarga este documento en PDF. Documentación en PDF para descargar gratis. Disponible también para leer online.

Abstract: We performed two-dimensional radiation hydrodynamic simulations ofsupercritical accretion flows around neutron stars NSs. In contrast with theaccretion flows onto black holes BHs, we find that the shell-shapedhigh-density regions form around the NSs, since the radiation force is enhancedin the innermost regions. The enhanced radiation force drives strong outflowsabove and below the disk. The mass-accretion rate onto the NS exceeds thecritical rate, $L { m E}-c^2$, with $L { m E}$ being the Eddingtonluminosity. However it is about $20-30%$ of that onto the BH, under thecondition that we employ the same mass-input rate, $\dot{M} { m input}$, whichis mass injected from the outer disk boundary per unit time. The mass-outflowrate is a few-times larger in flows around NSs than in flows around BHs. Thesupercritical NS accretion flows mainly release the accretion energy as thekinetic energy of the outflows, though the disk luminosity is predominant overthe kinetic energy output rate in the BH accretion flows. The resultingvelocity and mass-outflow rate of the outflows are $0.2-0.3c$ and$150-700L { m E}-c^2$, respectively, for the mass-input rate of $3\times10^2\lsim \dot{M} { m input}-L { m E}-c^2\lsim 3\times 10^3$. This impliesthat the SS433 jets can be roughly explained by the supercritical accretiononto a NS. However, the collimation angle of the outflows in our simulations$\sim 20^\circ$ is larger than that of the SS433 jets a few degrees.

Autor: Ken Ohsuga

Fuente: https://arxiv.org/