Accretion flows with comparable radiation and gas pressures. (arXiv:1902.04425v1 [astro-ph.HE])
<a href="http://arxiv.org/find/astro-ph/1/au:+Samadi_M/0/1/0/all/0/1">Maryam Samadi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Abbassi_S/0/1/0/all/0/1">Shahram Abbassi</a>, <a href="http://arxiv.org/find/astro-ph/1/au:+Gu_W/0/1/0/all/0/1">Wei-Min Gu</a>
By taking into account photon absorption, we investigate the vertical
structure of accretion flows with comparable radiation and gas pressures. We
consider two separate energy equations for matter and radiation in the
diffusion limit. In order to solve the set of radiation hydrodynamic equations
in steady state and axisymmetric configuration, we employ self-similar
technique in the radial direction. We need the reflection symmetry about the
mid-plane to find gas density at the equator. For a typical solution, we assume
that the gas pressure has 10-50% portion of the total pressure. In this paper,
since the radiation energy is involved directly, we are able to estimate how
much energy of viscous heating is transported in the radial direction and
advected towards the central object. Our results show that although the mass
accretion rate does not approach the Eddington limit, the energy advection is
rather high. Moreover, in a disc with greater accretion rate and less portion
of gas pressure at the total pressure, more energy is advected to its center.
In addition, as we expect the accretion flow becomes thicker with greater
values of gas pressure. Based on Solberg-H~Av{z}iland conditions, we notice
that the flow is convectively stable in all parts of such a disc.
By taking into account photon absorption, we investigate the vertical
structure of accretion flows with comparable radiation and gas pressures. We
consider two separate energy equations for matter and radiation in the
diffusion limit. In order to solve the set of radiation hydrodynamic equations
in steady state and axisymmetric configuration, we employ self-similar
technique in the radial direction. We need the reflection symmetry about the
mid-plane to find gas density at the equator. For a typical solution, we assume
that the gas pressure has 10-50% portion of the total pressure. In this paper,
since the radiation energy is involved directly, we are able to estimate how
much energy of viscous heating is transported in the radial direction and
advected towards the central object. Our results show that although the mass
accretion rate does not approach the Eddington limit, the energy advection is
rather high. Moreover, in a disc with greater accretion rate and less portion
of gas pressure at the total pressure, more energy is advected to its center.
In addition, as we expect the accretion flow becomes thicker with greater
values of gas pressure. Based on Solberg-H~Av{z}iland conditions, we notice
that the flow is convectively stable in all parts of such a disc.
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