Time-dependent two-dimensional radiation hydrodynamics of accreting matter onto highly magnetized neutron stars

Conference · Tue Nov 20 00:00:00 EST 1990

OSTI ID:6304820

Klein, R I ^[1]; Arons, J ^[2]

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1. California Univ., Berkeley, CA (USA). Dept. of Astronomy Lawrence Livermore National Lab., CA (USA)
2. California Univ., Berkeley, CA (USA). Dept. of Astronomy California Univ., Berkeley, CA (USA). Dept. of Physics

We present for the first time, the self-consistent solution of the two-dimensional, time-dependent equations of radiation-hydrodynamics governing the accretion of matter onto the highly magnetized polar caps of luminous x-ray pulsars. The calculations show a structure in the accretion column very different from previous one-zone uniform models. We have included all the relevant magnetic field corrections to both the hydrodynamics and the radiative transport. We include a new theory for the diffusion and advection of both radiation energy density and photon number density. For initially uniformly accreting models with super-Eddington flows, we have uncovered evidence of strong radiation-driven outflowing optically thin radiation filled regions of the accretion column embedded in optically-thick inflowing plasma. We follow the evolution of these photon bubbles for several dynamical timescales. The development of these photon bubbles'' indicates growth times on the order of a millisecond and show fluctuations on sub-millisecond timescales in agreement with a linear stability analysis. The photon bubbles are a consequence of the effect of radiative heat flux on the internal gravity waves in the strongly magnetized atmosphere and may result in observable fluctuations in the emitted luminosity leading to luminosity dependent changes in the pulse profile. This may provide important new diagnostics for conditions in accreting x-ray pulsars. 19 refs., 13 figs.

• Research Organization: Lawrence Livermore National Lab., CA (USA)
• Sponsoring Organization: DOE/DP; National Science Foundation (NSF)
• DOE Contract Number: W-7405-ENG-48
• OSTI ID: 6304820
• Report Number(s): UCRL-JC-105532; CONF-9009308-1; ON: DE91005228
• Resource Relation: Conference: NATO advanced workshop on stellar atmospheres: beyond classical models, Trieste (Italy), 3-7 Sep 1990
• Country of Publication: United States
• Language: English

Related Subjects

71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
NEUTRON STARS
STAR ACCRETION
PULSARS
COSMIC X-RAY SOURCES
EQUATIONS
HEAT FLUX
HYDRODYNAMICS
LUMINOSITY
PHOTONS
COSMIC RADIO SOURCES
COSMIC RAY SOURCES
ELEMENTARY PARTICLES
FLUID MECHANICS
MASSLESS PARTICLES
MECHANICS
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
STAR EVOLUTION
STARS
640102* - Astrophysics & Cosmology- Stars & Quasi-Stellar
Radio & X-Ray Sources