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Session 111 - Pulsars.
Display session, Saturday, January 10
Exhibit Hall,
The flow of a radiation-dominated ideal fluid through a standing, radiative shock is an important aspect of accretion onto high-luminosity X-ray pulsars. A complete understanding of the shock structure is required in order to analyze the role of Fermi energization in producing the power-law spectra observed from typical X-ray pulsars. We reconsider the problem in this paper by obtaining an analytical solution for the velocity profile based on an approximate set of hydrodynamical equations describing the steady, plane-parallel flow of a radiation-dominated ideal fluid along a magnetically confined accretion column, including the escape of radiation through the column walls. The requirement of downstream stagnation yields an interesting eigenvalue relation involving the accretion rate, the radius of the column, and the energy flux at the sonic point. Flows failing to satisfy this relation cannot be steady, and may display a variety of temporal behaviors. The simplicity of the analytical solution makes it a very convenient starting point for calculations of the emergent spectrum, which are currently underway.
The author(s) of this abstract have provided an email address for comments about the abstract: pbecker@hubble.gmu.edu
