Proton deceleration near the surface of an accreting neutron star

Thesis/Dissertation · Mon Jan 01 04:00:00 EST 1990

OSTI ID:5052852

Pakey, D D

In binary x-ray sources consisting of a neutron star accreting matter from a companion star, x-radiation is produced by the layer of hot, dense plasma that develops where the matter collides with the neutron star surface. The structure of this layer and the spectrum of the radiation produced there are determined by the way in which infalling protons deposit their energy as a function of the depth. The dominant stopping mechanism is binary Coulomb collisions with electrons in the plasma at the surface of the neutron star, a process that is strongly modified if the neutron star has a strong (B {approx gt} 10{sup 12} G) magnetic field. For magnetic fields of this size, the electron motion perpendicular to the field is quantized, collisions are anisotropic, and the protons deposit their energy much deeper than if the magnetic field is weaker. This thesis is a study of proton deceleration by multiple Coulomb collisions with electrons in a hot, strongly magnetized plasma. The evolution of the proton velocity-space distribution function is followed by integrating a Fokker-Planck equation numerically. The Fokker-Planck coefficients are calculated for conditions in which the electrons have a thermal distribution of velocities parallel to the field and remain in their lowest magnetic Landau levels. Nonrelativistic Landau wavefunctions are used for both the electrons and the accreting protons. The protons are assumed to be moving nearly parallel to the magnetic field initially.

• Research Organization: Illinois Univ., Urbana, IL (United States)
• OSTI ID: 5052852
• Country of Publication: United States
• Language: English

Related Subjects

640102* -- Astrophysics & Cosmology-- Stars & Quasi-Stellar
Radio & X-Ray Sources
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
ACCELERATION
BARYONS
BINARY STARS
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
DIFFERENTIAL EQUATIONS
DISTRIBUTION FUNCTIONS
ELECTROMAGNETIC RADIATION
ELECTRONS
ELEMENTARY PARTICLES
EQUATIONS
FERMIONS
FOKKER-PLANCK EQUATION
FUNCTIONS
HADRONS
IONIZING RADIATIONS
LEPTONS
MAGNETIC FIELDS
NEUTRON STARS
NUCLEONS
PARTIAL DIFFERENTIAL EQUATIONS
PROTONS
RADIATIONS
STAR ACCRETION
STAR EVOLUTION
STARS
WAVE FUNCTIONS
X RADIATION