Effects of small-angle scattering on a pulse of radiation with an application of x-ray bursts and interstellar dust

Journal Article · Thu Jun 01 04:00:00 EDT 1978 · Astrophys. J.; (United States)

DOI:https://doi.org/10.1086/156159· OSTI ID:6734833

Alcock, C; Hatchett, S

We have analyzed in detail the general problem of the propagation of a pulse of radiation through a uniform medium containing small-angle scatterers. Simple expressions for the first moment of the arrival time delay and for the second and fourth moments of the arrival angle of the pulse photons are given that are valid for any optical depth. Using the first two of these, we find a simple method of distance determination. Joint and individual distribution functions for arrival time and angle are derived in the small and large optical depth limits. An exponential tail in the arrival-time distribution is characteristic in both limits. The analysis has been applied to a burst of X-rays from a source near the galactic center propagating through the dust of the interstellar medium. The grains responsible for interstellar reddening can have very little observable effect. However, the observed lengths, energy dependence, and variability of the burst tails can be readily accounted for by a population of large (approx.3 ..mu..m) grains. We derive useful constraints on the grain distribution from observations of the burst tails.

• Research Organization: Division of Physics, Mathematics, and Astronomy, California Institute of Technology
• OSTI ID: 6734833
• Journal Information: Astrophys. J.; (United States), Journal Name: Astrophys. J.; (United States) Vol. 222:2; ISSN ASJOA
• Country of Publication: United States
• Language: English

Related Subjects

640105* -- Astrophysics & Cosmology-- Galaxies
71 CLASSICAL AND QUANTUM MECHANICS
GENERAL PHYSICS
COSMIC DUST
COSMIC PHOTONS
COSMIC RADIATION
COSMIC RAY SOURCES
COSMIC X-RAY SOURCES
CROSS SECTIONS
DUSTS
ELECTROMAGNETIC RADIATION
ELEMENTARY PARTICLES
GALAXIES
INTERSTELLAR GRAINS
INTERSTELLAR SPACE
IONIZING RADIATIONS
MASSLESS PARTICLES
MATHEMATICS
MILKY WAY
PARTICLES
PHOTONS
RADIATION TRANSPORT
RADIATIONS
SCATTERING
SPACE
STATISTICS
X RADIATION