NASA Scientific and Technical Aerospace Reports - The University ...

on the evolution of spectral (including X-ray, radio and infrared) and temporal properties of elected black holes in the hard
states. I will also talk about impact of ASTROSAT to the science objective of our group.
Author
Accretion Disks; Black Holes (Astronomy); Ejection; Galaxies
20100017690 Massachusetts Univ., Lowell, MA USA
Investigating Stimulated Wave-Particle Interaction of Radiation Belt Particles with Space-Borne Whistler Mode
Transmitters
Song, P.; Reinisch, B. W.; Huang, X.; Sales, G. S.; Tu, J.; Paznukhov, V. V.; March 30, 2009; 171 pp.; In English; Original
contains color illustrations
Contract(s)/Grant(s): UMLRF-003; F19628-05-C-0070; Proj-DARP; 63278E
Report No.(s): AD-A517099; AFRL-RV-HA-TR-2009-1121; No Copyright; Avail.: Defense Technical Information Center
(DTIC)
ONLINE: http://hdl.handle.net/100.2/ADA517099
We study the feasibility of transmitting whistler mode waves in space for stimulating wave-particle interaction in the
radiation belts. We investigated both theoretically and experimentally the antenna-plasma interaction, the whistler waves
radiated from a space-borne transmitter, and the VLF waves radiated from ground-based transmitters. We have developed a
one-dimensional model of the high-voltage-antenna-sheath-plasma both analytically and numerically, and compared the
results with the space transmission experiments made by the Radio Plasma Imager on the IMAGE satellite. We have developed
a general theory for whistler wave radiation in space. Our results have shown that previous antenna sheath theories need
significant modifications and the previous whistler wave radiation theory contains substantial mathematical errors and flaws.
The model developed a few decades ago to describe the whistler waves penetrating through the ionosphere and propagating
in the magnetosphere also needs significant improvements. This project has laid solid foundation for further investigations and
modeling of space-borne whistler transmissions.
DTIC
Radiation Belts; Transmitters; Wave-Particle Interactions; Whistlers
20100017726 California Univ., Berkeley, CA, USA
Broadband X-Ray Spectra of GX 339-4 and the Geometry of Accreting Black Holes in the Hard State
Tomsick, John A.; Kalemci, Emrah; Kaaret, Philip; Markoff, Sera; Corbel, Stephane; Migliari, Simone; Fender, Rob; Bailyn,
Charles D.; Buxton, Michelle M.; The Astrophysical Journal; 2008; Volume 680, No. 1, pp. 593; In English
Contract(s)/Grant(s): NNX08AJ59G; Copyright; Avail.: Other Sources
ONLINE: http://dx.doi.org/10.1086/587797
A major question in the study of black hole binaries involves our understanding of the accretion geometry when the
sources are in the ‘hard’ state, with an X-ray energy spectrum dominated by a hard power-law component and radio emission
coming from a steady ‘compact’ jet. Although the common hard state picture is that the accretion disk is truncated, perhaps
at hundreds of gravitational radii (Rg) from the black hole, recent results for the recurrent transient GX 339-4 by Miller and
coworkers show evidence for disk material very close to the black hole’s innermost stable circular orbit. That work studied
GX 339-4 at a luminosity of approximately 5% of the Eddington limit (L(sub Edd) and used parameters from a relativistic
reflection model and the presence of a thermal component as diagnostics. Here we use similar diagnostics but extend the study
to lower luminosities (2.3% and 0.8% L(sub Edd)) using Swift and RXTE observations of GX 339-4. We detect a thermal
component with an inner disk temperature of approximately 0.2 keV at 2.3% L (sub Edd). At both luminosities, we detect
broad features due to iron K-alpha that are likely related to reflection of hard X-rays off disk material. If these features are
broadened by relativistic effects, they indicate that the material resides within 10 Rg, and the measurements are consistent with
the disk’s inner radius remaining at approximately 4 Rg down to 0.8% L(sub Edd). However, we also discuss an alternative
model for the broadening, and we note that the evolution of the thermal component is not entirely consistent with the constant
inner radius interpretation. Finally, we discuss the results in terms of recent theoretical work by Liu and co-workers on the
possibility that material may condense out of an Advection-Dominated Accretion Flow to maintain an inner optically thick
disk.
Author
Accretion Disks; Black Holes (Astronomy); Radii; X Rays; X Ray Astronomy; X Ray Stars; Binary Stars
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