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

20100017373 Bay Area Environmental Research Inst., Sonoma , CA, USA; NASA Ames Research Center, Moffett Field,
CA, USA
Spectral Absorption Properties of Atmospheric Aerosols
Bergstrom, R. W.; Pilewskie, P.; Russell, P. B.; Redemann, J.; Bond, T. C.; Quinn, P. K.; Sierau, B.; Atmospheric Chemistry
and Physics; December 04, 2007; Volume 7, pp. 5937-5943; In English; Original contains black and white illustrations
Contract(s)/Grant(s): NNA06CA92A; Copyright; Avail.: Other Sources
ONLINE: http://dx.doi.org/10.5194/acp-7-5937-2007
We have determined the solar spectral absorption optical depth of atmospheric aerosols for specific case studies during
several field programs (three cases have been reported previously; two are new results). We combined airborne measurements
of the solar net radiant flux density and the aerosol optical depth with a detailed radiative transfer model for all but one of
the cases. The field programs (SAFARI 2000, ACE Asia, PRIDE, TARFOX, INTEX-A) contained aerosols representing the
major absorbing aerosol types: pollution, biomass burning, desert dust and mixtures. In all cases the spectral absorption optical
depth decreases with wavelength and can be approximated with a power-law wavelength dependence (Absorption Angstrom
Exponent or AAE). We compare our results with other recent spectral absorption measurements and attempt to briefly
summarize the state of knowledge of aerosol absorption spectra in the atmosphere. We discuss the limitations in using the AAE
for calculating the solar absorption. We also discuss the resulting spectral single scattering albedo for these cases.
Author
Absorption Spectra; Aerosols; Optical Thickness; Earth Observing System (EOS); Absorption Spectroscopy
20100017630 California Univ., Berkeley, CA, USA
Truncation of the Inner Accretion Disk Around a Black Hole at Low Luminosity
Tomsick, John A.; Yamaoka, Kazutaka; Corbel, Stephane; Kaaret, Philip; Kalemci, Emrah; Migliari, Simone; The
Astrophysical Journal - Letters; 2009; Volume 707, No. 1; 1 pp.; In English
Contract(s)/Grant(s): NNX08AJ59G; Copyright; Avail.: Other Sources
ONLINE: http://dx.doi.org/10.1088/0004-637X/707/1/L87
Most black hole binaries show large changes in X-ray luminosity caused primarily by variations in mass accretion rate.
An important question for understanding black hole accretion and jet production is whether the inner edge of the accretion
disk recedes at low accretion rate. Measurements of the location of the inner edge (R(sub in)) can be made using iron emission
lines that arise due to fluorescence of iron in the disk, and these indicate that R(sub in) is very close to the black hole at high
and moderate luminosities (greater than approximately equal to 1% of the Eddington luminosity, L(sub Edd). Here, we report
on X-ray observation of the black hole GX 339-4 in the hard state by Suzaku and the Rossi X-ray Timing Explorer (RXTE)
that extend iron line studies to 0.14% L(sub Edd) and show that R(sub in) increases by a factor of greater than 27 over the
value found when GX 339-4 was bright. The exact value of R(sub in) depends on the inclination of the inner disk (i), and we
derive 90% confidence limits of R(sub in) greater than 35R(sub g) at i=0degrees and R(sub in) greater than 175R(sub g)
ati=30degrees. This provides direct evidence that the inner portion of the disk is not present at low luminosity, allowing
for the possibility that the inner disk is replaced by advection- or magnetically-dominated accretion flows.
Author
Accretion Disks; Black Holes (Astronomy); Luminosity; Astrophysics; Approximation
20100017663 California Univ., Berkeley, CA, USA
Galactic Black Holes in the Hard State: A Multi-Wavelength View of Accretion and Ejection
Kalemci; Tomsick, John A.; Migliari; Corbel; Markoff; Proceedings of the 2nd Kolkata Conference on Observational Evidence
for Black Holes in the Universe; [2010]; Volume 1053, pp. 201; In English
Contract(s)/Grant(s): NNX08AJ59G; Copyright; Avail.: Other Sources
The canonical hard state is associated with emission from all three fundamental accretion components: the accretion disk,
the hot accretion disk corona and the jet. On top of these, the hard state also hosts very rich temporal variability properties
(low frequency QPOs in the PDS, time lags, long time scale evolution). Our group has been working on the major questions
of the hard state both observationally (with mult i-wavelength campaigns using RXTE, Swift, Suzaku, Spitzer, VLA, ATCA,
SMARTS) and theoretically (through jet models that can fit entire SEDs). Through spectral and temporal analysis we seek to
determine the geometry of accretion components, and relate the geometry to the formation and emission from a jet. In this
presentation I will review the recent contributions of our group to the field, including the Swift results on the disk geometry
at low accretion rates, the jet model fits to the hard state SEDs (including Spitzer data) of GRO J1655-40, and the final results
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