Mathematics – Probability
Scientific paper
May 2010
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=2010aas...21642409h&link_type=abstract
American Astronomical Society, AAS Meeting #216, #424.09; Bulletin of the American Astronomical Society, Vol. 41, p.837
Mathematics
Probability
Scientific paper
The explanation of the anomalous Microwave Foreground Emission based on the model of electric dipole emission from spinning dust proposed in Draine & Lazarian (1998ab) has been confirmed by numerous observations. In this paper we present an important refinement of the original model by improving our treatment of a number of physical effects. First, we consider a disk-like grain rotating with angular velocity at an arbitrary angle with the grain symmetry axis (i.e., imperfect alignment) and derive the rotational damping and excitation coefficients arising from infrared emission, plasma-grain interactions and electric dipole emission. The probability density function of dipole emission frequency for disk-like grains is obtained by using the Langevin equation, and then the emission spectra arising from spinning dust are computed for both cases with fast internal relaxation and without internal relaxation. Our results show that for fast internal relaxation, the peak emissivity of spinning dust, compared to earlier studies, increases by a factor of 2 for the Warm Neutral Medium (WNM), the Warm Ionized Medium (WIM), the Cold Neutral Medium (CNM) and the photodissociation Region (PDR), and by a factor 4 for the Reflection Nebulae (RN). Without internal relaxation, the increase of emissivity is comparable, but the emission spectrum is more extended to higher frequency. The increased emission results from the non-sphericity of grain shape and from the anisotropy in damping and excitation along directions parallel and perpendicular to the grain symmetry axis. Second, we provide a detailed numerical study of effects of transient spin-up of grains induced by single-ion collisions. The ionic impulses broaden the emission spectrum and increase the peak emissivity for the CNM, WNM and WIM, although the increases are not as large as those due to the grain wobbling.
Draine Bruce T.
Hoang Thiem
Lazarian Alex
No associations
LandOfFree
Improving the Model of Microwave Emission from Spinning Dust: Effects of Grain Wobbling and Transient Spin-up does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with Improving the Model of Microwave Emission from Spinning Dust: Effects of Grain Wobbling and Transient Spin-up, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and Improving the Model of Microwave Emission from Spinning Dust: Effects of Grain Wobbling and Transient Spin-up will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1891563