The Local Dust Foregrounds in the Microwave Sky. I. Thermal Emission Spectra

Analyses of the cosmic microwave background (CMB) radiation maps made by the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed anomalies not predicted by the standard inflationary cosmology. In particular, the power of the quadrupole moment of the CMB fluctuations is remarkably low, and the...

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Bibliographic Details
Published in:The Astrophysical journal 2009-11, Vol.705 (1), p.670-682
Main Authors: Dikarev, Valeri, Preuß, Oliver, Solanki, Sami, Krüger, Harald, Krivov, Alexander
Format: Article
Language:English
Subjects:
ABUNDANCE
ANISOTROPY
Astronomy
ASTROPHYSICS, COSMOLOGY AND ASTRONOMY
COSMOLOGY
DUSTS
Earth, ocean, space
ELECTROMAGNETIC RADIATION
EMISSION
EMISSION SPECTRA
EMISSIVITY
Exact sciences and technology
FREQUENCY DEPENDENCE
METEOROIDS
MICROWAVE RADIATION
OPTICAL PROPERTIES
OXYGEN COMPOUNDS
PARTICLES
PHYSICAL PROPERTIES
QUADRUPOLE MOMENTS
RADIATIONS
RELICT RADIATION
SILICATES
SILICON COMPOUNDS
SOLAR SYSTEM
SPECTRA
SURFACE PROPERTIES
VISIBLE RADIATION
WAVELENGTHS
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Summary:Analyses of the cosmic microwave background (CMB) radiation maps made by the Wilkinson Microwave Anisotropy Probe (WMAP) have revealed anomalies not predicted by the standard inflationary cosmology. In particular, the power of the quadrupole moment of the CMB fluctuations is remarkably low, and the quadrupole and octopole moments are aligned mutually and with the geometry of the solar system. It has been suggested in the literature that microwave sky pollution by an unidentified dust cloud in the vicinity of the solar system may be the cause for these anomalies. In this paper, we simulate the thermal emission by clouds of spherical homogeneous particles of several materials. Spectral constraints from the WMAP multi-wavelength data and earlier infrared observations on the hypothetical dust cloud are used to determine the dust cloud's physical characteristics. In order for its emissivity to demonstrate a flat, CMB-like wavelength dependence over the WMAP wavelengths (3 through 14 mm), and to be invisible in the infrared light, its particles must be macroscopic. Silicate spheres of several millimeters in size and carbonaceous particles an order of magnitude smaller will suffice. According to our estimates of the abundance of such particles in the zodiacal cloud and trans-Neptunian belt, yielding the optical depths of the order of 10-7 for each cloud, the solar system dust can well contribute 10 Delta *mK (within an order of magnitude) in the microwaves. This is not only intriguingly close to the magnitude of the anomalies (about 30 Delta *mK), but also alarmingly above the presently believed magnitude of systematic biases of the WMAP results (below 5 Delta *mK) and, to an even greater degree, of the future missions with higher sensitivities, e.g., Planck.
ISSN:0004-637X
1538-4357
DOI:10.1088/0004-637X/705/1/670