How much Microwave Emission can we See from Interplanetary Dust?
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How much Microwave Emission can we See from Interplanetary Dust? Valeri Dikarev at the Cosmic Structure and Evolution Workshop on September, 24, 2009 in Bielefeld
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How much Microwave Emission can we See from Interplanetary Dust?. Valeri Dikarev a t the Cosmic Structure and Evolution Workshop on September, 24, 2009 in Bielefeld. Why was interplanetary dust ignored?. IPD is not on the list of biases for WMAP. Why does IPD’s emissivity drops?. - PowerPoint PPT Presentation
Transcript of How much Microwave Emission can we See from Interplanetary Dust?
How much Microwave Emission can we See from Interplanetary Dust?
Valeri Dikarev
at the Cosmic Structure and Evolution Workshop
on September, 24, 2009 in Bielefeld
Why was interplanetary dust ignored?
• IPD is not on the list of biases for WMAP
Why does IPD’s emissivity drops?• Standard
emissivity law λ-2 for λ >> size
• IPD sizes from 10 to 100 μm
• Grün et al. (1985): the interplanetary meteoroid flux model
How do we know dust size distribution?
• In the size range above 100 μm: from Earth-bound measurements only!
Is interplanetary dust really ignorable?
• ‘Clouds’ are composed of macroscopic particles
A proper estimate of microwave emission should answer two questions
• How big should meteoroids be in order to stay hidden in the infrared light and mimic the CMB spectrum in the microwaves?
• How many such meteoroids are in the Solar system?
The optical constants
• Homogeneous silicate spheres
The optical constants
• Homogeneous carbonaceous spheres
The optical constants
• Homogeneous iron spheres
The absorption efficiencies
• Homogeneous silicate spheres
The absorption efficiencies
• Homogeneous carbonaceous spheres
The absorption efficiencies
• Homogeneous iron spheres
The excess temperature spectra
• Homogeneous silicate spheres, τIR=10-7
The excess temperature spectra
• Homogeneous carbonaceous spheres
How many big meteoroids are there?• The radial number density
distribution of 135 short-period comets, time-averaged
• The cumulative number of meteoroids from SP comets on the line of sight from the Earth in the anti-solar direction
• The optical depth of big (>100μm) meteoroids can reach 10-7 and match that of the ‘visible’ dust (from 10 to 100μm in size)
Summary
• Thermal emission from dust in the microwaves estimated as ~10 μK– Intriguingly close to anomaly magnitude (~30 μK)– Alarmingly higher than the currently presumed
systematic biases of WMAP data (5 μK)• Dust can be a low noise for the CMB studies• CMB (~100 μK) is a huge noise for the dust
studies
Results to appear in November’s ApJ
