how much microwave emission can we see from interplanetary dust? valeri dikarev at the cosmic...
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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
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!
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?
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