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, τ IR =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 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