diffuse galactic components in the gould belt system richard davis 8/7/20131ewass torku finland
TRANSCRIPT
EWASS Torku Finland 1
Diffuse Galactic components in the Gould Belt System
Richard Davis
8/7/2013
EWASS Torku Finland 3
Diffuse Galactic components in the Gould Belt System
• We perform an analysis of the diffuse low-frequency Galactic components in the Southern part of the Gould Belt system (130◦ ≤ l ≤ 230◦ and −50◦ ≤ b ≤ −10◦). Strong UV flux coming from the Gould Belt super-association is responsible for bright diffuse foregrounds that we observe from our position inside the system and that can help us improve our knowledge of the Galactic emission.
8/7/2013
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Diffuse Galactic components in the Gould Belt System
• Free-free emission and anomalous microwave emission (AME) are the dominant components at low frequencies (ν < 40 GHz), while synchrotron emission is very smooth and faint. We separate diffuse free-free emission and AME from synchrotron emission and thermal dust emission by using Planck data, complemented by ancillary data, using the “Correlated Component Analysis” (CCA) component separation method and we compare with the results of cross- correlation of foreground templates with the frequency maps.
8/7/2013
EWASS Torku Finland 5
Diffuse Galactic components in the Gould Belt System
• We estimate the electron temperature Te from Hα and free-free emission using two methods (temperature-temperature plot and cross-correlation) and we consistently obtain Te ranging from 7000 to 2000 K for a dust absorption fraction of fd = 0–0.5. We estimate the frequency spectrum of the diffuse AME and we recover a peak frequency (in flux density units) of 25.5 ± 1.5 GHz.
8/7/2013
EWASS Torku Finland 6
Diffuse Galactic components in the Gould Belt System
• By combining physical models for vibrational and rotational dust emission and adding the constraints from the thermal dust spectrum from Planck and IRAS we are able to get a good description of the frequency spectrum of the AME for plausible values of the local density and radiation field.
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