1. Observations of anomalous dust emission (AME) with AMI
Clive Dickinson
Jodrell Bank Centre for Astrophysics, University of Manchester
AMI discussion meeting, U. Cambridge, 30 September 2011

2. Why is AME interesting? AME is interesting!
We think it is electric dipole radiation from small spinning dust grains
An important foreground for CMB in total-intensity (possibly strongest at ~ GHz)
If polarized at any level, will be important for CMB in polarization!
Interesting physical phenomenon
New diagnostic for studying dust grains
Complementary to IR
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Davies et al. (2006)

3. Planck confirms spinning dust grains do exist!
Planck early results paper
(Planck collaboration et al. 2011)
arXiv:
Spinning dust
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3-colour image of the Perseus molecular cloud region

4. Ali-Hamoud, Hirata, Dickinson
Why is AMI useful?
~15 GHz is close to the peak of AME emission
Molecular clouds peak ~30 GHz
Diffuse emission peak ~15 GHz
Need to understand this!
15 GHz probes different grain properties
Large grains, larger dipole moments...
Fantastic follow-up instrument e.g. of Planck sources
Additional angular resolution
Low frequency side of peak or at the peak
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SPDUST
Ali-Hamoud, Hirata, Dickinson
(2009)

5. What should be done with AMI?
Survey of Galactic clouds
Which objects show significant AME, which do not?
What causes the peak to vary? (grains themselves or the environment?)
Low frequency side of AME peak (measuring slightly larger grains)
Follow-up observations from Planck, CBI etc.
Identify UCHII regions
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Planck collaboration et al. (2011)

6. AMI observations of Perseus
Christopher Tibbs (ex-Manchester student) now at IPAC, Caltech
Clive Dickinson, Anna Scaife etc...
Multiple pointings observed with AMI (2010)
Perseus molecular cloud known to emit large amount of AME with minimal free-free emission
COSMOSMOAS (Watson et al. 2005)
VSA (Tibbs et al. 2010)
AMI (Tibbs et al., in preparation)
Aims:
Confirm AME
Investigate correlations with FIR/mid-IR templates including PAH indicators
Investigate environment in detail (c.f. Tibbs et al. 2011)
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7. AMI observations of Perseus
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MIPS 24um - VSA contours

8. AMI observations of Perseus
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MIPS 24um - AMI 16 GHz contours

9. Galactic science with the VSA at 33 GHz
VSA Galactic plane survey, l ~ 27o – 46o and |b| < 4o, 13 arcmin beam.
Paper I:
1. Searching for AME, 40% of total is AME
2. Map of the Galactic plane
Paper 2
1. The VSA source catalogue
2. Used 33 GHz to 100 micron and 33 GHz to 2.7 GHz ratios to characterize sources
3. Investigating the clumpiness of the ISM

10. Proposal – AME in nearby galaxies
A survey of nearby face-on and edge-on HI rich spiral galaxies:
- search for AME (e.g. NGC6946, Scaife et al. 2010)
- deriving statistics of spatial distribution of AME relative to SF regions and spiral arms.
- quantitative studies: percentage of free-free due to AMI.
- estimating diffuse emission
- follow-up studies of selected candidates with EVLA and e-MERLIN.