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Latest results on Anomalous Galactic Microwave
Emission from the Cosmosomas Experiment
José Alberto Rubiño Martín (IAC-Tenerife)
Orsay, October 27th, 2006
BPOL Workshop
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Overview

• The COSMOSOMAS experiment
• Anomalous Microwave Emission in the Galaxy.
• Detection in Perseus molecular cloud.
• Diffuse emission at high galactic latitudes.
• Conclusions

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The Cosmosomas Experiment
(Aimed to measure COSMOlogical Structures On
Medium Angular Scales)
IAC team Carlos Gutiérrez Sergi
Hildebrandt Roger Hoyland Rafael Rebolo (P.I.)
J. Alberto Rubiño-Martín Bob Watson Former
collaborators Silvia Fernández Cerezo Juan
Macías Pérez Julio Gallegos
Consists of two circular scanning instruments
(COSMO11 and COSMO15) operating at four different
frequencies in the range 10-17 GHz.
(http//www.iac.es/project/cmb/cosmosomas/)
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COSMOSOMAS receivers layout
COSMO11 (one channel _at_ 10.8 GHz)
COSMO15 (3 channels _at_ 13, 15, 17 GHz)
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COSMO15 at Teide Observatory. Instrumental
setup, showing the 2.5 m flat primary mirror, the
2.4 m parabolic, and the HEMT-based receiver
cooled at 20 K.
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COSMOSOMAS window function
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COSMOSOMAS First 18 months of data
About 100 useful maps stacked at each
frequency. 25 of the whole sky observed 100,000
observed data points (0.3º x 0.3º
pixelization) Achieved sensitivity at high
Galactic latitude 40,50, 60, and 115
?K/beam at 11, 13, 15 and 17 GHz,
respectively.
Fernández-Cerezo et al. 2006, MNRAS.
(Hildebrandt et al. in prep. with COSMO11)
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COSMO15 13GHz band
Beam FWHM 54 x 66 Pixelization 20 x 20 25
of the whole sky
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COSMO15 15GHz band
Beam FWHM 49 x 60 Pixelization 20 x 20 25
of the whole sky
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COSMO15 17GHz band
Beam FWHM 46 x 51 Pixelization 20 x 20 25
of the whole sky
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COSMOSOMAS comparison with WMAP at the galactic
plane crossing
13 GHz 15 GHz 17 GHz
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Perseus Molecular Cloud
(Watson et al. 2005)
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G159.6-18.5 The Dust Ring

• G159.6-18.5 is an IRAS source in Perseus
  molecular cloud (d260 pc).
• HII region driven by O9.5-B0 V star, found to be
  in the center of the ring.

• Knots appearing around the ring in the IRAS 100
  µm map
• Knots are bright at 12 µm (suggest transiently
  heated small dust grains)
• Anderson et al. (2000) conclude that the ring is
  a ruptured blister HII region.

IRAS 100 µm
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G159.6-18.5
Watson, Rebolo, Rubiño-Martín et al. 2005, ApJ
624 L89
There is not enough information to make a
detailed model of emission, but the signal can be
fitted by a combination of two models of Drained
Lazarian (1998) 0.8WNM (to account for the
dense region facing the star) plus 0.3MC (to
account for dust warmer further in the cloud)
Cleanest detection of anomalous emission
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VSA-SE Observations in Perseus. Anomalous
Emission seen at 33GHz
Preliminary results of VSA-SE observations in the
Perseus region.
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Other regions with anomalous spectrum

• Recent tentative detections
• Finkbeiner et al. (2002) finds an excess signal
  from the diffuse HII region LHP201.6631.643.
• Cassanus et al (2004). Excess flux at 31GHz from
  the Helix planetary nebula.
• Finkbeiner, Langston Minter (2004) using Green
  Bank GPA (-4ogtbgt4o) found significant dust
  correlated emission.
• Cassanus et al (2005). Excess at 31GHz from the
  dark cloud LDN1622

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Polarization observations of anomalous
microwave emission at 11 GHz in the Perseus
molecular complex
Battistelli, Rebolo, Rubiño-Martín et al. 2006
ApJL.
Q difference between the radiation intensity
collected by COSMOSOMAS in the 0º plane
(North-South) and the 90º one. Q - 0.2 1.0
(95 c.l.) U difference between the
orientation 45º and 45º. U-3.42 (95 c.l.)
Overall polarization
parameter ?3.4 2. The maps are calibrated to
the nearby California Nebula (free-free
dominated) which is assumed unpolarized
(systematic error of less than 1).
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Polarization of rotational electric dipole
radiation Lazarian and Draine 2000 ApJ Are
the molecules aligned and their emission
polarized? The energy level splitting arising
from grain rotation ensures maximum efficiency of
paramagnetic dissipation time
dependent magnetization, energy dissipation and
torque causing the molecule to rotate with the
axis parallel to the magnetic field
COSMOSOMAS
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Emission at high galactic latitudes with
Cosmosomas.
Fernández-Cerezo, Gutiérrez, Rebolo,
Rubiño-Martín et al. 2006, MNRAS
(astro-ph/0601203)
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Cross correlation method

• xCMB contribution of the fluctuating component
  of the CMB
• xgal brightness fluctuations of the Galactic
  template map. a converts units of the Galactic
  template into antenna temperature
• ygal represents any residual Galactic
  contribution which is uncorrelated with xgal

Covariance matrix is sum of covariances of CMB
and noise
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Cross correlation method (II)
Minimizing
we obtain
The contribution of the galactic template map
(xgal) to the observed sky map is given by
(so this scaled quantity is in the units of
the observed sky map).
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Templates

• WMAP maps (23, 33, 41, 61 91 GHz)
• DIRBE 100 ?m, 140 ?m and 240 ?m.
• Haslam (408 MHz) and Reich Reich (1420MHz).
• Ha maps
• Radiosource catalogues (NVSS, GB6) are used to
  also correlated positions.

All maps are degraded to COSMOSOMAS resolution
and convolved with the scanning strategy of the
instrument
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Masks

• We adopt the Kp0 mask from WMAP team to account
  for galactic emission and point sources (0.6
  deg).
• We extend the mask to a radius of 0.9 deg around
  point sources to account for larger beam size.
  Mask extended around three most intense sources
  (3C345, 4C39.25, DA406)

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Cross-correlation of COSMOSOMAS and WMAP
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Implied CMB fluctuations in antenna temperature
in the combined COSMOSOMAS map
?TCMB 29.7 0.7 ?K (V band) ?TCMB 30.0
0.7 ?K (W band)
b gt 40
Consistent with the expected level of CMB
fluctuations using the best-fit power spectrum to
the WMAP data (30?K )
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Correlations with DIRBE 100 ?m

• Correlated signal can not be explained as
  synchrotron because of the spectral dependence
  and the amplitude (much larger than the diffuse
  correlated signal with the Haslam 408 MHz map).

• Correlated signal can not be explained as
  free-free in terms of the Ha correlations.

______COSMOSOMAS______
__________WMAP_________
13 GHz 15 GHz 17 GHz 23
GHz 33 GHz 41 GHz bgt30 deg 7.4
? 1.1 7.5 ? 1.1 6.5 ? 2.3 2.9 ?
0.2 0.5 ? 0.2 0.0 ? 0.1 bgt40 deg 3.7
? 1.4 5.3 ? 1.4 1.8 ? 2.8 3.7 ?
0.2 2.4 ? 0.2 1.4 ? 0.2
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Correlations with DIRBE 100 ?m (bgt20º)
(Banday et al. 2003)
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Correlations with DIRBE 100 ?m (bgt30o)
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CONCLUSIONS (I)

• The anomalous microwave emission is the dominant
  continuum emission process at 10-40 GHz in the
  Perseus molecular complex. Becomes comparable
  with thermal dust at 70-80GHz.
• The polarization level of this anomalous
  emission is less than 5 at 11 GHz. Our best
  estimate is 3.4?2 which would argue in favour
  of rotational electric dipole radiation of fast
  spinning small molecules.
• But this is the only existing measurement of the
  polarization of the anomalous emission!
  Measurements at higher frequencies are requiered.

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CONCLUSIONS (II)

• The DIRBE-correlated signal may turn out to be
  the dominant Galactic foreground seen by
  COSMOSOMAS at 1 degree scale and 15 GHz.
• It decreases significantly as we go to higher
  Galactic latitudes and higher frequencies. But
  there is signal detected up to b gt40.
• The largest correlations are found with the 100
  ?m map. There are significant detections (gt2 ?)
  at 140 and 240 ?m.
• The DIRBE-correlated signal is also detected in
  all the frequencies of WMAP is about 4 to the
  total temperature fluctuations in Q band, and
  progressively less as we increase the frequency.
• We find a remarkable agreement with predictions
  of intensity from spinning dust models.
• Measurements of polarized dust-correlated
  emission needed!

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Future work

• COSMO10 has obtained a map of similar sensitivity
  to those of COSMO15, and new results will be
  published soon (Hildebrandt et al. in prep.)
• COSMO15 is being re-adapted to be a
  polarization-sensitive experiment (using a
  rotating HWP to modulate polarization). First
  testing of the experiment expected in the next
  few months.