PGMS and SPASS: the polarized sky at 2'3 GHz

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PGMS and S-PASS the polarized sky at 2.3 GHz
Ettore CarrettiINAF Istituto di
RadioastronomiaBologna - Italy
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Outline

• Contamination of CMBP by synchrotron
• Parkes Galactic Meridian Survey (PGMS)
• S-band Polarization All Sky Survey (S-PASS)

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Synchrotron emission contamination

• All high Galactic latitudes T/S ? 0.3 (DRAO-1.4
  and WMAP-23GHz)
• Lowest emission regions T/S 10-2 - 10-3 15
  sky fract.
• Low emission regions
• T/S ? 0.05-0.1
• Sky fract. D(T/S) 3-s
• ---------------------------------
• 15 1 x 10-3
• 70 3.2 x 10-5
• 100 1.5 x 10-5
• Amarie et al., 2005, PRD, 72, 123006

_at_70 GHz a -3.1
Carretti et al., 2006, MNRAS Lett., 373, L93
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• Polarization surveys 1.4 GHz

• Need for observations at all Gal. latitudes
• Polarization surveys at the beginning.
• ALL SKY maps at 1.4 GHz, FWHM ? 36 (Wolleben et
  al. 2006 AA, Testori et al. 2004). However
• FR modifications
• Galactic Disc strongly
• depolarized b lt 30
• FR modification
• at b lt 50

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WMAP results

• WMAP data All-Sky Survey at 23 GHz
• Low S/N
  S/Nlt3 in 55 of the sky on 2 scale
• high Galactic latitudes have not sufficient S/N
  for accurate studies (but large local structures).

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survey needs

• What is necessary?
• radio frequency ? synchrotron dominates
• gt1.4 GHz ? to avoid depolarization
• not too high ? ? to have good S/N ? 2.3 GHz
• b 0º ? 90º ? to explore all latitudes
• where? ? region free from large local structures
• ? ? to avoid contamination

? PGMS
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PGMS Parkes Galactic Meridian SurveyE.
Carretti (PI), M. Haverkorn, D. McConnell, G.
Bernardi, N. McClure-Griffiths, S. Cortiglioni,
S. Poppi

• Aim to explore the polarized synchrotron
  emission behaviour as a function of the Galactic
  latitude.
• CMBP foregrounds Galactic Magnetic field
• 5 x 90 Meridian survey l 254, b -90,
  0
• PARKES 2.3 GHz
• 224 MHz BW (100 ch)
• FWHM 9
• sbeam 0.3 mK

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PGMS goals
The PGMS goes through low emission regions No
contamination from large local structrures. It
will check the normal limits of CMBP B-mode
detection... and its capability to investigate
the INFLATION physics.
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• PGMS Galactic disc fields (blt30º)

Obs over Jan 06 ? Sep 07

• b 0º, -30º
• s 0.5 mK
• L(Q2U2)1/2

Carretti et al., 2008, in prep.
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• PGMS high lat. fields (-55º gt b gt -85º)

• b -55º, -85º
• s 0.3 mK

Carretti et al., 2008, in prep.
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PGMS Spectra
Carretti et al., 2008, in prep.
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PGMS Slope vs Lat

• Two regions
• AREA lat slope
• disc b 0º, -20º ? -1.8 small scales
• high-mid lats b -20º, -90º ? -2.5 large
  scales (smoother)

Carretti et al., 2008, in prep.
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PGMS amplitude ? 3 lat. sections

• disc b 0º, -20º
• high lats b -40º, -90º
• transition b -20º, -40º

Carretti et al., 2008, in prep.
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PGMS -55º, -85º

• 30ºx5º field covering most of the high latitudes
• Measure of the mean conditions of PGMS high
  lats.
• ? -2.62 /- 0.11
• (as WMAP _at_ 22.8 GHz)
• T/S 3.5 x 10-3
• better than suborbital experiment aims (T/S
  10-2)
• close to intrinsic limit of 15 sky fraction (T/S
  10-3)

Carretti et al., 2008, in prep.
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PGMS the Galactic Magnetic field

• Galactic Disc
• RMs measurable with internal data (100 channels)
  
• sRM10 rad/m2 (9)
• Values of 100s of rad/m2
• Galactic Halo
• RMs measurable in combination with 1.4 GHz data
  (e.g. Testori et al. 2008 survey)
• sRM2 rad/m2 (36)
• N-p ambiguity for RM gt 50 rad/m2
• Values of 10-20 rad/m2

• The PGMS Meridian is free from large local
  structures.
• Frequency n 2.3 GHz

Through higher resolution method
(diffuse emission vs. point sources)
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• S-PASS S-Band Polarization All Sky Survey
• E. Carretti (PI), M. Haverkorn, L.
  Staveley-Smith, S. Cortiglioni, B. Gaensler,
  M. Kesteven, G. Bernardi, S. Poppi

• NEXT STEP S-PASS
• Aim to survey the whole southern sky _at_ 2.3 GHz.
• DEC lt 0 (unshaded area)
• PARKES 2.3 GHz
• 224 MHz BW 100 channels.
• FWHM 9
• sbeam lt 1.0 mK
• Long AZ scans
• at constant EL
• Started Oct 2007 To be end by 2009

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S-PASS

• 40 completed 44 expected by 1st year

• preliminary map
• smooth signal down to b5º-10º in the inner
  Galaxy
• emission present down to the Galactic plane in
  the outer Galaxy
• high galactic latitude emission behaviour well
  match the WMAPs 23 GHz map

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S-PASS (very) preliminary spectrum

• high Galactic latitudes WMAP mask (1st run only
  10 data)
• angular slope ? -2.6 /- 0.1 (as WMAP _at_ 22.8
  GHz)
• frequency slope to match 22.8 GHz ? -3.1
• Total Intensity ?I -3.1
  2.3 - 22.8 GHz
• FR effects marginal

Bernardi et al., 2004, MNRAS, 351, 436
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• STAPS Southern Twenty-cm All-sky Polarization
  Survey
• M. Haverkorn (PI), E. Carretti, B. Gaensler, C.
  Heiles, M. Kesteven, D.
  McConnell, N. McClure-Griffiths

• PIGGYBACK ON S-PASS it comes (almost) for free
• Aim to survey the whole southern sky _at_ 1.4 GHz.
• Galactic magnetic field by RM and RM-synthesis
• PARKES 1.3--1.8 GHz
• 512 channels
• FWHM 14 (_at_1.4 GHz).
• 20 complete
• S-PASS - STAPS improved angular resolution of RM
  mapping (36 ? 14)
• RM-synthesis see Maiks talk

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Conclusions

• PGMS behaviour w.r.t. Galactic lat.
• slopes ? 2 regions disc (? -1.8), mid-high
  lats (?-2.5)
• amplitude ? 3 regions disc, high lats (bgt40º),
  transition (mid lats)
• CMBP contamination synch T/S3x10-3 (_at_ 70
  GHz)
• Close to the intrinsic limit for sub-orbital
  exps. (T/S 10-3)
• better than suborbital exp aims (T/S 10-2)
• PGMS meridian good place to point a CMB exp to
• S-PASS next step, i.e. all-southern-sky
• 40 complete
• smooth emission down to b 5º-10º
• more next (end 2009)