Galactic Plane observations with QUaD

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Galactic Plane observations with QUaD

• Tom Culverhouse
• University of Chicago
• tlc_at_uchicago.edu

July 18th 2008 Pasadena
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Outline

• Context
• QUaD Instrument/Observing Strategy
• Survey Maps
• Diffuse emission
• Point Sources
• Conclude

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Galactic Plane Observations

• Understand foregrounds, component separation? pol
  CMB spectra over large fractions of sky
• Diffuse emission contributions from e.g.
  synchrotron, dust, spinning dust, free-free
• Little known at QUaD resolution (5/3.5) and
  frequency (100/150GHz) - WMAP ? big grain
  thermal dust
• Aim measure diffuse dust pol frac ? constrain
  models for foreground emission
• Aim measure T/pol properties of point sources
  ?astrophysical interest (e.g. SED data, pol
  properties, extend existing catalogues e.g.
  Paladini) Planck T/pol calibrators, focal plane
  geometry

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Collaboration

• Stanford S Church, E Wu, M Bowden, K. Thompson
• Caltech/JPL A Lange, J Bock, J Kovac, E Leitch,
  M Zemcov, B Rusholme
• Paris K Ganga
• Chicago J Carlstrom, C Pryke, T Culverhouse,
  R Friedman, R Schwarz (South Pole)
• Cardiff W Gear, P Ade, A Orlando S Gupta, A
  Turner
• Edinburgh A Taylor, Y Memari
• Maynooth A Murphy, C OSullivan, G Cahill
• Cambridge M Brown
• IST Lisbon P Castro
• Manchester L Picirillo, S Melhuish
• Goddard J Hinderks

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Focal Plane

• 12 pixels _at_ 100GHz (5 beam)
• 19 pixels _at_ 150GHz (3.5 beam)
• Two orthogonal PSBs per pixel
• Two orientation groups
• deck rotation
• Focal plane width 1.5?1.5 on sky

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Sky Coverage

• Nine patches per day centred on b0, 0.7º in dec
• 15º fore/back az scan _at_ 0.4º/s tracking fixed RA,
  constant el
• Step up 0.02º in el, repeat cover 6.3º in dec
  /day
• No crosslinking
• -28.5º lt dec lt -60º limit
• 110ltRAlt190 faint arm 210ltRAlt290 bright arm
• 5 days to cover el range of each arm, four
  repeats (2 days _at_ 2 dk angles)
• But QUaD sees ground pickup

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Lead-Trail Mapping

• Two sub-fields 1hr separation in RA over same az
  range
• Sky signal different, ground signal the same
• Difference lead and trail fields in timestream

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Effect Of No Field Diff!
Bad lead/trail az alignment data flagged
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Bright Arm

• Total 20 days on bright arm
• 210ltRAlt290
• -50lt l lt0

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Faint Arm

• Total 20 days on faint arm
• 110ltRAlt190
• -115lt l lt -65

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Map-making

• Field difference timestream
• AB (T), A-B (pol) PSBs in each feed
• Mask 5º in RA from b0
• Filter with 0th order poly (DC level)
• Coadd onto flat-sky RA/dec map post-filter
  half-scan variances as weights
• Accumulate over fields/days/feeds
• Absolute map calibration from WMAP/QUaD CMB cal
  (Pryke et al 2008)

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150GHz T Pre/Post Destriping

• linear filter in Fourier space
• Reduced-amplitude 1/f in all maps esp 150GHz T
• Negligible loss of power on small angular scales

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Bright Arm T maps
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Bright Arm Q maps
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Bright Arm U maps
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Faint Arm T maps
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Faint Arm Q maps
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Faint Arm U maps
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Bright Arm P/T maps
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Faint Arm P/T maps
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Bright Arm P/T Cross-section
Stokes Q?10!!

• Average along pixels of const b
• Pol fraction consistent with WMAP Kogut 2007 dust
  region 2
• P/T2 at b0 rising to 6 _at_ blt2º before noise
  gt signal
• Similar results for 100 and 150GHz

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Galactic Point Sources

• Fit elliptical gauss ? fluxes, spectral indices,
  number counts

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Preliminary T Source Distributions

• 438 sources from 180deg2 bright arm data i.e. 2.4
  deg-2
• Concentrated within b?2º
• ?mean2.5, ?rms2.8
• ? dusty sources
• Flux number count slope -0.63?0.1 _at_
  100GHz -0.79?0.2 _at_ 150GHz
• shallower than Archeops -1.5?0.2 _at_ 353GHz
• Incompleteness 10Jy at both freq

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Selected Polarised Sources

• Complex region
• P consistent with noise _at_100GHz
• P/T3 at 150GHz T
• Rising spectrum in T and P

• Molecular Cloud G328.2-0.5, also associated with
  HII, OH maser
• P/T4 _at_ 100GHz
• P/T5 _at_ 150GHz

• Galactic Centre radio arc P/T15
• Falling spectrum

• BUT low P/T sources (lt2) suffer systematic
  effects of optics
• Possible fix with subtraction

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Conclusions

• QUaD has measured diffuse T and Pol emission from
  low latitude section of Galactic Plane at
  100/150GHz with 5/3.5 arcmin resolution
• P/T 2 at b0, rising to 6 by b2º
• Bright arm Pol mostly aligned perpendicular to
  galactic plane ? consistent with model of
  galactic magnetic field
• Many point sources detected with IRAS
  counterparts mostly low frac pol but a few freaks