AUSAC Meeting · March 9 & 10, 2009
Chris Salter (NAIC – Arecibo)
The GALFA Consortium
GALFA-HI and GALFACTS (Courtesy: Steven Gibson)
AUSAC Meeting · March 9 & 10, 2009
GALFA Sub-Consortia
• H I Line (GALFA-H I)
• Continuum (GALFA-CON = GALFACTS)
• Radio Recombination Lines (GALFA-RRL)
• Each GALFA sub-consortium has its own membership and internal organization.
• All GALFA data will be made public through the National Virtual Observatory.
AUSAC Meeting · March 9 & 10, 2009
RRL Galactic-Plane Survey
• Galactic Structure
• Chemical Abundances
• Warm Diffuse ISM
• HII Regions
• Survey for |b| < 5o
• Integration time of 300s
• Commensal with PALFA & ZoA projects
• Share a “Mock spectrometer” database with ZoA (Δv≈4 kms-1)
• Record H163α−H174α, plus He & C α-lines and H β-lines
• Co-add transitions to increase signal-to-noise
• “Leap-Frog” Pointing to provide ON/OFFs
(PI: Yervant Terzian)
(Terzian & Lewis)
AUSAC Meeting · March 9 & 10, 2009
GALFACTS (GALFA Continuum Transit Survey) • Full-Stokes, all-Arecibo-sky, continuum
survey.
• Employs meridian NODding scans with subsequent “multi-beam” basket-weaving to optimize zero-levels.
• Bandwidth = 300 MHz → Faraday tomography, Ip(x, y, RM).
• Use “winking cal” for best possible calibration.
• Use of an original multi-beam CLEAN.
• Calibration run in Oct 2008 was first scheduled observations with Mock spectrometers.
• First GALFACTS region (1h<RA<7h; 20°<δ<38°) observed Nov-Dec 2008.
(GALFACTS Pilot Survey)
Now also observed at 327 MHz (Raja et al.) to provide finer resolution in RM for Faraday Tomography)
AUSAC Meeting · March 9 & 10, 2009
Mapping Technique: ZA Nodding + AZ Wagging
ALFA beams
Tracks after several passes
These are “woven” together to optimize zerolevels.
• P.I.: Russ Taylor
• Web Page: www.ucalgary.ca/ras/GALFACTS
• 14400 channels over 300-MHz bandwidth with “Mock spectrometer”
• Brightness sensitivity: rms~100 μJy/bm
• Meridian scanning speed ~1.5° per sec
• CIMA “Smart Basket-weaving” used
AUSAC Meeting · March 9 & 10, 2009
GALFACTS (continued)• Catalog of Poln. Percentage, Position
Angle & RM for 50,000 sources → Galactic Magnetic Field Studies.
• Thermal-nonthermal separation of low-b Galactic continuum emission.
• Provide thermal brightnesses for use by GALFA-RRL.
• Studies of discrete Galactic radio sources (e.g. SNRs & HII regions).
• Studies of high-b Galactic Loops.
• Foreground removal for EoR and Planck full-Stokes CMB studies.
• GALFA-HI TOG2 commensal project.
• First GALFACTS look at the Galactic Center quadrant via commensal observations with I-GALFA. (GALFACTS precursor imaging of the
Perseus Molecular Cloud region)
AUSAC Meeting · March 9 & 10, 2009
GALFA-HI Pointing Record as of 2008 March 14
GALSPECT has 8192 channels over 7.14 MHz → 0.18 km/s/channel, and ± 750 km/s total coverage
GALFA-H I ObservationsGALFA-HI Pointing Record as of 2009 February 26
AUSAC Meeting · March 9 & 10, 2009
GALFA H I Projects
a2186/2144/2390
a2048/2059a2010/2059a2130/2124
a2056/2051a2060
a2055
a2034
a1943
a2004
a2174/2294
a2221
ALFALFA/TOGS1 AGES/TOGS1 GALFACTS/TOGS2
I-GALFA/ZOA/ GALFACTS2 DISK-
HALOMBW/ZOA
PERSEUS
TAURUS
HALOCLOUDS
WINGS
a2220
a2222a2187
a2050
a2011 a2011a2172
a2172
a2147a2032
TIP MAGSTREAM GEM
OB1
TRUE FIL
SHELL
HIGH-LAT CLOUDS
HIGH-LATTURBULENCE
WATER FALL
OUTER HALO
PRECURSOR
COLDCLOUD
(Trms ~ 0.25 K)
(Trms ~ 0.15 K) (Trms ~ 0.04 K) (Trms ~ 0.35 K)
AUSAC Meeting · March 9 & 10, 2009
CGPSVGPS
SGPS
I-GALFA Plane H I Survey
10 x IGPS sensitivity, 4 x velocity resolution
I-GALFA Survey: 2008-9
AUSAC Meeting · March 9 & 10, 2009
I-GALFA (low-b Galactic Center Quadrant)
(PI’s: Steven Gibson & Bon Chul Koo)
• Over 50% completed in 2008
• Full completion expected during 2009
• Commensal with GALFACTS2
Cold HI Absorption in Molecular Clouds
Cold HI Emission at Higher Latitudes
Disc-Halo Interface
AUSAC Meeting · March 9 & 10, 2009
HI near Globular Cluster, Pal 4(PI: Jacco van Loon)
•Earlier LBW study detected HI in metal-poor cluster, M15 (van Loon et al, 2006).
• New stringent HI upper limits placed on clusters M3, NGC 5466 & Pal 13.
• Pal 4 is the 2nd most distant known globular cluster (D = 109 kpc).
• Large HI HVC discovered near Pal 4. Is it coincidence, gas stripped from the cluster by interaction with halo gas, or could both be situated in a 108 Mo dark halo?
AUSAC Meeting · March 9 & 10, 2009
An IVC Towards Abell 1367(PI: Kevin Douglas)
• Commensal GALFA-HI observations with EALFA-AGES of 10 fields.
• The Abell 1367 field is at b ≈ 70°−75°, and reveals possibly cometary IVCs.
• Brightness temperatures of the features are only 1K or less!
AUSAC Meeting · March 9 & 10, 2009
The Three Little Pigs (and a Friend)(PI: Josh Goldston Peek)
• Tiny clouds found at b ≈ 85°; Δθ ≈ 1'.
• VLA follow-up shows condensed cores , optically-thick, with TB ≈ 10K.
• Upper limits on OH emission from Arecibo.
AUSAC Meeting · March 9 & 10, 2009
GALFA Summary• Small GALFA-H I projects completed
• 3 Sub-Consortia (GALFA-H I, -CON, -RRL)
• TOGS1&2 in progress; data analysis on-going
• I-GALFA and GALFACTS in progress
• GALFA-RRL/ZOA/PALFA starting soon
• All final GALFA datasets will be on NVO
• GALFA website: www.naic.edu/alfa/galfa
AUSAC Meeting · March 9 & 10, 2009
End
AUSAC Meeting · March 9 & 10, 2009
GALFA - H I Projects
56% Mar 1716% Mar 1778% Mar 17
start ASAP
start May 3
AUSAC Meeting · March 9 & 10, 2009
Full-Stokes Multibeam CLEAN
(S. Guram,MSc Thesis,U. Calgary)
Stokes IDirty Image
MultibeamClean Image(HPBW=3.5°)
NVSSComparison(HPBW=0.7°)