geoffrey bower, uc berkeley
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Low Hanging Fruit inThe New Radio Sky
orRadio Surveys and Transients
with the Allen Telescope Arrayor
The Same Road Twice
Geoffrey Bower, UC Berkeley
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ATA-42 Operational SoonATA-42 Operational Soon
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peATA FiGSS ATA FiGSS
FFive ive GGHz Hz SSky ky SSurveyurvey• 5 GHz Counterpart to Sloan Digital Sky Survey
– Overlap with NVSS, FIRST & SDSS– 104 Square degrees– Arcminute resolution
• Highest Frequency Deep, Large Radio Survey– 0.6 mJy rms– Factor of ~10 more sensitive than GB6– 2 Smaller, deeper fields
• 6 calendar months to complete with ATA-42• Extendable in area and sensitivity
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FiGSS ScienceFiGSS Science• Detect 250,000 Sources• Cross with NVSS: 1.4-5 GHz Spectral Indices
– Separate star burst galaxies from AGN– Arp 220 detectable to z=0.16 (0.3, 0.5)
• Cross with SDSS, SWIRE, COSMOS– Galaxy evolution– Obscured star-formation and AGN science– AGN activity census– Radio continuum-star formation relations
• Polarization & Rotation Measure (103 --106 rad m-2) for all objects– Identify hidden or depolarized nonthermal sources: jets, SNe remnants – Dense probe of ISM B-field
• Galactic foregrounds for CMB and EOR• Community property
– Virtual Observatory catalog• Survey sample lists• NVSS+FIRST produced more than 1000 refereed citations
– Gravitational lens source list• Flat spectrum, compact objects Geometry of the Universe (ala CLASS project)
• Transient detection
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FiGSS Layer CakeFiGSS Layer Cake
10,000 Sq. Deg. 3 mJy
100 Sq. Deg. 1 mJy
10 Sq. Deg. 0.3 mJy
Daily
Every 10 Days
Every 100 Days
Overlap with SWIRE
Overlap with SDSS/FIRST/NVSS
Overlap COSMOS
Transients & Steady Sources
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Radio Transient Source CountsRadio Transient Source Counts
FiGGS
Orphan AfterglowsRSNeTidal FlaresIDV???
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Transients Discovered in the VLA ArchivesTransients Discovered in the VLA Archives• VLA
calibration check observations
• 1983-2003• ~1000 weekly
epochs • 1.4, 5, 8.4 GHz• 40 uJy
rms/epoch• Effective
surveyed area at 600 microJy ~10 sq degrees10 Transients Discovered (□◊Δ)
Very Deep, Multi-λ Images: 2.6 uJy rms
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The Same Road Twice:The Same Road Twice:Conclusions for Legacy ScienceConclusions for Legacy Science• The radio astronomy landscape is
changing– ATA is coming soon (also LOFAR, LWA, etc.)– Complementarity & synergy of efforts is critical
• ATA has powerful survey capability– Commensal RA & SETI
• FiGSS: simultaneous survey for transient and stationary sources
• Archival data are a powerful legacy product
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