Radio Transient Surveys with The Allen Telescope Array & the SKA. Geoffrey C Bower (UC Berkeley)

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1 Radio Transient Surveys with The Allen Telescope Array & the SKA Geoffrey C Bower (UC Berkeley)

2 Transient Science is Exploding New Phenomena

3 An Obscured Radio Supernova in M82 Discovered serendipitously Not detected at optical, uv, nir, x-ray Ongoing radio follow-up Brunthaler et al. 2009

4 Characterization of the Time Domain Transient Event Rates Wide Open Parameter Space ATA 24 Hours

5 Transient Parameter Space

6 The Allen Telescope Array 42 x 6.1m dishes Expansion goal of 350 Very wide FOV Continuous Frequency Coverage: GHz Flexible Signal Processing Project of UC Berkeley RAL & SETI Institute Funded through private/public partnership Key Science Surveys Transients Extragalactic Hydrogen Galactic Spectroscopy Pulsar Timing SETI

7 Imaging Transient Surveys ATATS PiGSS Galactic Center, Cygnus commensal surveys

8 ATATS: ATA 20 CM Survey Precursor to PiGSS 690 square degrees 280 pointings In 10 hours 12 epochs Croft & Bower et al

9 Flux Flux Comparison & Upper Limits on Transient Rate

10 PiGSS Results 10 square degrees, near confusion limit Daily Images Bower, Croft, Keating, Whysong, et al

11 3.1 GHz Counterpart to Sloan Digital Sky Survey Overlap with NVSS, FIRST & SDSS 10 4 Square degrees Arcminute resolution Highest Frequency Deep, Large Radio Survey ~1.5 mjy rms Factor of ~5-10 more sensitive than GB6 (5 GHz) Observed twice Smaller, deeper fields 10 sq deg repeated every day Bootes & Lockman fields 24 calendar months to complete with ATA-42 ATA PiGSS Pi GHz Sky Survey

12 Galactic Center Survey +1 Each 0.5 degree square has about 150 grid positions Synthesized Beams Latitude Longitude 1420 MHz Longitude 357 to 7 Latitude -1 to grid positions for a synthesized beam of 8 x 3 Frequency Band: MHz Water Hole marked by HI and OH 202 MHz available (not blocked by RFI)

13 Galactic Center & Cygnus Commensal with SETI survey 1.4 & 2.0 & 3.1 GHz Correlator Imaging 6 months, daily observing, 20 sq degrees 4 x area, 30 x time of VLA 330 MHz survey Transient Surveys Williams, Law et al

14 Non-Imaging Transient Searches Fly s Eye Mar s Lightning Kurtosis

15 ATA Fly s Eye Experiment Sensitive to rare, very bright (> 100 Jy) transients 200 sq deg FOV 600 hours of observing February, March and April TB of data 50,000 CPU-hour to process Analysis ongoing Fly s Eye Team: Bower, Werthimer, van Leeuwen, Cordes (Cornell) + ATA Team; Andrew Siemion, Peter McMahon, Jason Manley, Griffin Foster, Mark Wagner

16 Mar s Lightning Kurtosis Spectrometer Detect dust-storm induced lightning in Martian atmosphere Simultaneous observations with DSN monitoring antenna Beam-former feeds kurtosis spectrometer Ruf et al 2009 GRL

17 Individual Pulse Imaging Pulsar B msec dump time Each frame is during on pulse 6 antennas, 6 MHz BW Images by Casey Law & Dave McMahon Bridge between fast single dish pulse search & slow imaging transient search Next generation ATA/CASPER correlator will offer 500 MHz, 10 msec dump time Next generation experiments underway 8 antennas 100 MHz bandwidth 128 microsec rms

18 Radio Sky Surveys Project Array expansion 256 Term-limited, community-driven surveys Public/Private Partnership in funding $26M ops + $12M science / 8 years $40M construction Pitched to Astro 2010 Decadal Panel Build survey science community Develop large-n capability SKA Development in Data management Real time calibration, imaging Large-N correlators & BF Feeds & receivers

19 Transient Requirements for SKA Slow Transients Wide FoV High frequenies (> 3 GHz) arcsec angular resolution Real time flagging, calibration, imaging, followup System Hybrid Imaging Correlated sub-arrays for surveys and localization 1 millisecond timescale imaging Real time source identification Data buffering? Fast Transients Wide FoV Low frequencies (< 3 GHz) Low angular resolution required for discovery Real time processing + postprocessing, follow-up

20 Summary Transient parameter space is wide open New discoveries indicate rich phenomena ATA surveys are multi-pronged probe of parameter space What are there key questions & targets? Transient science case is very broad Planets, stars, compact objects, AGN, propagation effects, Radio analog to Type Ia SNe? Transient science case for SKA needs greater specificity How does that influence instrument and survey design?

21 ATA Job Opportunities Assistant Researcher --Friend of the telescope AAS #26370 ATA Deputy Director AAS #26371 Contact Geoff Bower or Don Backer for further information