Andrew Siemion SSL Colloquium April 10, 2009 Andrew Siemion SSL Colloquium April 10, 2009 Searching for Radio Ephemera: The Fly’s Eye AstroPulse Searching for Radio Ephemera: The Fly’s Eye AstroPulse and Beyond...

Orthogonal Searches - Fly's Eye - Allen Telescope Array Solid Angle: wide, 200 deg 2 Time Resolution: 0.6 ms (Incoherent Dedispersion) Dispersion Measures [0, 2000] Search Algorithms: Single pulses only - AstroPulse - Arecibo Multibeam Sky Survey Solid Angle: narrow, 0.04 deg 2 Time Resolution: 0.4 us (Coherent Dedispersion) Dispersion Measures [-830, 830] Search Algorithms: Single and Periodic Pulses uses Distributed Computing Both AstroPulse and Fly’s Eye are Ongoing

Fly’s Eye Acknowledgements Don Backer, Henry Chen, Matt Dexter, Terry Filiba, Rick Forester, Colby Kraybill, David MacMahon, Oren Milgrome, Mel Wright + ATA Staff, et al. AstroPulse Dave Anderson Bob Bankay Steve Boggs Jeff Cobb Eric Korpela Matt Lebofsky Josh Von Korff Dan Werthimer Geoff Bower Jim Cordes Griffin Foster Joeri van Leeuwen William Mallard Peter McMahon Mark Wagner Dan Werthimer And Copious Assistance From: Josh Von Korff Space Grant Summer Fellowship Program

Berkeley SETI

BOINC David Anderson, Rom Walton, Charlie Fenton et al.

Center for Astronomy Signal Processing and Electronics Research Henry Chen, Daniel Chapman, Terry Filiba, Griffin Foster, Suraj Gowda, William Mallard, Jason Manley, Peter McMahon, Vinayak Nagpal, Aaron Parsons, Andrew Siemion, Laura Spitler, Mark Wagner, Dan Werthimer UC Berkeley Radio Astronomy Laboratory Don Backer, Matt Dexter, Joeri van Leeuwen, David MacMahon, Oren Milgrome, Mel Wright, Lynn Urry Berkeley Wireless Research Center Bob Broderson, Chen Chang, Kevin Chao, Borivoje Nikolic, Brian Richards, John Wawrzynek Industrial and Academic Collaborators Xilinx, Fujitsu, HP, Sun Microsystems, NSF, NASA, NRAO, NAIC, Chris Dick, CfA, Haystack, Caltech, Stanford, Cornell, WVU, CSIRO/ATNF, UNCA/PARI, JPL/DSN, South Africa KAT, University of Oxford, Manchester/Jodrell Bank, GMRT, Bologna (SKA), Metsahovi Observatory/Helsinki University, Chalmers (Sweden), The National Astronomy Observatory Chinese Academy of Sciences, Nancay, NCRA/TIFR

CASPER The Friendly... Group Helping Open-source Signal-Processing Technology? (GHOST) ✴ Goal is to Develop High Performance Signal Processing Infrastructure for the Astronomy Community and Beyond. ✴ Open Source Everything. ✴ Use Commodity Off-the-shelf Hardware Where Possible. ✴ Provide Training and Tutorials (Wiki, Video Lectures, Workshops etc...) ✴ Promote Collaboration (30+ Universities and Observatories. ✴ Do Not Necessarily Concentrate or Specialize in Turn-Key Instruments.

Outline I. Pulse Search Background II. The Fly’s Eye Search III. AstroPulse IV. Future Directions

e p e e e e p p p p e e e e p p p p ISM Interstellar Dispersion

TIME (mS) FREQUENCY (MHz) Interstellar Dispersion Crab Pulsar Assuming a model of free electron density in the ISM, we can infer a distance of ~2000 pc.

Undoing Dispersion Coherent Dedispersion Incoherent Dedispersion ‣ Most common method. ‣ Performed post-detection. ‣ Relatively cheap computationally. ‣ Useful for millisecond pulses. ‣ Uncertainty limits sensitivity. ‣ Performed pre-detection. ‣ Very computationally intensive. ‣ Sensitive to pulses as short as bandwidth -1 In Both Cases: ★ Dedisperse at a number of trial dispersion measures. ★ Threshold resulting time series.

Known Sources ‣ Repeating Signals from Pulsars ‣ Giant Pulses from Pulsars ‣ RRATs or Nulling Pulsars Jocelyn Bell M. McLaughlin et al. 2005

Graphic Courtesy Sabine Hossenfelder Theoretical Sources Rees, 1977 According to Hawking (1974), black holes emit radiation at a rate inversely proportional to their mass, eventually leading to a very rapid release of energy as they finally wink out. As suggested by Rees (1977), this final explosion could include a large electromagnetic pulse (EMP).

Theoretical Sources

Other Possibilities... RFI, Radar ETI RFI ???

Observational Results Parkes Multibeam Pointing During Lorimer Detection (Lorimer 2007) Frequency vs. Time Waterfall (Lorimer 2007) ‣ Announced September 2007 ‣ Single pulse at L-band ‣ 30 Jy, saturated digitizer in one beam ‣ Located 3° from the SMC ‣ DM = 375 pc/cm 3 implies D ~ 1Gpc Exciting Results From Lorimer et al. Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, If this is a real event, pulses of this type could serve as an invaluable cosmological probe of the intergalactic medium.

The Fly’s Eye A Search for Highly Energetic Dispersed Radio Transients using the Allen Telescope Array

Fly’s Eye Timeline ‣ November 19, Dan Werthimer and Geoff Bower have lunch to discuss transient search projects using the ATA. ‣ November 20, Dan Werthimer tasks a group of mostly undergraduate students to begin building a transient instrument. ‣ December 22, Fly’s Eye Team installs Fly’s Eye at ATA. ‣ February, March Conducted 500 hours of weekend observations. ‣ April Present - Data analysis underway Lorimer, et. al., “A Bright Millisecond Radio Burst of Extragalactic Origin.” Science, 318, September 27, 2007 Fly’s Eye First Light December 22, 2007

Fly’s Eye Basics 44 independent spectrometers - constructed using a system of eleven iBOB/iADC quad spectrometers Built using open-source CASPER hardware and software libraries in about one month. Sky Coverage: beams square degrees Spectrometer Specifications (each): 208 MHz bandwidth, at 1430 MHz 128 spectral channels mS readout Distributions: Spatial, DM, Power, Pulse Width Sky Coverage: beams square degrees Spectrometer Specifications (each): 208 MHz bandwidth, at 1430 MHz 128 spectral channels mS readout Distributions: Spatial, DM, Power, Pulse Width Fly’s Eye Rack at ATA

IBOBs Clock source Ethernet Switch Control Computer Storage Server Fly’s Eye Rack at ATA High Level Fly’s Eye Diagram Fly’s Eye Instrument Rack

Fly’s Eye Control High Level Fly’s Eye Control Diagram

PSR B Detection FE Instrument Diagnostics I PSR B Detections in 41/44 Beams (15 minutes folded) PSR B (36 beams summed, 15 minutes folded) PSR B detected in 41/44 signal paths.

Giant Pulses From PSR B FE Instrument Diagnostics II Giant Pulses from PSR B (35 beams) Giant Pulse from PSR B (single beam) The Crab pulsar was observed for one hour, during which close to a dozen detectable pulses were detected (in summed data), the brightest of which was distinguishable in approximately half of single dish observations.

Observations Total observing time thus far is approximately 480 hours. Both North and South pointing observations were performed, primarily North due to kinder RFI environment. Total dataset is approximately 17 terabytes. Total observing time thus far is approximately 480 hours. Both North and South pointing observations were performed, primarily North due to kinder RFI environment. Total dataset is approximately 17 terabytes. Fly’s Eye Beam Pointing Diagram Drift scan Fly’s Eye observations were conducted in campaign mode on weekends between February and April Initial plan was for “fly’s eye” sky patch observing, eventually transformed to “horseshoe” constant declination strip. This pattern was chosen such that a known pulsar would traverse through all beams during an observation run, to be used for sanity checks and calibration during the analysis stage.

High Performance Storage System MySQL Database Data Storage Data is stored in 36 GB (58 minute).pcap ethernet capture files on a remote high performance storage system. Pointers to data files are stored in a local MySQL database

Data Analysis ‣ Data are broken up into ~10 minute single-spectrometer chunks ‣ DM search range: pc/cm 3 (with decimation, non- integer spacing) ‣ Computing grids used: 5 (Berkeley Wireless Research Center, UC Berkeley EECS, DOE NERSC) ‣ Total cores (peak): ~200 (Itanium64, Xeon, Sparc, Opteron) ‣ Total throughput (peak): ~200 Mbits/second Fly’s Eye Data Analysis Pipeline SigProc

RFI Rejection I Some narrow band intermittent RFI can be identified based on the variance of the powers of the frequency channel. These channels can then be ignored in dedispersion and pulse searching.

Post Processing RFI Removal Two basic criteria used for excision: An event is detected at the highest s/n at a low DM (< 50 pc/cm 3 ) -or- An event is detected at too broad a range of DMs

Pathological RFI Example A ‘Broken’ Satellite?

Example Preliminary Results Example Time vs. Sigma PlotExample Time vs. DM Plot Result Browser 480 hours of observations, 44 spectrometers, 10 minute sets, 9 plot types == over a million plots!

Automated First Pass A quick search through our data to find interesting high S/N events. Method: - Filter data to select sets with a low average detection S/N. - Tag events with a S/N greater than 8.5. Method: - Filter data to select sets with a low average detection S/N. - Tag events with a S/N greater than 8.5.

Fly’s Eye Status and Summary ‣ Current data will allow us to place significant constraints on the rate and distribution of bright short-duration transient events. ‣ Detection of Crab Giant Pulses has given us confidence that the Fly’s Eye instrument and processing pipeline are functional. ‣ A search through 480 hours of processed results found about 50% suitable for automated analysis (low rfi). Approximately 100 events with dispersion measure > 50 pc/cm 3 were found above 8.5 sigma. None appear to be of astrophysical origin. ‣ Plans for reprocessing of existing data, as well as instrument improvements to enable more precise localization.

AstroPulse A Multibeam Sky Survey for Microsecond Transient Radio Signals using Arecibo Observatory

Arecibo ALFA Receiver Arecibo L-band Feed Array (ALFA) Receiver System: ‣ 1.4 GHz ‣ 7 dual-polarization feeds ‣ 2.5 MHz Bandwidth ‣ Used for various surveys: PALFA, ALFALFA ‣ AstroPulse observes commensally ALFA Receiver (NAIC) ALFA Receiver and Gregorian Dome (NAIC)

Arecibo RF Downconverter Data Recorder PC Multibeam Datarecorder Installation Multibeam Datarecorder Instrument Rack AstroPulse records raw voltage data (just like not detected spectra. ‣ Bandwidth: 2.5 MHz ‣ Centered at: 1420 MHz ‣ Portion of the sky visible from Arecibo: 1/3 ‣ Beam width: 3.5' ‣ Beam transit time: 12 seconds ‣ Sky coverage rate: 1/3 of the sky in 8 months ‣ Sample rate: 2.5 MSamp/sec, 1 bit sampling ‣ Disk space required: 200 GB per day for 1 yr = 70 TB

Data Pipeline NERSC HPSS data storage silo (National Energy Research Scientific Computing Center) Arecibo Observatory SSL Computer Closet Participant PCs

TOGS Sky Coverage Turn-on GALFA Survey (TOGS) Sky Coverage Operating commensally, AstroPulse takes data nearly continuously.

Computing Power To process existing 70,000 hours of data in 6 months, AstroPulse requires 240 TFLOPS/s. BOINC’s 1,000,000 volunteers provide nearly 300 TFLOP/s, equivalent to some of the world’s most powerful supercomputers.

Client-based RFI Rejection Dispersion Measure Pulse Count Dispersion Measure Pulse Count Before and after RFI rejection TIME FREQUENCY RFI due to an air route radar system

Evaporating Black Holes Year log[detectable rate] (pc -3 yr -1 ) Phinney & Taylor, "A Sensitive Search for Radio Pulses from Primordial Black Holes and Distance Supernovae" Nature Vol. 277, 11 January 1979 O'Sullivan et, al. "Limits on Cosmic Radio Bursts With Microsecond Time Scales", Nature vol. 276, 7 December 1978 Katz & Hewitt 2003, “A Search for Transient Astronomical Radio Emission”, Pub. Astr. Soc. Pac., 115: , 2003 June Amy, Large & Vaughan “ A Search for Transient Events at 843 MHz”, Proc. ASA 8 (2) 1989 AstroPulse will either detect evaporating primordial black holes, or place the most stringent limits yet on EPBH event rates.

AstroPulse Status ‣ AstroPulse data is currently being distributed with ‣ Over 100,000 volunteers currently processing data. ‣ RFI, RFI, RFI

IV. Future Directions

Future Fly’s Eye Angular Localization of Transient Radio Bursts ‣ Reprocess! - Improve RFI rejection, implement new pulse search algorithms, search negative DMs - underway ‣ Improve ability to localize detections Fly’s Eye 44 input fast readout spectrometer becomes... Fly’s Eye 11 x 4 input fast readout correlator

PSR 700MHz Casey Law / ATA o Interferometric detection of PSR B based on a 5- minute ATA observation at 700MHz sampled at 0.1 sec.

Real Time Processing 4.5m Leuschner Observatory Radio Telescope Real time processing will enable the transmission of event notifications to observatories operating at other wavebands. Prototype system at Leuschner Observatory Eventually will operate commensally on incoherent sum at ATA (~3 deg FOV) ATA-42

Geoff Bower, et al. Wide-open Parameter Space

Geoff Bower, et al. Wide-open Parameter Space ?? ? ?