Pulsar Timing Arrays Current and Future Instrumentation - DCC

Pulsar Timing ArraysCurrent and Future InstrumentationJoseph LazioJet Propulsion Laboratory,California Institute of Technology© 2012 California Institute of Technology.Government sponsorship acknowledged.

• What are therequirements?Pulsar Timing ArraysCurrent and Future InstrumentationTiming precision andinstrumental performance• What exists?TelescopesFeeds, receivers, andbackendsIT infrastructure• What is on the horizon?

Pulsar Timing ArraysCurrent ResultsJ1713+074730 ns RMSJ1012+5307280 ns RMSJ1643-12241500 ns RMSDemorest et al. 2012, submitted

Timing Precision• Assume σ TOA ≤ 100 nsMay be necessary, but not sufficientconditionWSNRPσ TOA, n=WSNR• W pulse width• SNR signal-to-noise ratio• Assumes sufficient calibration oftelescope systemOther contributions can include pulse-phasejitter, uncorrected propagation effects

Radio Telescope

Radio TelescopeRadioFrequencyDataAcquisitionSystemDataStorageIntermediate FrequencyBasebandLocalOscillatorLocalOscillator

Radio TelescopeTNoise Temperature• Replace entire telescopesystem by resistor in a heatbath• Output voltage equivalent• Not necessarily physicaltemperature• T sys = T sky + T spill + T Rx + …• P = k B T∆ν

Radiometer EquationFor T PSR

Pulsar ObservationsObservational frequencydetermined by balancing• pulsar spectrum vs.•sky spectrum vs.•scatteringPulsarspectrumscatteringTypically about 1 GHzsky spectrum

Pulsar Timing ArraysCurrent Instrumentation

Pulsar Timing ArraysCurrent InstrumentationDiscovery of millisecondpulsars (MSPs)Robert C. Byrd Green BankTelescope (GBT) dedicated

Pulsar TimingHistorical Context• 1974: Hulse-Taylor binary pulsar– Arecibo telescope @ 430 MHz– ≤ 8 MHz bandwidth– 175 K system temperatureT sky = 25 K @ 430 MHz• 1982: first millisecond pulsar (B1937+21)– Arecibo telescope @ 1400 MHz– 16 MHz bandwidth– 40 K system temperatureT sky ~ 7 K @ 1400 MHz

Pulsar Timing ArraysCurrent InstrumentationTypical Parameters• A eff ~ 100 m• ∆ν ~ 100 MHz• T sys ~ 30 K• ∆t ~ 15 min.Current Publications• Yardley et al. 2011, “On detection of thestochastic gravitational-wave background usingthe Parkes pulsar timing array,” Mon. Not. R.Astron. Soc., 414, 1777• van Haasteren et al. 2011, “Placing limits on thestochastic gravitational-wave background usingEuropean Pulsar Timing Array data,” Mon. Not.R. Astron. Soc., 414, 3117• Demorest et al. 2012, “Limits on the StochasticGravitational Wave Background from the NorthAmerican Nanohertz Observatory forGravitational Waves,” ApJ, in press• Hobbs et al. 2010, “The International PulsarTiming Array project: using pulsars as agravitational wave detector,” Class. Quant.Grav., 27, 084013

Pulsar Timing ArraysNear FutureInstrumentationReceiver performancereaching fundamentallimits, e.g.,• T sys ≈ 20 K• ∆ν ~ 1 GHz forobservations near 1 GHzNew Pulsars• Major radio pulsarsurveys worldwide– HTRU (Parkes)– GBNCC (GBT)– GBT drift scan (GBT)– P-ALFA (Arecibo)• Multi-wavelength MSPsa.k.a. Fermi

Pulsar Surveysa “position” on the sky• New pulsars– Add more arms to PTA,increase sensitivity; or– For fixed amount ofobserving time, improvequality of PTA• Survey algorithm1. Observe position on sky2. Search resulting timeseries for periodic signal atperiod P with dispersionDM, with orbitalparameters– Loop

Pulsar Timing ArraysNear Future

Green Bank Ultimate PulsarProcessing Instrument(GUPPI)• BEE2 feeds 8 gamingsystems w/NVIDIA GPUs• 100, 200, or 800 MHzbandwidth• Large improvement intiming precision• ~1 TFLOP in real time• operationalPulsar Timing ArraysDigital Backends

Pulsar Timing ArraysDigital BackendsWide-bandwidth (1+ GHz),real-time systemsimplementing RFImitigation and folding(in construction)• Parkes HIPSR• Effelsberg ASTERIX andfollow-on• Arecibo PUPPIClone of GBT GUPPIFPGA-based Reconfigurable Open Architecture ComputingHardware (ROACH), developed by Center for AstronomicalSignal Processing and Electronics Research (CASPER, at UCBerkeley)

Pulsar Timing ArraysNew Feed & Rx Systems• GBT Wide-Band PulsarSystem• Arecibo Wide-Band System• Effelsberg Ultra-broad Band• Arecibo AO40• Five-hundred metreAperture SphericalTelescope (FAST) multi-feedsystem19 or 100 feed hornsT sys ~ 29K (5K sky + 9K spill + 4K coax jct + 7K dewar jct + 3K LNA)

Pulsar Timing ArraysNew Feed & Rx Systems• GBT Wide-Band PulsarSystem• Arecibo Wide-BandSystem• Effelsberg Ultra-broad Band• Arecibo AO40• Five-hundred metreAperture SphericalTelescope (FAST) multi-feedsystem19 or 100 feed hornsQuasi Self-Complementary Feed(developed under U.S. SKA auspices)

Pulsar Timing ArraysNew ApproachesSRT, Sardinia, ItalyEffelsberg 100-m, GermanyThe EuropeanPulsar TimingArray (EPTA):100-m classtelescopesNRT, Nancay, FranceWSRT, Westerbork, NLLovell, Jodrell Bank,UKUltimately forming the Large European Array for Pulsars (LEAP)

Large European Array for Pulsars = LEAP!Current status:Pulsar Timing ArraysNew Approaches- Hardware to record >128 MHz BW, 8 bits, baseband data inplace at all telescopes:ASTERIX-like systems at Effelsberg and Jodrell BankPUMA-II at WesterborkBON at NançayDFB (in APSR-mode, to be tested) at Sardinia- 24 hr observations at L-band, once per month (in additionto regular EPTA observations – 30 TB/site/session)- Data currently shipped by disk, internet tested- Successful addition of EFF-JB-WSRT,Nançay added within days/week, SRT in Q4/2012Almost there: 160-m dish!Only 10-sec of data:

Pulsar Timing ArraysNew ApproachesFor a set of N telescopes and M pulsars, what is the optimal schedulingthat maximizes the probability of detecting gravitational waves?Telescope InfrastructurePulsar Sample

Pulsar Timing ArraysFuture TelescopesKarl G. Jansky Very Large ArrayFive-hundred metre ApertureSpherical Telescope (FAST)• A eff ~ 130 m• YUPPI backendClone of GUPPI, implemented in existingcorrelator• Primarily a timing instrument• D eff ~ 300 m• 19 or 100-beam system• ~ 500 new MSPs discovered (projected)

Pulsar Timing ArraysFuture TelescopesAustralian Square KilometreArray Pathfinder (ASKAP)Karoo Array Telescope(MeerKAT)• A eff ~ 60 m• Phased array feed ~ 30 deg 2 field ofview• Primarily a search instrument• A eff ~ 100 m• Primarily a timing instrument

Square Kilometre ArrayThe Global Radio Wavelength Observatory• Originally: “Hydrogen telescope”Detect H I 21-cm emission from MilkyWay-like galaxy at z ~ 1• SKA science much broader⇒ Multi-wavelength, multimessenger• On-going technical development• International involvement

Radio Telescopes andAstrophysical SourcesSearch for additional dual SMBHs,progenitors of GW-emitting binary SMBHs• With VLBA now, SKA in the future• Relevant for future space-based GWmission7 pcB0402+679Very Long Baseline Array (VLBA)

• What are therequirements?Pulsar Timing ArraysCurrent and Future Instrumentation‣ Instrumental performanceimproving steadily• What exists?‣ Powerful set of telescopes• What is on the horizon?‣ Increasing capabilitywith new telescopes