Pulsar surveys at arecibo and green bank
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Pulsar surveys at Arecibo and Green Bank. David Champion Gravity Wave Meeting, Marsfield, Dec 2007. The PALFA survey. 7 beam receiver (ALFA) Gain is 11 K/Jy L-band 100 MHz bw (300 very soon) 256 channels (768 very soon) 64 µ s time resolution 1 Petabyte of data Pointings are 4.5 mins

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Pulsar surveys at Arecibo and Green Bank

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Pulsar surveys at Arecibo and Green Bank

David Champion

Gravity Wave Meeting, Marsfield, Dec 2007


The PALFA survey


7 beam receiver (ALFA)

Gain is 11 K/Jy

L-band

100 MHz bw (300 very soon)

256 channels (768 very soon)

64 µs time resolution

1 Petabyte of data

Pointings are 4.5 mins

Anti-centre only sparsely surveyed

Arecibo Multibeam Survey


The Survey Begins!


Quick Processing


Quicklook Processing Results

  • Uses SIGPROC processing pipeline

  • No acceleration search

  • Little RFI excision

  • Reduced resolution by 8 and 16 in frequency and time respectively

  • Good enough to find ‘normal’ pulsars

  • Runs in nearly real-time

  • Has found nearly 40 pulsars inc. 1 relativistic binary (all expected redections accounted for)

  • Capable of finding ~80% of the pulsars expected (RFI not accounted for)


Full Processing Pipeline

  • Each 4hr observing session produces 0.25TB of data (0.75 soon)

  • Full acceleration search

  • Processing is shared over many institutions using different clusters

  • Pipeline developed by Scott Ransom, Patrick Lazarus and myself

  • Each beam takes 22hrs to process


PSR J1903+0327 Discovery

  • 2.15 ms

  • 5th fastest outside GCs

  • 11th including GCs

  • DM of 297 pc cm-3

  • Estimated distance of 6.4 kpc

  • Timing RMS of ~3 µs


High DM and Short Period

  • Of the 4 faster pulsars, B1938+27 has the highest DM of 71 pc cm-3

  • Its DM/P, an estimate of detectability, is ~3x higher of any pulsar found in a blind survey

  • PALFA clearly has the potential to discover many MSPs


PALFA Summary

  • Has been slow to get to full processing

  • All data will be processed twice using different pipelines

  • Has the potential to find a large number of MSPs deep in the plane

  • Numbers of slow pulsars seems low but is likely RFI affected

  • Numbers of MSPs – too early to tell

  • RFI excision will be the key


Other Arecibo Surveys

Paulo’s 327 MHz survey

  • 50 MHz Bandwidth

  • All sky

  • Found 2 pulsars (I think)

  • Most of the data has yet to be processed


The GBT 350 Survey


GBT 350

  • 350 MHz

  • Bandwidth of 50 MHz

  • Beam is 0.6°

  • Gain of 2 K/Jy

  • Uses Pulsar Spigot backend

  • 1024 lags

  • 81.92 µs sample time


The Survey

  • North Galactic plane

  • 75° < l < 165°

  • |b| < 5.5°

  • Requires ~4000 pointings

  • Data can detect fastest MSPs up to DM = 100 pc cm-3

  • 120 seconds per pointing

  • Smin = 2 mJy for slow pulsars

  • Compared to previous surveys in the same sky:

    • > 4 times more sensitive to slow pulsars

    • > 10 times more sensitive to fast pulsars

  • The RFI environment is remarkably good


Reduced Resolution Processing

  • Takes 10% of the full processing time

  • Sensitive to periods > 50 ms (the majority of pulsars expected)

  • Standard periodicity search

  • Single pulse search


Results Thus Far

  • 33 pulsars discovered (nearly doubling the population in the survey area)

  • 5 discovered in single pulse search

  • Pulsars are being timed at GBT and WSRT

  • Timing solutions for 12

  • One pulsar discovered with a DM of only 4 pc cm-3


Searching For MSPs

  • The data is being reprocessed to search for MSPs

  • Increasing the population of MSPs in the north is a science driver for this survey

  • This survey is a pathfinder for a full sky survey at 350 MHz


Other GBT Surveys

  • A drift-scan at 350 MHz during track repair in summer 2007

    • 2048 lags

    • Requires 9700 DM trials

    • ‘pointings’ are 140 seconds

    • Each beam takes ~15 hrs to process

  • Potentially a full sky 350 MHz survey depending on the results of the current surveys


Summary

  • Large scale surveys at both telescopes show potential to discover more northern MSPs

  • Processing for MSPs is computationally very expensive in these surveys

  • No survey has processed enough high resolution data to give an expected number of MSPs


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