Pulsar surveys at Arecibo and Green Bank

David ChampionGravity Wave Meeting, Marsfield, Dec 2007

The PALFA survey

Arecibo Multibeam 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

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