FAST Low Frequency Pulsar Survey

Youling Yue (岳友岭 )FAST Project, NAOC

PKU Astrophysics Colloquium 2012

outline

• Current FAST receivers• Receiver for early pulsar survey:

Low frequency (~400MHz) 7-beam receiver• Pulsar survey simulation using PSRPOP• Gravitational wave detection limits• RFI• Single beam wideband receiver

No Band (GHz) Beams Pol. CryoTsys(K)

Science

1 0.07 – 0.14 1 RCP LCP

no1000

High-z HI(EoR),PSR, VLBI, Lines

2 0.14 – 0.28 1 RCP LCP

no400

High-z HI(EoR),PSR, VLBI, Lines

3 0.28 – 0.56 1 or multi RCP LCP

no150

High-z HI(EoR),PSR, VLBI, LinesSpace weather, Low frequency DSN

4 0.56 – 1.02 1 RCP LCP

yes60

High-z HI(EoR),PSR, VLBI, LinesExo-planet science

5 0.320 – 0.334 1 RCP LCP

no200

HI,PSR,VLBIEarly sciences

6 0.55 – 0.64 1 RCP LCP

yes60

HI,PSR,VLBIEarly Sciences

7 1.15 – 1.72 1 L wide RCP LCP

yes25

HI,PSR,VLBI,SETI,Lines

8 1.05 – 1.45 19 Lnarrow multibeam

RCP LCP

yes25

HI and PSR survey, Transients

9 2.00 – 3.00 1 RCP/LCP

yes25

PTA, DSN, VLBI, SETI

FAST receivers

From C. J. Jin

Need a receiver

• To work at low frequency (<1GHz) to meet early stage pointing accuracy

• To do a whole FAST sky pulsar survey (L-band 19-beam is not the best one)

7-beam receiver

• Propose to build a 7-beam receiver for early drift-scan pulsar survey, freq ~400-560MHz

• Similar design like current multibeam receivers, easy to build, ready in early 2016

Parkes Effelsberg Arecibo FAST

Pulsar science for 7-beam receiver

• Low frequency drift-scan pulsar survey– Detect ~2300 normal pulsar (~1700 new)– Detect ~300 MSP (~200 new), good for GW

detection • M31/M33 pulsar survey (tracking)• Radio transient survey– Use same data set (piggyback)– good option for a whole FAST sky (2.3π) survey

before PAF receiver is available

7-beam receiver details

• Optimized for pulsar (transients) survey at early science stage (Sept 2016 or earlier)

• Freq ~400MHz, BW ~150MHz (1/3 freq)• Cooled, Tsys without sky ~30K or less• Light weight• Horn, dipole, etc, not PAF• Inexpensive (maybe <1 Million USD)• Use 19-beam backends• data ~2.4PB (one whole FAST sky scan)

Drift survey simulation with PSRPOP

• FAST sky drift-scan survey for pulsar• Integration time ~40s at 400MHz• Two working case– Spherical surface, illuminated aperture Dill decrease as

frequency increase, Dill ~ 200m*(f/400MHz)^1/4 (very early stage)

– 300m diameter parabola• Two population– Normal pulsar– Millisecond pulsar

Drift survey simulation PSRPOP

PSRPOP website: http://psrpop.sourceforge.net/

Blue: ~100k pulsar generated Red: ~2300 detected by FAST

spherical surface

BW = 1/3 freqIntegration time ~60s *(400MHz/freq)Dill ~ 200m at 400MHz

Number of Normal pulsar detected

300m parabola

BW = 1/3 freqIntegration time ~40s *(400MHz/freq)

400MHz side is favored because of faster survey speed

Number of Normal pulsar detected

For comparison, FAST L-band suvey will detect ~5000 pulsars (Smits et al. 2009)

MSP survey simulation

• Normal pulsar and MSP are of different population: different spectral index, spatial distribution, etc

• Change spectral index and spectral index deviation so that the simulation meets both Parkes multibeam survey and 70cm survey

• Search through the parameter space to find the best point

Sample (~100k pulsar) generated by matching PMB results (L-band)Constrain spectral index and its deviation by matching 70cm survey Green region meets the observed ~20 MSPs from 70cm survey

15

Mean –1.6, deviation 0.35 used by Smits et al. 2009

Possible region?

16

17

GW detection limits adding new MSP from FAST drift scan survey36 from IPTA + 40 from FASTplot from K. J. Lee

RFI 2004 final freq and BWdepend on RFI

RFI 2005

Single beam wideband receiver for early pulsar timing

• Effelsberg, GBT, Parkes, Arecibo are developing or discussing wide band pulsar timing receivers ~500MHz-3GHz~700MHz-4GHz

• For FAST pulsar timing– 500MHz-3GHz

• For FAST early science ~270MHz-1450MHz– Low end limited by RFI– High end covers HI

Akgiray & Weinreb 2011

Thank YouComments are welcome

Possible region?

Mean –1.6, deviation 0.35 used by Smits et al. 2009