Recent pulsar observations with LOFAR

Jason Hessels
LOFAR TKP Meeting, Amsterdam, June 2011

Transcript

1. Recent Pulsar Observations with LOFAR Jason Hessels (ASTRON / UvA) with the LOFAR Pulsar Working Group (Stappers, Kondratiev, Alexov, Hassall, Kramer, Karastergiou, Noutsos, van Leeuwen et al.) LOFAR TKP Meeting - Amsterdam - June 27th, 2011
2. Recent Pulsar Observations with LOFAR Jason Hessels (ASTRON / UvA) with the LOFAR Pulsar Working Group (Stappers, Kondratiev, Alexov, Hassall, Kramer, Karastergiou, Noutsos, van Leeuwen et al.) LOFAR TKP Meeting - Amsterdam - June 27th, 2011
3. LOFAR TKP Meeting - Amsterdam - June 27th, 2011
4. LOFAR Pulsar Observations LOFAR TKP Meeting - Amsterdam - June 27th, 2011
5. LOFAR Pulsar Observations LOFAR TKP Meeting - Amsterdam - June 27th, 2011
6. Roughly speaking, beam-formed modes trade spatial resolution for time resolution. Station Beam Element Beam Tied-array Beams LOFAR TKP Meeting - Amsterdam - June 27th, 2011
7. Tile-out Primary Beam with Many “Tied-Array” Beams Important to regain FoV LOFAR TKP Meeting - Amsterdam - June 27th, 2011
8. Simultaneous Imaging + Pulsar Observations Obs. L2010_06928 PSR B0329+54 Thanks George Heald! LOFAR TKP Meeting - Amsterdam - June 27th, 2011
9. Beam-formed modes ...there are many possible. Mode Description Data Rate FoV (sq. deg.) Res. (deg.) Sens. (norm.) Incoherent (par. imaging) Stations added without proper phase correction. 2-250 GB/hr 12.5 2 6.0 Tied-array Stations added properly in phase. Up to 23TB/hr 0.2 0.03 36.0 Single Station For projects with high time, but lower sensitivity requirements. 2-250 GB/hr 12.5 2 1.0 Superstation Interesting balance of sensitivity and FoV. Up to 23TB/hr 9.0 0.2 12.0 Fly’s Eye Maximize total FoV for bright transient survey. Up to 8TB/hr 450 2 1.0 LOFAR TKP Meeting - Amsterdam - June 27th, 2011
10. Beam-formed modes ...there are many possible. Mode Description Data Rate FoV (sq. deg.) Res. (deg.) Sens. (norm.) Incoherent (par. imaging) Stations added without proper phase correction. 2-250 GB/hr 12.5 2 6.0 Tied-array Stations added properly in phase. Up to 23TB/hr 0.2 0.03 36.0 Single Station For projects with high time, but lower sensitivity requirements. 2-250 GB/hr 12.5 2 1.0 Superstation Interesting balance of sensitivity and FoV. Up to 23TB/hr 9.0 0.2 12.0 Fly’s Eye Maximize total FoV for bright transient survey. Up to 8TB/hr 450 2 1.0 Flexible to match different science goals! LOFAR TKP Meeting - Amsterdam - June 27th, 2011
11. 100+ Pulsars Detected with LOFAR LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels
12. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 • Tied-array beams • LBA observations (10-90MHz). • Polarimetry. • Surveys. • Other recent results.
13. Tied-array beams LOFAR TKP Meeting - Amsterdam - June 27th, 2011
14. Tied-array beams LOFAR TKP Meeting - Amsterdam - June 27th, 2011
15. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels & Greissmeier
16. Tied-array beam stability March 23rd, 2011 January 25th, 2011 January 25th, 2011 SNR CS/IS = 4.7 SNR CS/IS = 3.1 SNR CS/IS = 3.6 12 HBA sub-stations (sqrt(12) = 3.5) LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels
17. LBAs LOFAR TKP Meeting - Amsterdam - June 27th, 2011
18. LBAs LOFAR TKP Meeting - Amsterdam - June 27th, 2011
19. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels Station Calibration
20. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Previous delay correction Adjusted delay correction -ve Adjusted delay correction Coherent addition Incoherent addition Phasing the Superterp LBAs Credit: Kondratiev (data from just last week...)
21. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hassall
22. 0.5 degree Multiple Station Beams LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels
23. Recent LBA Pulsar Observations Large, intrinsic (and extrinsic) profile evolution across band 30-36 MHz 36-42 MHz 42-48 MHz 48-54 MHz 54-60 MHz 60-66 MHz 66-72 MHz 72-78 MHz (post station calibration) LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Stappers & Hassall
24. First LOFAR Pulsar Detection <30MHz!!! PSR B0809+74 detected all the way down to 16MHz! 16-22 MHz 10-16 MHz 22-28 MHz 28-34 MHz 30-36 MHz 36-42 MHz 42-48 MHz 48-54 MHz 54-60 MHz 60-66 MHz 66-72 MHz 72-78 MHz LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Stappers & Hassall
25. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hassall
26. Anomalously intensive pulses Single, narrow-band bright pulse • Investigate further with simultaneous LBA/HBA data. • Relation with classical “giant pulses”? LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Kondratiev
27. Anomalously intensive pulses LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Kondratiev
28. Polarimetry LOFAR TKP Meeting - Amsterdam - June 27th, 2011
29. Polarimetry LOFAR TKP Meeting - Amsterdam - June 27th, 2011
30. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Sobey & Noutsos
31. Polarimetry of PSR B0834+06 HA = -2 HA = -1 HA = 0 HA = +1 HA = +2 HA = +3 RM = 0 RM ~ 27 • Polarization profile is very stable as a function of hour angle • Calibration errors on the order of ~5-10%? LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Sobey
32. Polarimetry on Crab giant pulses giant pulse ! "!!! #!!! $!!! %&'( )!!! *!!!! 100 x P Crab LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Noutsos
33. Polarimetry on Crab giant pulses Somewhat polarized Somewhat polarized • Very little polarized flux seen in recent imaging observations • Crab giants normally highly polarized (diff Faraday rotation?) • > 10x more scattering than a few years ago • Crab has flared in gamma-rays twice recently P Crab 6 Superterp HBAs ; Δt = 15 min ; f = 122 MHz ; BW = 3 MHz Linear Circular P.A. > 3σ L giant pulse 100 x P Crab LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Noutsos
34. Time (20 x P_crab) Polarimetry on Crab giant pulses Credit: Aris Noutsos Credit: Ramesh Karuppusamy LOFAR TKP Meeting - Amsterdam - June 27th, 2011
35. Surveys LOFAR TKP Meeting - Amsterdam - June 27th, 2011
36. Surveys LOFAR TKP Meeting - Amsterdam - June 27th, 2011
37. LOFAR Pilot Pulsar Survey (LPPS) • Incoherent beams (all avail. stations) • 7 beams of 7 MHz each and 0.65ms samp. • 57 minutes per pointing (82GB) • ~167 sq. deg. FoV per pointing • ~200 pointings taken during Christmas 2010 • Data being processed on “Hydra” at the University of Manchester • Pipeline code written by Thijs Coenen (UvA) now ready for production. • Will (re)process all beams in the coming weeks. LOFAR TKP Meeting - Amsterdam - June 27th, 2011
38. ~400 7-beam pointings > -35 deg DEC LOFAR Pilot Pulsar Survey (LPPS) LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels
39. high resolution images; while in beam) formed mode the data is stored at high time resolution( but with limited spatial information' probes the interstellar material and magnetic fields( and can be used to map the Galactic free)electron distribution' Neutron stars provide constraints on stellar evolution models and supernovae' radio pulsar population( out to % kpc *#+' LOFAR will also elucidate the unknown low frequency end of the pulsar spectrum' For more information see *%+' This work: LPPS We are currently performing a first shallow survey of the northern sky: the LOFAR Pilot Pulsar Survey !LPPS"' All available LOFAR stations are used and Transients !RRAT"( and single dispersed bursts from general fast radio transients' The LPPS survey is currently underway interference can be identified by its absence of dispersion measure !i'e' no free electrons along the line of sight"( unnatural brightness( occurrence in RFI !DM " # cm$% pc& Re$detection J'())*')+) Re$detection J'(,%*#++# Re$detection J'()'*#-', Beam $ LPPS pointings contains . beams Beam # Beam % Beam / Beam & Beam . Beam - LOFAR Pilot Pulsar Survey (LPPS) LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Coenen
40. Redection of recent, faint GBT discovery LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Stappers
41. LOFAR Tied-Array Survey (LOTAS) • Tied-array (coherent) beams (Superterp) • 19 beams with full 48MHz and 1.3ms samp. • 17 minutes per pointing (246GB) • ~3.7 sq. deg. FoV per pointing • ~200 pointings taken from May 11-15th • Used CEP2 and the new Scheduler • Increase in sensitivity ~9xLPPS • Less affected by RFI? • Data being processed on CEP2 (takes ~5hrs per beam using 12 cores) LOFAR TKP Meeting - Amsterdam - June 27th, 2011
42. LOFAR Tied-Array Survey (LOTAS) Big thanks to Anna Scaife... Honorary Pulsar Person Dec = 0 Dec = 30 Dec = 50 For 12 Superterp HBA sub-stations Beam model LOFAR TKP Meeting - Amsterdam - June 27th, 2011
43. LOFAR Tied-Array Survey (LOTAS) -0.17 -0.058 0.06 0.18 0.29 0.41 0.53 0.65 0.77 0.88 1 LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Stappers
44. LOFAR Tied-Array Survey (LOTAS) -0.17 -0.058 0.06 0.18 0.29 0.41 0.53 0.65 0.77 0.88 1 0 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Stappers
45. LOFAR Tied-Array Survey (LOTAS) 6 0.18 0.29 0.41 0.53 0.65 0.77 0.88 1 1 3 4 8 10 12 13 16 18 LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Alexov & Hessels
46. Other recent results LOFAR TKP Meeting - Amsterdam - June 27th, 2011
47. Other recent results LOFAR TKP Meeting - Amsterdam - June 27th, 2011
48. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hassall Wide-band simultaneous obs.
49. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Greissmeier & Hessels First light for FR606 (Nançay)
50. LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Hessels, Romein & Mol Online coherent dedispersion
51. Fly’s Eye Observation with 47 HBA stations LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Alexov
52. Phase-coherent pulsar timing LOFAR TKP Meeting - Amsterdam - June 27th, 2011 Credit: Verbiest
53. Summary • Things are still advancing rapidly in terms of LOFAR pulsar observations. • Converging on the basic functionality we need for our science. • Several “first science” results are in the pipeline. LOFAR TKP Meeting - Amsterdam - June 27th, 2011