Recent results of pulsars and planets at UTR-2

Vyacheslav Zakharenko
LOFAR Transients Key Project Meeting, Meudon, December 2011

Transcript

1. Recent Results of Pulsar and Transient Searching in Decameter Range. V. Zakharenko Institute of Radio Astronomy of NAS of Ukraine, Kharkiv
2. (Extremely) Low frequencies PRO CONTRA •  Radio emission cone broadening •  High DM, RM… resolution •  Possible “off-pulse” emission •  Increasing of flux density at low frequencies (for some pulsars) High Scattering in ISM. Big dispersion delay Bad Signal/Noise due to galactic background Interference ~ 70-80 dB more than background.
3. 3 Decametric North Sky Survey for Searching of Pulsars and Transients. Beam positions. Advantages: 5 beams, tracking ~1 hour. Nearest beam data combining possibility Ў = 0° Ў = 60°
4. 4 Parameters of survey (not far but…):   δ = -10…90° (“full sky” ~ 40 days)   DM = 0…30 pc/cm3 (or more…)   P > 0.1 s   UTR-2; Sum, Diff, Mul of «N-S» & «E-W»   Band 16.5...33.0 MHz   τacc agreed with τsc for nearest pulsars (8 ms)
5. 5 1st stage: redetecting   δ = -10…90° full list   DM = 0…30 pc/cm3 74 pulsars   P > 0.1 s [ATNF pulsar catalog]   UTR-2; Σ «N-S» & «E-W»   Band 16.5...33.0 MHz   τacc agreed with τ for nearest pulsars (8 ms)   11-18 Oct 2010, 17-24 Jan 2011, 21-28 Mar 2011   ~ 250 hours, 60% daytime observations.
6. 6 Main goals of 1st stage: only ~10 PSRs with given parameters were detected in the decameter range - identification of disturbing factors for detection - ways to eliminate their influence - Fraction (Fr) of KNOWN pulsar (detected in the decameter range) for estimation: Fr * (N of PSRs)*(cone broad.-1) ≅ NEW PSRs
7. 7 Rotational phase vs DM Rotational Phase
8. 8 Redetection of PSR B0031-07 Green ~ ½ S/N Yellow ~ 1/10 S/N Red - DM in one of pulsar catalog
9. 9 Coordinates of 40 redetected (a) and 34 non-redetected (b) pulsars
10. 10 40 from 74 detected pulsars For 15 pulsars in bands 25±2 & 20±2 МHz and for 25 – (20…32 МHz): flux density, 50 and 10% intensity level, scattering time constant, exponent α sc 25 – 1000 MHz
11. Emission cone broadening W 25 /W 100 θ = Aν -α+θ0 , [Thorsett, 1991ApJ, 377,263] Our results: 1.3 ... 2.6 times vs P
12. 12 Pulsar detection rate: flux at 400 MHz Comparison of upper detection limit of non detected pulsars (diamonds) and PSR B1133+16 (red line)
13. 13 Raw spectrum, cleaned spectrogram and processed data of PSR B0525+21
14. SED spectrum, S/N vs time, compressed spectrogram and (apparent) dispersion delay with DM ≈ 2ž105 pc/cm3 “Off-pulse” emission: directivity diagram(s). B0809+74
15. Pulses and 1-dim ACF B0809+74
16. SED spectrum, S/N vs time, compressed spectrogram and (apparent) dispersion delay with DM ≈ 2ž105 pc/cm3
17. 17 Conclusion:   The high efficiency of pulsar and transient detection has been shown at decameter range   Parameters of emission of more than 40 pulsars were refined or obtained for the first time   New emission characteristics   New sources   ...
18. 18 Why only ~ 10 known pulsars at lowest frequencies?   Big dispersion delay (?) (DM=10 pc/cm3 ~100 s in Δf=16…30MHz). But with optimum DM compensations it is NOT a problem   Scattering in ISM. But in [Popov M.V. et al. Astronomy Reports. – 2006. – Vol. 50, – P. 562–568. ] shown that for Crab pulsar ("plerion“, Galaxy plane, DM≈57 pc/cm3) at 24 MHz τsc ≈ 3 s.
19. 19 The relative radio emission cone broadening between 25 and 100 MHz vs period
20. 20 Histogram: detected (solid line) and all (dash- dot line) pulsars depending on flux at 400 MHz. lin. log.
21. 21 Mean and std. dev. for DM errors without and with truncation of maximum deviation
22. 22 Error distribution of DM from ATNF compared to our observations. Allowable, significant and fatal errors for decameter wavelenght
23. 23   Of course Signal/Noise! 25 vs 100 MHz (ratio = 4) 25000 vs 500 K (galactic background ratio ~ 4 2…3 times) 0.5 vs 2 Jy (ratio ~ 4 1…2) Resulted ratio ~ 100…200 times. But Aeff UTR-2 =150 000 sq m   Interference ~ 70-80 dB more than background. But high interference immunity and filtering let us to clean raw data.
24. 24 DM comparison: catalog vs our observations № Name DM Err DM n Err № Name DM Err DM n Err 1 B0031-07 11.38 8 10.896 10 21 B1508+55 19.613 20 19.622 10 2 J0051+0423 13.9 1 13.936 10 22 B1530+27 14.698 18 14.706 10 3 B0053+47 18.09 4 18.144 10 23 B1540-06 18.403 4 18.303 10 4 B0148-06 25.66 3 25.661 10 24 B1604-00 10.682 5 10.688 10 5 B0320+39 26.01 3 26.162 10 25 B1612+07 21.39 3 21.402 10 6 B0329+54 26.833 10 26.783 10 26 B1633+24 24.32 4 24.540 10 7 B0450+55 14.495 7 14.602 10 27 J1741+2758 29.3 6 29.146 10 8 B0809+74 6.116 18 5.755 10 28 B1822-09 19.38 4 19.408 10 9 B0823+26 19.454 4 19.474 10 29 B1839+56 26.698 11 26.804 10 10 B0834+06 12.889 6 12.872 10 30 J1851-0053 24 4 24.556 10 11 B0919+06 27.271 6 27.316 10 31 J1908+0734 11.104 11 11.234 10 12 J0927+23 23 2 24.032 10 32 B1919+21 12.455 6 12.435 10 13 B0940+16 20.32 5 20.354 10 33 B1929+10 3.180 4 3.180 10 14 B0943+10 15.4 5 15.339 10 34 B1944+17 16.220 16 15.720 10 15 B0950+08 2.958 3 2.972 10 35 B1952+29 7.932 7 7.870 10 16 B1112+50 9.195 8 9.185 10 36 B2016+28 14.172 4 14.200 10 17 B1133+16 4.864 5 4.846 10 37 B2110+27 25.113 4 25.114 10 18 J1238+21 17.5 12 17.968 10 38 J2307+2225 7.08 3 6.842 10 19 B1237+25 9.242 6 9.268 10 39 B2310+42 17.2758 13 17.256 50 20 B1322+83 13.312 18 13.312 10 40 B2315+21 20.906 7 20.904 20
25. 25 First results: some answers #
26. 26 RF interference effect
28. 28 PSR B2110+27 ?
29. 29 Redetection of PSR B1919+21 DM, pc/cm3 New = 12.455 Old = 12.431 Our = 12.435 α sc < 3.90
30. 30 SN number and “products” Evan Keane. http://arxiv.org /abs/1008.3693v1 N/100years for SNs & PSRs, RRATs, XDINSs, Magnetars, CCOs
31. 31 дщшщїщяїэѕѓцфђэщ PSR B1822-09 ?