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
   

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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.
   

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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°
   

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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)
   

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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.
   

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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
   

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7. 7
   Rotational
   phase vs DM
   Rotational Phase
   

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8. 8
   Redetection of PSR B0031-07
   Green ~ ½ S/N
   Yellow ~ 1/10 S/N
   Red - DM in one of
   pulsar catalog
   

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9. 9
   Coordinates of 40 redetected (a) and 34
   non-redetected (b) pulsars
   

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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
    

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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
    

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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)
    

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13. 13
    Raw spectrum,
    cleaned
    spectrogram and
    processed data of
    PSR B0525+21
    

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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
    

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15. Pulses and
    1-dim
    ACF
    B0809+74
    

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16. SED spectrum, S/N vs
    time, compressed
    spectrogram and
    (apparent) dispersion
    delay with
    DM ≈ 2ž105 pc/cm3
    

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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
      ...
    

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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.
    

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19. 19
    The relative radio emission cone broadening
    between 25 and 100 MHz vs period
    

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20. 20
    Histogram: detected (solid line) and all (dash-
    dot line) pulsars depending on flux at 400 MHz.
    lin. log.
    

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21. 21
    Mean and std. dev. for DM errors
    without and with truncation of
    maximum deviation
    

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22. 22
    Error distribution of DM from ATNF
    compared to our observations. Allowable,
    significant and fatal errors for decameter
    wavelenght
    

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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.
    

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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
    

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25. 25
    First results: some answers #
    

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26. 26
    RF interference effect
    

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28. 28
    PSR B2110+27
    ?
    

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29. 29
    Redetection of PSR B1919+21
    DM, pc/cm3
    New = 12.455
    Old = 12.431
    Our = 12.435
    α sc
    < 3.90
    

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30. 30
    SN number and “products”
    Evan Keane.
    http://arxiv.org
    /abs/1008.3693v1
    N/100years for SNs
    &
    PSRs, RRATs, XDINSs,
    Magnetars, CCOs
    

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31. 31
    дщшщїщяїэѕѓцфђэщ PSR
    B1822-09
    ?
    

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