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Pulsar Blind search in the DC2 data

Gamma-ray Large Area Space Telescope. Pulsar Blind search in the DC2 data. Marcus Ziegler Bill Atwood Brian Baughman Robert Johnson. Data Selection. As input all sources listed in the LATSourceCatalog_v1 were used (=> 380 sources).

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Pulsar Blind search in the DC2 data

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  1. Gamma-ray Large Area Space Telescope Pulsar Blind search in the DC2 data Marcus Ziegler Bill Atwood Brian Baughman Robert Johnson

  2. Data Selection As input all sources listed in the LATSourceCatalog_v1 were used (=> 380 sources) • James Chiang and Johann Cohen helped to write a Python script to: • Pick a source from the catalog • Select all photons within a 2° radius around the source • (energy dependent cut based on GLAST PSF did not improve the signal) • Correct the photon arrival time • Output the data into a text file -> Calculate differences and Perform the FFT

  3. Finding a Pulsar Candidate Source MRF0035 Look for frequency with the highest power Found F0 = 19.371213 1/s DC2 Catalog = 19.371221 1/s

  4. Test statistic (signal/noise) -> Calculate the RMS of the power spectrum Test Statistik (signal to noise) = max_power_in_FFT / RMS Take a cloer look at sources with s/n > 45 Work with Joe Dolan in progress to get a measure of the significance of the found peaks. (See how likely it is that a random fluctuaton created a peak of the same height)

  5. Sources with large s/n Unknown large s/n source in the galactic plane. No natching pulsar in the database. Vela Geminga (2nd harmonic)

  6. Covered phase space Scan for pulsars (0.5 Hz to 64 Hz) Fdot/F up to 3x10-9 (300 steps @ 1x10-11) Scan for ms pulsars (0.5 Hz to 512 Hz) Fdot/F up to 3x10-11 (6 steps @ 0.5x10-11) All 100 pulsars from pulsar data base A maximum time difference of 65 000s was used -> Calculation took about 2 weeks on a PC Scan found 16 Radio Loud pulsars 3 Radio Quiet pulsars

  7. Blind Search Catalog with reprocessed DC2 Data

  8. Flux Sensitivity Pulsar with lowest flux: Off plane (b=11.9): PSR_J1852m2610 flux 3x10-7 Ph/cm2s In plane (b= -0.9) PSR_J1856p0113 flux 7x10-7 Ph/cm2s

  9. Barycenter time correction for MRF0168 position. Optimized pulsar spin parameter for MRF0168 pos. Radio :Ep= 220838550 F0= 11.19723954 F1=-1.5664e-011 F2= 6.26E-22 Optimized :Ep= 220838550 F0= 11.19723929 F1=-1.5578e-011 F2= -2.30E-20 Recover light curve for source MRF0168 (Vela) Vela Radio Position Ra = 128.83 Dec = -45.18MRF0168 Position Ra = 128.842 Dec = -45.168701 Light curve: Barycenter time correction for MRF0168 position. Pulsar spin parameter from radio position.

  10. Light curves of pulsars without radio data Epoch_MET = 220838550 F0 = 3.91691474178 F1 = -1.936137 e-013 F2 = 6.0 e-022 Epoch_MET = 220838550 F0 = 3.766282209980 F1 = -3.677283 e-013 F2 = -3.3 e-021 Epoch_MET = 220838550 F0= 5.885928323969 F1= -1.306230 e-012 F2= 1.0 e-021

  11. Summary + Future plans Thank you for this excellent data set to perform a realistic blind search! Bill’s differencing method is an easy and fast way of finding pulsations from pulsars 16 + 3 pulsars were found and the spin parameters/light curve an be derived • Things to improve • Add up harmonics to increase the sensitivity • Get PC with more memory to perform larger FFTs • (we are also looking into a hardware FFT implementation) • - Implement the alorythm into the the science tools

  12. Basic Idea Calculate the Fourier-Transform of the time differences of the photon arrival times Dtn. take only differences with Dt < max_diff max_diff used for DC2 data = 65 000s

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