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DC2 pulsars analysis: a population point-of-view

Gamma-ray Large Area Space Telescope. DC2 pulsars analysis: a population point-of-view. Massimiliano Razzano (INFN - Pisa) LAT DC2 Closeout Meeting (GSFC, May 31-June 2 2006). Outline. Analysis overview; Scripting in Python: the pyPulsar tool; Cuts and thresholds; The EGRET pulsars;

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DC2 pulsars analysis: a population point-of-view

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  1. Gamma-ray Large Area Space Telescope DC2 pulsars analysis:a population point-of-view Massimiliano Razzano (INFN - Pisa) LAT DC2 Closeout Meeting (GSFC, May 31-June 2 2006) M.Razzano - DC II Closeout Meeting

  2. Outline • Analysis overview; • Scripting in Python: the pyPulsar tool; • Cuts and thresholds; • The EGRET pulsars; • Detecting pulsars in the LAT source catalog; • The flux distribution; • The brightest MSP; • Beyond the LAT source catalog; • Conclusions and DC2 follow-up

  3. Analysis overview • I will present an analysis to detect pulsars with radio counterparts in the D4; • An automatic procedure for testing the periodicity of pulsars has been conducted to find high-confidence identification; • More detailed analysis on some pulsars (e.g. EGRET pulsars or MSP pulsars); • The basic characteristics of the detected pulsars have been derived; • A preliminary note: • Yes, I was involved in the DC2 pulsars generation…but…. • We put a lot of pulsars in the DC2 sky… • DC2 pulsar truth is on my PC in some obscure directory with some obscure name… • It is almost impossible to me to remember names like PSR XYZM+IJKF12345… • Through hypnosis Julie and Seth forced me to forget everything… Believe me…by doing this analysis, I completely ignored the DC2 truth..

  4. Why scripting? Why Python? • Scripts are very useful to create some automatized analysis (see also D.Smith’s talk); • Scripts allow to perform the basic data reduction in automatic way (applying cuts, barycentering, etc…); • Scripts can be done using bash/tcsh shell or using scripting languages like Python For these analysis a set of Python scripts have been developed • With Python more complex operations can be done easily (e.g. parsing); • A lot of Python extension are availabe (e.g. pyROOT, pyFits, sihyppo); • See www.python.org for much informations about Python;

  5. pyAnScripts (scripts for various pulsar-related analysis) pyPulsar (class for managing data and analysis of a pulsar) Analysis results LAT Pulsar Tools Python scripting: pyPulsar pyPulsar is a set of Python classes and scripts for doing pulsar analysis • pyGtTools • (classes for interfacing with LAT Pulsar Science Tools) • pyGtBary • pyGtPsearch • pyGtEphcomp • pyGtPhase • pyGtSelect

  6. Python scripting: pyPulsar (II) • A list of pulsar is given in input (extracted from D4, from coincidences with LAT Source catalog, etc…); • For every pulsar the ROI is selected and FT1 barycentered; • Periodicity test is applied (here only Chi2) and phase assigned; • The output file contain chance probability of the periodicity test; • Plots of detected pulsars and determination of population parameters (e.g. using ROOT macro);

  7. About cuts and thresholds… • For each pulsar an specific selection in ROI, energy, etc. can be done; • For each pulsar list the analysis was performed for 2 energy ranges and with corresponding selection of the ROI according to the PSF; What is the threshold for pulsar detection? After some tests and some discussions I decided to use a more “conservative” detection limits, according to the EGRET pulsars papers

  8. Geminga The EGRET pulsars Vela The first exercise is the analysis of the EGRET pulsars, testing periodicity and recovering lightcurve Seeing that pulsars does pulse…. Crab

  9. E>100MeV ROI with R=3° Periodic at C.L. > 99.99% E>100MeV ROI with R=3° Periodic at C.L. > 99.99% E>100MeV ROI with R=3° Periodic at C.L. > 99.99% E>200MeV ROI with R=3° Periodic at C.L. > 99.99% E>300MeV ROI of R=1.5° Periodic at C.L. > 99.99% E>100 MeV ROI with R=1° Periodic at C.L. > 99.85% All-sky count map of the simulation of 55 days for DC2 M.Razzano - DC II Closeout Meeting

  10. Pulsars in the LAT source catalog? As first step a search for coincidence between LAT sources and pulsars in D4 Radius dependent on energy (LAT_Cat_v2) 49 pulsars found

  11. Low confidence High confidence Pulsars in the Lat catalog: summary The first step is the analysis for E>100MeV

  12. 1014G 103yr Low confidence High confidence 109G Pulsars in the Lat catalog: populations Youngest non-MSP have age≈103 y (Vela & Crab) and B≈5x1012 G Oldest non-MSP have age≈108 y (Vela & Crab) and B≈2x1011 G Low confidence High confidence 4 MSP detected at high confidence and 1 at low confidence (B<109gauss, age>109y)

  13. Phase curve after periodicity test Period=2,31 ms Fit with power-law + exponential cutoff a=1.01±0.01 Ecut=37,1±1,3 GeV PSR J0904-5008, the brightest MSP In the LAT Catalog its flux is 1.7 x 10-7 ph/cm2/s

  14. An interesting plot is the LogN-LogS (see D.J.Thompson ’03) Low confidence High confidence Slope=-1.04±0.19 The low coincidence show a change of slope. Various possible origins (background, geometry,luminosity distributions) Pulsars in the LAT catalog: DC fluxes The high confidence pulsars follow a similar distribution

  15. Low conf High conf E>100MeV Beyond the LAT catalog: Summary(I) • The next step is the scan on the entire D4 database. First for E>100MeV • We expect to find more pulsars since there is the help of the periodicity signature

  16. Low conf High conf E>1GeV Beyond the LAT catalog: Summary(I) • Then I repeat the scan for E>1GeV • The pulsar detected will be different because of many reasons (different ROI,different spectra of pulsars, etc…) The number of high+low is increased. In order to have a final sum we must make an OR of the results at 2 energies

  17. E>1GeV E>100MeV More MSP at E>1GeV (Spectral shape) Beyond the LAT catalog:population After merging E100MeV and E1GeV results Find the differences….

  18. Conclusions and DC2 follow-up • LAT pulsars will be a big amount, then an automatic system for pre-analysis should be very useful; • Python could be a good candidate, pyPulsar is under development: available in CVS (/users/razzano/pyPulsar); • The LAT sensitivity will permit study of different sub-population of pulsars: this was the case of DC2; • At least 4 MSP can be detected during DC2 in the LAT source catalog; • At E < 10-7 ph/cm2/s the logN-logS shows a change in slope: it will be the same with real data? • By scanning the D4 32 high-confidence pulsars have been found: why discrepancies with other analyses? Most probably differences in putting threshold and in cuts; • Detection is very sensitive to cuts and threshold: study of optimal cuts is strongly needed; • Explore other test statistics, in particular the H-test: try different strategies for detecting more pulsars; Special thanks to Dave, Patrizia, Alice, Isabelle, Gottfried and the other people of PSR group for the very interesting discussions and suggestions !

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