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) 06/02/2006 M.Razzano - DC II Closeout Meeting

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

Yes, I was involved in the DC2 pulsars generation…but…. 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..

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;

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

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);

About cuts and thresholds… What is the threshold for pulsar detection? 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; Energy Radius of ROI E>100MeV 3° E>1GeV 1° 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 Energy c2 chance probability Reference No detection P > 2 x10-3 The same as below Low-confidence detection 10-9 < P < 2 x10-3 Limit of B0656+14 (Ramanamurthy et al. 1996) High-confidence detection P < 10-9 Limit of B1951+32 (Ramanamurthy et al. 1995)

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

All-sky count map of the simulation of 55 days for DC2 E>200MeV ROI with R=3° Periodic at C.L. > 99.99% E>100 MeV ROI with R=1° Periodic at C.L. > 99.85% E>100MeV Periodic at C.L. > 99.99% E>300MeV ROI of R=1.5° All-sky count map of the simulation of 55 days for DC2 06/02/2006 M.Razzano - DC II Closeout Meeting

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

Pulsars in the Lat catalog: summary The first step is the analysis for E>100MeV Low confidence High confidence No detection 13 Low confid. 14 High confid. 22

Pulsars in the Lat catalog: populations Youngest non-MSP have age≈103 y (Vela & Crab) and B≈5x1012 G Low confidence High confidence 1014G 103yr 109G Oldest non-MSP have age≈108 y (Vela & Crab) and B≈2x1011 G Low confidence High confidence Name RA Dec period pdot PSR_J1955p2149 298,98 21,82 0,00169861 1,87E-20 PSR_J0904m5008 136,07 -50,14 0,00231079 3,94E-20 PSR_J1659m5022 254,98 -50,37 0,00262529 7,64E-21 PSR_J0717m1235 109,45 -12,59 0,00329634 7,23E-21 PSR_J1735m5757 263,96 -57,96 0,00689783 3,36E-20 PSR_J1745m0952 266,28 -9,876 0,0193763 9,50E-20 4 MSP detected at high confidence and 1 at low confidence (B<109gauss, age>109y)

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

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

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 E>100MeV Low conf High conf No detection 42 Low confid. 26 High confid. 29

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…) E>1GeV Low conf High conf No detection 38 Low confid. 34 High confid. 25 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

Beyond the LAT catalog:population E>100MeV After merging E100MeV and E1GeV results No detection 14 Low confid. 51 High confid. 32 E>1GeV More MSP at E>1GeV (Spectral shape) Find the differences….

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 !