DC2 pulsars analysis: a population point-of-view

1
DC2 pulsars analysisa population point-of-view
Massimiliano Razzano (INFN - Pisa) LAT DC2
Closeout Meeting (GSFC, May 31-June 2 2006)
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
  generationbut.
• 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 XYZMIJKF12345
• Through hypnosis Julie and Seth forced me to
  forget everything

Believe meby 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.Smiths 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
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

Energy Radius of ROI
Egt100MeV 3
Egt1GeV 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 gt 2 x10-3 The same as below
Low-confidence detection 10-9 lt P lt 2 x10-3 Limit of B065614 (Ramanamurthy et al. 1996)
High-confidence detection P lt 10-9 Limit of B195132 (Ramanamurthy et al. 1995)
8
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
All-sky count map of the simulation of 55 days
for DC2
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
Pulsars in the Lat catalog summary
The first step is the analysis for Egt100MeV
No detection 13
Low confid. 14
High confid. 22
12
Pulsars in the Lat catalog populations
Youngest non-MSP have age103 y (Vela Crab) and
B5x1012 G
Oldest non-MSP have age108 y (Vela Crab) and
B2x1011 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 (Blt109gauss, agegt109y)
13
PSR J0904-5008, the brightest MSP
In the LAT Catalog its flux is 1.7 x 10-7 ph/cm2/s
14
Pulsars in the LAT catalog DC fluxes
The high confidence pulsars follow a similar
distribution
15
Beyond the LAT catalog Summary(I)

• The next step is the scan on the entire D4
  database. First for Egt100MeV
• We expect to find more pulsars since there is the
  help of the periodicity signature

No detection 42
Low confid. 26
High confid. 29
16
Beyond the LAT catalog Summary(I)

• Then I repeat the scan for Egt1GeV
• The pulsar detected will be different because of
  many reasons (different ROI,different spectra of
  pulsars, etc)

No detection 38
Low confid. 34
High confid. 25
The number of highlow is increased. In order to
have a final sum we must make an OR of the
results at 2 energies
17
Beyond the LAT catalogpopulation
After merging E100MeV and E1GeV results
No detection 14
Low confid. 51
High confid. 32
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 lt 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 !