Title: DC2 pulsars analysis: a population point-of-view
1DC2 pulsars analysisa population point-of-view
Massimiliano Razzano (INFN - Pisa) LAT DC2
Closeout Meeting (GSFC, May 31-June 2 2006)
2Outline
- 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
3Analysis 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..
4Why 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
5Python 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
6Python 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)
7About 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)
8The EGRET pulsars
Vela
The first exercise is the analysis of the EGRET
pulsars, testing periodicity and recovering
lightcurve
Seeing that pulsars does pulse.
Crab
9All-sky count map of the simulation of 55 days
for DC2
10Pulsars 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
11Pulsars in the Lat catalog summary
The first step is the analysis for Egt100MeV
No detection 13
Low confid. 14
High confid. 22
12Pulsars 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)
13PSR J0904-5008, the brightest MSP
In the LAT Catalog its flux is 1.7 x 10-7 ph/cm2/s
14Pulsars in the LAT catalog DC fluxes
The high confidence pulsars follow a similar
distribution
15Beyond 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
16Beyond 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
17Beyond the LAT catalogpopulation
After merging E100MeV and E1GeV results
No detection 14
Low confid. 51
High confid. 32
Find the differences.
18Conclusions 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 !