Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 1

Pulsar Blind search in the DC2 data Pulsar Blind search in the DC2 data Gamma-ray Large Gamma-ray Large Area Space Area Space TelescopeTelescope

Marcus Ziegler

Bill Atwood

Brian Baughman

Robert Johnson

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 2

Data SelectionData SelectionAs 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

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 3

Finding a Pulsar CandidateFinding a Pulsar Candidate

0 20 40 60 80 100

0. 0002

0. 0004

0. 0006

0. 0008

0.001

0. 0012

0. 0014

0. 0016

0. 0018

Power (f) PSR_J2229p6114

F in Hz

Source MRF0035

Look for frequency with the highest power

Found F0 = 19.371213 1/sDC2 Catalog = 19.371221 1/s

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 4

Test statistic (signal/noise)Test statistic (signal/noise)-> Calculate the RMS of the power spectrum

Test Statistik (signal to noise) = max_power_in_FFT / RMS

1

10

210

210 3

Nu

mb

er

of

So

urc

es

410 51010Test Statistic

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)

Take a cloer look at sources with s/n > 45

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 5

Sources with large s/n Sources with large s/n

0 20 40 60 80 1000

0.005

0. 01

0.015

0.02

0.025

0.03

0.035

0.04

Power (f)

F in Hz

Beacon MRF0054

0 20 40 60 80 1000

0.0005

0.001

0.0015

0.002

0.0025

0.003

0.0035

0.004

Power (f)

F in Hz

Vela

0 20 40 60 80 1000

0. 0005

0.001

0. 0015

0.002

0. 0025

0.003

0. 0035

0.004

Power (f)

F in Hz

Geminga

Unknown large s/n source in the galactic plane. No natching pulsar in the database.

Vela

Geminga (2nd harmonic)

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 6

-15

-14

-13

-12

-11

-10

-9

-8

0.1 1 10 100 1000-16

F in Hz

log -F.

Covered phase spaceCovered phase space

-15

-14

-13

-12

-11

-10

-9

-8

0.1 1 10 100 1000-16

F in Hz

log -F.

-15

-14

-13

-12

-11

-10

-9

-8

0.1 1 10 100 1000-16

F in Hz

log -F.

All 100 pulsars from pulsar data base

-15

-14

-13

-12

-11

-10

-9

-8log -F

.

0.1 1 10 100 1000-16

F in Hz

Radio LoudRadio Quiet

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)

Scan found16 Radio Loud pulsars3 Radio Quiet pulsars

A maximum time difference of 65 000s was used-> Calculation took about 2 weeks on a PC

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 7

Blind Search Catalog with reprocessed DC2 DataBlind Search Catalog with reprocessed DC2 Data

Source_Name L B Test Stat. F0 F1

MRF0054 60.7250 -0.1490 45147 5.885925293 -5.89E-13 Unknown Pulsar

MRF0178 270.4636 -2.1509 39249 432.7524414 0 PSR_J0904m5008

MRF0168 263.5487 -2.7792 36248 11.19723511 -1.46E-11 PSR_B0833m45 Vela

MRF0197 333.9964 -13.5126 8255 144.9731293 0 PSR_J1735m5757

MRF0138 195.1298 4.2706 6575 8.435333252 0 PSR_J0633p1746 2xGeminga

MRF0035 106.5808 2.9079 5842 19.37121582 -3.10E-11 PSR_J2229p6114

MRF0152 227.1264 0.0131 5279 303.3667603 0 PSR_J0717m1235

MRF0154 313.6165 0.1659 3286 14.66723633 -1.91E-11 PSR_J1420m6048

MRF0058 43.4240 -0.3462 2429 3.916915894 -3.92E-13 Unknown Pulsar

MRF0143 359.2044 1.0902 1693 3.097106934 0 PSR_J1739m2903

MRF0157 283.1113 -0.6045 1671 7.148910522 -3.57E-12 PSR_J1015m5719

MRF0081 9.4664 -11.9035 1345 2.973205566 0 PSR_J1852m2610

MRF0182 333.6831 -3.7332 798 2.936828613 0 PSR_J1638m5226

MRF0155 354.2894 -0.3422 481 3.766281128 -1.88E-13 Unknown Pulsar

MRF0151 337.1501 0.1752 300 6.492370605 -1.95E-12 PSR_J1637m4642

MRF0187 184.5983 -5.8240 244 59.81793213 -7.54E-10 PSR_B0531p21 3xCrab

MRF0184 350.5521 -4.7896 168 1.952316284 0 PSR_J1741m3927

MRF0057 16.8639 -0.9900 79 3.581832886 -1.07E-12 PSR_J1825m1446

MRF0342 34.6358 -0.8559 45 3.73916626 -2.24E-12 PSR_J1856p0113

MRF0077 12.1927 -5.6679 42 6.218170166 -3.17E-11 ?

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 8

Flux Sensitivity Flux Sensitivity

h1Entries 380

Mean 3.859e-007

RMS 3.675e-007

0 0.2 0.4 0.6 0.8 1 1.2 1.4 1.6 1.8 2

-6100

5

10

15

20

25

30

h1Entries 380

Mean 3.859e-007

RMS 3.675e-007

Photons/cm /s2

Nu

mb

er o

f s

ou

rce

s

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

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 9

Recover light curve for source MRF0168 (Vela)Recover light curve for source MRF0168 (Vela)

Vela Radio Position Ra = 128.83 Dec = -45.18MRF0168 Position Ra = 128.842 Dec = -45.168701

h1Entries 21795

Mean 0.5024

RMS 0.2636

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

150

200

250

300

350

400

h1Entries 21795

Mean 0.5024

RMS 0.2636

Ligh t_Curve MRF0168 100 bins

0 500 1000150 020002500300 0350 0400045005000

3100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

h2Entries 21795

Mean x 2.293e+006

Mean y 0.5024

RMS x 1.408e+006

RMS y 0.2636

h2Entries 21795

Mean x 2.293e+006

Mean y 0.5024

RMS x 1.408e+006

RMS y 0.2636

time vs Phase Light curve:

Barycenter time correction for MRF0168 position. Pulsar spin parameter from radio position.

Radio :Ep= 220838550 F0= 11.19723954 F1=-1.5664e-011 F2= 6.26E-22Optimized :Ep= 220838550 F0= 11.19723929 F1=-1.5578e-011 F2= -2.30E-20

0 500 1000150 020002500300 0350 0400045005000

3100

0.1

0.2

0.3

0.4

0.5

0.6

0.7

0.8

0.9

1

h2Entries 21795

Mean x 2.293e+006

Mean y 0.5645

RMS x 1.408e+006

RMS y 0.2287

h2Entries 21795

Mean x 2.293e+006

Mean y 0.5645

RMS x 1.408e+006

RMS y 0.2287

time vs Phaseh1Entries 21795

Mean 0.5645

RMS 0.2287

0 0.1 0.2 0.3 0.4 0.5 0.6 0.7 0.8 0.9 1

100

200

300

400

500

600

700

h1Entries 21795

Mean 0.5645

RMS 0.2287

Light_Curve MRF0168 100 bins Barycenter time correction for MRF0168 position. Optimized pulsar spin parameter for MRF0168 pos.

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 10

Light curves of pulsars without radio dataLight curves of pulsars without radio data

Epoch_MET = 220838550F0 = 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 = 220838550F0= 5.885928323969 F1= -1.306230 e-012F2= 1.0 e-021

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 11

Summary + Future plansSummary + 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

Marcus Ziegler SCIPP/UCSC DC2 Closeout Meeting 12

Basic IdeaBasic Idea

take only differences with t < max_diff

max_diff used for DC2 data = 65 000s

Calculate the Fourier-Transform of the

time differences of the photon arrival times tn.