Timing studies and PSR J0437-4715 analysis Till Eifert, HU Berlin April, 2005.

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Timing studies and PSR J0437-4715 analysis Till Eifert, HU Berlin April, 2005

Transcript of Timing studies and PSR J0437-4715 analysis Till Eifert, HU Berlin April, 2005.

Timing studies and PSR J0437-4715 analysis

Till Eifert, HU Berlin

April, 2005

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 2

Outline

○ Analysis of pulsar timing data

• Improvement of barycenter correction

• Implementation of binary correction

○ PSR J0437-4715

• Data analysis, first results

○ Conclusion / Outlook

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 3

Analysis of pulsar timing data

Given: GPS event time stamp from CentralTrigger

intrinsic accuracy of GPS 10 μs

~ 30 μs from peak jitter of optical pulsar measurements

Phase of a pulsar waveform depends on:○ Spin-down (→ ATNF PSR DB)

○ Motion of Earth within the solar system (→ barycenter correction)

○ Orbital motion of the pulsar (→ binary correction)

Crosscheck with TEMPO:

○ Standard tool from radio astronomers

○ Evolving since 1972

○ Accuracy < μs range, proved by extensive tests with 6 years of data.

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 4

Barycenter correction

t = toa in TDT (UTC + leap seconds) system

tb units: Barycentric Dynamical Time (TDB)

∆tSSB correction to solar system barycenter (Roemer time delay)

∆tE solar system “Einstein delay” (gravitational

redshift & time dilation due to motions of the Earth

= TDB correction)

∆tS “Shapiro delay” (caused by propagation of the

pulsar signal through curved spacetime)

Taken from F. Schmidt

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 5

CRASH vs. TEMPO

CRASH vs. TEMPO timing corrections:

○ ∆tE (TDB) (< 25 μs)

○ ∆tS + ∆tSSB (< 0.12 ms)

○ proper motion, parallax not used for

phase calculation in old Crash!

Good enough?

For young PSR: Yes!

What about ms PSR?

TDB (Crash – Tempo)

SSB + Shapiro (Crash – Tempo)

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 6

CRASH vs. TEMPO

PSR J0437 ephemeris

(P ~ 5.7ms, proper motion ~ 100 mas/yr,

parallax ~ 7 mas)

∆tb < 2 ms

Thus, CRASH not applicable for

analysis over long observation

period of close ms PSR!

∆tbary (Crash – Tempo)

∆p (Crash – Tempo)

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 7

Improvements

New in Crash module:

○ New TDB algorithm

○ New barycenter algorithm,

taking into account:

• Shapiro delay

• Proper motion

• Parallax

○ New routines to read in

TEMPO and GRO parameter

files

○ Two binary models added

∆tbary (Crash – Tempo)

∆p (Crash – Tempo)

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 8

Improvements (zoomed)

New in Crash module:

○ New TDB algorithm

○ New barycenter algorithm,

taking into account:

• Shapiro delay

• Proper motion

• Parallax

○ New routines to read in

TEMPO and GRO parameter

files

○ Two binary models added

∆tbary (Crash – Tempo)

∆p (Crash – Tempo)

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 9

Binary models

PSR in binary system → significant acceleration

Blandford-Teukolsky (BT) model:

○ Keplerian ellipse

○ Newtonian dynamics

○ Einstein delay patched into model afterwards

○ additional effects are accommodated by nonzero time derivatives

Damour-Deruelle (DD) model:

○ more general

○ Roemer time delay

○ Orbital Einstein and Shapiro delay

○ Aberration caused by rotation

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 10

Checking BT model correction against TEMPO

∆tbinary < 10-9 s

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 11

Checking DD model correction against TEMPO

∆tbinary < 10-10 s

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 12

Outline

○ Analysis of pulsar timing data

• Improvement of barycenter correction

• Implementation of binary correction

○ PSR J0437-4715

• Data analysis, first results

○ Conclusion / Outlook

→ New code: good agreement (<μs) with TEMPO

Code will be merged with CVS head soon

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 13

PSR J0437-4715

○ Distance ~ 140 pc

○ P ~ 5.75 ms, dP/dt ~ 10-20

○ Low B ~ 108 -1010G

○ Binary orbit ~ 5.74 days

○ Low mass companion ~ 0.2 M

○ Not eclipsing

○ No optical brightness variation

○ Pulsed emission visible in radio,

X-rays Harding, A.K., Usov, V. V., Muslimov, A. G., 2005, ApJ, 622, 531

Polar Cap model prediction

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 14

PSR J0437-4715

Radio observation at Parkes

Two phase cycles!

ROSAT High Resolution Imager (HRI)

ROSAT Position Sensitive Proportional Counter (PSPC)

Chandra High Resolution Camera (HRC)

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 15

Data analysis

○ Data from October 2004

○ 22 runs with 4 telescopes (passed quality check), ~ 9.1 h livetime

○ Zenith angle range: 23.9 – 30 deg

○ Energy threshold ~ 200 GeV

○ Std. Hd Cuts: desert/phase1_0510_south

○ Background model: SevenBackgroundMaker

○ PSR analysis: ephemeris from ATNF

○ Statistical tests: Z2, H

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 16

DC analysis

Std. Hd cuts

9.1 h livetime

Significance: 0.4 σ

What about AC?

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 17

Timing analysis

Question: just a fluctuation or possible hint for pulsed TeV emission?

(note: fluctuation is on the right phase position!)

On region

Z21 = 5.6 (Prob. 0.06)

Z22 = 5.7 (Prob. 0.23)

H = 5.6

OFF region with highest H = 3.8

All energies, DC: 0.4 σ

OFF regions (summed)

~ flat

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 18

Timing analysis, energy bins

On region

Z21 = 6.4 (Prob. 0.04)

Z22 = 6.7 (Prob. 0.15)

H = 6.4

All energies < 0.5 TeV, DC: 0.5 σ

OFF regions flat

All energies > 0.5 TeV, DC: -0.2 σ

On region

Z21 = 0.2 (Prob. 0.92)

Z22 = 2.2 (Prob. 0.70)

H = 0.2

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 19

Zenith angle

0

0.5

1

1.5

2

2.5

3

24 25 26 27 28 29 30 31

Zenith angle [deg]

DC

Sig

nif

ican

ce [

sig

ma]

DC SignificanceEnergy < 0.5 TeV

Maximize signal/noise ratio for low energy by using very small

zenith angles only

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 20

Timing analysis All energies < 0.5 TeV, zenith angle < 25 deg

On regionDC: 2.0 σ 5.6 h livetime

Z21 = 9.4 (Prob. 0.009)

Z22 = 11.3 (Prob. 0.02)

H = 9.4

OFF regions flat (max H = 2.2)

with std. HD cuts !

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 21

Conclusion / Outlook

○ We have developed and tested the tools to analyse

ms PSR (sub μs agreement with TEMPO)

○ It is difficult to ignore the fluctuation at the right

phase position

○ Optimizing cuts on MC with exp. cut-off spectra

○ Cross-check with Mathieu’s model analysis

○ We need more data with very low zenith angle

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 22

Leap seconds in UTC

|UT1-UTC| < 0.9 seconds

→ leap seconds

UT1: time scale based on the Earth’s rotation (irregular fluctuations, general

slowing down)

UTC: TAI (International Atomic Time) + leap seconds

Taken from Earth Orientation Center

H.E.S.S. Collaboration Meeting, Palaiseau , 2005 Till Eifert, HU Berlin p. 23

Data analysis

On region

Z21 = 9.1 (Prob. 0.01)

Z22 = 9.3 (Prob. 0.05)

H = 9.1

All energies: 0.2 - 0.45 TeV, all zenith angle