1 / 23

Timing studies and PSR J0437-4715 analysis

Timing studies and PSR J0437-4715 analysis. Till Eifert, HU Berlin April, 2005. Outline. Analysis of pulsar timing data Improvement of barycenter correction Implementation of binary correction PSR J0437-4715 Data analysis, first results Conclusion / Outlook.

aman
Download Presentation

Timing studies and PSR J0437-4715 analysis

An Image/Link below is provided (as is) to download presentation Download Policy: Content on the Website is provided to you AS IS for your information and personal use and may not be sold / licensed / shared on other websites without getting consent from its author. Content is provided to you AS IS for your information and personal use only. Download presentation by click this link. While downloading, if for some reason you are not able to download a presentation, the publisher may have deleted the file from their server. During download, if you can't get a presentation, the file might be deleted by the publisher.

E N D

Presentation Transcript

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

  2. Outline • Analysis of pulsar timing data • Improvement of barycenter correction • Implementation of binary correction • PSR J0437-4715 • Data analysis, first results • Conclusion / Outlook Till Eifert, HU Berlin p. 2

  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. Till Eifert, HU Berlin p. 3

  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 Till Eifert, HU Berlin p. 4

  5. CRASH vs. TEMPO TDB (Crash – 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? SSB + Shapiro (Crash – Tempo) Till Eifert, HU Berlin p. 5

  6. ∆tbary (Crash – Tempo) 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! ∆p (Crash – Tempo) Till Eifert, HU Berlin p. 6

  7. ∆tbary (Crash – Tempo) 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 ∆p (Crash – Tempo) Till Eifert, HU Berlin p. 7

  8. ∆tbary (Crash – Tempo) 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 ∆p (Crash – Tempo) Till Eifert, HU Berlin p. 8

  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 Till Eifert, HU Berlin p. 9

  10. Checking BT model correction against TEMPO ∆tbinary < 10-9 s Till Eifert, HU Berlin p. 10

  11. Checking DD model correction against TEMPO ∆tbinary < 10-10 s Till Eifert, HU Berlin p. 11

  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 Till Eifert, HU Berlin p. 12

  13. PSR J0437-4715 Polar Cap model prediction • 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 Till Eifert, HU Berlin p. 13

  14. PSR J0437-4715 Chandra High Resolution Camera (HRC) Two phase cycles! ROSAT Position Sensitive Proportional Counter (PSPC) ROSAT High Resolution Imager (HRI) Radio observation at Parkes Till Eifert, HU Berlin p. 14

  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 Till Eifert, HU Berlin p. 15

  16. DC analysis Std. Hd cuts 9.1 h livetime Significance: 0.4 σ … What about AC? Till Eifert, HU Berlin p. 16

  17. Timing analysis All energies, DC: 0.4 σ On region OFF regions (summed) Question: just a fluctuation or possible hint for pulsed TeV emission? (note: fluctuation is on the right phase position!) ~ flat Z21 = 5.6 (Prob. 0.06) Z22 = 5.7 (Prob. 0.23) H = 5.6 OFF region with highest H = 3.8 Till Eifert, HU Berlin p. 17

  18. Timing analysis, energy bins All energies < 0.5 TeV, DC: 0.5 σ All energies > 0.5 TeV, DC: -0.2 σ On region On region Z21 = 6.4 (Prob. 0.04) Z22 = 6.7 (Prob. 0.15) H = 6.4 Z21 = 0.2 (Prob. 0.92) Z22 = 2.2 (Prob. 0.70) H = 0.2 OFF regions flat Till Eifert, HU Berlin p. 18

  19. Zenith angle Maximize signal/noise ratio for low energy by using very small zenith angles only DC Significance Energy < 0.5 TeV Till Eifert, HU Berlin p. 19

  20. Timing analysis All energies < 0.5 TeV, zenith angle < 25 deg On region DC: 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 ! Till Eifert, HU Berlin p. 20

  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 Till Eifert, HU Berlin p. 21

  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 Till Eifert, HU Berlin p. 22

  23. Data analysis All energies: 0.2 - 0.45 TeV, all zenith angle On region Z21 = 9.1 (Prob. 0.01) Z22 = 9.3 (Prob. 0.05) H = 9.1 Till Eifert, HU Berlin p. 23

More Related