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DC2 Pulsar studies using known ephemeredes

DC2 Pulsar studies using known ephemeredes. David Smith for Denis Dumora,Thierry Reposeur, Damien Parent, & Marie-Helène Grondin CENBG/In2p3/CNRS Bordeaux, France. Topics. Census Localization Sensitivity Multiwavelength lightcurves, and ephemeredes quality.

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DC2 Pulsar studies using known ephemeredes

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  1. DC2 Pulsar studies using known ephemeredes David Smith for Denis Dumora,Thierry Reposeur, Damien Parent, & Marie-Helène Grondin CENBG/In2p3/CNRS Bordeaux, France

  2. Topics • Census • Localization • Sensitivity • Multiwavelength lightcurves, and ephemeredes quality. • Fluxes and Phase-resolved spectroscopy • Beyond DC2…

  3. 1. Census • Start from a single .fits file with all 55 days and the full sky, as per Thierry’s method (see e.g. Marcus’ posting,https://confluence.slac.stanford.edu/display/DC2/2006/05/03/New+Merged+DC2+Fits+File ) • “Damien’s script” – loop over all 98 PSR’s listed in the ephemeredes D4.fits file (“DC2_pulsardb_v2.fits”) and execute gtselect gtbary gtpsearch gtpphase. Translate output to root, output is “storyboard”  .pdf file with one page per pulsar, see • https://confluence.slac.stanford.edu/display/DC2/2006/04/24/Automatic+phase+analysis+of+pulsars • We find 44 pulsars. • Next slides: examples of script output (a few of the 98 pages…)

  4. gtselect on 3° radius. Dark circle shows 0.5° “cookie cutter”.

  5. Here, 1° cut. We played with <500/E cut: unsatisfying.

  6. 5 EGRET pulsars appear clearly. Here is the 6th. We can re-produce Max Razzano’s (*) result for ‘1951+32 but it’s not a “clean detection”,i.e. “stat test” not much above noise level of ~20. (*) https://confluence.slac.stanford.edu/display/DC2/ First+Analysis+of+EGRET+pulsars+with+DC2+Re-generated+data++%28M.Razzano%29

  7. Sky map: of 98 pulsars listed in D4.fits, 44 are easily detected • Of the 98 pulsars listed in the D4 ephemeredes, we pick up 35 (all crosses). Of those, 16(?) are in Jean Ballet’s catalog (other color crosses or other shapes). • For fun also add Marcus’ sources? Tally overlap of his and the 98 and ours? • As ‘1951+32 was seen by EGRET but not in 3rd catalog, so we have ones like that.

  8. 44 of 98: names & addresses “seen” ==1 criteria currently subjective, work in progress… 44 seen in 2 cut sets 12 more in 1 cut set

  9. Sky map: of the 44 detections, 27 are in J. Ballet catalog.

  10. 27 of 44: names & addresses MRF0233_v2 is 1706-44 MRF0040_v2 is 1951+32

  11. 2. Localisation • Science requirement is 0.5 arc minutes = 0.0083 degrees (for what exposure and what background?). This is called SOURCELOC in the DC2 results we’re supposed to generate, • https://confluence.slac.stanford.edu/display/DC2/DC2+Analysis+Results • 27 pulsars with known positions in D4.fits ephemeredes database and also positions in J. Ballet catalog (gtsrcid prob >70%) • Plot distributions of position difference (next slide). • Blazars will do this better in the long run, but pulsars have advantages at low galactic latitude, and can be seen quickly enough for ISOC to do monitoring.

  12. PSR positions vs LAT Catalog positions RMS=0.014° (0.84 arc min) Post DC2: better selection of LAT catalog sources and use of position uncertainties… By Damien Parent

  13. 3. Sensitivity • After closeout truth unveiled, will compare detections vs MC intensity ; pulse widths ; background level ; spectrum hardness… • Meanwhile: for an idealized pulsar, detection versus intensity. For LAT paper? Parabola. Here, 1E-6. Crab intensity Level seen for ‘1951… By Thierry Reposeur & Damien Parent (>30 MeV) /cm²/s

  14. Determining pulsar sensitivity… • FromL.M. Kuiper et al.(2001)pulsar “Total Pulse emission” is 2E-4 MeV/cm²/s, or ~7E-6 /cm²/s for E>30 MeV. • Preceding slide: ~1E-8 detection threshold for “crab” background level, so “sensitivity” is 0.07 Crab after one year. • For background level of PSR B1951+32, about 3 times higher. • After DC2 Truth Revealed will fill in plot for range of pulse shapes, spectra, backgrounds…

  15. 4a. Multiwavelength light curves • Absolute phase critical for much pulsar science, e.g. beam geometry versus energy. • Radio peak defines phase=0 for most pulsars. Ephemeredes must be accurate and up to date. Crab, L.M. Kuiper et al.(2001) (Cartoon courtesy Alice Harding)

  16. 6 x EGRET versus DC2 phases Study by Denis Dumora Dotted lines: Fierro light curves from Max R Colored histos: DC2 results Absolute phase is strange… Stable weekly, daily.

  17. 4b. About ephemeredes quality • A few of the DC2 pulsars had bad ephemeredes: • 1055-52 had an unphysical f2 of 1E-12, making f1>0 within the 55 days (pulsars don’t normally speed up…) • 1638-5226 had a database frequency quite different from the observed (gtpsearch) frequency. • We’re working on having the best radio ephemeredes possible…in real life, accidents happen, so check your numbers (blind test results were useful to us, thanks Marcus). • Another example on next slide.

  18. Frequency drift… Several DC2 pulsars have wiiiide single peaks, not EGRET-like. Physics, or messy ephemeredes? For this one, clear drift. Sharper peak if you set f1=f2=0. 55 days (MET seconds) Pisa made the tower straight but not the plot.

  19. celeste nebula 50 GeV 5. Flux & Phase-resolved spectroscopy • Again, important in understanding beam geometry. • gtselect doesn’t include “phase” so use fselect instead. • We have some preliminary non-DC2 likelihood results, but this will be a post-DC2 study. Kuiper data & fits naïvely extended to 50 GeV

  20. 6. Beyond DC2 • currently fmerge fappend of the 7 one-week files but will want to do gtselect from the GSFC server but won’t want to fill the GUI in by hand for all 250 candidates thus we request a way to submit lists to the server • Learn how to unpack the irf’s to see parameter vs parameter eg Area versus angle relative to detector? • In real life, some first-year radio ephemeredes applied to weak gamma candidates will have gaps, overlaps, anomalies. We need to develop & exercise tools to handle this. • Phase-resolved spectroscopy studies are only at their start. • 1 GeV search then gtpsearch gives new pulsars, need to feed freq back to pre-cut. • loosen cuts to get more photons? Go back to the merit tuples and learn how to put them in the right .fits format. Perhaps this will be a post-closeout study. Eduardo and I started looking at the merit files during the very first days of DC2, then bordeaux-psr went off to Science Tools and Fits land.

  21. Conclusions • Discoveries with two months of simulated data multiply the number of known radio-loud gamma ray pulsars by SEVEN. • For our group, DC2 was a raging success : Before, we were ignorant about Science Tools ; now we’re in the thick of it, with bold plans to prepare for real data. • For that, many thanks to the people who made DC2 happen.

  22. Appendix Extra slides

  23. 60 GeV Crab Pulsar LimitAp. J. 566, 343-357 (2002) (Fierro et al) CELESTE: Eo<26 GeV <0.5 g /minute

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