June 29, 2005DC2 Software Workshop — 1 Progress on Pulsar Tools Development Masaharu Hirayama (GLAST SSC, GSFC/UMBC) James Peachey (GLAST SSC, HEASARC)

June 29, DC2 Software Workshop — 2 Typical Pulsar Analysis 1.Download data and screen events. For maximum pulse-detection sensitivity, select only events within a small region, typically size of a couple of PSFs. 2.Correct event times – barycentric correction. To cancel Doppler effect resulting from the orbital motions of the Earth and the spacecraft. 3.Find pulsar ephemeris at the time of observation. Option 1: Use a radio ephemeris as is. Option 2: Scan pulse frequencies around extrapolation of radio ephemeris. Option 3: Search for pulsations even if no radio ephemeris is available. 4.Calculate pulse phase for each photon. 5.Use pulse phases in your analysis. Pulse shape (or pulse profile) Phase-resolved spectrum Phase-resolved image

June 29, DC2 Software Workshop — 3 Pulsar Tools Components Pulsar ephemerides database (D4) –List of pulsar timing solution maintained during the mission for potential LAT sources. –Downloadable as a FITS file. Pulsar ephemeris extractor gtpulsardb (U11) –Basic front end to the pulsar ephemerides database. Photon arrival time converter glbary/gtbary (U10) –Converts photon arrival times in a photon list to those at the solar system barycenter. Pulsar phase assignment pulsePhase/gtpulsephase (U12) –Assigns pulse phase to each photon in a photon list. Pulsar profile & periodicity tests gtpsearch (A3) –Epoch-folds photon arrival times at trial pulse frequencies and estimate significance of pulsation at each frequency. Pulsar period search gt??? (A4) –Searches for periodic emission from a point source.

June 29, DC2 Software Workshop — 4 Pulsar Tools In Action Pulsar ephemerides (D4) Satellite position history (D2) Pulsar period search (A4) Pulsar phase assign (U12) Periodicity test (A3) Arrival time correction (U10) Ephemeris extract (U11) TIME PULSE_PHASE Event Summary FITS File (D1) Data sub- selection (U2) Likelihood (A1) Pulse profile (A3) gtpulsardb gtpulsephase gtbary gtpsearch fv gt???

June 29, DC2 Software Workshop — 5 Major Design Changes Since 9/2002 Review Binary demodulation (arrival time correction for binary pulsars) will be performed on the fly. –Originally this task was assigned to photon arrival time converter (U10). This had the following problems: The FITS standards for photon lists have no support for binary- demodulated times. For U10 an existing tool (FAXBARY in FTOOLS) was adopted for use with GLAST data, and it does not support binary demodulation. –As of the end of build 9 it is performed in pulse phase assignment (U12), periodicity tests (A3), and period search (A4). Single TIME column in an event file. –Original plan was to include multiple time columns in event files, in order to preserve original event times while performing time corrections. This had the following problems: The HEASARC standards for an event file assume a single time column. (Desired HEASARC compliance). Existing analysis tools may recognize TIME column only.

June 29, DC2 Software Workshop — 6 Current Status of Development DesignExisting counterparts ImplementationTesting Ephemerides database Defined in detail IdentifiedExamples available Used in ST checkout 2 Ephemeris extractor CompleteNoneCompleteDone Arrival time converter Algorithms identified IdentifiedCompleteDone Phase assignment Algorithms identified IdentifiedComplete for solitary pulsars Done Pulse profile & period scan Algorithms identified IdentifiedComplete for solitary pulsars Done Period searchAlgorithms identified IdentifiedAfter DC2Not yet

June 29, DC2 Software Workshop — 7 Data Challenge 2 Ready for Data Challenge 2 –Pulsar ephemerides database (D4) Database format defined and examples available. Ingest protocol defined. Extractor (U11) available. –Photon arrival time converter (U10) –Pulse phase assignment (U12) for solitary pulsars –Pulsar periodicity tests (A3) for solitary pulsars Will be ready by Data Challenge 2 –Arrival time corrections for binary pulsars Pulsar periodicity tests (A3) Pulse phase assignment (U12) Major tasks beyond Data Challenge 2 –Pulsar period search (A4) – re-use of FTOOLS counterparts? –Bayesian approach for periodicity tests (A3)

June 29, DC2 Software Workshop — 8 Further Developments Ephemeris computer –Reads pulsar ephemerides database (D4) and compute pulsar- related parameters (such as pulse frequency) at a given moment in time. –Also serves as a sanity checker for first-time users of our pulsar ephemerides database (D4). User-interface –GUI under development for all SAE tools. –Web interface for database extractor? Orbital phase assignment –To assign an orbital phase to each photon (just like a pulse phase for each photon). –Pulse phase assignment tool (U12) is a natural candidate to do this task.

June 29, 2005DC2 Software Workshop — 9 Backup Slides

June 29, DC2 Software Workshop — 10 Pulsar Tools Pulsar ephem. (D4) Level 1 (D1) LAT Point source catalog (D5) Interstellar em. model (U5) Pointing/livetime history (D2) Astron. catalogs (D6) Level 0.5 IRFs (D3) Alternative source for testing high- level analysis Alternative for making additional cuts on already- retrieved event data Pt.ing/livetime simulator (O1) Observation simulator (O2) Pt.ing/livetime extractor (U3) Data sub- selection (U2) Data extract (U1) Exposure calc. (U4) Likelihood (A1) Map gen (U6) Src. ID (A2) Event display (UI1) Pulsar profiles (A3) 1 Catalog Access (U9) Pt.ing/livetime extractor (U3) Pulsar phase assign (U12) Pulsar period search (A4) GRB spectral-temporal modeling (A10) Source model def. tool (U7) Arrival time correction (U10) GRB temporal analysis (A7) 2 GRB LAT DRM gen. (U14) GRB spectral analysis (A8) 2 GRB event binning (A5) GRB unbinned spectral analysis (A9) GRB visual- ization (U13) IRF visual- ization (U8) Ephemeris extract (U11) GRB rebinning (A6) 2 Data in

June 29, DC2 Software Workshop — 11 Algorithms Periodicity tests –Chi-squared test (Leahy et al. 1983, ApJ 266, 160; Vaughan et al. 1994, ApJ 435, 362) –Zn 2 test (Buccheri et al. 1983, A&A 128, 245) –Rayleigh test (equivalent to Zn 2 test for n = 1) –H test (De Jager et al. 1989, A&A 221, 180) –Bayesian approach (Gregory and Loredo 1992, ApJ 398, 146; Gregory and Loredo 1996, ApJ 473, 1059) Period search –Discrete Fourier transforms (Ransom 2002, AJ 124, 1788) –Lomb-Scargle periodogram (Lomb 1976, Ap&SS 39, 447; Scargle 1982, ApJ 263, 835; Press & Rybicki 1989, ApJ 338, 277)

June 29, DC2 Software Workshop — 12 Pulsar Ephemerides Database (D4, U11) Full definition of D4 FITS file complete. –Similar to the CGRO catalog, with some improvements. –Ephemerides ingest protocol defined. –Ephemerides extractor tool (U11) available. Examples of D4 FITS file available. –Contents based on the CGRO catalog. –To be used in Data Challenge 2. Action items: –Discuss on ephemerides data ingest with the pulsar IDS.

June 29, DC2 Software Workshop — 13 Photon Arrival Time Converter (U10) Existing counterparts identified. –FAXBARY seems to be “re-usable” for GLAST. –FAXBARY: FTOOLS originally developed for XTE, now available for other missions such as Swift. FAXBARY modified to adopt to GLAST data. –Tested with simulated data in Science Tools checkout 2. –To be used in Data Challenge 2. Action items: –Deliver to the LAT team as a part of the HEADAS package.

June 29, DC2 Software Workshop — 14 Pulsar Phase Assignment (U12) Basic functionality implemented and tested. –Single set of frequency ephemeris can be given. –Multiple ephemerides can be read from database (D4). –Probably already good enough for Data Challenge 2. –To be used in Data Challenge 2. Action items: –Implement arrival time corrections for binary pulsars.

June 29, DC2 Software Workshop — 15 Pulsar Profile & Periodicity Tests (A3) Basic functionality implemented and tested. –Single set of initial frequency ephemeris can be given by a user or read from database (D4). –Good enough for Data Challenge 2. –To be used in Data Challenge 2. Most of periodicity tests implemented and tested. –Chi-squared test (Leahy et al. 1983, ApJ 266, 160; Vaughan et al. 1994, ApJ 435, 362) –Zn 2 test (Buccheri et al. 1983, A&A 128, 245) –Rayleigh test (equivalent to Zn 2 test for n = 1) –H test (De Jager et al. 1989, A&A 221, 180) Action items: –Implement arrival time corrections for binary pulsars. –Identify periodicity tests to be implemented (if any).

June 29, DC2 Software Workshop — 16 Pulsar Period Search (A4) Suggested algorithms for period search. –Discrete Fourier transforms (Ransom 2002, AJ 124, 1788) –Lomb-Scargle periodogram (Lomb 1976, Ap&SS 39, 447; Scargle 1982, ApJ 263, 835; Press & Rybicki 1989, ApJ 338, 277) Existing counterparts identified. –“powspec” (XRONOS) calculates power spectrum density –“perdgrm” (FTOOLS) computes Lomb-Scargle periodogram Action items: –Test existing tools with GLAST data format. –Implement Python wrapper if needed.

June 29, DC2 Software Workshop — 17 Pulsars for GLAST LAT Pulsars are point sources GLAST expected to detect pulsations from pulsars –10-50% are predicted to be radio quiet like Geminga –Most need 1 year exposure for detection Sparse data –One photon per 500 pulses (Crab 30 MeV – 300 GeV) Scanning with large FOV –All sources get some exposure every day throughout a year –Large number of short observations Plot by D.J. Thompson

June 29, DC2 Software Workshop — 18 What Pulsar Tools Are Needed? Barycentric corrector Photon arrival time converter glbary/gtbary (U10) Pulsar ephemeris “finder” Case 1: use a radio ephemeris as is. Pulsar ephemerides database (D4) Pulsar ephemeris extractor gtpulsardb (U11) Case 2: scan around a radio ephemeris. Pulsar profile & periodicity tests gtpsearch (A3) Case 3: search for pulsations. Pulsar period search gt??? (A4) Pulse phase calculator Pulsar phase assignment pulsePhase/gtpulsephase (U12)