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Status of pulsar simulation for DC 2

Gamma-ray Large Area Space Telescope. Status of pulsar simulation for DC 2. Massimiliano Razzano Nicola Omodei GLAST DC2 Software Workshop (Goddard Space Flight Center, June 27 th -29 th 2005). g ray pulsar simulation for GLAST.

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Status of pulsar simulation for DC 2

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  1. Gamma-ray Large Area Space Telescope Status of pulsar simulation for DC 2 Massimiliano Razzano Nicola Omodei GLAST DC2 Software Workshop (Goddard Space Flight Center, June 27th-29th 2005)

  2. g ray pulsar simulation for GLAST PulsarSpectrum is a simulator developed in Pisa used for simulating gamma ray emission from pulsars Key features: It can reproduce spectra and lightcurves of known g ray pulsars; Flexible architecture to facilitate creation of pulsar sources; Simulation of timing effects due to period changes and motion of GLAST and Earth in the Solar System; Full phenomenological model now implemented; Pulsar parameters easy to implement; Capability of simulation of pulsar catalogs; Compatibily with LAT software (Gleam, observationSim);

  3. Pulsar model Model parameters (phenomenological, physical) ( XML File ) Pulsar Data (Flux,Period,…) (Ascii datafile) Standalone 2Dim ROOT hist LAT software (ObsSim,Gleam) An overview of PulsarSpectrum Simulator Engine

  4. Different alternatives for lightcurves: • Random curves (Lorentz peaks); • From existing TimeProfiles (useful for simulating known pulsars); • For diagnostic purposes is possible to generate a d-Dirac shaped profile; Example of TimeProfile (arbitrary units) The phenomenological model (I)lightcurve

  5. We choose this analytical spectral shape: (Nel and De Jager,1995): • Description of the high energy cutoff; • Parameters are obtained from fits on the known g ray pulsars (e.g. ref. N,DJ95, and DJ 2003); • Flux normalisation based on 3rdEGRET catalog (ph/cm2/s, E>100MeV); • By changing values of the parameters we can simulate different pulsars; Example for Vela-like PSR F(E>100) ~9*10-6 ph/cm2/s, • En=1GeV,E0=8GeV; • g=1.62,b=1.7; The phenomenological model (II)spectrum

  6. Lightcurve Spectrum The phenomenological model (III)the final product We combine lightcurve and spectrum:  TH2D ROOT histogram Now multiplication, but more complicated combination laws are not too difficult to simulate; (goal for phase-resolved analysis) According to the flux the photons are extracted and then the time arrivals of photons are de-corrected

  7. The Nv is computed is a system where period is constant • We should switch between the “reference systems” S (Pdot is = 0, period constant) S~ (Pdot is not 0, period not constant, e.g. the real world) • Phase assignment in analysis: • # of rotations: • Integrating and taking the fractional part: Period derivatives

  8. Barycentric decorretions The first step in data analysis is to transform the photon arrival times at the spacecraft (MET expressed in TT) to the Solar System Barycenter (expressed in TDB): The simulator must de-corrects for these effects: At present 3 main effects are taken into account: • Conversion TTTDB; • Geometric corrections due to lighttravel time from GLAST location to Solar System Barycenter • Relativistic delay due to gravitaional field of Sun (Shapiro delay)

  9. A tools for managing catalogs (population plots, creation of xml files, etc.) is under development 1-day catalog simulation Simulating pulsar catalogs PulsarSpectrum is also been tested for simulation of many pulsars in the sky. This feature allows the possibility to simulate entire pulsar catalogs. For each pulsar a log file is produced in order to keep track of the simulated pulsars • Up to now: • Simulated mini-catalog with EGRET pulsars; • Tests with catalog provided by A.Harding with more than 1k pulsars;

  10. PulsarDataList XML file ASCII ephem file gtpulsardb Ephemerides fits file Pulsar database For each pulsar simulated in DC2 there must be a correspondant entry in the pulsar database (D4) PulsarSpectrum • PulsarSpectrum next implemented features (under tests) are devoted to interfacing with database: • Multiple entries (allowing the possibility to insert different ephemerides for different time ranges, as in observations) • Output txt file that can be converted with gtpulsardb in a FITS file compatible with SAE standard.

  11. 1-day simulation of EGRET pulsars + diffuse emission PulsarSpectrum and Science Tools Testing the SAE Pulsar Analysis Tools Thanks to the simulation of timing effects, e.g barycentric decorrections, PulsarSpectrum is useful for testing Pulsar Analysis Tools in the SAE (glbary, pulsePhase, gtpulsarDb, stpsearch) Simulations and ScienceTools reports in Science Tools 1st Checkout (Oct,12-Oct 29 2004) and 2nd Checkout (Mar,21-Apr,8)

  12. 1-week of Crab 1-week of Vela 1-week of 1706-44 (artificial lightcurve ) Some screenshots from Checkout 2

  13. Summary for DC2 From http://glast.gsfc.nasa.gov/ssc/dev/psr_tools/testplanDC2.html

  14. Status of work • Full simulation code implemented and tested; • Phenomenological model included; • Simulation of period change with time; • Effects of GLAST and Earth motion and of gravitational field of Sun on timing (barycentric de-corrections) • Simulation of EGRET pulsars; • Use of PulsarSpectrum for testing the LAT Analysis Tools for pulsars; • Participation to Science Tools Checkouts. Up to now 1st and 2nd Checkout; • Development of some accessories tools (e.g. pulsar catalogs manager) • Simulating catalogs of pulsars in preparation for DC2 Pulsar simulation: Conclusions • Work in progress and plans for future… • Inclusion of more realistic timing effects (timing noise, glitches,etc.); • Development of simulation of binary pulsar systems; • Work with LAT Pulsar Science Group for studying GLAST performances on pulsar science; • Begin studies of analysis techniques for pulsar blind searches; • Work on the development to fit optimally the requirements for DC2; • Provide to DC2 users output ephemerides database of the simulated pulsars;

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