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

 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  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);

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

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

The phenomenological model (II) spectrum Example for Vela-like PSR F(E>100) ~9*10 -6 ph/cm2/s, E n =1GeV,E 0 =8GeV; g=1.62,b=1.7; 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  ray pulsars (e.g. ref. N,DJ95, and DJ 2003); Flux normalisation based on 3 rd EGRET catalog (ph/cm 2 /s, E>100MeV); By changing values of the parameters we can simulate different pulsars;

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) The phenomenological model (III) the final product According to the flux the photons are extracted and then the time arrivals of photons are de-corrected LightcurveSpectrum

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

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)

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; A tools for managing catalogs (population plots, creation of xml files, etc.) is under development 1-day catalog simulation

Pulsar database For each pulsar simulated in DC2 there must be a correspondant entry in the pulsar database (D4) 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. PulsarDataListXML file PulsarSpectrum ASCII ephem file gtpulsardb Ephemerides fits file

PulsarSpectrum and Science 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 1 st Checkout (Oct,12-Oct ) and 2 nd Checkout (Mar,21-Apr,8) 1-day simulation of EGRET pulsars + diffuse emission Testing the SAE Pulsar Analysis Tools

Some screenshots from Checkout 2 1-week of Crab 1-week of (artificial lightcurve ) 1-week of Vela

Summary for DC2 What to simulatePriorityRemark PulsarSpectrum simulations Light travel time between the spacecraft and the solar system barycenter Must have in DC2 Those effects must be taken into account in pulsar simulations to match the barycentric correction tool to be used in DC2. See also note on barycentric "de-correction" in pulsar simulation below.note on barycentric "de-correction" in pulsar simulation Implemented Difference between TDT and TDBMust have in DC2Implemented Shapiro delay in the solar systemMust have in DC2Implemented Pulsars for periodicity tests with known ephemerides Must have in DC2 To simulate studies of known radio pulsars Ok.Catalogs for DC2 t.b.d. Pulsars for blind periodicity searches Good to have in DC2 To simulate blind searches for Geminga-like pulsars using A4 Ok. Catalogs for DC2 t.b.d. Variety of pulse profiles Good to have in DC2 Duplicate the light curves of the EGRET pulsars? Implemented random and user-defined (e.g. EGRET pulsars) Realistic energy spectra Good to have in DC2 Such as spectral cutoffs, etc. Parameterized power law with cutoff Pulse phase dependent energy spectra Nice to have sometime Power-law index and/or cut-off energy changes with pulse phase? To be implemented Binary pulsars Nice to have sometime Related effects include: light travel time in a binary system, gravitational time dilation in a binary system, and Shapiro delay in a binary system. To be implemented Glitches and timing noise Nice to have sometime Similar to the Vela and the Crab pulsars? Multiple ephemerides implemented and under tests.possible approximated glitches From

Pulsar simulation: Conclusions 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 1 st and 2 nd Checkout;  Development of some accessories tools (e.g. pulsar catalogs manager)  Simulating catalogs of pulsars in preparation for DC2 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;