S. Digel, 15 Feb 2005
Julie (mostly) and I have organized groups to define pulsars and blazars for DC2. A GRB group has not been specifically organized; the already-existing collaboration science working team (or the newly-reconstituted CSWT) for GRBs will be solicited to provide GRBs. Similarly, the science working team for diffuse emission will provide a LAT-specific diffuse emission model.
The near-term goal is to have a proof of concept, i.e., an actual XML sky model with relevant characteristics, like pulsing pulsars and flaring blazars, by Feb. 25.
Toby Burnett, Alice Harding, Massimiliano Razzano, & David Smith
Progress: Alice has generated a catalog of simulated gamma-ray pulsars, based I think on her work with Gonthier, Perrot, et al. The catalog includes timing, spectral, and light curve information.
Massimiliano has written a script or tool to convert the catalog to XML for obsSim. He has also modified pulsarSpectrum to allow light curves to be specified and to accommodate the spectra profiles (power-law with cutoff) for the simulated pulsars.
Issues: Among the open issues, David has pointed out that DC2 will of course include the known gamma-ray pulsars (which are not in the cataog of synthetic pulsars), and that some care should be taken to make the coordinates of the phony pulsars consistent with, e.g., catalogs of radio and X-ray sources. This does not need to be done before Feb. 25, of course.
The arrival time de-corrections for pulsarSpectrum still need to be cross checked with glbary, and Massimiliano plans to start on that shortly.
Simulated pulsar sources don't yet (put possibly should be able to) read from the pulsar ephemeris database. We don't have a DC2 version of the ephemeris database yet anyway, although the pulsar group surely will be tapped to provide that (or the input to it), too.
Toby Burnett, Jim Chiang, Julie McEnery, & Gino Tosti
Progress: [As reported at the software meeting a couple of weeks ago] Jim has implemented the SpectralTransient source in anticipation of desires for DC2 simulations of blazars. This is an extension of the SimpleTransient source in that it allows spectral parameters (broken power law) to be specified for each segment of the light curve.
Julie has sent Jim some synthetic light curves, and an algorithm for spectral truncation due to absorption against the EBL as a function of redshift.
Jim plans to generate a set of sources with fluxes and redshifts consistent with the luminosity function that he derived some time ago from EGRET detections of blazars, and scale the synthetic light curves appropriately.
Issues: In the time before DC2, Jim may implement a more efficient way to carry around source specifications for a large number of bazars, something more efficient than having a separate ASCII input file for SpectralTransient for each bazar.
Also in the DC2 time frame, as for pulsars, already-known blazars and correlations with radio and X-ray catalogs should be introduced.
As described (see slide 5) at the collaboration meeting last September, we are updating GALPROP and will use gamma-ray intensities that it generates as the (precomputed) model for the interstellar diffuse emission of the Milky Way.
Progress: Jim has implemented the MapCube source, which allows diffuse sources and their spectral variations to be specified in an (x, y, E) cube of intensity.
Troy Porter (LSU) has calculated a new model for the Interstellar Radiation Field, using in particular updated models for the distribution and properties of interstellar dust. This is being evaluated, along with differences between it and the older model by Andy Strong, before being incorporated in GALPROP.
Issues: MapCube has not been extensively tested yet. I hope to do that soon.
Also, before DC2 we should be able to incorporate a parameterized version of the pion production function found by Tune Kamae from calculations that included the effects of diffractive dissociation. My understanding is that code for the production function is being developed by a student of Kamae's, whose name I do not know, and that the code will be provided to Strong & Moskalenko for GALPROP.
Several longer-term issues are known, including updating models for the distribution of interstellar gas. What can be done before DC2 remains to be determined. For DC2, Julie (and maybe others, too) have pointed out that the model of diffuse emission released with the science tools should not be the same as the model used to generate the simulated data.
I have no specific news about the status of the source definition or the simulation tools. David Band has software to make GBM burst data for simulated LAT GRBs, but I do not know whether the LAT GRB sources currently generate the detailed parameterization that the software requires.