Gamma-ray Large Area Space Telescope Introduction S. Ritz Technical and Production Status L. Klaisner Instrument Science Operations Center Plans R. Cameron Project Status, Cost and Schedule L. Klaisner S. Ritz 1
Why study γ s? Gamma rays carry a wealth of information: γ rays do not interact much at their source: they offer a direct view into Nature s largest accelerators. similarly, the Universe is mainly transparent to γ rays: can probe cosmological volumes. Any opacity is energy-dependent. conversely, γ rays readily interact in detectors, with a clear signature. γ rays are neutral: no complications due to magnetic fields. Point directly back to sources, etc. Two GLAST instruments: LAT: 20 MeV >300 GeV GBM: 10 kev 25 MeV Large Area Telescope (LAT) Launch: February 2007 GLAST Burst Monitor (GBM) S. Ritz 2
GLAST Science GLAST will have a very broad menu that includes: Systems with supermassive black holes Gamma-ray bursts (GRBs) Pulsars Solar physics Origin of Cosmic Rays Probing the era of galaxy formation Discovery! Particle Dark Matter? Other relics from the Big Bang? Testing Lorentz invariance. New source classes. Huge increment in capabilities. GLAST draws the interest of both the the High Energy Particle Physics and High Energy Astrophysics communities. GLAST is the highest-ranked initiative in its category in the National Academy of Sciences 2000 Decadal Survey Report. S. Ritz 3
GLAST LAT High Energy Capabilities EGRET on GRO firmly established the field of high-energy gamma-ray astrophysics and demonstrated the importance and potential of this energy band. GLAST is the next great step beyond EGRET, providing a huge leap in capabilities: Very large FOV (~20% of sky), factor 4 greater than EGRET Broadband (4 decades in energy, including unexplored region E > 10 GeV) Unprecedented PSF for gamma rays (factor > 3 better than EGRET for E>1 GeV) Large effective area (factor > 5 better than EGRET) Results in factor > 30-100 improvement in sensitivity Much smaller deadtime per event (25 microsec, factor >4,000 better than EGRET) No expendables long mission without degradation S. Ritz 4
Sources EGRET 3 rd Catalog: 271 sources S. Ritz 5
Sources LAT 1 st Catalog: >9000 sources possible S. Ritz 6
Anticenter Region simulation: S. Digel S. Ritz 7
Overview of LAT Precision Si-strip Tracker (TKR) 18 XY tracking planes. Single-sided silicon strip detectors (228 µm pitch) Measure the photon direction; gamma ID. Hodoscopic CsI Calorimeter(CAL) Array of 1536 CsI(Tl) crystals in 8 layers. Measure the photon energy; image the shower. Segmented Anticoincidence Detector (ACD) 89 plastic scintillator tiles. Reject background of charged cosmic rays; segmentation removes self-veto effects at high energy. Electronics System Includes flexible, robust hardware trigger and software filters. ACD [surrounds 4x4 array of TKR towers] γ e + e Tracker Calorimeter Systems work together to identify and measure the flux of cosmic gamma rays with energy 20 MeV - >300 GeV. S. Ritz 8
GLAST LAT Collaboration United States California State University at Sonoma University of California at Santa Cruz - Santa Cruz Institute of Particle Physics Goddard Space Flight Center Laboratory for High Energy Astrophysics Naval Research Laboratory Ohio State University Stanford University (SLAC and HEPL/Physics) University of Washington Washington University, St. Louis France IN2P3, CEA/Saclay Italy INFN, ASI Japanese GLAST Collaboration Hiroshima University ISAS, RIKEN Swedish GLAST Collaboration Royal Institute of Technology (KTH) Stockholm University PI: Peter Michelson (Stanford & SLAC) ~120 Members (including ~60 Affiliated Scientists, plus 20 Postdocs, and 25 Graduate Students) LAT Project is a partnership between NASA and DOE, with international contributions from France, Italy, Japan and Sweden. Managed at Stanford Linear Accelerator Center (SLAC). S. Ritz 9
Highlights of Recent Activities Successful Mission CDR! Collaboration meeting at SLAC 27-30 September Instrument test data analysis workshop Hardware and software status Science organization and planning Operations planning Cooperation with other experiments (multi-wavelength planning) GeV-TeV Symposium (joint with Mission Science Working Group) Senior Scientist Advisory Committee year 1 data release plan proposal new members performance updating science planning policies Data Challenges very successful DC1; planning/working now for DC2 S. Ritz 10
Instrument Test Data Analysis A suite of detailed test data-taking runs is being defined for each stage of the build. Using the data, there are two basic categories of data analysis: (mostly) automated, basic go/no-go tests. These are done by I&T, with ~instant result turn-around to support the schedule. this work: more detailed analyses using (mostly) the same data. A key opportunity to look for more subtle, sophisticated, and detailed effects:» To uncover and quantify any instrumental effects early that could have an impact on science data analysis & feedback realism into the Monte Carlo» Are there additions to the go/no-go test suite?» To apply reconstruction algorithms to real data» To start the work that will evolve in the Instrument Science Operations Center (ISOC)» To grow a group to participate in the beam tests analysis effort (after instrument delivery) Relies on strong collaboration-wide support. First workshop in June, second in September. Regular meetings via vrvs. S. Ritz 11
Operations Phase LAT Organization Chart Dr. Rob Cameron appointed LAT Instrument Science Operations Center manager extensive operations experience at SAO / Chandra X-ray Center LAT Collaboration Science Groups (LSGs) responsible for collaboration s analysis and extraction of science results from LAT data 11 Science Groups plus Multi-λ Coordination Working Group each science group to have 2 coleads; with one resident at Stanford day-to-day efforts coordinated by Analysis Coordinator, also resident at Stanford-SLAC S. Ritz 12
Science Analysis Groups process started for updating the groups groups organized around expected collaboration publications, particularly during the 1 st year all-sky survey phase; each group should have responsibility for 2-3 key (category 1) papers. Science Analysis Groups 1. Catalogs 2. Galactic Diffuse and Molecular Clouds 3. Extragalactic Diffuse 4. Blazars and Other AGNs 5. Other Galaxies (including clusters) 6. Pulsars, SNRs, and Plerions 7. Unidentified Sources and Population Studies 8. Dark Matter and Exotic Physics 9. Gamma-Ray Bursts 10. Solar System Sources 11. Calibration and Analysis Methods LAT Multiwavelength Observation Coordination Group S. Ritz 13
Space at SU SLAC for ISOC and Analysis efforts Fred Kavli Building at SLAC KIPAC (Kavli Institute of Particle Astrophysics and Cosmology) Roger Blandford, Director Steve Kahn, Deputy Director S. Ritz 14
Space at SU SLAC for ISOC and Analysis efforts new building on campus - replacement space for HEPL -campus part of KIPAC S. Ritz 15
GeV-TeV Symposium 30 September at SLAC LAT Team and Mission Science Working Group have held ~annual joint science symposia on a wide variety of topics. This year: GeV-TeV Astrophysics in the GLAST Era + Very useful workshop discussion about cooperation among experiments! S. Ritz 16
Data Challenges DC1 early alpha-testing. End-to-end testing of analysis software. Provide feedback on what works and what is missing from the data formats and tools. Walk before running: design a progression of studies. DC1. Modest goals. Contains most essential features of a data challenge. 1 simulated day all-sky survey simulation find the sources, including GRBs a few physics surprises exercise: exposure, orbit/attitude handling, data processing pipeline components, analysis tools DC2 in 2005. More ambitious goals. ~One simulated month. toy one-month catalog. add source variability (AGN flares, pulsars). add GBM. DC3 in 2006. Support for flight science production. S. Ritz see http://www-glast.slac.stanford.edu/software/workshops/feb04dc1closeout/coverpage.htm 17
The DC1 Sky One day all-sky survey. Generated E>20 MeV. E>100 MeV with some other cuts for illustration Lots to analyze! A few surprises to find S. Ritz 18
Data Challenge 1 Sky isotropic diffuse 3C273 3C279 Sources 3EG and more, with a twist a number of physics surprises in the DC1 data, including: 110 GeV gamma-ray line source at the galactic center new source populations all surprises were detected at some level! S. Ritz 19
LAT Data Challenges: Updated Plan for DC2 DC2, based on lessons from DC1 1 simulated month of all-sky survey gammas (backgrounds: see next slide) key sky addition: source variability AGN variability, including bright flares, quiescent periods expand burst variety. Include GBM. pulsars, including Gemingas, w/ orbit position effects. more realistic all-sky attitude profile background rate varies with orbit position more physics surprises update geometry (including s/c); add nominal hardware problems (and misalignments?); add deadtime effects and corrections Analysis Goals: produce toy 1-month 1 catalog try out transient releases and quicklook analyses, monitor sources point source sensitivity and localization studies try first systematic pulsar searches (timing!) diffuse analyses recognize simple hardware problems (connect with ISOC) benchmark processing times, data volume, data transfers. S. Ritz 20
Summary Strong involvement of physicists at all levels of the project ready for earliest instrument test data analysis strategizing/prioritizing as issues arise getting ready early to do great science via data challenges and updating organization of science groups increasing cooperation with other experiments, helping to lead the way. Very strong support by SLAC of the international science collaboration and the management of the fabrication. The hardware is coming! Great excitement in a team that continues to grow even closer and stronger. S. Ritz 21