The Physics program of the Gamma-Ray Large Area Space Telescope Luca Latronico

1. Gamma-ray Large Area Space Telescope The Physics program of the Gamma-Ray Large Area Space Telescope Luca Latronico on behalf of the LAT collaboration 7th UCLA Symposium Sources and Detection of Dark Matter and Dark Energy in the Universe Marina del Rey – 23 February 2006

2. Gamma Ray Burst Monitor (GBM) Large Area Telescope (LAT) Spacecraft The GLAST observatory The GLAST instruments • LAT: 20MeV – >300GeV • PI: P. Michelson (SU) • GBM: 10KeV – 30MeV • PI: C. Meegan (UofA, Huntsville) Launch Vehicle Delta II – 2920-10H Launch Location Kennedy Space Center Orbit Altitude 575 Km Orbit Inclination 28.5 degrees Orbit Period 95 Minutes Orientation +X to the Sun Launch Date August 2007 LAT mass 3000Kg LAT power 650W • Gamma-rays as probes of the universe • travel undeviated by EM fields • emitted by most energetic process • Can go down to z ~700 • Satellite to go below ~30GeV atmosphere cutoff

3. The LAT Collaboration United States • California State University at Sonoma (SSU) • University of California at Santa Cruz - Santa Cruz Institute of Particle Physics (UCSC/SCIPP) • Goddard Space Flight Center – Laboratory for High Energy Astrophysics (NASA/GSFC/LHEA) • Naval Research Laboratory (NRL) • Ohio State University • Stanford University – Hanson Experimental Physics Laboratory (SU-HEPL) • Stanford University - Stanford Linear Accelerator Center (SU-SLAC) • Texas A&M University – Kingsville (TAMUK) • University of Washington (UW) • Washington University, St. Louis (WUStL) International multi-agency mission France • Centre National de la Recherche Scientifique / Institut National de Physique Nucléaire et de Physique des Particules (CNRS/IN2P3) • Commissariat à l'Energie Atomique / Direction des Sciences de la Matière/ Département d'Astrophysique, de physique des Particules, de physique Nucléaire et de l'Instrumentation Associée (CEA/DSM/DAPNIA) Italy • Agenzia Spaziale Italiana (ASI) • Istituto di Astrofisica Spaziale (IASF, CNR) • Istituto Nazionale di Fisica Nucleare (INFN) Japan GLAST Collaboration (JGC) • Hiroshima University • Institute for Space and Astronautical Science (ISAS) • RIKEN Swedish GLAST Consortium (SGC) • Royal Institute of Technology (KTH) • Stockholm University total Collaboration members: 161 Members: 77 Affiliated Sci. 67 Postdocs: 17

4. 0.01 GeV 0.1 GeV 1 GeV 10 GeV 100 GeV 1 TeV Physics program - the sky above 20 MeV sky map • GLAST will be a reference gamma-ray observatory: • 5 years life requirement – 10 years goal • will provide high energy g data (public) for the first time with unprecedented resolution/statistics • vast, interdisciplinary physics program and scientific community (astro-particle and traditional astrophysics) • multi-wavelength campaigns (AGNs) • networked to other space/ground facilities for alert (bursts and transients) unidentified sources pulsar GRB from EGRET solar flares Aeff x7 (~1m2) FOV  x5 (2.4sr) Max En.  > x30 (>300GeV) Deadtime  x310-4 (26ms) AGN SNR and CR acceleration Goal: measure direction, arrival time and energy of incoming photons Constraints: mass, power, consumables, reliability, redundancy typical of use in space to GLAST point source sensitivity (>100MeV) > x30 (3x10-9cm-2s-1) dark matter

5. Elsasser Manheimm astro/ph-0405235 Morselli et al astro/ph-0305075 Some possible Dark Matter Searches Hunter et al (1997) • WIMP annihilation in galactic centre or galactic halos • talk by L.Wai • Extragalactic WIMP annihilation relic • SUSY dark matter • Kaluza Klein dark matter • talk by A. Lionetto • Active DM and New Physics working group (46 members) • this science require large sensitivity on a broad energy range, localization power, energy resolution, time resolution for variability search … key elements for the whole GLAST physics program

6. g e+ e- The LAT instrument: how we built it • Overall modular design: • 4x4 array of identical towers - each one including a Tracker, a Calorimeter and an Electronics Module. • Surrounded by an Anti-Coincidence shield (not shown in the picture). • Tracker/Converter (TKR): • Silicon strip detectors (single sided, each layer is rotated by 90 degrees with respect to the previous one) • W conversion foils • ~80 m2 of silicon • ~106 electronics chans • fully digital electronics • High precision tracking, small dead time • Anti-Coincidence (ACD): • Segmented (89 tiles) • Self-veto @ high energy limited • 0.9997 detection efficiency (overall) • Calorimeter (CAL): • 1536 CsI crystals • Analog 4 range readout • 8.5 X0 • Hodoscopic • Shower profile reconstruction (leakage correction)

7. Ground Cosmic Rays muons in the full LAT

8. Technology impact – angular resolution EGRET (1991-2000) Phases 1-5 • Spark chamber • sense electrode spacing ~mm • sensitive layer depth ~cm • up to 28 hit over >1m LAT (2007- >2012) 1-yr simulation • Si-strip detectors • sense electrode spacing ~0.2mm • better single hit resolution • sensitive layer depth ~0.4mm • up to 36 hit over 0.8m • converter proximity to minimize MCS Cygnus region (150 x 150), Eg > 1 GeV

9. Active Galactic Nuclei • AGNs major component of EG g-rays: • vast amount of energy from a very compact central volume • large fluctuations in the luminosity • energetic, highly collimated, relativistic particle jets • prevailing idea: accretion onto super-massive black holes (106 – 1010 solar masses) • AGN physics • Catalogue AGN classes from a large sample (thousands new sources expected at our sensitivity) • measure spectrum in uncovered gamma-ray energy band • identify leptonic (SSC/ESC) and hadronic (p0 decay) contributions • track flares (down to mins) and correlate to other wavelengths • EBL search from spectra roll-off at large z

10. g lines 50 GeV 300 GeV Dark Matter Spectroscopy • EM Calorimeter technology impact • hodoscopic, granular for shower imaging • large electronics dynamic range • specific energy dependent recon strategies • correct TKR loss at low E • correct shower leakage at high E • large energy coverage crucial to provide overlap with ground ACT • absolute CAL calibration • m + beam test on ground • heavy ions on orbit • cross-calibration with ACT on known bright sources (e.g. Crab) • confirm LAT on orbit calibration • help reduce systematics at ACT

11. Gamma Ray Bursts • GRBs phenomenology: • Dramatic variations in the light curve on a very short time scale • Isotropic distribution in the sky (basically from BATSE, on board CGRO, but little data @ energies > 50 MeV) • Non repeating (as far as we can tell…) • Spectacular energies (~ 1051 – 1052 erg) • GRBs physics: • GLAST should detect ~ 200 GRBs/year above 100 MeV (a good fraction of them localized to better than 10’ in real time) • 10 keV-300 GeV coverage from GBM+LAT: spectroscopy and timing studies to identify acceleration mechanism • Quantum gravity effects from time dispersion of light curve vs Z • large energy lever arm • minimal dead time Simulated GRB spectrum GBM NaI GBM BGO LAT 100GeV 10KeV 100MeV

12. LAT status Current status: • Integration of Detectors and Electronics complete • Flight software test in progress (SPACECRAFT INTERFACE) (EVENT PROCESSING) Coming milestones: • LAT environmental tests at NRL - april • Calibration Unit Beam test at CERN August/September • Integration with the spacecraft • Launch – august 2007 (TRIGGER) Trigger Power (POWER) bottom view of the LAT and associated electronics

13. GLAST launch – 8/2007 • GLAST is the next generation satellite g-ray observatory • prime physics on a wide range of topics, including DM and new physics searches, is expected (10 active science working groups) thanks to excellent instrument performance • GLAST put together the HEP and astrophysics communities to build a high performance detector for a first rank physics program – hopefully the shared scientific interest on the nature of Dark Matter will see revolutionary discoveries animation by P. Michelson – LAT PI

14. Pulsars • detect new gamma-ray pulsars (~250) • large effective area • direct pulsation search in the g-ray band • high time resolution + absolute time recording (2ms with GPS) • precise test of polar cap vs outer gap emission models • energy resolution

15. E (MeV) Resolution and sensitivity for CR physics • SNR widely believed to be the source of CR proton acceleration after shell interaction with interstellar medium • the p0 bump again from NN interaction GLAST has the capability to • identify many SNR • resolve SNR shells from core neutron star • measure SNR spectra GLAST simulations showing SNR -Cygni spatially and spectrally resolved from the compact inner gamma-ray pulsar – a clear p0 decay signature from the shell would indicate SNR as a source of proton CR

16. EGRET - 5 years map GLAST 1 year sky-survey simulation Technology impact – sensitivity • HEP detectors and electronics for • low aspect ratio for enhanced FOV • low noise detectors for self-trigger capability and high data rate - L0T ~10KHz • highly efficient ACD and on-board computing power for background reduction - up to ~104 • fast detectors and electronics for reduced dead time - ~26ms Integral Flux (E>100 MeV) cm-2s-1 Populate large catalog of sources to subtract from residual background  particularly relevant for extra-galactic DM search

17. Resolving the background • With a best PSF ~arcminnew can • complete EGRET catalog (unidentified sources) • build a LAT catalog • resolve diffuse into sources • identify new classes of sources and possibly DM sources (NO radio partner) AO PSF vs Energy Improvements expected and under evaluation due to converter reduction