Transcript ppt
How many neutralinos are there? To determine the current number of neutralinos (relic abundances), we need to solve the Boltzmann equation for early and late times Negligible at earlier times dn dt Hubble Constant Negligible at late times 3Hn xx v [( n ) (n ) ] 2 Expansion of universe Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Depletion of neutralinos eq 2 Creation of neutralinos1 Why are we so excited about GLAST? • GLAST will – Study gamma radiation from Universe with a lot more details than previous missions – explore regions never explored before in space – gives us insight in how the Universe evolved • The GLAST Project allows us to – develop a successful partnership between DOE and NASA 2 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Gamma ray Large Area Space Telescope GLAST will measure the direction, energy and arrival time of g rays Orbit 575 km, circular LAT: main instrument Inclination 28.5o Lifetime 5 years (min) Launch Date 2007 Launch Vehicle Delta 2920H-10 Launch Site Kennedy Space Center GBM: smaller instrument catching bursts of radiation 3 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Why do we need a satellite ? 2007 GLAST 2001 LAT Balloon Flight 4 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Why g rays ? Gamma rays: similar to visible light but with higher frequency • Universe is transparent to g rays g center of galaxies radiate gamma rays • g not affected by magnetic fields • g probes early times of the Universe satellite ~ 500 km Gamma rays: 5 most violent energy processes found in Nature Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Light – a Fingerprint of the Universe Credit; Lund Observatory Optical Credit: COBE Team Infrared Credit: WMAP COBE Team Team Microwave Microwave g Rays The electromagnetic spectrum carries a lot of information about the evolution of the Universe Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 6 found 300 10,000 objects in 10inyrs LAT :EGRET expects to objects in 2 yrs LAT: expects to find find 300 objects 2 days 7 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Gamma-Ray Bursts • Last from milliseconds to ~ 100 seconds • Brightest phenomenon in Universe • Several bursts expected daily • Do not know what causes them ! 8 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 AGN - Supermassive Black Holes ? Black Hole Extragalactic Jet galaxies radiate gamma rays (very powerful) Where does the energy come from? Accretion disk Black holes inside the galaxy?? 9 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Dark Matter How is matter measured in the galaxy? 1. By calculating how fast stars go around the center of the galaxy 2. By measuring light from the galaxy and using results in an equation to obtain amount of matter 1 and 2 give different results !!!! Strong Evidence that Dark Matter exists Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 10 Dark Matter Simulations Credit: B. Moore, www.nbody.net Past z = 20 We do not know what dark matter is but we can guess z = 10 z=5 We use simulations to indicate how dark matter is formed z=1 Today GLAST could measure dark matter and explain its origins Simulations of Local Group Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 11 GLAST LAT Overview g Tracker ACD Get rid of background Measures direction e+ e– Grid (& Thermal Radiators) Calorimeter Measures Energy ~150 collaborators 12 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 How do we see gamma rays? Eg --> me+c2 + me-c2 LAT detects the There are 100,000 gamma ray particles indirectly charged through pairLAT external to the conversions for every gamma ray (into incharged space particles) Charged particles The unwanted create current in each charged particle detector is background REJECTED by the outermost detector ( in green) Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 g Charged particle background electron positron 13 Two Tower Integration Installation of Tower A in Single bay Tower A in Grid. Tower B being installed in grid. 14 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 Overview of LAT Mechanical Systems Radiator Cut-outs for possible S.A. launch locks Hole to accommodate Solar Array mast VCHP reservoirs LAT in the Delta-II fairing Radiator Mount Bracket at 4 corners of Grid 15 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 GLAST Feb 2007 launch 16 Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004