1. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 1 How many neutralinos are there? Expansion of universe Depletion of neutralinos Creation of neutralinos Negligible at late times Negligible at earlier times To determine the current number of neutralinos (relic abundances), we need to solve the Boltzmann equation for early and late times Hubble Constant

2. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 2 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

3. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 3 Gamma ray Large Area Space Telescope GLAST will measure the direction, energy and arrival time of  rays LAT: main instrument GBM: smaller instrument catching bursts of radiation Orbit 575 km, circular Inclination 28.5 o Lifetime 5 years (min) Launch Date 2007 Launch Vehicle Delta 2920H-10 Launch Site Kennedy Space Center

4. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 4 2007 GLAST 2001 LAT Balloon Flight Why do we need a satellite ?

5. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 5 Why  rays ? satellite ~ 500 km center of galaxies radiate gamma rays  Universe is transparent to  rays  not affected by magnetic fields  probes early times of the Universe Gamma rays: most violent energy processes found in Nature Gamma rays: similar to visible light but with higher frequency

6. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 6 Light – a Fingerprint of the Universe The electromagnetic spectrum carries a lot of information about the evolution of the Universe Optical  Rays Credit; Lund ObservatoryCredit: COBE Team Infrared Credit: COBE Team Microwave Credit: WMAP Team Microwave

7. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 7 EGRET found 300 objects in 10 yrs LAT: expects to find 300 objects in 2 days LAT : expects to find 10,000 objects in 2 yrs

8. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 8 Gamma-Ray Bursts Last from milliseconds to ~ 100 seconds Brightest phenomenon in Universe Several bursts expected daily Do not know what causes them !

9. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 9 galaxies radiate gamma rays (very powerful) Where does the energy come from? Black holes inside the galaxy?? AGN - Supermassive Black Holes ? Extragalactic Jet Accretion disk Black Hole

10. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 10 Dark Matter total dark halo stars gas total dark halo stars gas total dark halo stars gas total dark halo stars gas 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

11. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 11 Simulations of Local Group Dark Matter Simulations We do not know what dark matter is but we can guess We use simulations to indicate how dark matter is formed GLAST could measure dark matter and explain its origins Credit: B. Moore, www.nbody.net z = 20Past z = 5z = 10 Todayz = 1

12. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 12 GLAST LAT Overview e+e+ e–e–  Tracker Grid (& Thermal Radiators) Calorimeter ACD ~150 collaborators Measures direction Measures Energy Get rid of background

13. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 13  How do we see gamma rays? E  --> m e + c 2 + m e - c 2 electronpositron LAT detects the gamma ray indirectly through pair conversions (into charged particles) Charged particles create current in each detector There are 100,000 charged particles external to the LAT for every gamma ray in space The unwanted charged particle background is REJECTED by the outermost detector ( in green) Charged particle background

14. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 14 Two Tower Integration Installation of Tower A in Single bay Tower A in Grid. Tower B being installed in grid.

15. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 15 Hole to accommodate Solar Array mast Overview of LAT Mechanical Systems LAT in the Delta-II fairing Radiator Cut-outs for possible S.A. launch locks VCHP reservoirs Radiator Mount Bracket at 4 corners of Grid

16. Eduardo do Couto e Silva - ATC/LM Colloquium, June 2004 16 GLAST Feb 2007 launch