1. 1st page of proposal with 2 pictures and institution list 1

2. Milagro@SAGENAP OUTLINE I. Astrophysics from Milagro Brenda Dingus, University of Wisconsin--Madison II.The Milagro Detector Gus Sinnis, Los Alamos National Laboratory III.Results from Milagro Don Coyne, University of California Santa Cruz IV.Completion of Milagro with Outriggers Tony Shoup, University of California Irvine V.Budget & Funding History Jordan Goodman, University of Maryland BOTTOM LINE Large field of view TeV observatory has unique scientific abilities that complement VERITAS / GLAST. Milagro has been built to budget and is now taking data. Milagrito & preliminary Milagro data indicate the scientific goals are within reach. A significant improvement in the sensitivity can be accomplished by completing the planned construction. Need support for Milagro operations, data analysis, and last 10% of construction. 2

3. Astrophysics from Milagro 3 TeV Astrophysics Lower Energy Bump is Synchrotron Emission from Relativistic Electrons Higher Energy Bump is ? Electron Inverse Compton Scattering AND/OR Proton Induced Cascades Peak of Both Bumps is sensitive to E particle, B, n photon, n gas Peak of Both Bumps exhibits greatest VARIABILITY Typical Multiwavelength Spectrum from High Energy  -ray source

4. Astrophysics from Milagro 4 Astrophysical Sources TeV All Sky Map

5. Astrophysics from Milagro 5 Why so Few Observed TeV Sources? Perhaps Fewer TeV Accelerators, but X-ray emission from supernova remnants and a ctive galactic nuclei => TeV electrons Sources of ultrahigh energy cosmic rays likely to emit TeV  -rays TeV  -rays are Attenuated  (TeV) +  (eV) --> e - + e + Attenuation can be internal to the source or in transit Transit attenuation depends on model of Galaxy Formation Observation of ~200 GeV  -rays implies z<0.3 Better TeV Observatories are Required Improved Flux Sensitivity to Detect Weaker Sources VERITAS, HESS, MAGIC, CANGAROO Lower Energy Threshold to Detect Distant Sources STACEE, CELESTE, Solar 2 Large Field of View, High Duty Factor to Identify New and Flaring Sources MILAGRO, Tibet EA , ARGO Primack et al, 1999

6. Astrophysics from Milagro 6 TeV Observatories GeV Observatories EGRET0.6sr30% live time GLAST2.4sr90%live time TeV Observatories Atmospheric0.003sr5-10% live time Cherenkov => ~ dozen sources / year Telescopes with plotted sensitivity Milagro2sr> 90%live time

7. Astrophysics from Milagro 7 Variability of Active Galactic Nuclei (AGN) GeV Observations 66-93 AGN detected (Hartman et al, 1999) >70% are variable (Mukherjee et al, 1999) Some variability is correlated with other wavelengths  but some is NOT TeV Observations Mrk 421 & Mrk 501 Detected by Many Observers Both Variable Mrk 421 Rapid Flares Mrk 501 Long High State Other AGN Only detected once Only detected by 1 Observer 1ES2344+514 PKS2155-304 1ES1959+650 3C66A Whipple Mrk501 light curve Quinn et al 1999 X-ray > 100 MeV

8. Astrophysics from Milagro 8 Gamma Ray Bursts (GRBs) Rapid Variability, Unknown Direction, ~ 1 / day / 4  sr => Large Field of View, High Duty Factor ESSENTIAL Slew time for Pointed TeV Observatories

9. Astrophysics from Milagro 9 Are GRBs near enough? Distance has been measured to the host galaxies or optical afterglows of ~ dozen GRBs % of GRBs near enough for TeV observations is uncertain Distance distributions inferred from the BATSE-measured fluence distribution varies from <0.1% (Schmidt,1999) to ~10% (Dermer, 2000) of GRBs being within z < 0.3. Different distance distributions are expected from hypernovae (death of massive stars) than from neutron star - neutron star coalescences More than one population of GRB sources may exist with different distance distributions

10. Astrophysics from Milagro 10 TeV  -rays from GRBs GeV Observations => Relativistically expanding fireball with Bulk Lorentz Factors of 100-1000 Average EGRET spectrum from brightest bursts => E -1.95±0.25 differential power law extending to 10 GeV Evidence of TeV emission from GRB970417a from Milagrito (Atkins et al. 2000 ApJ Lett in press) GRB Spectral evolution from model of Dermer, 1999

11. Astrophysics from Milagro 11 Extended Sources Atmospheric Cherenkov Telescopes are less effective at rejecting cosmic-ray background for non-point sources Long integration time of Milagro can improve sensitivity Supernova Remnants Sizes can extend to a few degrees Highest energy observations identify proton produced  -rays Galactic Plane GeV flux measurements are higher than model prediction Excess can be explained by Inverse Compton emission which may be observable in TeV  -rays Milagro observes 10 6 cosmic-rays/day within 1 o of plane and Air Cherenkov Telescope u.l. are ~10 -3 of the cosmic ray flux Non-Transient Sources IC p+p Brem. Poh l & Esposito, 1998

12. Astrophysics from Milagro 12 The Unknown 60% of EGRET sources are unidentified Many are Galactic Some have hard spectra Some are variable (one exceeded the Crab flux once) TeV detections would measure more precise position New TeV sources may exist Milagrito performed 1st all sky TeV survey No point sources with continuous flux > 5 x Crab flux exist in Northern Hemisphere (A. Smith et al. 1999) Possible new sources include Evaporation of Primordial Black Holes Galactic Black Holes with Relativistic Jets X-ray Binaries TeV- selected Active Galactic Nuclei ??????

13. Astrophysics from Milagro 13 Astrophysics from Milagro TeV  -ray observations add to our understanding of Nature’s Highest Energy Particle Accelerators GeV-TeV  -ray astrophysics is an active and growing field with new observations and observatories Milagro is an All-Sky TeV monitor of the northern hemisphere with unique, but complementary, capabilities to the many current and planned TeV pointed observatories