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

1st page of proposal

with 2 pictures and institution list

1

Milagro@SAGENAP

OUTLINE

I. Astrophysics from MilagroBrenda Dingus, University of Wisconsin--Madison

II. The Milagro DetectorGus Sinnis, Los Alamos National Laboratory

III. Results from MilagroDon Coyne, University of California Santa Cruz

IV. Completion of Milagro with OutriggersTony Shoup, University of California Irvine

V. Budget & Funding HistoryJordan 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

Astrophysics from MilagroAstrophysics from Milagro 3

Radio Optical X-ray GeV TeV

E2 dN/dEorν Fν

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 Eparticle, B, nphoton, ngas

Peak of Both Bumps exhibits greatest VARIABILITY

Typical Multiwavelength Spectrum

from High Energy -ray source


Astrophysical Sources

TeV All Sky Map


Why so Few Observed TeV Sources?

Perhaps Fewer TeV Accelerators, but X-ray emission from supernova remnants and

active 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 transitTransit attenuation depends on model of Galaxy FormationObservation 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 SourcesSTACEE, CELESTE, Solar 2

Large Field of View, High Duty Factor to Identify New and Flaring Sources

MILAGRO, Tibet EA, ARGO

Primack et al, 1999


TeV Observatories

GeV Observatories

EGRET 0.6 sr 30% live time

GLAST 2.4 sr 90% live time

TeV Observatories

Atmospheric 0.003 sr 5-10% live timeCherenkov => ~ dozen sources / yearTelescopes with plotted sensitivity

Milagro 2 sr > 90% live time


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

3C66AWhipple Mrk501 light curve

Quinn et al 1999

X-ray

> 100 MeV


Gamma Ray Bursts (GRBs)

Rapid Variability, Unknown Direction, ~ 1 / day / 4 sr

=> Large Field of View, High Duty Factor ESSENTIAL

Slew time for PointedTeV Observatories


date redshift total energyfor isotropic emission

970228 0.695 5 x 10 51 ergs970508 0.835 8 x 10 51 ergs970828 0.958971214 3.412 3 x 10 53 ergs980425 0.0085 7 x 10 47 ergs980613 1.096980703 0.967 1 x 10 53 ergs990123 1.600 3 x 10 54 ergs990510 1.619 3 x 10 53 ergs990712 0.43991208 0.706 1 x 10 53 ergs991216 1.02000301C 2.0335 2 x 10 51 ergs

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 uncertainDistance 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


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


Extended SourcesAtmospheric Cherenkov Telescopes are less effective at rejecting

cosmic-ray background for non-point sourcesLong integration time of Milagro can improve sensitivity

Supernova RemnantsSizes can extend to a few degreesHighest energy observations identify proton produced -rays

Galactic Plane GeV flux measurements are higher than model predictionExcess can be explained by Inverse Compton emission which

may be observable in TeV -raysMilagro observes 106 cosmic-rays/day within 1o 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


The Unknown

60% of EGRET sources are unidentifiedMany are Galactic Some have hard spectraSome are variable (one exceeded the Crab flux once)TeV detections would measure more precise position

New TeV sources may existMilagrito 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

??????


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

Documents

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