Wide-Field Gamma-Ray Instruments: Milagro Results Plans for HAWC

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Wide-Field Gamma-Ray InstrumentsMilagro
ResultsPlans for HAWC
Scientific Goals Experimental Techniques Recent
Results Future Plans

• Gus Sinnis
• Los Alamos National Lab
• TeVPA 2008 Beijing

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Modern Gamma-Ray Telescopes
High Sensitivity HESS, MAGIC, VERITAS, CANGAROO
Low Energy Threshold EGRET/FERMI
Large Aperture/High Duty Cycle Milagro, Tibet,
ARGO
Large Area Excellent Background
Rejection Excellent Angular Resolution Low Duty
Cycle/Small Aperture
Space-based (Small Area) Background Free Good
Angular Resolution Large Duty Cycle/Large Aperture
Large Area Good Background Rejection Good
Angular Resolution Large Duty Cycle/Large Aperture
Sky Survey 100 MeV - 10 GeV AGN
Physics Transients (GRBs) lt 100 GeV
Unbiased Sky Survey Extended sources Highest
energies Transients (GRBs)
Surveys of limited regions of sky High
Resolution Energy Spectra Source morphology
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Science Goals of Ground-Based Observatories

• Cosmic-ray origins
• High-energyW and high resolutionA spectra of
  Galactic sources
• Galactic diffuse emissionW
• Discover Galactic cosmic-ray acceleratorsA
• Particle acceleration
• Transient phenomena (AGN flares and GRBs)
• prompt emissionW delayedA
• orphan flaresW, TeV duty factorsW, fastest
  phenomenaA
• Multi-wavelength (GLAST, x-ray, optical, radio)
  WA, multi-messengerA
• Source morphologyA
• PulsarsA
• Fundamental Physics
• Lorentz invariance (GRBW, AGNA)
• Dark matter detectorA (annihilation gammas from
  neutralinos)
• Discovery
• Unbiased sky survey (2.6? sr) to 2 of Crab
  NebulaW
• Deep Galactic survey to 0.1 of CrabA

W Wide field instrument A Air Cherenkov Array
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The Milagro Collaboration

• Abdo, Allen, Berley, DeYoung, Dingus, Ellsworth,
  Gonzalez, Goodman, Hoffman, Huentemeyer,
  Kolterman, Linnemann, McEnery, Mincer, Nemethy,
  Pretz, Ryan, Saz Parkinson, Shoup, Sinnis, Smith,
  Williams, Vasileiou, Yodh

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Water Cherenkov Technology
Provides fully active area Converts gs to
electrons g electron 61

• gammas
• electrons

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Milagro Gamma-Ray Observatory

• Angular resolution0.5o
• 1700 Hz trigger rate

• 2600m above sea level
• 2 sr field-of-view
• 95 duty factor

A. Abdo, B. Allen, D. Berley, T. DeYoung,B.L.
Dingus, R.W. Ellsworth, M.M. Gonzalez, J.A.
Goodman, C.M. Hoffman,P. Huentemeyer, B.
Kolterman, J.T. Linnemann, J.E. McEnery, A.I.
Mincer, P. Nemethy, J. Pretz, J.M. Ryan, P.M. Saz
Parkinson, A. Shoup, G. Sinnis, A.J. Smith, D.A.
Williams, V. Vasileiou, G.B. Yodh
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How Milagro Works

• Direction via timing (1 ns)
• Background rejection via muons
• Energy via shower size

time
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Background Rejection in Milagro

• Bottom layer (6 mwe overburden) detects
  penetrating component of hadronic EAS
• Reject 95 of background
• Retain 50 of gammas
• Rejection is highly energy dependent!

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Milagro Wide Field View of Galaxy (10-50 TeV)
Boomerang PWN
Confirmed by HESS
Cygnus Region
Sources are extended Correlated with EGRET GeV
catalog Hard spectra (-2.3 connects to
EGRET) Clearly visible diffuse component
Geminga
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Galactic Diffuse Emission
Cygnus Region with Matter Density Contours
overlaying Milagro Observation
?? component due to CR-matter interactions Inverse
Compton to e- ? (CMB) interactions
Milagro
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Large-Scale Cosmic-Ray Anisotropy
New analysis technique forward backward
asymmetry Milagro results consistent with Tibet
AS? discovery Modulation amplitude 5x10-3 with
deficit at RA180o
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Large-Scale Cosmic-Ray AnisotropyTime Dependence
Amplitude of anisotropy has been increasing over
past 6 years (solar max to solar min) Error bars
include systematic errors
Solar Max 2000-2001
Solar Min 2007/8
9/22/2006
8/14/2002
5/10/2005
4/1/2001
12/27/2003
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Intermediate-Scale Cosmic-Ray Anisotropy at 10
TeV

• Excesses are hadronic particles not gamma rays
• Anisotropy 6x10-4 (10 of the large-scale
  anisotropy)
• Larmor radius of 10 TeV proton in 1 ?G is .01pc
• Lifetime of 10 TeV neutron is 0.1 pc
• Explanations difficult requires ordered B-field
  (Drury Aharonian 2008)

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Straightforward Improvements to Milagro

• Higher Altitude closer to shower maximum
• Larger area (especially of muon detector)
• Optical isolation of detector elements

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HAWC High Altitude Water Cherenkov

• 10-15x more sensitive than Milagro
• 1 Crab in 5 hrs, 10 Crab in 3 minutes
• Located at base of volcán Sierra Negra
• latitude 18º 59
• altitude 4100m
• Inside Parque Nacional Pico de Orizaba
• 2 hours from Puebla (INAOE)

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The HAWC Collaboration
Instituto Nacional de Astrofísica Óptica y
Electrónica Alberto Carramiñana, L. Carasco, E.
Mendoza, S. Silich, G. T. Tagle Universidad
Nacional Autónoma de México R. Alfaro, E.
Belmont, M. Carrillo, M. González, A. Lara, Lukas
Nellin, D. Page, V. A. Reese, A. Sandoval, G.
Medina Tanco,O. Valenzuela, W. Lee Benemérita
Universidad Autónoma de Puebla C. Alvarez, A.
Fernandez, O. Martinez, H. Salazar Universidad
Michoacana de San Nicolás de Hidalgo L.
Villasenor Universidad de Guanajuato David
Delepine, Victor Migenes, Gerardo Moreno, Marco
Reyes, Luis Ureña UC Irvine G. Yodh University
of New Hampshire J. Ryan

• Los Alamos National Laboratory
• B. Dingus, J. Pretz, G. Sinnis
• Uniersity of Maryland
• D. Berley, R. Ellsworth, J. Goodman, A. Smith, G.
  Sullivan, V. Vasileiou
• University of New Mexico
• J. Matthews
• University of Utah
• D. Kieda, P. Huentemeyer
• Pennsylvania State University
• Ty DeYoung
• NASA Goddard
• J. McEnery
• Naval Research Laboratory
• Abdo
• U.C. Santa Cruz
• M. Schneider

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HAWC Design

• 1000 large tanks (4m dia x 4m height)
• 1 PMT/tank (looking up)
• Non-reflective interior
• 22,000 m2 enclosed area
• 4100 m above sea level

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HAWC Performance Effective Area

• At low energies (lt1 TeV), HAWC has 30x the
  effective area of Milagro
• larger dense sampling area (5x)
• higher altitude
• Larger muon detection area (10x)

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HAWC Performance Angular Resolution

• At similar energies, HAWCs angular resolution is
  1.5x better than Milagro.
• larger area
• higher altitude
• optical isolation
• Resolution defined as sigma of a 2-d Gaussian.

Resolution at 10 TeV
Angular Resolution (degrees)
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HAWC Background Rejection

• 10x better hadron rejection than Milagro above 10
  TeV
• larger muon detection area (10x)
• optical isolation
• 2.5x higher gamma efficiency at lower energies (lt
  10 TeV)

Gammas
Size of HAWC
Protons
Size of Milagro deep layer
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HAWC Performance Energy Resolution I
Fixed first interaction elevation 30km
Energy Resolution in an EAS is dominated by the
fluctuations in the depth of first interaction
Distribution of height of 1st interaction
10 TeV gamma-ray shower Longitudinal Profile
HAWC elevation 4.1km
http//www.ast.leeds.ac.uk/fs/photon-showers.html

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HAWC Performance Energy Resolution II

• EAS arrays can measure shower size very well
  (lt20 resolution)
• Shower fluctuations (depth of 1st interaction)
  dominate energy resolution of array.
• Because of increased altitude HAWC will have much
  better energy resolution than Milagro

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Point Source Sensitivity
2000 km2 sr hr
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High-Energy Spectra with HAWC

• HESS J1616-508
• 0.2 Crab _at_ 1 TeV
• dN/dE ? -2.3
• Highest energy 20 TeV

Simulated HAWC data 1 year no cutoff
Simulated HAWC data 1 year 40 TeV cutoff
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Transient Phenomena AGN and GRB

• PKS J2155-304 (z0.117) 50x quiescent (1 hr)
  dN/dEkE-3.5
• 6 s in HAWC

GLAST and HAWC sensitivity for a source of
spectrum dN/dEKE-2 z0 no E cutoff z0.1 Eexp7
00GeV z0.3 Eexp260GeV z0.5 Eexp170GeV
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Transient Phenomena AGN Flares

• HAWC will obtain TeV duty factors, search for
  orphan flares, notify other observers in real
  time.
• All sources within 2 p sr would be observed
  every day for 5 hrs.
• HAWC sensitivity 10 Crab in 3 min and 1 Crab in
  5 hrs

Worldwide Dataset of TeV Observations of Mrk421
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Conclusions

• The role of wide-field instruments now
  established
• Large sensitivity gain (gt10x) is achievable
• Strong Scientific Motivation
• Highest energies (gt5-10 TeV)
• Extended sources
• Galactic diffuse emission
• Unique TeV transient detector (GRBs and AGN
  flares)
• 4x Crab in 15 minutes
• HAWC Status
• Fall 2007 Full proposal submitted to NSF and
  CONyCT
• July 2008 NSF funds 1M MRI grant for HAWC
• Develop site infrastructure (roads, power, water,
  internet)
• RD for large tank
• US funding decision awaits Particle Astrophysics
  SAG (early 2009)

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Thank You!

• "Confirming an idea is always gratifying. But
  finding what you don't expect opens new vistas on
  the nature of reality. And that's what humans,
  including those of us who happen to be
  physicists, live for.
• -Brian Greene NYT 9/12/2008