Post on 16-Dec-2015
Wide-Field Gamma-Ray Instruments:Milagro ResultsPlans for HAWC
Gus Sinnis
Los Alamos National Lab
TeVPA 2008 Beijing
Scientific Goals
Experimental Techniques
Recent Results
Future Plans
Modern Gamma-Ray Telescopes
Large Aperture/High Duty CycleMilagro, Tibet, ARGO
Large Area
Good Background Rejection
Good Angular Resolution
Large Duty Cycle/Large Aperture
Unbiased Sky Survey
Extended sources
Highest energies
Transients (GRB’s)
Low Energy ThresholdEGRET/FERMI
Space-based (Small Area)
“Background Free”
Good Angular Resolution
Large Duty Cycle/Large Aperture
Sky Survey 100 MeV - 10 GeV
AGN Physics
Transients (GRBs) < 100 GeV
High SensitivityHESS, MAGIC, VERITAS,
CANGAROO
Large Area
Excellent Background Rejection
Excellent Angular Resolution
Low Duty Cycle/Small Aperture
Surveys of limited regions of sky
High Resolution Energy Spectra
Source morphology
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
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
The Milagro Collaboration
TeV gamma at 2600m asl
Water Cherenkov Technology
CASA-MIA
Milagro
• gammas• electrons
Provides fully active areaConverts ’s to electrons: electron ~ 6:1
60 m 80 m
Milagro Gamma-Ray Observatory• 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
8’ dia. x 3’ deep
• Angular resolution~0.5o
• 1700 Hz trigger rate
How Milagro Works
• Direction via timing (~1 ns)• Background rejection via muons• Energy via shower size
8 meters
e
80 meters
50 meters
time
time
position
ARGO
Background Rejection in Milagro
Bottom layer (6 mwe overburden) detects penetrating component of hadronic EAS
Reject 95% of backgroundRetain 50% of gammasRejection is highly energy dependent!
Proton MC Proton MC
Data Data MC MC
Boomerang PWN
Cygnus Region
Confirmed by HESS
Geminga
Milagro Wide Field View of Galaxy (10-50 TeV)
Sources are extendedCorrelated with EGRET GeV catalogHard spectra (-2.3 connects to EGRET)Clearly visible diffuse component
Tibet ASEGRET
Galactic Diffuse Emission
Cygnus Region with Matter Density Contours overlaying Milagro
Observation
component due to CR-matter interactions
Inverse Compton to e- (~CMB) interactions
Cygnus Region65o < l < 85o
GALPROP (Strong et al.)
EGRET data
Milagro
Milagro
EGRET data
GALPROP (Strong et al.)
30o < l < 65o
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 RA=180o
Large-Scale Cosmic-Ray Anisotropy:Time Dependence
4/1/
2001
8/14
/200
2
5/10
/200
5
9/22
/200
6
12/2
7/20
03
Solar Max 2000-2001
Solar Min 2007/8
Amplitude of anisotropy has been increasing over past 6 years (solar max to solar min)
Error bars include systematic errors
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)
BA
heliotailGeminga
Galactic Plane
HAWC: High Altitude Water Cherenkov
10-15x more sensitive than Milagro1 Crab in 5 hrs, 10 Crab in 3 minutes
Located at base of volcán Sierra Negra• latitude : 18º 59’• altitude : 4100mInside Parque Nacional Pico de Orizaba2 hours from Puebla (INAOE)
The HAWC Collaboration
Instituto Nacional de Astrofísica Óptica y ElectrónicaAlberto Carramiñana, L. Carasco, E. Mendoza,
S. Silich, G. T. TagleUniversidad 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. LeeBenemérita Universidad Autónoma de Puebla
C. Alvarez, A. Fernandez, O. Martinez, H. SalazarUniversidad Michoacana de San Nicolás de Hidalgo
L. VillasenorUniversidad de Guanajuato
David Delepine, Victor Migenes, Gerardo Moreno, Marco Reyes, Luis Ureña
UC IrvineG. Yodh
University of New HampshireJ. Ryan
Los Alamos National LaboratoryB. Dingus, J. Pretz, G. Sinnis
Uniersity of MarylandD. Berley, R. Ellsworth, J. Goodman, A.
Smith, G. Sullivan, V. VasileiouUniversity of New Mexico
J. MatthewsUniversity of Utah
D. Kieda, P. HuentemeyerPennsylvania State University
Ty DeYoungNASA Goddard
J. McEneryNaval Research Laboratory
A.AbdoU.C. Santa Cruz
M. Schneider
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
150 m150 m15
0 m
150
m100 MeV photons shown
100 MeV 1/50 photons shown
HAWC Performance: Effective Area• At low energies (<1 TeV), HAWC has ~30x the effective area of Milagro
• larger dense sampling area (5x)• higher altitude• Larger muon detection area (10x)
HAWC w/reconstruction
HAWC w/Rejection
Milagro w/reconstruction
Milagro w/Rejection
HAWC Performance: Angular Resolution
• At similar energies, HAWC’s 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 TeVA
ngul
ar R
eso
lutio
n (d
egre
es)
HAWC Background Rejection
Gam
mas
Pro
ton
s
Size of Milagro deep layer
Size of HAWC
• 10x better hadron rejection than Milagro above 10 TeV• larger muon detection area (10x)• optical isolation
• 2.5x higher gamma efficiency at lower energies (< 10 TeV)
HAWC Performance: Energy Resolution I
http://www.ast.leeds.ac.uk/~fs/photon-showers.html
Fixed first interaction elevation: 30km
HA
WC
ele
vatio
n 4.
1km
10 TeV
gamm
a-ray shower Longitudinal P
rofile
Distribution of height of Distribution of height of 11stst interaction interaction
Energy Resolution in an EAS is dominated by the fluctuations in the depth of first interaction
HAWC Performance: Energy Resolution II
• EAS arrays can measure shower size very well (<20% 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
Point Source Sensitivity
IACTs 50 hrs (~0.06 sr/yr)IACTs 50 hrs (~0.06 sr/yr)
1 yr1 yr
EAS 5 yrs (~2EAS 5 yrs (~2 sr) sr)
2000 km
2000 km22 sr
hr sr
hr
High-Energy Spectra with HAWC
HESS J1616-508
0.2 Crab @ 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
Transient Phenomena: AGN and GRB
PKS J2155-304 (z=0.117) 50PKS J2155-304 (z=0.117) 50xx quiescent (1 hr) dN/dE=kE quiescent (1 hr) dN/dE=kE-3.5-3.5
6 6 in HAWC in HAWC
10-1
210
-10
10-8
TeV AGN flares
GRB <1 MeV
GLAST and HAWC sensitivity for a source of spectrum dN/dE=KE-2
z=0 no E cutoffz=0.1 Eexp~700GeVz=0.3 Eexp~260GeVz=0.5 Eexp~170GeV
Gus SinnisAGIS Collaboration Meeting June 2008
Worldwide Dataset of TeV Observations of Mrk421
Transient Phenomena: AGN Flares
• HAWC will obtain TeV duty factors, search for orphan flares, & notify other observers in real time.
• All sources within ~2 sr would be observed every day for ~ 5 hrs.• HAWC sensitivity: 10 Crab in 3 min and 1 Crab in 5 hrs
3 min3 min
5 hr5 hr
Conclusions
• The role of wide-field instruments now established• Large sensitivity gain (>10x) is achievable• Strong Scientific Motivation
– Highest energies (>5-10 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) • R&D for large tank
– US funding decision awaits Particle Astrophysics SAG (early 2009)
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