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Multiwavelength Astronomy:Probing Nature’s
Particle Accelerators
Brenda Dingus Los Alamos National Lab
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Shedding Some Lighton Potential Neutrino Sources
Brenda Dingus Los Alamos National Lab
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Brenda Dingus, 31 May 2008
Nature’s Particle Accelerators
HST Image of M87 (1994)
Black Hole producing relativistic jet of particles
Binary Neutron Star Coalescing
Artist Conception of Short GRBs
Spinning Neutron Star powering a relativistic wind
Massive Star Collapsing into a Black Hole
SuperComputer Calculation
Chandra Image of Crab
HESS TeV+ x-ray
TeV image of Vela Jr. Supernova Remnant
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Brenda Dingus, 31 May 2008
Astrophysical Particle Accelerators
Radio Optical X-ray GeV TeV
E 2 dN/dEor
E dN/dln(E)[ergs/cm2 sec]
[ Photon Energy]
Multiwavelength Spectral Energy Distribution
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Brenda Dingus, 31 May 2008
Astrophysical Particle Accelerators
Radio Optical X-ray GeV TeV
E 2 dN/dEor
E dN/dln(E)[ergs/cm2 sec]
[ Photon Energy]
Multiwavelength Spectral Energy Distribution
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Brenda Dingus, 31 May 2008
�Electromagnetic Processes:• Synchrotron Emission
– Probes Magnetic Field, Electron Energy
• Inverse Compton Scattering– Probes Photon Field, Electron Energy
• Bremmstrahlung – Probes Electron Energy, Matter Density
�Hadronic Cascades• p + p −> π+ + πo +… −> e + ν + γ +…• p + γ −> π+ + πo +… −> e + ν + γ +…
E γ ~ E ν ~ 0.1 E p
Gamma-Ray Production
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Brenda Dingus, 31 May 2008
�Electromagnetic Processes:• Synchrotron Emission
– Probes Magnetic Field, Electron Energy
• Inverse Compton Scattering– Probes Photon Field, Electron Energy
• Bremmstrahlung – Probes Electron Energy, Matter Density
�Hadronic Cascades• p + p −> π+ + πo +… −> e + ν + γ +…• p + γ −> π+ + πo +… −> e + ν + γ +…
E γ ~ E ν ~ 0.1 E p
Gamma-Ray Production
Which γ-ray sources are neutrino sources?
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Brenda Dingus, 31 May 2008
Crab Pulsar Wind Nebula
Electron Energies
Synchrotron Self Compton (electrons Inverse Compton scatter on synchrotron emission) spectrum removes the degeneracy to determine B and the electron energies
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Brenda Dingus, 31 May 2008
Active Galactic Nuclei
Suzaku
BeppoSAX
MAGIC,EBL corr.
MAGIC, CAT
M. HayashidaICRC 2007Preliminary
Massive Black Hole Accelerates Jet of Particles to Relativistic Velocities
Urry & PadovaniSimultaneous variability of x-rays and TeV γ-rays supports Synchrotron Self Compton and/or Inverse Compton with external photons
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Brenda Dingus, 31 May 2008
Supernova Remnants
HESS observation of RX J1713-39 shows γ-rays (false color) are spatially correlated with x-rays (contours)
Supernova Remnants are believed to be theaccelerators of Galactic cosmic rays.
Therefore, γ-rays should be produced by cosmic rays interacting with molecular clouds near SNR.
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Brenda Dingus, 31 May 2008
GRBs Observed up to 20 GeVHigh Energy Component Varies Slower than Low Energy Component (Gonzalez, 2003 Nature 424, 749)
The highest energy gamma-ray detected by EGRET from a GRB was ~20 GeV and was over an hour late. (Hurley, 1994 Nature 372, 652)
Evidence of Much More Fluence in aHigher Energy Component (Atkins, 2003, Ap J 583 824)
GRB940217
GRB970417
GRB941017
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Brenda Dingus, 31 May 2008
Galactic Source Characteristics� Angularly Extended
• High Energy Particles can move away from the accelerator before interacting to produce gamma-rays
� Hard Spectrum• Typical Differential photon index of dN/dE ~ E -2.3 (i.e. harder than the observed Galactic cosmic rays of dN/dE ~ E -2.7 )
� Source Classes• Pulsars • Pulsar Wind Nebula• Supernova Remnants• X-ray Binaries• Massive Stellar Winds• Molecular Clouds• Galactic Center• Dark Accelerators (gamma-raysources without counterparts)
HESS Pulsar Wind Nebulae
1o
0.5o0.5o
1o
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Brenda Dingus, 31 May 2008
Extragalactic Source Characteristics� Extreme Rapid Variability
• Few minute variations probe size scales smaller than Schwarzschild radius
� Hard Intrinsic Spectrum� Source Classes
• Blazars (active galactic nuclei with jets pointed at Earth)–FSRQs at GeV energies–BL Lacs at TeV energies
• M87 (nearby non-blazar active galactic nucleus)
• GRBs (up to 20 GeV)• EGRET high latitude unidentified sources
PKS2155-304Aharonian, et al. 2007
� PKS 2155-304• < 2 hr flare with > 50x quiescent flux• Few week moderate state preceded flare
� Most TeV blazars not variable• Observation bias?
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Brenda Dingus, 31 May 2008
Gamma-Ray Detectors� Space-Based� Imaging Atmospheric Cherenkov Telescopes� Extensive Air Shower Detectors
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Brenda Dingus, 31 May 2008
Space Based Gamma-Ray Telescopes�Compton Observatory 1991-2000
• BATSE, OSSE, Comptel at ~< MeV• EGRET 30 MeV – 30 GeV
�GLAST 5 June 2008 !!!• ~50 x EGRET’s sensitivity• 1 day of GLAST = 9 yrs of EGRET
γ
e+ e– calorimeter (energy measurement)
particle tracking detectors
conversion foil
anticoincidenceshield
Pair-Conversion Telescope
EGRET
GLAST
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Brenda Dingus, 31 May 2008
TeV Observational Techniques
Atmospheric Cherenkov Telescope Extensive Air Shower DetectorGround Based Gamma-Ray Astronomy
HESS,MAGIC,VERITAS Milagro, Tibet AS, ARGO
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Brenda Dingus, 31 May 2008
Gamma-Ray Detectors ~ Current CapabilitiesExtensive Air Shower(EAS) Observatories
Imaging Atmospheric Cherenkov Telescopes (IACTs)
Space-BasedGLAST
10-12 (Milagro lifetime)10-13 (50 hours)10-12(1 year)Sensitivity (ergs/cm2sec)85%(55o) 2.7 sr~10%0.5o
>>99%1 m2
1 GeV
95%10%Duty Cycle(45o) 1.8 sr (2o) 0.003 srAperture~50%~15%Energy Resolution0.7o0.05oAngular Resolution>95%>99%Background Rejection104 m2104 m2Area20 TeV1 TeVOptimal γ-ray Energy
HESSMAGICVERITAS
MilagroTibet ASγARGO
EGRETAGILEGLAST
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Brenda Dingus, 31 May 2008
The 100 MeV Catalog of EGRET
GLAST will detect 1000s of sources as well as new classes of sources
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Brenda Dingus, 31 May 2008
Jim HintonICRC 2007
TeV Catalog
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Brenda Dingus, 31 May 2008
Abdo, et al. ApJ Lett 2007
Milagro Observation of Galactic Sources
• 5 of the 7 Milagro TeV Excesses have GeV counterparts.• Only 13 GeV counterparts in this region - excluding Crab.• Probability of the chance coincidence is 3x10-6
LS I + 61 303
HESS J0632+057
IC443
H H
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Brenda Dingus, 31 May 2008
Abdo, et al. ApJ Lett 2007
Milagro Observation of Galactic Sources
• 5 of the 7 Milagro TeV Excesses have GeV counterparts.• Only 13 GeV counterparts in this region - excluding Crab.• Probability of the chance coincidence is 3x10-6
LS I + 61 303
HESS J0632+057
IC443
H H
AMANDA’s 3 Lowest Chance ProbabilitySource Excesses
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Brenda Dingus, 31 May 2008Multiwavelength Milky Way
0.1 GeV
Milagro 10 TeV gamma-rayTeV gamma ray
Milagro HESS
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Brenda Dingus, 31 May 2008
Galactic Diffuse γ-rays� Gamma-rays probe Cosmic Rays Fluxes and Spectra outside the Earth’s environment� Different spatial and spectral characteristics of electrons and protons
GALPROP Conventional (solid) and Optimized (dashed) Models
65o < l < 85o
|b| < 2o
30o < l < 65o
|b| < 2o
MilagroObs.
Inverse Compton ScatteringCMBDustStarlight
Pion DecayExtragalactic BackgroundBrems.
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Brenda Dingus, 31 May 2008
Galactic Diffuse Emission (Spatial Distribution)
Cygnus Region65o<longitude<85o
Inner Galaxy30o<longitude<65o
GALPROP Modelπo decay Inverse Compton Total
GALPROP Modelπo decay Inverse Compton Total
• Different Latitude Distribution for Different Regions of the Galaxy• Milagro Measures Width of Galaxy at TeV energies• Pionic Component Width determined by Matter Density• Inverse Compton Component Width determined by diffusion of electrons
γ/TeV
/cm2/s
r/sec
@ 15
TeV
γ/TeV
/cm2/s
r/sec
@ 15
TeV
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Brenda Dingus, 31 May 2008
Extensive Air Shower Detectors Survey the TeV Sky
Tibet AS γ ARGO
Milagro
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Brenda Dingus, 31 May 2008
CrabNebulaMrk 421
Cygnus Region
Milagro Performed Deepest Survey of TeV Gamma-Ray Sky
Detected Crab Nebula and Mrk421 (known TeV sources)7 New TeV Galactic source candidates (Abdo, et al. ApJ Lett 2007)
• Several candidates are angularly extended few deg. diameter• 5 of 7 are consistent with 14 GeV sources in Milagro f.o.v. 1
is Geminga -- the brightest GeV source in Milagro f.o.v.• 3 confirmed by Tibet AS, 1 confirmed by HESS
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Brenda Dingus, 31 May 2008
Future of EAS DetectorsMilagro Turned Off April 2008
• 4 years of operation of full detector• See this month’s CERN Courier for
general highlightsARGO producing 1st results
• ~2 x sensitivity of Milagro
High Altitude Water Cherenkov (HAWC) Observatory is next generation version of Milagro• > 10 x sensitivity of Milagro
–HAWC: Detect Crab in ~ 1 day (5σ)–Milagro: Detects Crab in 3 months
• < $10M including new site
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HAWC Detector Design• 900 water tanks(5 meter diameter and 4.3 meter deep
• One 8” PMT/tank
• Tank array covers area of 150m x 150m with 78% coverage
DAQ trailer
Road
HAWC Tank Array in GEANT 4
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Brenda Dingus, 31 May 2008
Tanks vs Pond� Less expensive� Build incrementally� Expandable &
upgradeable
GEANT4 SimulationMuon (thinned 1/50) produces up to 100s of pes depending on impact parameter
100 MeV γ−ray (thinned 1/200) produces 1pe/60 MeV independent of impact parameter
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Brenda Dingus, 31 May 2008
HAWC Site Location is Sierra Negra, Mexico• 4100 m above sea level• Easy Access• 2 hr drive from Puebla • 4 hr drive from Mexico City
• Existing Infrastructure• Few km from the US/Mexico Large Millimeter Telescope
• Power, Internet, Roads• Sierra Negra Scientific Consortium of ~7 projects
• Excellent Mexican Collaborators• ~15 Faculty at 7 institutions have submitted proposal to CONACYT for HAWC
• Experience in HEP, Auger, and astrophysics (including TeV)
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Brenda Dingus, 31 May 2008
HAWC CollaborationUSA:Los Alamos National Laboratory Brenda Dingus, Gus Sinnis, Petra Huntemeyer, John PretzUniversity of Maryland Jordan Goodman, Andrew Smith, Vlasios Vasileiou, Greg SullivanUniversity of Utah Dave KiedaUniversity of New Mexico John MatthewsMichigan State University Jim LinnemannPennsylvania State University Ty DeYoungNASA/Goddard Space Flight Center Julie McEneryUniversity of New Hampshire James RyanUniversity of California, Irvine Gaurang YodhMexico:Instituto Nacional de Astrofísica Óptica y Electrónica (INAOE)Alberto Carramiñana, Eduardo MendozaUniversidad Nacional Autónoma de México (UNAM)Instituto de Astronomía: Magdalena González, Dany Page, William Lee, Hector Hernández, Deborah Dultzin, Erika BenitezInstituto de Física: Arturo Menchaca, Rubén Alfaro, Andres Sandoval, Ernesto Belmont Instituto de Ciencias Nucleares: Lukas Nellen, G. Medina-TancoInstituto de Geofísica: José Valdés Galicia, Alejandro LaraBenemérita Universidad Autónoma de PueblaHumberto Salazar, Oscar Martínez, Cesar Álvarez, Arturo FernándezUniversidad Michoacana de San Nicolás de Hidalgo Luis VillaseñorCINVESTAV Arnulfo ZepedaUniversidad de GuanajuatoDavid Delepine, Gerardo Moreno, Marco Reyes, Luis Ureña, Victor Migenes
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Brenda Dingus, 31 May 2008
HAWC Sensitivity
e µ γ
(a) Larger Effective Area at Lowest Energies
(b) Better Angular Resolution
(c) Improved Background Rejection
=> 10-15 x improvement in flux sensitivity
=> (10-15)2 = 100-200 x faster to observe same flux
(a)
(b)
(c)
100 GeV 1 TeV 10TeV 100 TeV
100 GeV 1 TeV 10TeV 100 TeV
Hadro
n Effic
iency
Ang.
Res.
(deg)
Ef
f. Area
(m2 )
100 GeV 1 TeV 10TeV 100 TeV
100 GeV 1 TeV 10TeV 100 TeV 10-3
105
0.3o
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Brenda Dingus, 31 May 2008
E F(> E
) (Te V
/c m2 s)
Sensitivity to Crab-like (dN/dE=E-2.6) Point Source
GeV
� HESS/VERITAS, MAGIC, Whipple, CTA sensitivity in 50 hours, (~0.2 sr/year)� GLAST sensitivity in 1 year (4π sr)� HAWC sensitivity in 1(5) years shown as solid (dashed) line (2π sr)� HAWC exposure>10 TeV in 5 years is 5x1015 cm2sec = 1 km2 x 140 hrs
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Brenda Dingus, 31 May 2008
HAWC’s Field of View
= 2.6 π sr= 1.8 π sr
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Brenda Dingus, 31 May 2008
HAWC Science Objectives
�Constrain the origin of cosmic rays via HAWC’s observations of γ-rays up to 100 TeV from discrete sources and the Galactic plane.�Probe particle acceleration in extreme magnetic and gravitational fields via HAWC’s observations of transient TeV sources, such as gamma ray bursts and supermassive black holes.�Explore new TeV physics via HAWC’s unbiased sky survey with a detection threshold of ~30 mCrab in two years.
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Brenda Dingus, 31 May 2008
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3Highest energy ~20 TeV
HAWC’s High Energy Reach
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Brenda Dingus, 31 May 2008
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3Highest energy ~20 TeVSimulated HAWC data for 1 year with no cutoff
HAWC’s High Energy Reach
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Brenda Dingus, 31 May 2008
HESS J1616-5080.2 Crab @ 1 TeV α=-2.3Highest energy ~20 TeVSimulated HAWC data for 1 year with 40 TeV exponential cutoff
HAWC’s High Energy Reach
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Brenda Dingus, 31 May 2008
HAWC’s Transient Reach
Orphan Flare
• Some TeV flares are correlated with x-ray flares and some are orphan TeV flares -- excellent candidates for neutrino sources.
• HAWC would detect such a flare in <15 minutes and promptly notify multiwavelength observers.
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Brenda Dingus, 31 May 2008
Expect the Unexpected with Unbiased SurveysFor example, Milagro Observes Anisotropy in 10 TeV Cosmic Rays� 10 deg size scale with a fractional excess of 7e-4 above the cosmic ray
background (15 σ)� Excess is not gamma rays, but charged cosmic rays (7 σ)� Explanations are difficult because the gyroradius of a 10 TeV proton in
a 1 µG field is 0.01 parsecs=2000 AU� Maybe Geminga SNR??? Salvati & Sacco astroph0802.2181
Heliotail
Geminga
GalacticPlane
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Brenda Dingus, 31 May 2008
Summary• Multiwavelength Spectra probe Nature’s Particle Accelerators• Gamma rays provide > 6 orders of magnitude of energy in the multiwavelength spectrum
• The physics of these accelerators is constrained by gamma-ray observations, but more information is needed
• Increased Sensitivity of New Gamma-Ray Observatories guarantees New Discoveries
• Neutrino Detections would revolutionize our understanding
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Brenda Dingus, 31 May 2008
Thank youto Neutrino 2008
organizers.Good on ya!
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Brenda Dingus, 31 May 2008
Cosmic Ray Anisotropy1o RA bins (unsmoothed) for 10o<Dec.<20o
Large Scale Feature at ~180 deg observed by many detectors.Smaller Scale Features require larger numbers of events.
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Brenda Dingus, 31 May 2008
Milagro & Tibet AS γ Observations
K. Munakata, M. Amenomori, et al AIP Conf Vol 932, 283
Mrk421Crab
Cygnus region
Abdo, A. et al astroph0801.3827
Milagro Observation using Background Calculation over 2 hour (30o in RA) intervals
Tibet AS Observation after subtracting model of large scale anisotropy
K. Munakata, M. Amenomori, et al AIP Conf Vol 932, 283
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Brenda Dingus, 31 May 2008
Galactic Sources are Extended
Sextended ≈ Spointσ sourceσ detector
σEAS ~0.5o σIACT ~0.1o
HAWC’s large fov of 2 sr:Entire source & background are simultaneously observableBackground is well measured
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Brenda Dingus, 31 May 2008
Milagro Observation in Galactic Coordinates
Crab Nebula
30°
210°
90° 65°
Cygnus Region
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Brenda Dingus, 31 May 2008
• Gammas have NARROW lateral distribution of electrons
• Protons have BROAD lateral distribution of muons
Lateral Distribution of Extensive Air Showers
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Brenda Dingus, 31 May 2008
Gamma/Hadron Separation
Gamm
asProton
s
30 GeV 70 GeV 230 GeV
20 GeV 70 GeV 270 GeVSize of HAWC
Size of Milagro deep layer Energy Distribution at ground level
Rejection factor ~ e-<µ>
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Brenda Dingus, 31 May 2008
Background Rejection in MilagroProton MC Proton MC
Data Dataγ MC γ MC
Hadronic showers contain penetrating component: µ’s & hadrons
– Cosmic-ray showers lead to clumpier bottom layer hit distributions– Gamma-ray showers give smooth hit distributions
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Brenda Dingus, 31 May 2008
Milagro Background Rejection (Cont’d)
( )mxPE
nFitfOut+fTop=A ∗4
mxPE: maximum # PEs in bottom layer PMTfTop: fraction of hit PMTs in Top layerfOut: fraction of hit PMTs in OutriggersnFit: # PMTs used in the angle reconstruction
S/B increases with increasing A4 so analysis weights events by S/B as determined by the A4value of the event
Background Rejection Parameter