Multiwavelength Astronomy: Probing Nature’s Particle Accelerators Brenda Dingus Los Alamos National Lab dingus@lanl.gov
Shedding Some Light on Potential Neutrino Sources Brenda Dingus Los Alamos National Lab dingus@lanl.gov
Nature’s Particle Accelerators Black Hole producing Spinning Neutron Star TeV image of Vela Jr. relativistic jet of particles powering a relativistic Supernova Remnant wind HST Image of M87 (1994) HESS TeV + x-ray Chandra Image of Crab Binary Neutron Star Massive Star Collapsing Coalescing into a Black Hole SuperComputer Calculation Artist Conception of Short GRBs Brenda Dingus, 31 May 2008
Astrophysical Particle Accelerators Multiwavelength Spectral Energy Distribution E 2 dN/dE or E dN/dln(E) [ ergs/cm 2 sec ] Radio Optical X-ray GeV TeV [ Photon Energy] Brenda Dingus, 31 May 2008
Astrophysical Particle Accelerators Multiwavelength Spectral Energy Distribution E 2 dN/dE or E dN/dln(E) [ ergs/cm 2 sec ] Radio Optical X-ray GeV TeV [ Photon Energy] Brenda Dingus, 31 May 2008
Gamma-Ray Production � 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 + + π o + … −> e + ν + γ + … • p + γ −> π + + π o + … −> e + ν + γ + … • E γ ~ E ν ~ 0.1 E p Brenda Dingus, 31 May 2008
Gamma-Ray Production � 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 + + π o + … −> e + ν + γ + … • p + γ −> π + + π o + … −> e + ν + γ + … • Which γ -ray sources E γ ~ E ν ~ 0.1 E p are neutrino sources? 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 Brenda Dingus, 31 May 2008
Active Galactic Nuclei Massive Black Hole MAGIC, CAT BeppoSAX Accelerates Jet of Particles to Relativistic Velocities Suzaku MAGIC, EBL corr. M. Hayashida ICRC 2007 Preliminary Simultaneous variability of x-rays and TeV γ -rays supports Urry & Padovani Synchrotron Self Compton and/or Inverse Compton with external photons Brenda Dingus, 31 May 2008
Supernova Remnants Supernova Remnants are believed to be the accelerators of Galactic cosmic rays. Therefore, γ -rays should be produced by cosmic rays interacting with molecular clouds near SNR. HESS observation of RX J1713-39 shows γ -rays (false color) are spatially correlated with x-rays (contours) Brenda Dingus, 31 May 2008
GRBs Observed up to 20 GeV High Energy Component Varies GRB940217 Slower than Low Energy Component (Gonzalez, 2003 Nature 424, 749) GRB941017 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 GRB970417 More Fluence in a Higher Energy Component (Atkins, 2003, Ap J 583 824) Brenda Dingus, 31 May 2008
Galactic Source Characteristics Angularly Extended � High Energy Particles can move • HESS Pulsar Wind Nebulae away from the accelerator before interacting to produce gamma-rays Hard Spectrum � 0.5 o Typical Differential photon index of 0.5 o • 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 • 1 o 1 o Supernova Remnants • X-ray Binaries • Massive Stellar Winds • Molecular Clouds • Galactic Center • Dark Accelerators (gamma-ray • sources without counterparts) Brenda Dingus, 31 May 2008
Extragalactic Source Characteristics � Extreme Rapid Variability • Few minute variations probe PKS2155-304 size scales smaller than Aharonian, et al. 2007 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 � PKS 2155-304 • M87 (nearby non-blazar • < 2 hr flare with > 50x quiescent flux active galactic nucleus) • Few week moderate state preceded flare • GRBs (up to 20 GeV) • EGRET high latitude � Most TeV blazars not variable unidentified sources • Observation bias? Brenda Dingus, 31 May 2008
Gamma-Ray Detectors � Space-Based � Imaging Atmospheric Cherenkov Telescopes � Extensive Air Shower Detectors Brenda Dingus, 31 May 2008
Space Based Gamma-Ray Telescopes � Compton Observatory 1991-2000 • BATSE, OSSE, Comptel at ~< MeV • EGRET 30 MeV – 30 GeV EGRET � GLAST 5 June 2008 !!! • ~50 x EGRET’s sensitivity • 1 day of GLAST = 9 yrs of EGRET GLAST Pair-Conversion Telescope γ anticoincidence shield conversion foil particle tracking detectors e – calorimeter e + (energy measurement) Brenda Dingus, 31 May 2008
TeV Observational Techniques Ground Based Gamma-Ray Astronomy Atmospheric Cherenkov Telescope Extensive Air Shower Detector HESS,MAGIC,VERITAS Milagro, Tibet AS , ARGO Brenda Dingus, 31 May 2008
Gamma-Ray Detectors ~ Current Capabilities Space-Based Imaging Atmospheric Extensive Air Shower Cherenkov Telescopes (EAS) Observatories GLAST (IACTs) Optimal γ -ray Energy 1 GeV 1 TeV 20 TeV 10 4 m 2 10 4 m 2 1 m 2 Area Background Rejection >>99% >99% >95% 0.5 o 0.05 o 0.7 o Angular Resolution Energy Resolution ~10% ~15% ~50% (55 o ) 2.7 sr (2 o ) 0.003 sr (45 o ) 1.8 sr Aperture Duty Cycle 85% 10% 95% 10 -13 (50 hours) Sensitivity (ergs/cm 2 sec) 10 -12 (1 year) 10 -12 (Milagro lifetime) EGRET HESS Milagro AGILE MAGIC Tibet AS γ GLAST VERITAS ARGO Brenda Dingus, 31 May 2008
The 100 MeV Catalog of EGRET GLAST will detect 1000s of sources as well as new classes of sources Brenda Dingus, 31 May 2008
TeV Catalog Jim Hinton ICRC 2007 Brenda Dingus, 31 May 2008
Milagro Observation of Galactic Sources H H LS I + 61 303 IC443 HESS J0632+057 Abdo, et al. ApJ Lett 2007 • 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 • Brenda Dingus, 31 May 2008
Milagro Observation of Galactic Sources H H LS I + 61 303 IC443 HESS J0632+057 Abdo, et al. ApJ Lett 2007 • 5 of the 7 Milagro TeV Excesses have GeV counterparts. AMANDA’s 3 Lowest Only 13 GeV counterparts in this region - excluding Crab. Chance Probability • Probability of the chance coincidence is 3x10 -6 Source Excesses • Brenda Dingus, 31 May 2008
0.1 GeV Milagro HESS TeV gamma ray Milagro 10 TeV gamma-ray Multiwavelength Milky Way Brenda Dingus, 31 May 2008
o < l < 65 o 30 Galactic Diffuse γ -rays o |b| < 2 GALPROP Conventional (solid) and Optimized (dashed) Models � Gamma-rays probe Cosmic Rays Fluxes and Milagro Spectra outside the Obs. Earth’s environment � Different spatial and spectral characteristics of electrons and protons o < l < 85 o 65 o Inverse Compton Scattering |b| < 2 CMB Dust Starlight Pion Decay Extragalactic Background Brems. Brenda Dingus, 31 May 2008
Galactic Diffuse Emission (Spatial Distribution) • 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/sr/sec @ 15 TeV γ /TeV/cm2/sr/sec @ 15 TeV Inner Galaxy Cygnus Region 30 o <longitude<65 o 65 o <longitude<85 o GALPROP Model GALPROP Model π o decay Inverse Compton Total π o decay Inverse Compton Total Brenda Dingus, 31 May 2008
Extensive Air Shower Detectors Survey the TeV Sky ARGO Tibet AS γ Milagro Brenda Dingus, 31 May 2008
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 Cygnus Region Crab Mrk 421 Nebula Brenda Dingus, 31 May 2008
Future of EAS Detectors Milagro Turned Off April 2008 • 4 years of operation of full detector • See this month’s CERN Courier for general highlights ARGO 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 (5 σ ) – Milagro: Detects Crab in 3 months • < $10M including new site Brenda Dingus, 31 May 2008
HAWC Detector Design • 900 water tanks HAWC Tank Array in GEANT 4 (5 meter diameter and 4.3 meter deep DAQ trailer Road • One 8” PMT/tank • Tank array covers area of 150m x 150m with 78% coverage
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