Astrophysics of the High-Energy Universe10-14 August 2015
Instituto Nacional de Astrofísica Optica y Electrónica (INAOE)Puebla, Mexico
Charles Dermer (Naval Research Laboratory)
Dr. Charles D. DermerNaval Research Lab, Code 7653
Washington, DC 20375‐5352 USA202‐767‐2965
Lecture 1. The High-Energy Universe
The most energetic and powerful radiations in nature are made by particles accelerated through Fermi processes in black‐hole jets powered by rotation.
Outline
Fermi 5 year > 1 GeV -ray sky
1. Multi‐wavelength and multi‐messenger astronomy2. Fermi Gamma‐ray Space Telescope3. Diffuse radiation backgrounds
3. Point sources, diffuse sources, and spectral energy distributions4. High‐energy sources, processes, and themes
“The commerce of science is original discovery. That’s our silver and gold.” E.O. Wilson
Multiwavelength Astronomy
thermal vs. nonthermal
rays: particle acceleration or dark matter signatures
log (Hz)
= h/mec2
GeV vs. TeV astronomy
GBM LAT VHE
0. Compton Gamma-Ray Observatory: Pioneering -ray space observatory (1991-2000)
1. Swift Gamma-ray Burst Explorer (NASA 2004 MidEx)2. High Energy Stereoscopic Observatory (HESS)
(Ground-based -ray telescope; Namibia, 2004)3. Very Energetic Radiation Imaging
Telescope Array System (VERITAS) (Arizona; 2007)
4. Major Atmospheric Gamma-rayImaging Cherenkov Telescopes (MAGIC)(Canary Islands; 2004)
5. Fermi Gamma-raySpace Telescope (2008)
6. High Altitude Water Cherenkov (HAWC) (Puebla, Mexico 2015)
7. Cherenkov Telescope Array (CTA South: Chile, 2020;CTA North: Canary Islands)
4
High-Energy Observatories
MAGIC
Compton
Swift
HESSHESS
VERITASHAWC
MAGIC
ssss
Worldwide Radio Networks of Observers
5
TANAMI: Tracking AGN with Austral Milliarcsecond InterferometryMOJAVE: Monitoring of Jets of AGN with VLBA Experiments
Optical Networks: WEBT-- GASP
6
Whole Earth Blazar Telescope
GLAST-AGILE Support Program
Multimessenger Astronomy
Photons
Cosmic rays/ Ultra-High Energy Cosmic Rays
Gravitational waves Neutrinos
8
Fermi Gamma-ray Space Telescope (2008– )
Gamma-ray Burst Monitor (GBM)8 keV – 40 MeV (12+2 detectors)Views entire unocculted sky
NASA/DoE Project Launched June 11, 2008 NRL Fermi Involvement
– Calorimeter– Environmental testing– Interdisciplinary scientist
USA (GSFC/SLAC/NRL)Italy/Japan/Sweden/Germany
Large Area Telescope (LAT)20 MeV → 300 GeV2.4 sr Field of View
9
Launch! June 11, 2008
Launch from Cape Canaveral Air Station 11 June 2008 at 12:05PM EDT
Circular orbit, 565 km altitude (96 min period), 25.6 deg inclination.
10
First light and Observatory Renaming
Gamma ray Large Area Space Telescope (GLAST) becomes Fermi Gamma-ray Space Telescope
4 days of observationunits: 10-8 ph(>100 MeV) cm-2 s-1
Bright sources F-8 ~ 100Limiting 2 wk EGRET sensitivity F-8 ~ 15Limiting Fermi 1 year sensitivity: F-8 ~ 0.5
11
e+ e–
Overview of LAT: How it works
Precision Si-strip Tracker (TKR) Measure the photon direction; gamma ID. pitch = 228 m, 8.8×105
channels, 18 planes
Hodoscopic CsI Calorimeter (CAL) Measure the photon energy; image the shower.
Segmented Anticoincidence Detector (ACD) Reject background of charged cosmic rays; segmentation removes self-veto effects at high energy.
Electronics System Hardware trigger, software filters
Systems work together to identify and measure the flux of cosmic gamma rays with energy 20 MeV - >300 GeV
Calorimeter
Tracker
ACD
12
Operations and observing modes
Almost all observations in survey mode - the LAT observes the entire sky every two orbits (~3 hours), each point on the sky receives ~30 mins exposure during this time.
– 39 deg rocking angle to Sept 2, 50 deg after September 3, 2009. Very high ontime! , Autonomous Repointing
– In response to bright GBM-detected GRBs, LAT-triggered GRBs Dedicated Pointings
– Crab flares, bright blazars, -ray novae
LAT sensitivity on 4 different timescales: 100 s, 1 orbit (96 mins), 1 day and 1 year
Optical transients– Meteors, Comets– Supernovae
Hammer-Aitoff Projection of the Full Sky
13
Gamma-ray transients– Blazars– Gamma Ray Bursts
All-sky/Large field-of-view coverage provided by Fermi and HAWC
Large Field-of-View vs. Pointing (Narrow-Field) InstrumentsSources of Background
14
The Fermi LAT (3 month) Sky
Fermi >1 GeV 5 Year Sky Map
Fermi: >10 GeV Skymap
Calibration and AnalysisCatalogsGalactic SourcesDiffuse and Molecular Clouds (and Other Galaxies) Sources in the Solar SystemBlazars and other AGNsGamma Ray BurstsDark Matter and New Physics
HAWC, successor of Milagro, is a large‐field‐of‐view TeV telescope.
Fermi ‐ray sky
• >100 MeV, 36 months• Galactic ‐ray glow:
accelerated particles meet target gas and photons
• ~80% of the emission is diffuse
• Transient and flaring sources
• Normal and ms pulsars• Blazars• GRBs• Other ‐ray galaxies• Unidentified sources
18
Sample of Early Discoveries from Fermi
W44
Crab Nebula
GRB090902All sources Blazars
Populations
3C279
Energy Units
Microphysical quantities related to electron mass and energy
2cmE e
F Spectra: Point Sources
Photon flux:
Energy flux (density):
Flux density F in Jansky1 Jy = 10-23 erg cm-2 s-1 Hz-1
Energy Flux:
F in Jansky-Hertz or erg cm-2 s-1
Notation:
Blazar 3C 454.3
dAdtddN
)(
)(
z = 0.858
Ned Wright’s cosmology calculator z = 0.859 dL =1.7e28 cm 13.7 Gyr *c = 1.3e28 cm
SUN
Solar constant: 1400 Watt/m2
1.4x106 erg/s‐cm2
Earth‐Sun distance: (1 AU): 1.5x1013 cm
Solar luminosity: 4x1033 erg/s
Solar mass: 2x1033 gm
Macrophysical quantities related to Sun
Optical Energy Fluxes
25th magnitude star has energy flux 10-15 erg cm-2 s-1
Instrumental Sensitivities
10-20
10-18
10-16
10-14
10-12
10-10
10-8
10-6
6 9 12 15 18 21 24 27 30
F S
ensi
tivity
(erg
cm
-2 s
-1)
log [(Hz)]
BATSE/GBM
EGRET
GLAST LAT
VLAChandra
HESS/VERITAS
Optical; 25th mag.
Optical; 30th mag.
Swift BAT
sensitivity for nominal observing times
human eye
JWST
Spitzer MIPS
IRAC
ASM
PCA
RXTE HEXTE ACT/GRB
Fermi
Sensitivities of High Energy Instruments
10-13
10-12
10-11
10-10
10-9
10-8
0.001 1 1000 106
Sen
sitiv
ity (e
rg c
m-2
s-1
)
E(MeV)keV GeV TeV
EGRET
(1 year)
GLAST Whipple
VERITAS/ HESS
OSSECOMPTEL
INTEGRAL/ IBIS
ACT(concept)
MAGIC
(106s)
Crab Total
(106s)
Fermi
INTEGRAL SPI
100 MeV ×10-6 ph(>100 MeV)/cm2-s = 1.6×10-10 erg/cm2-s
2 spectrum
Point Sources and Diffuse Emission
Photon intensity: ph/(cm2-s-energy-sr)
Intensity: (cm2-s-sr)-1
Energy intensity: energy/(cm2-s-sr)
Blackbody intensity: erg/(cm2-s-Hz-sr)
Point-source detection significance in a diffuse background:
Signal counts:
Background counts:
dddtdAdN
)()(
dddtdA
d
)(
dddtdA
d
)(
1)/exp(/2)(
23
kThch
bb
BS
)()( EEAdEtfS
)()( EEAdEtB (now use Bayesian techniques)
GLAST flaring rate: Dermer & Dingus 2004
Diffuse Radiations
Fermi High-Energy Subjects and Sources
Calibration and AnalysisEnergy/Effective Area; FoV; ImagingLLE/Transient/Source/Diffuse Classes
CatalogsBSL/LBAS/1FGL/1LAC/2FGL/2LAC/3FGL/3LAC 1st PSR/2nd PSR/GRB/SNR/1FHL/FAVA
Galactic SourcesPulsars
normal (radio‐loud and radio quiet), msPulsar Wind Nebulae/Crab/flaresGlobular ClustersSNRsHigh‐mass X‐ray/gamma‐ray binariesNovae
Diffuse, Molecular Clouds, and Other GalaxiesDiffuse Galactic EmissionGalactic Center/Fermi BubblesLMC, SMC, M31Starburst GalaxiesCosmic‐ray ions/electrons/positronsExtragalactic Background LightDiffuse Isotropic gamma‐ray background/EGB
Sources in the Solar SystemEarth/CRsSun/ Quiescent and Solar FlaresMoonJupiter/Zodiacal LightTGFs
Blazars and other AGNsBlazars/ FSRQs and BL LacsRadio GalaxiesRLNLSy1
Gamma Ray BurstsLong SoftShort HardSGRs
Dark Matter and New PhysicsDM lines and featuresAxionsLorentz Invariance ViolationPrimordial Black Hole AnnihilationMagnetogenesis
205 132 1500 700 1900 1017 2100 1450
45 114 7/28 62/6
High-Energy Astrophysical Processes
Particle Interactions and RadiationLeptonicHadronicPhotonsMagnetic FieldsCascades
Acceleration PhysicsFermi ProcessesElectric Field AccelerationMagnetic Reconnection
Relativistic Flows
Black Hole PhysicsAccretionBlandford‐Znajek ProcessJet formation
Dark Matter Decay and Annihilation
ep (ion)
e + e → e´ + e´ Thermalizatione + e → e´ + e´ + Electron‐electron bremsstrahlunge + e → e´ + e´ + e+ + e‐ Electron‐electron pair production
e + p → e´ + p’ Thermalizatione + p → e´ + p’ + Electron(‐proton) bremsstrahlung CRe + p → e´ + p’ + e+ + e‐ Electron‐proton pair production
e + → e´ + ’ Compton scattering CR, Jetse + → e´ + ’ + ″ Double Compton scatteringe + → e´ + e+ + e‐ Triplet pair productione + B → e´ + B + ’ Synchrotron emission CR, Jets
p + p → p´ + p´ Thermalization (including elastic nuclear scattering)p + p → p´ + p´ + Proton bremsstrahlungp + p → p´ + p´ + Secondary nuclear production CR, p + → p´ + e+ + e‐ Bethe‐Heitler pair production UHECRsp + → p´ + Photopion production UHECRs, p + B → p´ + B + ’ Proton synchrotron emission Jets
+ → ´ + ’ Photon‐photon scattering + → e+ + e‐ pair production Jets + B → e+ + e‐ + B Magnetic pair production Pulsars
(some) High-Energy Radiation Processes
High-Energy Astronomy Themes
Cosmic Ray and Ultra‐High Energy Cosmic Ray Origin
The Search for Dark Matter
Extreme Stars and the Endpoints of Stellar Evolution
Structure and Content of the Galaxy in rays
Nonthermal Particle Acceleration in Nature
The Black‐Hole Universe
Radiation and Field Content of the Universe
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