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Gamma Ray Sources
Chuck Dermer Naval Research Laboratory
Washington, DC USATAUP 2007, Sendai, Japan, September 2007
Ground-based Cherenkov:• VERITAS • HESS• Cangaroo III• MAGIC MAGIC-2• Milagro
Topics in Astroparticle and Underground Physics
Space-based:• EGRET GLAST• AGILE
Ongoing revolution in our understanding of -ray sources
TeV astronomy GeV astronomy
+ multi-wavelength/ multi-messenger information
(talk by W. Hoffman) focus on GeV and extragalactic sources
The Gamma-Ray Sky
Diffuse/unresolved emissions(Quasi)-quiescent radiationsPulsing sources
Flaring sourcesBursting sources
EGRET Detector
Spark Chamber Energy range: ~100 MeV – 5 GeVPointing Instrument (psf ~ 5.7° at 100 MeV)Two week observation: ~106 secField-of-view: ~1/24th of the Full Sky
Two-week detection threshold 1510-8 ph(>100 MeV) cm-2 s-1
(high-latitude sources; background limited)
F Threshold energy flux: 10-10 ergs cm-2 s-1
Energetic Gamma Ray Experiment Telescopeon the Compton Gamma Ray Observatory
Flew 1991 -- 2000
GLAST Detector
LAT Tracker Energy range: ~ 50 MeV – 100 GeVScanning Instrument (psf ~ 3.5° at 100 MeV)Views whole sky every 3 hours Field-of-view: ~1/5th of the Full Sky
One year detection threshold 0.410-8 ph(>100 MeV) cm-2 s-1
(high-latitude sources; background limited)F threshold energy flux: 3 10-12 ergs cm-2 s-1
Gamma Ray Large Area Space Telescope Large Area Telescope + GLAST Burst Monitor
Launch: February 2008(talk by C. Cecchi)
EGRET (> 100 MeV) All-Sky Map
• Requires background cosmic-ray/gas model to find -ray sources
Catalog of Established High Energy (> 100 MeV) Gamma-Ray Sources
High mass binaries/microquasars
GRBs
(Hartman et al. 1999)
(271 Sources, plus 5 GRBs)
(66/27 hi/low confidenceAGNs)
+ Radio galaxy (Cen A)
Casandjian & Grenier ‘07
Revised EGRET Catalog
Before:
After:
• 107 3EG sources not confirmed
– most Gould Belt sources
• 32 new sources from 9-year data
• GeV/TeV irradiated cloud "sources"
-Ray Supernova Remnants
• No unambiguous identification of a SNR with EGRET
• SNR maps with HESS– RX J1713.7-3946
– Vela Jr
– RCW 86
• Cosmic Ray Origin Problem– rays from Compton-
scattered CMB
– rays from CR p + p,N 0
• Detection of 0 bump with GLAST
Aharonian et al. 2007
Detection of LMC with EGRET = 19 10-8 ph(>100 MeV) cm-2 s-1
(Sreekumar et al.1992)
spectral shape consistent with that expected from cosmic ray interactions with matter
Scale to local galaxies (SMC, Andromeda)
Starburst Galaxies (M82, NGC 253; 3 Mpc)
IR Luminous Galaxies (Arp 220; 72 Mpc) (Torres 2004)
Normal, Starburst and IR Luminous Galaxies
Clusters of Galaxies
F few10-13 ergs cm-2 s-
1 at 1 TeV
Implies >> years required to detect with a km-scale telescope
UHECRs and secondary rays from clusters? (talk by S. Inoue)
Berrington and Dermer (2005)
Inte
gral
pho
ton
flux
ph(
>E
cm
-2 s
-1)
(Armengaud, Sigl, &Miniati 2006)
3C 296
Radio Galaxies and Blazars
3C 279, z = 0.538
L ~1045 x (f/10-10 ergs cm-2 s-1) ergs s-1
Mrk 421, z = 0.031
Cygnus A
L ~5x1048 x (f/10-9 ergs cm-2 s-1) ergs s-1
FR2/FSRQ
FR1/BL Lac
FR1/2 dividingline at radio power1042 ergs s-1 BL Lacs: optical emission line equivalent
widths < 5 Å
Redshift Distribution of EGRET -Ray Blazars
Standard Blazar Model
• Collimated ejection of relativistic plasma from supermassive black hole
• Relativistic motion accounts for lack of attenuation; superluminal motion; super-Eddington luminosities
• High energy beamed rays made in Compton or photo-hadronic processes
• FSRQs have intense external radiation field from broad line-region gas
Evolution from FSRQ to BL Lac Objects in terms of a reduction of fuel from surrounding gas and dust
FSRQ
BL Lac
Sambruna et al. (1996); Fossati et al. (1998)Böttcher and Dermer (2000)Cavaliere and d’Elia (2000)
Understanding the blazar main sequence
Blazar Main Sequence: Supermassive Black Hole Growth and Evolution
Black Hole Jet Physics
Variability and Black Hole Mass
Energy Source: Accretion vs. Rotation
Two Component Synchrotron/ Compton Leptonic Jet Model
Location of -ray Emission Region
Accretion Disk
SMBH
RelativisticallyCollimated Plasma Outlfows
Observer
BLR clouds
Dusty Torus
Ambient Radiation Fields
BL Lac vs. FSRQ
Hadronic Jet Model
Leptonic Blazar Modeling
z = 0.538
L ~5x1048 x (f/1014 Jy Hz) ergs s-1
Temporally evolving SEDs
Evolution of electron distribution with time: information about acceleration (e.g., loop diagrams);Correlated behavior expected for leptonic emissions
Infer B field, Doppler power, jet power, location
Böttcher et al. 2007
• Infer intrinsic spectrum with EBL absorption • Implied large Doppler factors of TeV blazars• Orphan TeV flares• Linear jets
Aharonian et al., Nature, 2005
Evidence for Anomalous -Ray Components in Blazars
z = 0.186
d ~ 200 Mpc
l jet
~ 1 Mpc (lproj
= 240 kpc)
Deposition of energy through
ultra-high energy neutral
beams (Atoyan and Dermer 2003)
Pictor A in X-rays and radio (Wilson et al, 2001 ApJ 547)
Pictor APictor A
Sreekumar et al. (1998)
Blazars as High Energy Hadron Accelerators
astro-ph/0610195
Synchrotron and IC fluxes from the pair-photon cascade for the Feb 1996 flare of 3C279
(3C 279)
dotted - CRs injected during the flare; solid - neutrons escaping from the blob, dashed - neutrons escaping from Broad Line Region (ext. UV) dot-dashed - rays escaping external UV field (produced by neutrons outside the blob)3dot-dashed- Protons remaining in the blob at l = R
BLR
Powerful blazars / FR-II Neutrons with E
n > 100 PeV and rays with E > 1PeV take away
~ 5-10 % of the total WCR
(E > 1015eV=1 PeV) injected at R<RBLR
UHE neutrons & -rays: energy & momentum transport from AGN core
UHE -ray pathlengths in CMBR:
l ~ 10 kpc - 1Mpc
for the En ~ 1016 - 1019 eV
• Neutron decay pathlength:
ld (
n) =
0 c
n , (
0 ~ 900 s)
ld ~ 1 kpc - 1Mpc
for the predicted E~ 1017 - 1020 eV
•High redshift jets: photomeson
processes on neutrons turn on
solid: z = 0 dashed: z = 0.5
Detection of single high-energy from blazars neutral beams could power large-scale jets
Neutrinos: expected fluences/numbers
Expected - fluences calculated for 2 flares, in 3C 279 and Mkn 501, assuming proton aceleration rate Qprot(acc) = Lrad(obs) ; red curves - contribution due to internal photons, green curves - external component (Atoyan & Dermer 2003) Expected numbers of for IceCube-scale detectors, per flare:● 3C 279: N = 0.35 for = 6 (solid curve) and N = 0.18 for = 6 (dashed) Mkn501: N = 1.2 10-5 for = 10 (solid) and N = 10-5 for = 25 (dashed) (`persistent') -level of 3C279 ~ 0.1 F (flare) , ( + external UV for p )
N ~ few - several per year can be expected from poweful HE FSRQ blazars. N.B. : all neutrinos are expected at E>> 10 TeV
GRBs
Multiple Classes1. Long duration GRBs
2. X-ray flashes
3. Low-luminosity GRBs
4. Short Hard Class of GRBs
Long Duration GRBsMassive Star Origin
Collapse to Newly Formed Black Hole
Prompt phase: internal or external relativistic shocks
Afterglow phase: external shock
Mean redshift: ~1 (BATSE), ~2 (Swift)GRB/Supernova connection
Kouveliotou et al. 1993
Anomalous -ray Emission Components in GRBs
Long (>90 min) -ray emission
(Hurley et al. 1994)
Anomalous High-Energy Emission Components in GRBs
Evidence for Second Component from BATSE/TASC Analysis
Hard (-1 photon spectral index) spectrum during
delayed phase
−18 s – 14 s
14 s – 47 s
47 s – 80 s
80 s – 113 s
113 s – 211 s
100 MeV
1 MeV
(González et al. 2003)
GRB 941017
Second Gamma-ray Component in GRBs: Other Evidence
Delayed -ray emission from superbowl burst GRB 930131
Low significance Milagrito detection of GRB 970417A(Requires low-redshift GRB to avoid attenuation by diffuse IR background)
Atkins et al. 2002Sommer et al. 1994
Photon and Neutrino Fluence during Prompt Phase
Hard -ray emission component from hadronic-induced electromagnetic cascade radiation inside GRB blast wave Second component from outflowing high-energy neutral beam of neutrons, -rays, and neutrinos
e
pnep
2
),,(0
Nonthermal Baryon
Loading Factor fb = 1
tot = 310-4 ergs cm-2
= 100
Gamma-Ray Bursts as Sources of High-Energy Cosmic Rays
Solution to Problem of the Origin of Ultra-High Energy Cosmic Rays
(Wick, Dermer, and Atoyan 2004)
(Waxman 1995, Vietri 1995, Dermer 2002)
Hypothesis requires that GRBs can accelerate cosmic rays to energies > 1020 eV
Injection rate density determined by GRB formation rate (= SFR?)
GZK cutoff from photopion processes with CMBR
Ankle formed by pair production effects
(Berezinsky and Grigoreva 1988,Berezinsky, Gazizov, and Grigoreva 2005)
Star Formation Rate: Astronomy Input
Hopkins & Beacom 2006
USFR
LSFRHB06
SFR6,pre-Swift
Le & Dermer 2006
SFR6,Swift
SFR6,pre-Swift
Fitting Redshift and Opening-Angle Distribution
Cosmogenic GZK -Ray Intensity
(Le & Dermer 2006)
Der
mer
, un
pu
bli
shed
cal
cula
tion
s, 2
007
astro-ph/0611191
Neutrinos from GRBs in the Collapsar Model
(~2/yr)
Nonthermal Baryon Loading Factor fb = 20
Dermer & Atoyan 2003
requires Large Baryon-Loading
(diffuse background from GRBs: talk by K. Murase)
Sreekumar et al. (1998)
Unresolved -Ray Background
Strong, Moskalenko, & Reimer (2000)
Data:
Star-forming galaxies (Pavlidou & Fields 2002)
Starburst galaxies (Thompson et al. 2006)
Pulsar contribution near 1 GeVGalaxy cluster shocks (Keshet et al. 2003, Blasi Gabici & Brunetti 2007)
Dark matter contribution (talk by Bergstrom)
BL Lacs: ~2 - 4% (at 1 GeV) FSRQs: ~ 10 - 15%
astro-ph/0610195
GeV -ray Astronomy: Some Important Problems
Particle acceleration theory
Origin of galactic cosmic rays
Jet physics, differences between radio/-ray black hole sources
Blazar demographics
Search for hadronic emission components: Acceleration of UHECRs in extragalactic sources (predictions for astronomy)
Origin of diffuse/unresolved -ray background
Summary
Waiting for GLAST…