COSMIC RAY ORIGINS. Stella Bradbury, University of Leeds, U.K. g -ray sources the cosmic ray connection detection technique galactic and extragalactic accelerators future instruments and new targets Ultra High Energies. Cosmic Rays ?.
Stella Bradbury, University of Leeds, U.K.
On 7th August 1912, Victor Hess demonstrated that the flux of “ionising radiation” increased above 2 km altitude
Simulated Cherenkov lateral distribution at ground:
local muon ?
The Compton Gamma Ray Observatory 1991 - 2000 Telescope camera subtends 0.12º
EGRET 100 MeV - 30 GeV
g Telescope camera subtends 0.12º-ray sources
EGRET solar flare spectrum :
Diffuse background due to p Telescope camera subtends 0.12º+CR + Hnuclei p0 g g observed but where do we get the p+CR from?
The Crab Nebula Telescope camera subtends 0.12º, standard candle of TeV astronomy.
Chandra X-ray image
VLT optical image
TeV g-rays - point source
Spectral energy distribution Telescope camera subtends 0.12º g-ray production mechanism?
TeV spectrum consistent with e- synchrotron self-Compton emission magnetic field ~16 nT within 0.4 pc of the pulsar.
1st order Fermi acceleration
Detection of TeV Telescope camera subtends 0.12ºg-rays from Cassiopeia A by HEGRA can still be explained as e- inverse Compton without e.g. a po decay component
Chandra X-ray image of Cas A
Still no conclusive evidence for acceleration of relativistic nuclei
Giant molecular clouds Telescope camera subtends 0.12º could act as a target for p+CR + H p0 g + g if bathed in uniform cosmic rays or as a cosmic beam dump for a neighboring particle accelerator
such as a black hole binary:
Cosmic ray production must be high in starburst galaxies where there is a high supernova rate and strong stellar winds?
Active Galactic Nuclei Telescope camera subtends 0.12º
~ 1 % of galaxies have a bright central nucleus that outshines the billions of stars around it
Radio and X-ray observations reveal relativistic jets presumed to be powered by a central supermassive black hole
Rapid TeV Telescope camera subtends 0.12ºg-ray flares emission region only ~ size of solar system!
Whipple Telescope - Mkn 421
g Telescope camera subtends 0.12º-ray Production Mechanism?
Assume emission region is associated with shock accelerated particles, then pick any combination of :
Markarian 501 Telescope camera subtends 0.12ºApril ‘97
Markarian 501 Spectral Energy Distribution Telescope camera subtends 0.12º
TeV Telescope camera subtends 0.12ºg-ray Energy Spectra of Mkn 421 & Mkn 501
Common feature is a cut-off at E0 ~ 4 - 6 TeV. Is this intrinsic to such objects - limit of accelerator?
There are only 6 established TeV g-ray emitting AGN; the most recent flared to a detectable level on 17/05/02
Extragalactic Infrared Background Telescope camera subtends 0.12º :
may cut-off g-ray flux from distant AGN as gg-ray + gIR e- + e+ ( cross-section peaks ateg-ray etarget~ 2 (mec2)2 )
TeV Telescope camera subtends 0.12ºg-ray detection of AGN 600 million light years away limits on IR background density 10 more restrictive than direct satellite measurement in 4 - 50 mm range plagued by foreground starlight
A whole new class of objects? Telescope camera subtends 0.12º
20 keV - 1 MeV
VLT optical afterglow of GRB000131 - at redshift 4.5 1013 light years distant
(epoch of galaxy formation?)
In 1969-70 the Vela 5 nuclear test detection satellites discovered g-ray bursts.
A hypernova ? Telescope camera subtends 0.12º
Cosmological distances require an astronomical energy source!
Invoke shocks in beamed jets!
Merging neutron stars ?
Future Instruments Telescope camera subtends 0.12º
GLAST Telescope camera subtends 0.12ºlaunch due September 2006
> 5 years
20 MeV - 300 GeV
Lowering the energy threshold of ground-based Telescope camera subtends 0.12ºg-ray detection
Solar arrays: very large mirror area but small field of view.
STACEE (2001 - ) 50 GeV - 250 GeV > 2000 m2 of heliostats reflect Cherenkov light via a secondary mirror onto a photomultiplier camera in the tower.
CELESTE, Solar II & GRAAL use the same principle.
The MAGIC Telescope Telescope camera subtends 0.12º on La Palma
Imaging telescope with a single 17m diameter dish.
VERITAS Telescope camera subtends 0.12º array of 12m telescopes in Arizona:
H.E.S.S. Telescope camera subtends 0.12º - an array of 4 ( 16 ?) 12 m diameter telescopes
Flux sensitivity Telescope camera subtends 0.12º:
bridging the gap between ground-based instruments and satellite data
g Telescope camera subtends 0.12º-rays from Cold Dark Matter?
Simulated GLAST detection above diffuse background
c c g g
UN-conventional TARGETS Telescope camera subtends 0.12º