Acronyms and Alphanumerics H.E.S.S. takes a look at RX J17133946 G347.30.5

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Acronyms and AlphanumericsH.E.S.S. takes a look
at RX J1713-3946 (G347.3-0.5)

• High-energy particle acceleration in the shell
  of a supernova remnant F. A. Aharonian et. al.
  (Nature 432, 75 (November 4, 2004))
• Presenter Paul Edmon
• 2-24-05
• Journal Club

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Overview

• H.E.S.S.
• Cosmic Rays
• RX J1713.7-3946
• Gamma Ray Results from H.E.S.S. of RX
  J1713.7-3946
• Conclusions

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Victor Hess

• Born in 1883 in Austria
• 1936 Nobel Prize Winner
• Discovered Cosmic Rays by making multiple balloon
  flights and measuring atmospheric ionization

Courtesy of Nobelprize.org
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H.E.S.S.
Courtesy of The H.E.S.S. Project

• High Energy Stereoscopic System
• Location Khomas Highland, Namibia
• Uses 4 Atmospheric Cherenkov Detectors
• Completed December 2003

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H.E.S.S.

• Four 13m Diameter Telescopes with a 960
  PhotoMultiplier Tube (PMT) Camera which has a
  field of view of 5
• Spaced in a 120m square
• Angular resolution of a few arcmins
• Effective Energy Range of 100 GeV to 10 TeV with
  an Energy Resolution of 15-20
• Sensitivity of 10-13 erg cm-2 s-1

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The Obligatory Graph
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Extensive Air Shower (EAS)

• Shower of particles when a cosmic ray interacts
  with an atom in the upper atmosphere
• These particles produce more particles as they
  decay and interact
• The larger the energy of the incident particle
  the larger the shower
• Can determine type of particle, its energy and
  direction if you can reconstruct the shower
  accurately
• Particles traveling faster than the local speed
  of light will produce Cherenkov Radiation in the
  UV

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RX J1713-3946 (G347.3-0.5)

• SNR of a supposed SN Type II
• Possible Neutron Star at center of SNR
• Galactic SNR at 1 kpc in the constellation of
  Scorpius
• Bright X-Ray SNR
• Has been imaged by
• ASCA
• ROSAT
• XMM-Newton
• Chandra
• Candidate for Active Galactic Cosmic Ray
  Production

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H.E.S.S. looks at the SNR

• Looking at Gamma Rays, which generate EAS
• 18.1 hours of live time data in two parts between
  May and August 2003
• Two Telescopes operating independently and then
  data was searched using GPS Timestamp to find
  coincidences
• Two Telescopes using a hardware coincidence
  trigger
• After cleaning the data for well reconstructed
  events the Energy Threshold ended up at 800 GeV,
  but lowered the error considerably

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Gamma Ray Map of SNR

• Fluxes above 1 TeV in each region (10-8 photons
  m-2 s-1)
• N 3.0 0.6
• W 4.1 0.8
• SE 5.9 1.0
• I 1.7 0.6
• Total Flux above 1 TeV
• 1.46 .54 x 10-7 photons m-2 s-1
• 66 of Crab Nebula

Courtesy of Nature
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Gamma Ray Data

• Photon Index (G)
• H.E.S.S. 2.19 0.24
• CANGAROO-II 2.84 0.35
• Note CANGAROO-II only measured NW area.
• Integral Flux between 1 and 10 TeV 3.5 x 10-11
  ergs cm-2 sec-1
• X-Ray Flux 10-10 ergs cm-2 sec-1

Courtesy of Nature
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Gamma Ray and X-Ray

• X-Ray Data from ASCA
• 1-3 keV range
• Relatively the same Angular Resolution
• X-Ray Emission
• Non-thermal Continuum
• No Line Emission
• Probably synchrotron radiation from 100 TeV
  electrons

Courtesy of Nature
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Gamma Ray Sources

• Cosmic Rays running into gas atoms
• CO data indicates that the SNR is running into a
  molecular cloud in the NW.
• These collisions produce particle showers which
  include p0 which decay producing gamma rays
• Bremmstrahlung from electrons
• Inverse Compton Emission
• From energetic electrons in the low density
  Eastern Region

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Cosmic Ray Connection

• Morphology supports that the particles are
  accelerated at the shock, then interacting and
  radiating in the molecular cloud
• If the Cosmic Rays make up a significant portion
  of the flux then if the density of the cloud
  exceeds 100 cm-3 then the energies implied by
  gamma ray flux and spectrum would be 1049 n-1
  ergs in the 10 to 100 TeV range

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Cosmic Ray Connection

• This is consistent with the SNR origin for
  Galactic Cosmic Rays, which involves a 10
  conversion efficiency from mechanical energy of
  the explosion to non-thermal particles
• The production of Cosmic Rays would follow an
  approximate E-2 power law from energies of
  several GeV to one PeV
• The extension of the gamma ray spectrum to 10 TeV
  requires an extremely effective accelerator to
  get particles up to at least 100 TeV

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Conclusions

• TeV flux probably from Cosmic Rays interacting
  with local particles
• This would support the SNR origin for Galactic
  Cosmic Rays
• First time an object has been identified as an
  active celestial gamma ray source by both
  coincidence and morphology
• More data needs to be taken with full H.E.S.S.
  Array to determine the definite source of gamma
  ray emission

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Sources

• Ahoranian, F.A. et. al. High-energy particle
  acceleration in the shell of a supernova
  remnant, Nature, 432, 75, November 4, 2004
• Victor F. Hess-Biography Nobelprize.org, 2004,
  http//nobelprize.org/physics/laureates/1936/hess-
  bio.html
• The H.E.S.S. Project an Array of Imaging
  Atmospheric Cherenkov Telescopes, 2005,
  http//www.mpi-hd.mpg.de/hfm/HESS/HESS.html