Very-High-Energy Gamma-Ray Astronomy with VERITAS Martin Schroedter Iowa State University
Summary Very-high-energy astronomy began 20 years ago with 1 source. Now ~80 more VHE discoveries have been made (binaries, pulsars, nebulae, massive stars, galaxies) VHE particles test the limits of physical laws. They probe astrophysical regions not yet explored. They open up the possibility to discover physics beyond the standard model.
Why VHE Gamma Rays? Dark matter and dark energy Relativistic jets and black holes Extragalactic infrared/optical light Neutron stars Primordial black holes Ultra-high energy cosmic rays Gamma-ray bursts Lorentz invariance Low E High E
Electromagnetic Spectrum HE VHE GeV 10-15 TeV 10-18 Proton Strings? 10 23 10 26 Non-thermal universe http://en.wikipedia.org/wiki/file:em_spectrum_properties_edit.svg Photon energy = Frequency * Planck s constant Can produce all these photons in the lab.
Outline Gamma-ray detection Detection technique History VERITAS Science Future
Gamma-ray Detection z(m) 1 TeV -ray produces relativistic particle shower Upper atmosphere ~2 o Cherenkov wavefront 1 m (3 ns) thick 120 m 1 2 3 8 km x(m) Detection area: 50,000 m 2 larger than football field! Energy: 0.1-50 TeV Angular res.: <0.12 o Energy resolution: 15% y( o ) 1 3 Sky view Scale well reconstructed source location 2 x( o )
Gamma-Ray / Cosmic-Ray
VERITAS Smithsonian Astrophysical Observatory Purdue University Iowa State University Washington University in St. Louis University of Chicago University of Utah University of California, Los Angeles McGill University University College Dublin University of Leeds Adler Planetarium Funded in US by: Smithsonian, DOE, NSF Argonne National Lab Barnard College DePauw University Grinnell College University of California, Santa Cruz University of Iowa University of Massachussetts Cork Institute of Technology Galway-Mayo Institute of Technology National University of Ireland, Galway University of Delaware/Bartol Research Institute ~ 25 Associate Members
VERITAS: Site Located at basecamp of Fred Lawrence Whipple Observatory at 1250 m altitude T2 Spring 2006 T3 Fall 2006 T4 Spring 2007 Prototype T1 Fall Jan 2003 2005
VERITAS Telescope Camera: 499 UV-sensitive Photomultiplier tubes Custom light concentrators Trigger: Nearest-neighbors Read-out: 64 μs deep Time resolution: 2 ns 3.5 o Electronics trailer Telescope: Spherical Davis-Cotton design Diameter: 12 m, Area: 111 m 2 Focal length: 12 m 350 mirror facets
Event: Gamma-Ray Arrival direction from the sky Composite Camera View
Event: Cosmic-ray Arrival direction from the sky PMT signals digitized With 500 MSPS FADCs
VHE Gamma-Ray Sky Map Active Galactic Nuclei (AGN) X-ray binary Shell-type supernova remnant Pulsar UnID and Wolf-Rayet 2009 LSI 61 RX J1713 Cas A Cen X-3 Vela Jr. IC443 MGRO 1908 Vela X Crab
Outline Detection method Science Supernova remnants Jets from supermassive black holes Extragalactic background light Future
Supernova Remnants IC 443 - Jellyfish Nebula X-ray: blue Radio: green Optical: red Distance: 5000 lyr Age: 3000-30,000 years
VHE -rays Overlap with CO indicating molecular cloud in line of sight Maser emission suggests SNR shock interacting with cloud VHE emission could be: a) CR-induced pion production in cloud b) associated with pulsar wind nebula to the south Color image: -ray significance E>300 GeV Angular resolution: Energy spectrum: dn/de E -3.0 ± 0.4 Acciari et al. ApJL 698 L133 (2009)
Outline Detection method Science Future Advanced Gamma-Ray Imaging System (AGIS)
Future Imaging Atmospheric Cherenkov Instrument AGIS VERITAS Whipple 10 m 2012 2007 1989
Future Imaging Atmospheric Cherenkov Instrument Event Containment VERITAS AGIS Whipple 10 m 2007 100 m 2012 1989