TeV Gamma-ray Astronomy and UHECR-1 Trevor C. Weekes, Whipple Observatory, Harvard-Smithsonian Center for Astrophysics

July 22-23, 2004 Trevor Weekes Watson Fest Outline Relevance to UHECR’s Relevance to UHECR’s Atmospheric Cherenkov Imaging Technique Atmospheric Cherenkov Imaging Technique Status of TeV Observations Extragalactic TeV Sources Extragalactic TeV Sources Observations of the UHECR Sources Observations of the UHECR Sources Next Generation Telescopes

July 22-23, 2004 Trevor Weekes Watson Fest Relevance of TeV Astronomy to Studies of UHE Cosmic Rays Historical Precedent Historical Precedent Similar Techniques Similar Techniques Understanding of discrete Source (e.g. UHECR-1) demands study at other wavelengths; TeV Band is the Highest Energy Band in which Cosmic Sources have been reliably detected Understanding of discrete Source (e.g. UHECR-1) demands study at other wavelengths; TeV Band is the Highest Energy Band in which Cosmic Sources have been reliably detected Existence of Extragalactic Sources of Relativistic Particles has been established Existence of Extragalactic Sources of Relativistic Particles has been established New Generation of TeV Telescopes have the sensitivity for detection of TeV component of UHECR sources New Generation of TeV Telescopes have the sensitivity for detection of TeV component of UHECR sources

July 22-23, 2004 Trevor Weekes Watson Fest Why study TeV Gamma rays? Why do we study elephants when mosquitoes are easier to find and more plentiful? Why do we study elephants when mosquitoes are easier to find and more plentiful? TeV gamma-rays, like elephants, are bigger, more difficult to produce, and stretch the the production models to their limits!

July 22-23, 2004 Trevor Weekes Watson Fest Simple Technique, Simple Detectors, Small Budgets

July 22-23, 2004 Trevor Weekes Watson Fest Early Expectations of TeV Gamma-ray Astronomy We would find the Origin of the Cosmic Radiation which would entail: which would entail: * Single source or class of sources * Unambiguous detection of the 70 MeV bump in the spectrum * Source(s) would be in the Galaxy In short: locate the “Smoking Gun” of Cosmic Ray Origins!

July 22-23, 2004 Trevor Weekes Watson Fest Atmospheric Cherenkov Imaging Atmospheric Cherenkov Imaging Cherenkov Imaging gives the ability to distinguish compact images of gamma-ray showers from more irregular images from hadronic showers Arrival Directions also determined with high accuracy __ Atmospheric height 20 km  e+e+ e_e_  5o5o p To record the Cherenkov light images of gamma-ray initiated air showers, a large camera, consisting of an array of PMTs in the focal plane of a large optical reflector, is used.

July 22-23, 2004 Trevor Weekes Watson Fest HadronGammaGamma Gamma ray Muon RingSky Noise Types of images seen by atmospheric Cherenkov camera

July 22-23, 2004 Trevor Weekes Watson Fest The First TeV Sources *Imaging systems came into operation *First Galactic Source detected (Crab Nebula/ Whipple Observatory) 1989 *First Extragalactic Source detected (Mrk 421/Whipple Observatory) 1992

July 22-23, 2004 Trevor Weekes Watson Fest Tev Gamma-ray Sky Status c Sources reported in refereed literature; 10 are Extragalactic, 8 are Galactic

July 22-23, 2004 Trevor Weekes Watson Fest Catalog Name SourceTypeDate/GroupEGRETGrade TeV NGC 253 Starburst2003/CANG.noB TeV C66ABlazar1998/CrimeayesC- TeV Crab Nebula SNR1989/WhippleyesA TeV VelaSNR1997/CANG.yesC TeV Cen X-3 Binary1999/DurhamyesC TeV Mrk 421 Blazar1992/WhippleyesA TeV M87 Radio Gal. 2003/HEGRAnoC TeV H Blazar2002/WhipplenoA TeV SN1006SNR1997/CANG.noB TeV Mrk 501 Blazar1995/WhipplenoA TeV PSR SNR1995/CANG.noA TeV RXJ SNR1999/CANG.noB+ TeV ES Blazar1999/TAnoA TeV CygOB2? OB Assoc. 2002/HEGRAnoC TeV PKS Blazar1999/DurhamyesA TeV BL Lacertae Blazar2001/CrimeayesC TeV Cas A SNR1999/HEGRAnoB TeV ES Blazar1997/WhipplenoC

July 22-23, 2004 Trevor Weekes Watson Fest + New Sources ~ 2004 Galactic Center Galactic Center PSR at periastron PSR at periastron Others? See following papers on results from HESS and MAGIC Others? See following papers on results from HESS and MAGIC (also credibility of some southern sources has been questioned) (also credibility of some southern sources has been questioned) But no source (Galactic or Extragalactic) has yet been unambiguously identified as a source of Hadronic Cosmic Rays; all the TeV gamma rays could have Electron Progenitors.

July 22-23, 2004 Trevor Weekes Watson Fest TeV Catalog of AGN Catalog Name SourceDate/GroupTypeRedshift TeV Mrk /WhippleHBL0.031 TeV H /WhippleHBL0.129 TeV Mrk /WhippleHBL0.033 TeV ES /TAHBL0.048 TeV PKS /DurhamHBL0.116 TeV ES /WhippleHBL0.044 Horan, Weekes, 2003 HBL = High frequency BL Lac All confirmed sources Spectra measured Light-curves determined Multi-wavelength Correlations Only two in EGRET Catalog

July 22-23, 2004 Trevor Weekes Watson Fest Time Variability: AGN Light Curves Variation in Nightly Rates from Markarian 421 Whipple Observatory 1995 Buckley et al. 1996

July 22-23, 2004 Trevor Weekes Watson Fest Variations Seen on Many Time-scales Markarian 421 Whipple Observatory Hours - minutes Markarian 501 HEGRA Days-months

July 22-23, 2004 Trevor Weekes Watson Fest TeV Results: Correlations with X-rays TeV Results: Correlations with X-rays

July 22-23, 2004 Trevor Weekes Watson Fest Mrk421 Spectral Variability Power LawCutoff Term Exponent of Power Law Changes with Total Intensity. Cutoff Term Remains the Same Krennrich et al. 2003

July 22-23, 2004 Trevor Weekes Watson Fest Multiwavelength Results: Power Spectra Synchrotron Compton Mrk 501 Similar double peaked Power Spectra seen in other AGN

July 22-23, 2004 Trevor Weekes Watson Fest AGN Jet Emission Mechanisms Electron Progenitors: Synchrotron Self Compton External Compton Proton Progenitors: Proton Cascades Proton Synchrotron (Buckley, Science, 1998) Cosmic Cannon: Looking down the Barrel of the Cannon

July 22-23, 2004 Trevor Weekes Watson Fest Detection of Radio Galaxy, M87 HEGRA Group 4.1 sigma detection Weak source but important Nearby Radio Galaxy (Virgo A) Off axis jet source Aharonian et al. 2003

July 22-23, 2004 Trevor Weekes Watson Fest Galactic Center: TeV Source Galactic Center: TeV Source CanCan CANGAROO-III E > 250 GeV 10% 0f Crab Detection: strong Steep spectrum: -4.6+/-0.5 Tsuchiya et al., ApJL (2004) HESS Definitive results See next talk! Whipple 10 m telescope Observations Southern Source E > 2.5 TeV 40 % of Crab 3.7 sigma Kosack et al. ApJL (2004)

July 22-23, 2004 Trevor Weekes Watson Fest TeV Gamma-ray Astronomy: A Legitimate New Astronomical Discipline Essential Features of an Astronomical Discipline: Location of Sources Location of Sources Measurement of Spectrum Measurement of Spectrum Time Variability Time Variability Correlation with other wavelengths Correlation with other wavelengths Ready to be used to aid in the Exploration of UHECR Sources

July 22-23, 2004 Trevor Weekes Watson Fest Study of Arrival Directions of Ultra High Energy Cosmic Rays UHECRs may be diffuse…or they may come from discrete sources UHECRs may be diffuse…or they may come from discrete sources Since these must be nearby, they should be easily recognizable at long wavelengths Since these must be nearby, they should be easily recognizable at long wavelengths If not, and if the production of UHECRs is their unique property, they should still be source of TeV gamma rays If not, and if the production of UHECRs is their unique property, they should still be source of TeV gamma rays Detection of coincident TeV source would confirm existence of UHECR source and give better location Detection of coincident TeV source would confirm existence of UHECR source and give better location

July 22-23, 2004 Trevor Weekes Watson Fest Possible Sources of UHECR’s: New Challenge for TeV Astronomy Possible Clustering into discrete sources of 92 cosmic rays with E > 4 x 10^19 eV (results from AGASA, Havarah Park, Yakutsk, Volcano Ranch) Marginally statistically significant correlation of Doublets and Triplets with Supergalactic Plane Uchihori et al. 2000

July 22-23, 2004 Trevor Weekes Watson Fest TeV Counterpart to UHECR Source: Extragalactic Cascade Ferrigno, Blasi, Marco astro-ph/ Electromagnetic Cascades initiated by photopion production of UHECR on extragalactic radio and microwave background may give detectable flux of TeV photons.

July 22-23, 2004 Trevor Weekes Watson Fest Whipple Search for TeV Emission in Error box of Fly’s Eye 3 x 10^20 eV UHECR Search made at 12 positions within the Error Box; no evidence for TeV emission Akerlof et al The Most Important Direction in the Universe

July 22-23, 2004 Trevor Weekes Watson Fest Akerlof et al TeV maps from six of the twelve fields surveyed; no evidence of an excess. Field includes quasar 3C147 of historical interest….but too distant to be a candidate.

July 22-23, 2004 Trevor Weekes Watson Fest Next GENERATION TELESCOPES Philosophy Philosophy Improve Flux Sensitivity Improve Flux Sensitivity Reduce Energy Threshold Reduce Energy Threshold Multiple > “10 m” telescopes Multiple > “10 m” telescopes New Technology where appropriate. New Technology where appropriate. Arrays of Imaging Telescopes Now on line: CANGAROO III HESS MAGIC ( VERITAS to come )

July 22-23, 2004 Trevor Weekes Watson Fest World Picture of sub-TeV Observatories Four Major Observatories ideally distributed to give maximum coverage CANGAROO III, 4 tel., 2004 HESS, 4 tel., 2004 VERITAS, tel tel. MAGIC, 1 tel., tel., 2006

July 22-23, 2004 Trevor Weekes Watson Fest p Chicago Airport Display

July 22-23, 2004 Trevor Weekes Watson Fest VERITAS Four telescope system Four telescope system 12 m aperture 12 m aperture 80m separation 80m separation Filled triangle configuration Filled triangle configuration 499 pixel camera (0.15º/ 499 pixel camera (0.15º/ pixel, 3.5º FOV) Kitt Peak, Tucson (32ºN, 36ºW, 1800m a.s.l.) Kitt Peak, Tucson (32ºN, 36ºW, 1800m a.s.l.) Current status Current status Prototype telescope operating at Whipple basecamp Prototype telescope operating at Whipple basecamp Funded Funded Sources detected Sources detected VERITAS-4 in 2006 VERITAS-4 in 2006

July 22-23, 2004 Trevor Weekes Watson Fest 1 GeV100 GeV GLAST (2 Years) VERITAS-4 (3  in 50 hrs) Whipple 10 m (3  in 50 hrs)

July 22-23, 2004 Trevor Weekes Watson Fest Prototype VERITAS Telescope VERITAS Movie Cameras: Advanced technology cameras; 500 Mhz FADCs 2 ns slices through shower images (Leeds group has played major role in their design and construction)

July 22-23, 2004 Trevor Weekes Watson Fest Typical Event: Prototype

July 22-23, 2004 Trevor Weekes Watson Fest Results: Markarian 421 Alpha<8 gives: ON =1570 OFF=635.8 Sigma=19.9 Total Exposure=18.7 hours Mean rate=0.83 gammas/min

July 22-23, 2004 Trevor Weekes Watson Fest Summary Not one source but many Extragalactic Sources in profusion No Smoking Gun YET for Cosmic Ray Origins A New Astronomical Discipline is Established Foundations are laid for Major Advances with next Generation Systems working with auger, GLAST, icecube, etc. THESE MAY BE THE important PROBES OF UHECR SOURCES

July 22-23, 2004 Trevor Weekes Watson Fest You have read the book: now watch the movie! (in 2 ns slices) VERITAS Movie Camera