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The TeV Gamma-ray Universe Trevor C. Weekes Harvard-Smithsonian Center for Astrophysics

The TeV Gamma-ray Universe Trevor C. Weekes Harvard-Smithsonian Center for Astrophysics. Motivation/Techniques The TeV Sky Future Prospects. A Lonely TeV Cosmic Ray. The Lonely TeV Proton takes a mate and produces a family; many of the off spring go astray but dutiful gamma rays

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The TeV Gamma-ray Universe Trevor C. Weekes Harvard-Smithsonian Center for Astrophysics

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  1. The TeV Gamma-ray Universe Trevor C. WeekesHarvard-Smithsonian Center for Astrophysics Motivation/Techniques The TeV Sky Future Prospects

  2. A Lonely TeV Cosmic Ray Nu Vus of the Universe weekes

  3. Nu Vus of the Universe weekes

  4. The Lonely TeV Proton takes a mate and produces a family; many of the off spring go astray but dutiful gamma rays carry on the family tradition and relay its message. Nu Vus of the Universe weekes

  5. The Relativistic Universe The Relativistic Universe is defined by the presence of high energy particles, the sites where the particles are accelerated, the mechanisms by which they are accelerated, and the regions through which they propagate. Their presence is indicated by the emission of TeV gamma rays. Nu Vus of the Universe weekes

  6. EGRET Nu Vus of the Universe weekes

  7. Simple Technique, Simple Detectors, Low Budget Collection Area = Size of Football Field Nu Vus of the Universe weekes

  8. Development of GeV-TeV TeV Sources Zero ~ 12 > 100 1000? • First Generation Systems 1960 – 1985 • Weak or no discrimination • Lebedev, Glencullen, Whipple, Narrabri, Crimea • Second Generation Systems 1985 – 2004 • Atmospheric Cherenkov Imaging Telescopes • Whipple, Crimea, CAT, HEGRA, Durham, CANGAROO …… • Third Generation Systems 2004 – 2010 • Arrays of Large ACITs • MAGIC, HESS, CANGAROO-III, VERITAS, MACE • Fourth Generation Systems 2010 - • TBD New Technology Increase in Scale New Technology? Nu Vus of the Universe weekes

  9. Development of MeV-GeV 100 MeV Sources One 30 (15) 270 10,000? • First Generation Systems 1960 – 1972 • Spark Chambers • Balloons • Controversy • Second Generation Systems 1972-1991 • Spark Chambers • Small Satellites • SAS-II, COS-B • Third Generation Systems 1991-2007 • Spark Chamber • Bigger • EGRET on CGRO • Fourth Generation Systems 2007-2012+ • New Technology: Solid State • AGILE, GLAST New Technology Increase in Size New Technology What? Nu Vus of the Universe weekes

  10. Early Expectations of TeV Gamma-ray Astronomy Find the Origin of the Cosmic Radiation: * Single source or class of sources * Unambiguous detection of the 70 MeV bump in the spectrum * Source(s) would be in the Galaxy Locate the “Smoking Gun” of Cosmic Ray Origins! The reality has been quite different! * Many different sources (too many!) * No unambiguous proton source detection * Many sources are Extragalactic

  11. Atmospheric Cherenkov Imaging Technique (ACIT) • Proposed in 1977 • *Imaging systems came into operation 1984 • (Whipple, Crimea) • *First TeV Source detected (Crab Nebula/ • Whipple Observatory) 1989 • Standard Candle for TeV Gamma-ray Astronomy • Strongest Steady Source in TeV Sky Nu Vus of the Universe weekes

  12. TeV Image of Crab (not resolved) Synchrotron Compton Compton Synchrotron Model for TeV Gamma-ray emission (first proposed by Gould, 1964) Electron Progenitor Prototype Model for most TeV gamma-ray sources Nu Vus of the Universe weekes

  13. Detection of TeV Gamma-ray AGN Markarian 421 Cross = X-ray source Dotted line : EGRET error circle Contours: TeV source intensity (29 sigma) Markarian 421 Weak Source in EGRET but strong at TeV energies Variation in Nightly Rates from Markarian 421 Hours-days-months

  14. TeV Catalog of AGN HBL = High frequency BL Lac All confirmed sources Spectra measured Light-curves determined Multi-wavelength Correlations Only two in EGRET Catalog Horan, Weekes, 2003 Nu Vus of the Universe weekes

  15. Multiwavelength Results: Power Spectra Mrk 501 Compton Synchrotron Similar double peaked Power Spectra seen in other AGN

  16. AGN Jet Emission Mechanisms Electron Progenitors: Synchrotron Self Compton External Compton Proton Progenitors: Proton Cascades Proton Synchrotron Electron Synchrotron Self Compton Models most consistent with TeV AGN…..but observations are complex and require more sophisticated Modelling of Jets.

  17. Limitations of ACIT Telescopes • Second Generation Telescopes successful but…. • Limited Flux Sensitivity • Hitting the “Muon Wall” • Need Lower Energy for GLAST Overlap • Array Concept demonstrated by HEGRA

  18. ARRAYS (Third Generation) Arrays of Cherenkov telescopes viewing the same shower and improving the energy threshold, the angular resolution and the energy resolution; muon background removed. Factor of 10-20 improvement in flux sensitivity Fac Nu Vus of the Universe weekes

  19. VERITAS, (Arizona) 4 tel. 2006 7 tel. 2008? MAGIC (La Palma), 1 tel., 2004 2 tel., 2008 CANGAROO III, 4 tel., 2006 (Australia) HESS, (Namibia) 4 tel., 2003 5 tel., 2007 The Big 5 TeV ACIT Observatories MACE (India) 2 tel. 2008

  20. Iowa State University Adler Planetarium Leeds University Barnard College McGill University DePauw University National University of Ireland, Dublin Grinnell College Purdue University U.C. Santa Cruz Smithsonian Astrophysical Observatory U. Mass. University of California, Los Angeles N.U.I., Galway University of Chicago Cork I.T. University of Utah Galway-Mayo I.T. Washington University, Saint Louis VERITAS: Very Energetic Radiation Imaging Telescope Array System The VERITAS Collaboration First two 12 m telescopes of VERITAS now in operation at temporary site at Whipple Observatory Basecamp, December, 2005 Four telescopes in operation in 2006 Seven telescopes in 2008? Funding from NSF/DOE/Smithsonian/PPARC/SFI/NSERC

  21. 1 GeV 100 GeV Whipple 10 m (3s in 50 hrs) GLAST (2 Years) VERITAS-4(3s in 50 hrs) Di Differential Flux Sensitivity VERITAS, HESS and MAGIC will overlap and complement GLAST Nu Vus of the Universe weekes

  22. HESS European Collaboration; M.P.I (Heidelberg) 4 x 12 m Telescopes Completed in Dec. 2003 Located in NAMIBIA First of the Big 5 to come on-line Direction ~ arc-min Energy Resolution ~ 10% Background ~ 0 Nu Vus of the Universe weekes

  23. Pulsar Nebula AGN Other, UNID SNR The TeV Sky - 2005 Diverse Categories of TeV Gamma-ray sources: AGN SNR (Plerion and Shell) Radio Galaxy Microquasar Galactic Plane Binary Extended Sources Dark Sources Galactic Center 1ES 1218 H1426 M87 Mrk501 PSR B1259 1ES 1101 1ES1959 SNR G0.9 RXJ 1713 RXJ 0852 Cas A LS 5039 GC Vela X TeV 2032 Crab 1ES 2344 HessJ1303 Cygnus Diffuse MSH 15-52 PKS 2155 H2356 PKS 2005 R.A.Ong Aug 2005 Nu Vus of the Universe weekes

  24. Catalog of TeV AGN c. 2005 Nu Vus of the Universe weekes

  25. Gamma-ray Meets IR-Photon Spectrum at earth: E-2 exp(-t(E)) Absorption: exp(-t(E)) Source: dN/dE ~E-2 e+ g-ray IR-photon e- • Extragalactic Background Light (EBL) causes • spectral distortion due to g + g  e+ + e- • Optical depth depends on integral over the EBL spectrum • from the threshold for pair creation up to higher energies Nu Vus of the Universe weekes

  26. EBL Detections & Limits From Dwek & Krennrich 2004, ApJ Nu Vus of the Universe weekes

  27. HESS Survey: New Sources Gal. Center HESS J1804-216 HESS J1825-137 HESS J1837-069 HESS J1834-087 HESS J1813-178 G0.9+0.1 30° 0° LS 5039 HESS J1713-381 HESS J1702-420 HESS 1632-478 HESS J1745-303 HESS J1634-472 HESS J1708-410 330° 359° Sources > 6 sigma (9 new, 11 total) Sources > 4 sigma (7 new) HESS J1614-518 HESS J1640-485 RX J1713.7-3946 HESS J1616-508 Nu Vus of the Universe weekes

  28. Microquasar: LS 5039 7 sigma detection by HESS Identification based on position Consistent with EGRET Source No time variability Hard spectum Microblazar? Nu Vus of the Universe weekes

  29. Relativistic Jets and TeV Sources Nu Vus of the Universe weekes

  30. HESS and MAGIC Spectrum Good agreement between HESS and MAGIC. Galactic Center • Hard spectrum G = 2.2. • No evidence for variability on a variety of time scales. Unlikely to be dark matter because of energy spectrum. Nu Vus of the Universe weekes

  31. HESS Gamma: color ASCA X-ray: Lines Hard spectrum G ~ 2 Not a simple power-law. RX J1713-394 (1) CANGAROO detection ~7s. Shell Supernova Remnant HESS confirmation ~ 40s. Extended Bright Source Close Correlation with X-rays Spectrum Cosmic Ray Source? Nu Vus of the Universe weekes

  32. RX J1713-394 (2) Weak Radio CO Distributions: Target Material? Progenitors: Electrons or Protons “No decisive conclusions can yet be drawn regarding the parent population dominantly responsible for the gamma-ray emission from RX J1713.7-3946” Not the Smoking Gun! Nu Vus of the Universe weekes

  33. Future of GeV/TeV Gamma-ray Astronomy GLAST: the Next Generation Gamma-ray Space Telescope: 2007-2012 Also smaller version: AGILE (2006) Not clear what GeV space telescope might come after GLAST

  34. Future of GeV/TeV Gamma-ray Astronomy (ground-based) Third generation Observatories coming on-line (<2008) It is easy to extend/scale-up ground-based observatories HESS-2: Add 28m telescope: improved sensitivity at lower threshold (50 GeV) in coincidence mode (stereo) Fourth generation Observatories under discussion (>2010) e.g. HE-ASTRO proposed by Vladimir Vassiliev Nu Vus of the Universe weekes

  35. HE-ASTRO Because the size of the HE-ASTRO, ~1 km2, is much larger than the size of the Cherenkov light pool, ~108 cm2, the number of telescopes required is > 200 A Coupling distance: d=80m Nu Vus of the Universe weekes

  36. HE-ASTRO (specifications) • Image pixel size – 0.0146o • Readout image – 128 x 128 pixels • Readout Image size – 1.875o x 1.875o • NSB per pixel – 0.032 (20 nsec gate) • ADC – 8 bit (S/N improved, 10– >8) • Pixel dimension 12mm x 12mm • Sensor area – 12.3 mm x 12.3 mm • Shutter exposure – a few msec • Image integration time - 20 ns • Optical system TBD • Array trigger protocol TBD • Data Rates ~80 Mb/secper node • Online data processing TBD • TeV Astrophysics Workshop, Palaiseau, April, 2005 (Vassiliev) • Array of 217 telescopes • Elevation 3.5km • Telescopes’ coupling distance 80m • Area ~1.0km2 (~1.6km2) • Single Telescope Field of View ~15o • FoV area ~177 deg2 • Reflector Diameter ~7m • Reflector Area ~40 m2 • QE 50% (200-400 nm) • Trigger sensor pixel size 0.146o • Trigger Sensor Size ~31.2cm • NSB rate per Trigger pixel ~3.2 pe per 20 ns • Single Telescope NSB Trigger Rate 1KHz • Energy Range 20–200 GeV • Differential Detection Rate Peak ~30 GeV • Single Telescope CR trigger rate ~30 kHz Nu Vus of the Universe weekes

  37. Science coming soon (from a TeV Source near you) Astronomy and Astrophysics > 300 sources Old: SNR, AGN, Microquasars, Binaries, Dark Sources New: Clusters, Starburst, Pulsars, Others Cosmological Questions EBL Measured Magnetic Fields Distant Transients detected Lorentz Invariance Origin of Cosmic Rays Sources (ACIT Observatories) UHE Sources Distribution (EAS Arrays) Galactic Plane Physics Dark Matter?? GRBs ?? Prompt: ( Arrays EAS) PBHs Delayed: (ACIT Observatories) Nu Vus of the Universe weekes

  38. Summary (1): The TeV Sky (present) Diverse Categories of TeV Gamma-ray sources: AGN SNR (Plerions and Shell) Radio Galaxies Microquasar Galactic Plane Binary Extended Sources Dark Sources Galactic Center but no confirmed detections (yet!) of: Pulsars Clusters of Galaxies GRBs Starburst Galaxies UHE Sources No Smoking Gun for Origin of the Cosmic Radiation …but Cosmic Particle Acceleration is Ubiquitous

  39. Summary (2): The TeV Sky (future) Within a few years there will be five major ground-based gamma-ray observatories using the ACIT in operation. These will be complemented by: Space Telescopes: AGILE, GLAST (lower E, wide field) Air Shower Arrays: Milagro, Tibet(high E, wide fields) Neutrino Telescopes: IceCube, KM3 The Next Generation of TeV Gamma-ray Observatories using the ACIT are now under discussion: (lower energy, wider fields, large collection area) Watch this space!

  40. Why study TeV Gamma-rays? Why are Elephants the most popular animals in the zoo? They are easy to see and they tell us much! Nu Vus of the Universe weekes

  41. Cosmological studies of High Energy Transient Phenomenato determine: • Redshift evolution of these objects • Population properties of AGN and GRBs • Redshift evolution of EBL (z=0-6) • Major contributors to EBL (stars, dust, AGN, Population III objects, relic particles, SFR, GFR, IMF, BH accretion histories, supernovae feedback, merger history) • Cosmological magnetic fields and their evolution • High energy properties of space-time Nu Vus of the Universe weekes

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