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VERITAS Collaboration Recent Results:

VERITAS Collaboration Recent Results:. Frank Krennrich (Iowa State University) for the VERITAS collaboration. March, 13 2002. Outline. - Whipple 10m & ground-based g -ray astronomy - Recent results from Whipple 10m - VERITAS: impact on science to come - Summary.

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VERITAS Collaboration Recent Results:

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  1. VERITAS CollaborationRecent Results: Frank Krennrich (Iowa State University) for the VERITAS collaboration March, 13 2002

  2. Outline - Whipple 10m & ground-based g-ray astronomy - Recent results from Whipple 10m - VERITAS: impact on science to come - Summary

  3. History of the Whipple 10m 0.01 – 100 TeV Imaging Camera Area ~ 100,000 m2 E ~ 0.2 – 100 TeV Dq/q~ 0.2 o

  4. Cosmic Ray Rejection Technique g-ray proton • g-ray images: - narrow, short, smooth • Hadronic images: - broad, long - local muons, patchy • hadron rejection: 99.7% (10-3) Courtesy W.Hofmann Crab Nebula 7 s in 1hour

  5. Science Highlights: Whipple 10m • 1997 Flare of Mrk 501 • z = 0.034 • 1989 Discovery of TeV • photons from the Crab Weekes et al. 1989, ApJ, 342, 379 37 Catanese et al. 1997, ApJ, 487, L143 151 • 2001 Discovery of • 1H1426+428 • (z = 0.129) • 1992 TeV photons from • the blazar Mrk 421 • z = 0.031 Horan et al. 2002, ApJ, in press Punch et al. 1992, Nature, 358, 477 109 489 • 2001 Flare Mrk 421 • 1996 Giant & short flare • from • Mrk 421 489 Gaidos et al. 1996, Nature, 383, 319 Krennrich et al. 2001, ApJL, 560, L45 109

  6. Mrk 501 Flare in 1997 Whipple - X-ray peak at E > 100 keV  extreme BL Lac • dN/dE ~ • E-1.95K 0.07 e –(E/E ) • E = 4.6 K 0.8 TeV 0 0 HEGRA • dN/dE ~ • E-1.92K 0.03 e –(E/E ) • with E = 6.2 K 0.4 TeV 0 0 Origin of cutoff? IR-background, intrinsic to source etc.

  7. Mrk 421 spectrum (2001) Whipple: average spectrum in high state - 23,000 photons above 260 GeV - average g-ray rate 3.7 Crab • dN/dE ~ E-2.14K 0.03 e –(E/E ) • with E = 4.3 K 0.3 TeV • (- 1.4 + 1.7 TeV)syst 0 0 Krennrich et al. 2001, ApJL, 560, L45

  8. Spectral Variability of Mrk 421 Spectra @ Fluxes 1 – 10 Crab Flux-Index correlation preliminary preliminary • dN/dE ~ E-a e –(E/E ) ; E = 4.3 TeV 0 0 VERITAS collaboration (in preparation)

  9. X-ray/TeV correlation: Mrk 421 TeV lightcurve & TeV spectral variation X-ray/TeV lightcurve preliminary preliminary preliminary VERITAS collaboration (in preparation) Courtesy of G. Fossati , J. Buckley & M. Jordan

  10. Recent Results: 1H1426+428 - X-ray peak at E > 100 keV  extreme BL Lac - z = 0.129 - <rate> ~ 100 mCrab • dN/dE ~ E-3.44K 0.36 Horan et al. 2000, HEAD Meeting, Honolulu, No. 32, 05.03 Aharonian et al. 2002, A&A, in press Horan et al. 2002, ApJ, in press Petry et al. 2002, ApJ, in preparation

  11. VERITAS - 7x Davis-Cotton ~ 110 m2 - focal length ~ 12 m - steel structure - ground-glas mirrors - 499 pixels: ~ 0.15o - distance 80 m - 500 MHz FADC - Front-end/moonlight operation - Sub-arrays

  12. Improvements with VERITAS • Combine stereoscopic view with improved • 10m type telescope • improved angular resolution • enhanced background suppression • lower energy threshold • improved energy resolution • cross-calibration with GLAST •  absolute energy calibration - 50 GeV – 50 TeV - Dq/q~ 0.03o@1TeV ~ 0.09o@100GeV - Flux sensitivity: 15 mCrab @100GeV 5 mCrab @300GeV VERITAS 80 m

  13. Scientific Objectives • Active Galactic Nuclei • (Diffuse) Galactic Plane • Infrared Background • Pulsars g + g e+ + e - • Gamma Ray Bursts • Supernova Remnants • Neutralino Annihilation, • Primordial Black Holes, • Quantum Gravity, …

  14. Summary - spectral cutoffs for Mrk 421, Mrk 501 (1-10 Crab)  IR cutoff? IC-peak? KN-cross section? - spectral variability of Mrk 421 cutoff variable? - detection of blazars with redshift up to z = 0.129 but background dominated, steep spectrum

  15. Sensitivity: VERITAS-4 - 100 GeV – 50 TeV - Dq/q~ 0.04o @1TeV ~ 0.12o @100GeV - Flux sensitivity: 200 mCrab @100GeV 6 mCrab @300GeV - 50 GeV – 50 TeV - Dq/q~ 0.03o @1TeV ~ 0.09o @100GeV - Flux sensitivity: 15 mCrab @100GeV 5 mCrab @300GeV VERITAS-7

  16. Sensitivity of Telescope Arrays

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