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Recent TeV Observations of Blazars & Connections to GLAST

Recent TeV Observations of Blazars & Connections to GLAST. Frank Krennrich Iowa State University VERITAS Collaboration. GSFC, October 24, 2002. AGN. VERITAS Collaboration:. Frank Krennrich (krennrich@iastate.edu) for the VERITAS collaboration. Collaboration members:

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Recent TeV Observations of Blazars & Connections to GLAST

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  1. Recent TeV Observations of Blazars & Connectionsto GLAST Frank Krennrich Iowa State University VERITAS Collaboration GSFC, October 24, 2002 AGN

  2. VERITAS Collaboration: Frank Krennrich (krennrich@iastate.edu) for the VERITAS collaboration Collaboration members: Iowa State U. Leeds U. (U.K.) McGill University (Canada) Purdue U. Smithsonian Astrophysical Observatory UCLA University College, Dublin (Ireland) U. of Chicago U. of Utah Washington U.

  3. Outline • Introduction  atmospheric Cherenkov imaging technique  brief overview of TeV blazars • Astrophysics results with Whipple 10m telescope  Mrk 421 2000/2001, Mrk 501 1997 spectra  H1426+428, 1ES1959+650 • Next generation instrument: VERITAS • VERITAS – GLAST connection • Summary

  4. 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 100 optical photons/m2 TeV within a few ns

  5. 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

  6. 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 • H1426+428 • (z = 0.129) • 1992 TeV photons from • the blazar Mrk 421 • z = 0.031 Horan et al. 2002, ApJ, 571, 753 Petry 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 ~10 Crab Krennrich et al. 2001, ApJL, 560, L45 489 Gaidos et al. 1996, Nature, 383, 319 Krennrich et al. 2002, ApJL, 575, L9 109

  7. “Whipple” blazars at 300 GeV Mrk 421 0.031 Mrk 501 0.034 1ES2344 0.044 1ES1959 0.048 H1426 0.129 • > 70 “EGRET” blazars at 1 GeV • Redshift z = 0.03 – 2.28 z Mrk 421 H1426+428 Mrk 501 1ES1959+650 1ES2344+514 3C66 1ES2155-304 TeV blazar

  8. Search for new TeV Blazars: PKS 2155-304 Mrk 501 Mrk 421 H1426+428 1ES1959+650 1ES2344+514 Costamante, L. & Ghisellini, G. 2001, A&A, 384, 56

  9. Mrk 501 • z = 0.034 • X-ray BL • Marginal GeV • > 40 s TeV Mrk 421 • z = 0.031 • X-ray BL • Weak GeV • > 86 s TeV

  10. Multiwavelength spectra Mrk 501 Mrk 421 • Peak at 1 keV/~50 GeV • X-ray/TeV correlation • Peak: 100 keV/200 GeV • X-ray/TeV correlation Catanese et al., ??? Catanese & Weekes, PASP, 111, 3191193 (1999)

  11. Mrk 421 in 2000/2001: • 23,000 g-rays at E> 300 GeV Courtesy of J. Holder (see also Holder et al., 2001, Proc. 27th ICRC, Hamburg)

  12. Mrk 421/Mrk 501 spectra Mrk 501 dN/dE ~ E-1.95K 0.07 e –(E/ E ) • with E0 = 4.6 K 0.8 TeV 0 Samuelson et al. 1998, ApJL, 501, L17 Krennrich et al. 1999, ApJ, 511, 149 Mrk 421 dN/dE ~ E-2.14K 0.03 e –(E/E ) • with E0 = 4.3 K 0.3 TeV • (- 1.4 + 1.7 TeV)syst 0 Krennrich et al. 2001, ApJL, 560, L45

  13. Mrk 421 <spectral variability>  on average, g-ray luminosity peak shifts to larger energies with increasing flux! Krennrich, F. et al. 2002, ApJL, 575, L9

  14. <Mrk 501> 1997 vs. Mrk 421 high state Mrk 501 1997 average  spectral index varies but cutoff region remains stable!  imagine instrument with 20 times the sensitivity of Whipple • separate constant from variable component  IR-background density Mrk 421 high state (set I)

  15. Mrk 421: spectral variability: VHE-g-ray X-ray Krennrich et al. 2002, ApJL, 575, L9 Property of a specific blazar or emission mechanism? Fossati et al. 2000, ApJ, 541, 166 Krennrich et al. 1999, ApJ, 511, 149

  16. ½ Hourly Spectral Variability: Feb. 2 Feb. 27 Feb. 1 P = 3.4 x 10-3 March 19 March 25 March 27 P = 8.5 x 10-4 P = 4.0 x 10-3

  17. ½ Hourly Spectral Variability VERITAS collaboration (in preparation)

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

  19. weak signal ~ 80mCrab H1426+428: 2000 2000 2001 2001 from Horan et al. 2002, ApJ, 571, 753

  20. H1426+428 spectrum: Whipple 2001: dN/dE ~ E-3.50K 0.35 K 0.05 Petry et al. 2002, ApJ, in press HEGRA 2001: dN/dE ~ E-2.60K 0.6 K 0.05 Aharonian et al. 2002, A&A, 384, L23 Whipple+HEGRA: dN/dE ~ E-3.54K 0.27 K 0.05 Petry et al. 2002, ApJ, in press

  21. 2002 Flares from 1ES1959+650: IAU circular 7903 (VERITAS collaboration), 2002 Holder et al. 2002, in preparation

  22. Conclusion from blazar observations • Spectral cutoffs for Mrk 421/501 at ~ 4 TeV:  possible evidence for absorption from IR background  or due to internal break due to sKN~ E-1 (when ghnsoft > me c2) • Spectral variability (Mrk 421):  g-ray luminosity peak shifts with <flux> increase  a-flux correlation holds over 5 years! • Rapid variability (Mrk421):  tvariability ~ 15 min.  g ~ 10  emission region 10-4 - 10-5 pc • H1426+428:  first detection of blazar with z ~ 0.129 at E >300 GeV  steep spectrum: dN/dE ~ E-3.54K 0.27 K 0.05 • Future: source list steadily growing (5 Whipple blazars)  VERITAS

  23. VERITAS: Very Energetic Radiation Imaging Telescope Array System • 50 GeV – 50 TeV • Area: = 100,000 m2 (1 TeV) = 40,000 m2 (300 GeV) = 1,000 m2 (50 GeV) • Angular res.: 0.03o – 0.14o • Energy resolution: 10-18% • Observation strategy: pointed exposures

  24. Arrays of Imaging Telescopes I VERITAS - 50 GeV – 50 TeV - Dq/q~ 0.03o@1TeV ~ 0.09o@100GeV - Flux sensitivity: 15 mCrab @100GeV 5 mCrab @300GeV 80 m

  25. DESIGN 12 m Reflectors 500 PMT Cameras 3.5o FOV 7-telescope Array

  26. Telescope: mount, mirrors Camera: PMTs, amps Electronics: FADCs, trigger DAQ: High speed Readout & analysis TECHNICAL PROGRESS

  27. TELESCOPE Pedestal Overall Optical Support Structure Accomodates 12m mirror

  28. CAMERA PMT Installation Camera Box Construction Cabling inside

  29. FRONT-END PMT Assembly Amplifiers Current Monitoring

  30. Point Source Sensitivity VERITAS Stacee HESS MAGIC Cangaroo III

  31. GLAST/VERITAS cross-calibration: Crab Nebula • Overlap: 50 GeV – 100 GeV - 1 TeV • GLAST: • DE/E ~ 5-10% @ 10 GeV –100 GeV • VERITAS: DE/E ~ 20-10% @ 50 GeV-1000 GeV • 20-25% uncertainty in the absolute energy of IACTs!  fix with GLAST/VERITAS cross- calibration using overlap! • GLAST (40 days exposure)  150 (10) photons above 10 (100) GeV  10% accuracy in absolute E GLAST VERITAS Hillas et al., ApJ, 503, 744 (1998)

  32. GLAST Connections: • Unified AGN picture  ~ several 103 GeV blazars  blazar classification studies (GeV blazars) • Jet models  broad studies daily-yearly flux variations • EBL cutoff  probe 0.1 mm – 0.01 mm • Blazar spectra  20 MeV – 100 GeV • Unified AGN picture  ~ 102 sub-TeV blazars  classification studies (extreme blazars) • Jet models  detailed studies min. - yearly spectral variations • EBL cutoff  probe 0.1 mm – 50 mm • Blazar spectra  50 GeV – 50 TeV

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