Constraints on the Very High Energy Emission from BL Lacertae Objects

We present results from observations of 29 BL Lacertae objects, taken with the Whipple Observatory 10 m gamma-ray telescope between 1995 and 2000. The observed objects are mostly at low redshift (z < 0.2), but observations of objects of up to z = 0.444 are also reported. Five of the objects are EGRET sources and two are unconfirmed TeV sources. Three of the confirmed sources of extragalactic TeV gamma rays were originally observed as part of this survey and have been reported elsewhere. No significant excesses are detected from any of the other objects observed, on timescales of days, months, or years. We report 99.9% confidence level flux upper limits for the objects for each observing season. The flux upper limits are typically 20% of the Crab flux, although for some sources, limits as sensitive as 6% of the Crab flux were derived. The results are consistent with the synchrotron self-Compton model predictions considered in this work.

[1]  D. Horan.  TEV OBSERVATIONS OF EXTRAGALACTIC SOURCES AT THE WHIPPLE OBSERVATORY , 2004 .

[2]  I. D. Perez,et al.  Search for High-Energy Gamma Rays from an X-Ray-selected Blazar Sample , 2003, astro-ph/0309063.

[3]  N. Bannister,et al.  The imaging X-ray detector for Lobster-ISS , 2003, physics/0305025.

[4]  J. E. Grindlay,et al.  EXIST: mission design concept and technology program , 2002, SPIE Astronomical Telescopes + Instrumentation.

[5]  T. Stanev,et al.  BL Lac objects in the synchrotron proton blazar model , 2002, astro-ph/0206164.

[6]  R. Mukherjee,et al.  Predictions of the High-Energy Emission from BL Lacertae Objects: The Case of W Comae , 2002, astro-ph/0208171.

[7]  T. Weekes,et al.  Detection of the BL Lacertae Object H1426+428 at TeV Gamma-Ray Energies , 2002, astro-ph/0202185.

[8]  L. Costamante,et al.  TeV candidate BL Lac objects , 2001, astro-ph/0112201.

[9]  A. Stepanian,et al.  BL Lac: A new ultrahigh-energy gamma-ray source , 2001, astro-ph/0111448.

[10]  V. Vassiliev.  Extragalactic background light absorption signal in the TeV γ-ray spectra of blazars , 1999, astro-ph/9908088.

[11]  P. M. Chadwick,et al.  A Search for Very High Energy Gamma Rays from Active Galactic Nuclei Visible from the Southern Hemisphere , 1999 .

[12]  E. Feigelson,et al.  The RGB Sample of Intermediate BL Lacertae Objects , 1999, astro-ph/9905133.

[13]  T. Weekes,et al.  The Flux Variability of Markarian 501 in Very High Energy Gamma Rays , 1999, astro-ph/9903088.

[14]  E. Pian,et al.  Correlated variability of MKN 421 at X-ray and TeV wavelengths on time scales of hours , 1999, astro-ph/9902224.

[15]  A. Caccianiga,et al.  The REX Survey: A Search for Radio-emitting X-Ray Sources , 1998, astro-ph/9810254.

[16]  B. Dingus,et al.  Proceedings of the 26th International Cosmic Ray Conference , 1999 .

[17]  F. Stecker.  Intergalactic Extinction of High Energy Gamma-Rays , 1998, astro-ph/9812286.

[18]  A. Comastri,et al.  A theoretical unifying scheme for gamma-ray bright blazars , 1998, astro-ph/9807317.

[19]  P. J. Boyle,et al.  Discovery of Gamma-Ray Emission above 350 GeV from the BL Lacertae Object 1ES 2344+514 , 1998 .

[20]  Italy.,et al.  A unifying view of the spectral energy distributions of blazars , 1998, astro-ph/9804103.

[21]  O. Kalekin,et al.  Blazar 3C 66A: Another extragalactic source of ultra-high-energy gamma-ray photons , 1998 .

[22]  J. Buckley.  What the Wild Things Are , 1998, Science.

[23]  Mannheim.  Possible production of high-energy gamma rays from proton acceleration in the extragalactic radio source markarian 501 , 1998, Science.

[24]  Paolo Giommi,et al.  The Deep X-Ray Radio Blazar Survey. I. Methods and First Results , 1998, astro-ph/9801024.

[25]  T. Weekes,et al.  Discovery of >350 GeV Gamma Rays from the BL Lacertae Object 1ES 2344+514 , 1997, astro-ph/9712325.

[26]  Giuseppe Vacanti,et al.  The Spectrum of TeV Gamma Rays from the Crab Nebula , 1997 .

[27]  T. Weekes,et al.  Multiwavelength Observations of a Flare from Markarian 501 , 1997, astro-ph/9707179.

[28]  Italy.,et al.  Unifying models for X-ray selected and Radio selected BL Lac Objects , 1997, astro-ph/9704113.

[29]  P. Madau,et al.  ON THE ORIGIN OF THE GAMMA -RAY EMISSION IN BLAZARS , 1996 .

[30]  A. Marscher,et al.  An Analysis of the Synchrotron Self-Compton Model for the Multi--Wave Band Spectra of Blazars , 1996 .

[31]  Christine D. Wilson,et al.  Detection of Gamma Rays with E > 300 GeV from Markarian 501 , 1996 .

[32]  P. Giommi,et al.  A Sample-oriented catalogue of BL Lacertae objects , 1995, astro-ph/9511065.

[33]  Christine D. Wilson,et al.  Upper limits on TeV gamma-ray emission from active galactic nuclei , 1995 .

[34]  P. Padovani,et al.  UNIFIED SCHEMES FOR RADIO-LOUD ACTIVE GALACTIC NUCLEI , 1995, astro-ph/9506063.

[35]  R. Blandford,et al.  Pair cascades in extragalactic jets. 1: Gamma rays , 1995 .

[36]  P. Giommi,et al.  The Connection between X-Ray-- and Radio-selected BL Lacertae Objects , 1994, astro-ph/9412073.

[37]  T. Weekes,et al.  Instrumentation for very high energy gamma-ray astronomy , 1995 .

[38]  Martin J. Rees,et al.  Comptonization of Diffuse Ambient Radiation by a Relativistic Jet: The Source of Gamma Rays from Blazars? , 1994 .

[39]  R. Schlickeiser,et al.  On the Location of the Acceleration and Emission Sites in Gamma-Ray Blazars , 1993, astro-ph/9312052.

[40]  Charles D. Dermer,et al.  Model for the high-energy emission from blazars , 1993 .

[41]  Giuseppe Vacanti,et al.  Survey of Candidate Gamma-Ray Sources at TeV Energies Using a High-Resolution Cerenkov Imaging System: 1988--1991 , 1993 .

[42]  G. Ghisellini,et al.  A jet model for the gamma-ray emitting blazar 3C 279 , 1992 .

[43]  M. Punch,et al.  Detection of TeV photons from the active galaxy Markarian 421 , 1992, Nature.

[44]  T. Weekes,et al.  A high resolution imaging detector for TeV gamma-ray astronomy , 1990 .

[45]  Otaviano Helene,et al.  Upper limit of peak area , 1983 .

[46]  A. Konigl.  Relativistic jets as X-ray and gamma-ray sources. , 1981 .