Detection of Gamma Rays with E > 100 MeV from BL Lacertae

doi:10.1086/303998

The Astrophysical Journal

Quick search Find article

Quick search

All journals This journal only

Find article
Volume number: Issue number (if known): Article or page number:

The Astrophysical Journal Volume 480 Number 2 Create an alert RSS this journal

M. Catanese et al. 1997 ApJ 480 562 doi:10.1086/303998

Detection of Gamma Rays with E > 100 MeV from BL Lacertae

FREE

M. Catanese¹, C. W. Akerlof², S. D. Biller³, P. Boyle⁴, J. H. Buckley⁵, D. A. Carter-Lewis¹, M. F. Cawley⁶, V. Connaughton^4,5, B. L. Dingus^7,8, D. J. Fegan⁴, C. E. Fichtel⁷, J. P. Finley⁹, J. A. Gaidos⁹, W. K. Gear¹⁰, R. C. Hartman⁷, A. M. Hillas³, F. Krennrich¹, R. C. Lamb¹, R. W. Lessard⁴, Y. C. Lin¹¹, J. E. McEnery⁴, A. P. Marscher¹², G. Mohanty¹, R. Mukherjee^7,8, J. Quinn⁴, E. I. Robson¹³, A. J. Rodgers³, H. J. Rose³, F. W. Samuelson¹, G. Sembroski⁹, M. S. Schubnell², J. A. Stevens¹³, H. Teräsranta¹⁴, D. J. Thompson⁷, T. C. Weekes⁵, C. Wilson⁹ and J. Zweerink¹

Show affiliations

¹ Department of Physics and Astronomy, Iowa State University, Ames, IA 50011-3160
² Randall Laboratory of Physics, University of Michigan, Ann Arbor, MI 48109-1120
³ Department of Physics, University of Leeds, Leeds, LS2 9JT, Yorkshire, England, UK
⁴ Physics Department, University College, Dublin 4, Ireland
⁵ Fred Lawrence Whipple Observatory, Harvard-Smithsonian Center for Astrophysics, P.O. Box 97, Amado, AZ 85645-0097
⁶ Physics Department, St. Patrick's College, Maynooth, County Kildare, Ireland
⁷ NASA/Goddard Space Flight Center, Code 662, Greenbelt, MD 20771
⁸ Universities Space Research Association
⁹ Department of Physics, Purdue University, West Lafayette, IN 47907
¹⁰ Royal Observatory, Blackford Hill, Edinburgh, EH9 3HJ, Scotland, UK
¹¹ Hansen Experimental Physics Laboratory, Stanford University, Stanford, CA 94305
¹² Department of Astronomy, Boston University, 725 Commonwealth Avenue, Boston, MA 02215
¹³ Joint Astronomy Centre, 660 North A'oh bar o k bar u Place, University Park, Hilo, HI 96720
¹⁴ Metsähovi Radio Research Station, Helsinki University of Technology, Otakaari 5A, SF-02150 Espoo, Finland

Tag this article Full text PDF (234 KB) View as HTML

Abstract References Cited By

We present evidence for the first detection of gamma rays from the extragalactic object BL Lacertae. Observations taken with EGRET on the Compton Gamma Ray Observatory between 1995 January 24 and 1995 February 14 indicate a 4.4 σ excess from the direction of BL Lacertae. The corresponding flux is (40 ± 12) × 10^-8 photons cm^-2 s^-1 above 100 MeV. The combination of all previous observations where BL Lacertae was in EGRET's field of view result in a 2.4 σ excess and a corresponding 95% confidence upper limit of 14 × 10^-8 photons cm^-2 s^-1, indicating that its gamma-ray emission is variable, at least on timescales of several months. Observations of BL Lacertae between 22 and 375 GHz were also taken between 1995 January 24 and 1995 February 14, and the flux levels for those measurements are similar to the historical average values for this object. A deep exposure on BL Lacertae with the Whipple Observatory 10 m gamma-ray telescope shows no evidence of emission above 350 GeV during a period 9 months after the EGRET observations. The 99.9% confidence flux upper limit derived from these observations is 0.53 × 10^-11 photons cm^-2 s^-1, which implies a large reduction in the gamma-ray emission of BL Lacertae between EGRET and Whipple Observatory energies. This reduction should result from processes intrinsic to BL Lacertae because it is near enough to Earth that intergalactic background IR fields should not significantly reduce the flux of gamma rays to which the Whipple Observatory telescope is sensitive.

Your last 10 viewed

Detection of Gamma Rays with E > 100 MeV from BL Lacertae
M. Catanese et al. 1997 ApJ 480 562
XANES and XEOL studies of Eu-doped calcium tungstate in silica synthesized by sol-gel method
J Y Peter Ko et al 2009 J. Phys.: Conf. Ser. 190 012078
Free-response operator characteristic models for visual search
T P Hutchinson 2007 Phys. Med. Biol. 52 L1
A sample injection port for the gas-liquid chromatographic analysis of irradiated organic compounds
M F Barakat 1967 J. Sci. Instrum. 44 1031
Scalar fields on SL(2, R) and H² × R geometric spacetimes and linear perturbations
Masayuki Tanimoto 2004 Class. Quantum Grav. 21 5355
A generalized linear Hubble law for an inhomogeneous barotropic universe
J-F Pascual-Sánchez 2000 Class. Quantum Grav. 17 4913
A Comprehensive Study of Infrared OH Prompt Emission in Two Comets. II. Implications for Unimolecular Dissociation of H2O
Boncho P. Bonev and Michael J. Mumma 2006 ApJ 653 788
Scanning Electron Microscopy: Physics of Image Formation and Microanalysis, Second Edition
L Reimer 2000 Meas. Sci. Technol. 11 1826
Indium hydroxide to bixbyite-type indium oxide transition probed in situ by time resolved synchrotron radiation
L Schlicker et al 2009 Nanotechnology 20 495702
Elliptic flow and initial eccentricity in Cu+Cu and Au+Au collisions at RHIC
Rachid Nouicer (for the PHOBOS Collaboration) 2007 J. Phys. G: Nucl. Part. Phys. 34 S887

Users also read

What's this?

This innovative new feature generates a list of articles 'also read' by other users based on them reading the original article. Article abstracts citations and references are all considered and weighted accordingly. We hope that this will help you find relevant papers for your research.

IOPscience

The Astrophysical Journal

The Astrophysical Journal

Detection of Gamma Rays with E > 100 MeV from BL Lacertae

Users also read

Share

View by subject

Export