Discovery of very high energy gamma-ray emission from the low-frequency peaked BL Lacertae object BL Lacertae

Abstract

The MAGIC collaboration observed BL Lacertae for 22.2 hr during 2005 August to December and for 26 hr during 2006 July to September. The source is the historical prototype and eponym of a class of low-frequency peaked BL Lacertae (LBL) objects. A very high energy (VHE) gamma-ray signal was discovered with a 5.1 sigma excess in the 2005 data. Above 200 GeV, an integral flux of 0.6+-0.2 x 10^(-11) cm^(-2) s^(-1) was measured, corresponding to approximately 3% of the Crab flux. The differential spectrum between 150 and 900 GeV is rather steep with a photon index of -3.6+-0.5. The light curve shows no significant variability during the observations in 2005. For the first time a clear detection of VHE gamma-ray emission from an LBL object was obtained with a signal below previous upper limits. The 2006 data show no significant excess. This drop in flux follows the observed trend in optical activity.

Accepted for publication in ApJ Letters, 4 pages, 5 figures, Figure-5 revised, Minor corrections following the referee report

References in corpus (18)

• A Unifying View of the Spectral Energy Distributions of Blazars
• A theoretical unifying scheme for gamma-ray bright blazars
• The Connection between X-ray- and Radio-Selected BL Lacertae Objects
• A Proton Synchrotron Blazar Model for Flaring in Markarian~501
• Implications of Cosmological Gamma-Ray Absorption II. Modification of gamma-ray spectra
• Observations of Mkn 421 with the MAGIC Telescope
• Detection of VHE radiation from the BL Lac PG 1553+113 with the MAGIC telescope
• Observations of a Correlated Gamma-Ray and Optical Flare for BL Lacertae
• X-ray Observations of BL Lacertae During 1997 Outburst and its Association with Quasar-like Characteristics
• A New Analysis Method for Reconstructing the Arrival Direction of TeV Gamma-rays Using a Single Imaging Atmospheric Cherenkov Telescope
• Observation of VHE gamma-ray emission from the Active Galactic Nucleus 1ES1959+650 using the MAGIC telecope
• Observations of 54 Active Galactic Nuclei with the HEGRA System of Cherenkov Telescopes
• Supermassive Black Hole Masses of AGNs with Elliptical Hosts
• BL Lacertae: complex spectral variability and rapid synchrotron flare detected with BeppoSAX
• Constraints on the Very High Energy Emission from BL Lacertae Objects
• ASCA and contemporaneous ground-based observations of the BL Lacertae objects 1749+096 and 2200+420 (BL Lac)
• Rapid Synchrotron Flares from BL Lacertae Detected by ASCA and RXTE
• BL Lac: A New Ultrahigh-Energy Gamma-Ray Source

Cited by in corpus (79)

• The Spectral Energy Distribution of Fermi bright blazars
• Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra
• The power of blazar jets
• High-energy neutrinos in the context of multimessenger physics
• Implications of very rapid TeV variability in blazars
• The Extragalactic Background Light and the Gamma-ray Opacity of the Universe
• Blazars as Ultra-High-Energy Cosmic-Ray Sources: Implications for TeV Gamma-Ray Observations
• TeV BL Lac objects at the dawn of the Fermi era
• Fermi Discovery of Gamma-Ray Emission from NGC 1275
• The extragalactic background light, the Hubble constant, and anomalies: conclusions from 20 years of TeV gamma-ray observations
• Extragalactic Background Light from Hierarchical Galaxy Formation: Gamma-ray Attenuation up to the Epoch of Cosmic Reionization and the First Stars
• Spine-sheath layer radiative interplay in subparsec-scale jets and the TeV emission from M87
• Indications for a pair-production anomaly from the propagation of VHE gamma-rays
• Fermi observations of TeV-selected AGN
• Long-term optical monitoring of TeV emitting Blazars
• Discovery of Very High Energy gamma-rays from 1ES 1011+496 at z=0.212
• Rapid TeV Gamma-Ray Flaring of BL Lacertae
• VERITAS Discovery of >200GeV Gamma-ray Emission from the Intermediate-frequency-peaked BL Lac Object W Comae
• Multiwavelength observations of a TeV-Flare from W Comae
• Discovery of Very High Energy gamma-rays from the blazar S5 0716+714
• Discovery of Variability in the Very High Energy Gamma-Ray Emission of 1ES 1218+304 with VERITAS
• Limits on the extragalactic background light in the Fermi era
• Multiband variability studies and novel broadband SED modeling of Mrk 501 in 2009
• Constraining blazar distances with combined Fermi and TeV data: an empirical approach
• Lognormal variability in BL Lacertae
• The first Fermi multifrequency campaign on BL Lacertae: characterizing the low-activity state of the eponymous blazar
• Synoptic studies of seventeen blazars detected in very high-energy gamma-rays
• Gamma-ray Spectral Evolution of NGC1275 Observed with Fermi-LAT
• The RINGO2 and DIPOL Optical Polarisation Catalogue of Blazars
• SSC radiation in BL Lac sources, the end of the tether
• X-ray Polarization of BL Lacertae in Outburst
• Gamma-Ray Observational Properties of TeV-Detected Blazars
• The WEBT Campaign on the Intermediate BL Lac Object 3C66A in 2007-2008
• X-ray Polarization Observations of BL Lacertae
• Multi-wavelength study of flaring activity in BL Lac object S5 0716+714 during 2015 outburst
• Multiwavelength observations of the blazar BL Lacertae: a new fast TeV gamma-ray flare
• Constraints on the Extragalactic Background Light from Very High Energy Gamma-Ray Observations of Blazars
• Upper Limits from HESS AGN Observations in 2005-2007
• A Fast Very High Energy $\gamma$-ray Flare from BL Lacertae during a Period of Multiwavelength activity in June 2015
• Importance of axion-like particles for very-high-energy astrophysics
• Suzaku and Multi-wavelength Observations of OJ 287 during the Periodic Optical Outburst in 2007
• A thirteen-year-long broadband view of BL Lac
• The high-energy $\gamma$-ray emission of AP Librae
• X-ray spectral studies of TeV gamma-ray emitting blazars
• VERITAS Upper Limit on the VHE Emission from the Radio Galaxy NGC 1275
• The TeV emission of Ap Librae: a hadronic interpretation and prospects for CTA
• Long-term monitoring of PKS 2155$-$304 with ATOM and H.E.S.S.: investigation of optical/$\gamma$-ray correlations in different spectral states
• Astrophysical ZeV acceleration in the relativistic jet from an accreting supermassive blackhole
• Systematic search for VHE gamma-ray emission from X-ray bright high-frequency BL Lac objects
• Determination of Central Engine Position and Accretion Disk Structure in NGC 4261 by Core Shift Measurements
• A Hard X-Ray View of Two Distant VHE Blazars: 1ES 1101-232 and 1ES 1553+113
• GENJI Programme: Gamma-ray Emitting Notable AGN Monitoring by Japanese VLBI
• Prospects for Very High Energy Blazar Survey by the Next Generation Cherenkov Telescopes
• The physical properties of \textit{Fermi} TeV BL Lac objects jets
• Studies of active galactic nuclei with CTA
• Origin of the X-rays and Possible GeV-TeV Emission from the Western Hot Spot Of Pictor A
• MAGIC upper limits to the VHE gamma-ray flux of 3C454.3 in high emission state
• Accretion and plasma outflow from dissipationless discs
• Intergalactic absorption and blazar gamma-ray spectra
• VHE Gamma-Ray Induced Pair Cascades in Blazars and Radio Galaxies: Application to NGC 1275
• Optical flux and spectral variability of BL Lacertae during its historical high outburst in 2020
• Circumnuclear Dust in AP Librae and the source of its VHE emission
• From Radio to TeV: The surprising Spectral Energy Distribution of AP Librae
• Constraining Extragalactic Background Light From TeV Blazars
• Lower Bound on the Cosmic TeV Gamma-ray Background Radiation
• VERITAS Observations of Six Bright, Hard-Spectrum Fermi-LAT Blazars
• Mechanism of very high energy radiation in BL Lacertae object 3C 66A
• High-(Energy)-Lights -- The Very High Energy Gamma-Ray Sky
• Propagation of very-high-energy $\gamma$-rays from distant blazars
• Status of Very High Energy gamma-ray Astronomy as of early 2008
• Very high energy observations of the BL Lac objects 3C 66A and OJ 287
• Prospects of additional contribution at Optical-NIR band of EBL in the light of VHE spectra
• WEBT multiwavelength monitoring and XMM-Newton observations of BL Lacertae in 2007-2008. Unveiling different emission components
• The TeV Blazar Measurement of the Extragalactic Background Light
• Is Low-Frequency-Peaked BL Lac Object OJ 287 a TeV Emitter?
• Revisiting the evidences for spectral anomalies in distant blazars: new data on the photon-ALP mixing
• Ultimate synchrotron cutoff in gamma-ray spectra of blazars as a signature of the converter mechanism
• The Major Gamma-ray Imaging Cherenkov Telescopes (MAGIC)
• Observations of low- and intermediate-frequency-peaked BL Lacs above 100 GeV with VERITAS