Discovery of Very High Energy Gamma Rays from 1ES 1440+122

Abstract

The BL Lacertae object 1ES 1440+122 was observed in the energy range from 85 GeV to 30 TeV by the VERITAS array of imaging atmospheric Cherenkov telescopes. The observations, taken between 2008 May and 2010 June and totalling 53 hours, resulted in the discovery of $\gamma$-ray emission from the blazar, which has a redshift $z$=0.163. 1ES 1440+122 is detected at a statistical significance of 5.5 standard deviations above the background with an integral flux of (2.8$\pm 0.7_{\mathrm{stat}}\pm 0.8_{\mathrm{sys}}$) $\times$ 10${}^{-12}$ cm${}^{-2}$ s${}^{-1}$ (1.2\% of the Crab Nebula's flux) above 200 GeV. The measured spectrum is described well by a power law from 0.2 TeV to 1.3 TeV with a photon index of 3.1 $\pm$ 0.4${}_{\mathrm{stat}}$ $\pm$ 0.2${}_{\mathrm{sys}}$. Quasi-simultaneous multi-wavelength data from the Fermi Large Area Telescope (0.3--300 GeV) and the Swift X-ray Telescope (0.2--10 keV) are additionally used to model the properties of the emission region. A synchrotron self-Compton model produces a good representation of the multi-wavelength data. Adding an external-Compton or a hadronic component also adequately describes the data.

8 pages, 4 figures. Accepted for publication in MNRAS

References in corpus (8)

• Observations of the Crab Nebula with H.E.S.S
• Background Modelling in Very-High-Energy gamma-ray Astronomy
• The First VERITAS Telescope
• Energy spectra of gamma-rays, electrons and neutrinos produced at interactions of relativistic protons with low energy radiation
• The Imprint of The Extragalactic Background Light in the Gamma-Ray Spectra of Blazars
• Status of the VERITAS Observatory
• Optical spectroscopy of BL Lacertae objects. Broad lines, companion galaxies and redshift lower limits
• A New Model for Gamma-Ray Cascades in Extragalactic Magnetic Fields

Cited by in corpus (9)

• Mildly relativistic magnetized shocks in electron-ion plasmas -- II. Particle acceleration and heating
• Galactic and Extragalactic Sources of Very High Energy Gamma-rays
• Model-independent Redshift Estimation of BL Lac Objects through VHE Observations
• The `blazar sequence' in TeV band
• Propagation of very-high-energy $\gamma$-rays from distant blazars
• The optimal on-source region size for detections with counting-type telescopes
• Properties and Possible Physical Origins of $\gamma$-ray Emission in Extreme Synchrotron Blazars
• Highlights from the VERITAS AGN Observation Program
• Revisiting the evidences for spectral anomalies in distant blazars: new data on the photon-ALP mixing