Discovery of VHE gamma-rays from the blazar 1ES 1215+303 with the MAGIC Telescopes and simultaneous multi-wavelength observations

TL;DR

This paper reports the first detection of VHE gamma-ray emission from the blazar 1ES 1215+303 using MAGIC telescopes, combined with multi-wavelength observations, revealing its high-energy behavior and spectral characteristics.

Contribution

The study provides the first VHE detection of 1ES 1215+303 and analyzes its multi-wavelength emission, offering insights into its spectral energy distribution and emission mechanisms.

Findings

First VHE detection of 1ES 1215+303 at 9.4 sigma significance.

Correlation between VHE, optical, and X-ray high states in 2011.

Spectral energy distribution consistent with a one-zone SSC model, requiring extreme parameters.

Abstract

Context. We present the discovery of very high energy (VHE, E > 100GeV) gamma-ray emission from the BL Lac object 1ES 1215+303 by the MAGIC telescopes and simultaneous multi-wavelength data in a broad energy range from radio to gamma-rays. Aims. We study the VHE gamma-ray emission from 1ES 1215+303 and its relation to the emissions in other wavelengths. Methods. Triggered by an optical outburst, MAGIC observed the source in January-February 2011 for 20.3 hrs. The target was monitored in the optical R-band by the KVA telescope that also performed optical polarization measurements. We triggered target of opportunity observations with the Swift satellite and obtained simultaneous and quasi-simultaneous data from the Fermi Large Area Telescope and from the Mets\"ahovi radio telescope. We also present the analysis of older MAGIC data taken in 2010. Results. The MAGIC observations of 1ES 1215+303 carried out in January-February 2011 resulted in the first detection of the source at VHE with a statistical significance of 9.4 sigma. Simultaneously, the source was observed in a high optical and X-ray state. In 2010 the source was observed in a lower state in optical, X-ray, and VHE, while the GeV gamma-ray flux and the radio flux were comparable in 2010 and 2011. The spectral energy distribution obtained with the 2011 data can be modeled with a simple one zone SSC model, but it requires extreme values for the Doppler factor or the electron energy distribution.