The MAGIC telescopes discovered Very High Energy (VHE, E>100 GeV) γ-ray emission com- ing from the distant Flat Spectrum Radio Quasar (FSRQ) 4C +21.35 (PKS 1222+21, z=0.432) [1, 2]. It is the second most distant VHE gamma-ray source, with well measured redshift, de- tected until now. The observation was performed on 2010 June 17 (MJD 55364.9) using the two 17 m diameter imaging Cherenkov telescopes on La Palma (Canary Islands, Spain). The MAGIC detection coincides with high energy MeV/GeV γ-ray activity measured by the Large Area Tele- scope (LAT) on board the Fermi satellite. The averaged integral flux above 100 GeV measured by MAGICis(4.6±0.5)×10−10cm−2s−1 (∼1CrabNebulaflux). TheMAGICmeasuredspectrum can be well described by a simple power law from 70 GeV to at least 400 GeV. The combined VHE and MeV/GeV spectrum corrected for the absorption by the extragalactic background light is consistent with a simple power law from 3 GeV up to 400 GeV, suggesting that the emission is coming from the same single component in the jet. The absence of a spectral cutoff indicates that the γ-ray emission region is outside of the Broad Line Region. We also detected fast variability in VHE γ-rays with a flux doubling time of 8.6+1.1 minutes. This fast variability together with the −0.9 spectral signatures are very challenging for the present jet emission models of FSRQs.

Becerra Gonzalez, J., Stamerra, A., Saito, K., Terzic, T., Mazin, D., Prandini, E., et al. (2010). MAGIC discovery of the distant quasar 4C +21.35 in VHE gamma rays. In Proceedings of the 25th Texas Symposium on Relativistic Astrophysics. Frank M. Rieger (Chair), Christopher van Eldik and Werner Hofmann.

MAGIC discovery of the distant quasar 4C +21.35 in VHE gamma rays

STAMERRA, ANTONIO;
2010

Abstract

The MAGIC telescopes discovered Very High Energy (VHE, E>100 GeV) γ-ray emission com- ing from the distant Flat Spectrum Radio Quasar (FSRQ) 4C +21.35 (PKS 1222+21, z=0.432) [1, 2]. It is the second most distant VHE gamma-ray source, with well measured redshift, de- tected until now. The observation was performed on 2010 June 17 (MJD 55364.9) using the two 17 m diameter imaging Cherenkov telescopes on La Palma (Canary Islands, Spain). The MAGIC detection coincides with high energy MeV/GeV γ-ray activity measured by the Large Area Tele- scope (LAT) on board the Fermi satellite. The averaged integral flux above 100 GeV measured by MAGICis(4.6±0.5)×10−10cm−2s−1 (∼1CrabNebulaflux). TheMAGICmeasuredspectrum can be well described by a simple power law from 70 GeV to at least 400 GeV. The combined VHE and MeV/GeV spectrum corrected for the absorption by the extragalactic background light is consistent with a simple power law from 3 GeV up to 400 GeV, suggesting that the emission is coming from the same single component in the jet. The absence of a spectral cutoff indicates that the γ-ray emission region is outside of the Broad Line Region. We also detected fast variability in VHE γ-rays with a flux doubling time of 8.6+1.1 minutes. This fast variability together with the −0.9 spectral signatures are very challenging for the present jet emission models of FSRQs.
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Utilizza questo identificativo per citare o creare un link a questo documento: http://hdl.handle.net/11365/42886
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