MAGIC DISCOVERY OF VERY HIGH ENERGY EMISSION FROM THE FSRQ PKS 1222+21

By J. Aleksi'c, L. Antonelli, P. Antoranz, Michael Backes, J. Barrio, D. Bastieri, J. Gonz'alez, W. Bednarek, A. Berdyugin, K. Berger and 139 more. 2011

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Very high energy (VHE) γ-ray emission from the flat spectrum radio quasar (FSRQ) PKS 1222+21 (4C 21.35, z = 0.432) was detected with the MAGIC Cherenkov telescopes during a short observation (∼0.5 hr) performed on 2010 June 17. The MAGIC detection coincides with high-energy MeV/GeV γ-ray activity measured by the Large Area Telescope (LAT) on board the Fermi satellite. The VHE spectrum measured by MAGIC extends from about 70 GeV up to at least 400 GeV and can be well described by a power-law dN/dE ∝ E−Γ with a photon index Γ = 3.75 ± 0.27stat ± 0.2syst. The averaged integral flux above 100 GeV is (4.6 ± 0.5) × 10−10 cm−2 s−1 (∼1 Crab Nebula flux). The VHE flux measured by MAGIC varies significantly within the 30 minute exposure implying a flux doubling time of about 10 minutes. The VHE and MeV/GeV spectra, corrected for the absorption by the extragalactic background light (EBL), can be described by a single power law with photon index 2.72 ± 0.34 between 3 GeV and 400 GeV, and is consistent with emission belonging to a single component in the jet. The absence of a spectral cutoff constrains the γ-ray emission region to lie outside the broad-line region, which would otherwise absorb the VHE γ-rays. Together with the detected fast variability, this challenges present emission models from jets in FSRQs. Moreover, the combined Fermi/LAT and MAGIC spectral data yield constraints on the density of the EBL in the UV–optical to near-infrared range that are compatible with recent models.

Subfields: Astronomy and Astrophysics, Nuclear and High Energy Physics

View Paper: https://www.semanticscholar.org/paper/10e78cd969af5b544829390789bf101f72c57956

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Citations in the corpus

Reconnection-driven plasmoids in blazars: fast flares on a slow envelope (2012, background): “…PKS 2155–304 (Aharonian et al. 2007; hereafter referr d to as PKS 2155), Markarian 501 (Albert et al. 2007; Mrk 501), and the prototype object of the class BL Lac (Arlen et al. 2013); and the FSRQ source PKS 1222+ 16 (Aleksić et al. 2011; hereafter PKS ⋆ E-mail: dgiannio@purdue.edu (DG) 1222)].”
Semi-analytic modeling of the EBL and consequences for extragalactic gamma-ray spectra (2011, methodology): “…3.0 3.10 ± 0.23 ± 0.10 1.94 2.03 1ES 1011+496 (+) 0.212 Albert et al. (2007d) MAGIC 0.12 0.75 4.00 ± 0.50 2.95 3.10 S5 0716+714 (+) 0.31a Mazin et al. (2009) MAGIC 0.2 0.7 3.45 ± 0.54 1.47 1.74 PKS 1222+21 (+) 0.432 Aleksić et al. (2011a) MAGIC 0.07 0.4 3.75 ± 0.27 ± 0.2 2.32 2.60 3C 66A (+)…”
THE FIRST FERMI-LAT CATALOG OF SOURCES ABOVE 10 GeV (2013, background): “The high activity from this flare was also observed at VHE on 2010 June 17 by MAGIC (Mariotti 2010; Aleksić et al. 2011).”
Dark matter and fundamental physics with the Cherenkov Telescope Array (2012, methodology): “5 h duration flare like the one reported in [149] would not be enough for CTA to detect a significant effect in any of the tested ALP scenarios, i.”
MINUTE-TIMESCALE >100 MeV γ-RAY VARIABILITY DURING THE GIANT OUTBURST OF QUASAR 3C 279 OBSERVED BY FERMI-LAT IN 2015 JUNE (2016, background): “Moreover, this is only the second case when such timescales are reported for an FSRQ blazar, after PKS 1222+216 (Aleksić et al. 2011), while Fermi-LAT had only ever detected variability as short as hour timescal in some FSRQs (e.g.,Abdo et al. 2011a; Saito et al. 2013; Hayashida et al. 2015).”
Kinematics of Parsec-scale Jets of Gamma-Ray Blazars at 43 GHz within the VLBA-BU-BLAZAR Program (2017, background): “A strong outburst of very high-energy emission (E > 100 GeV) with a short timescale of variability was observed by MAGIC during this period of jet activity (Aleksić et al. 2011) when B1-B3 were ejected.”