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

Journal Article · Sun Mar 20 00:00:00 EDT 2011 · Astrophysical Journal Letters

DOI:https://doi.org/10.1088/2041-8205/730/1/L8· OSTI ID:21560407

Aleksic, J; Blanch, O ^[1]; Antonelli, L A; Bonnoli, G ^[2]; Antoranz, P ^[3]; Backes, M ^[4]; Barrio, J A ^[5]; Bastieri, D ^[6]; Becerra Gonzalez, J; Berger, K ^[7]; Bednarek, W ^[8]; Berdyugin, A ^[9]; Bernardini, E ^[10]; Biland, A; Boller, A; Braun, I ^[11]; Bock, R K; Borla Tridon, D ^[12]; Bretz, T ^[13]; Canellas, A ^[14]

---

1. IFAE, Edifici Cn., Campus UAB, E-08193 Bellaterra (Spain)
2. INAF National Institute for Astrophysics, I-00136 Rome (Italy)
3. Dipartimento di Fisica, Universita di Siena, and INFN Pisa, I-53100 Siena (Italy)
4. Fakultaet fuer Physik, Technische Universitaet Dortmund, D-44221 Dortmund (Germany)
5. Grupo de Fisica Atlas Energias, Universidad Complutense, E-28040 Madrid (Spain)
6. Dipartimento di Fisica, Universita di Padova and INFN, I-35131 Padova (Italy)
7. Inst. de Astrofisica de Canarias, E-38200 La Laguna, Tenerife (Spain)
8. Division of Experimental Physics, University of Lodz, PL-90236 Lodz (Poland)
9. Tuorla Observatory, University of Turku, FI-21500 Piikkioe (Finland)
10. Deutsches Elektronen-Synchrotron (DESY), D-15738 Zeuthen (Germany)
11. ETH Zurich, CH-8093 (Switzerland)
12. Max-Planck-Institut fuer Physik, D-80805 Muenchen (Germany)
13. Fakultaet fuer Physik und Astronomie, Universitaet Wuerzburg, D-97074 Wuerzburg (Germany)
14. Facultat de Fisica, Universitat de Barcelona (ICC/IEEC), E-08028 Barcelona (Spain)

Very high energy (VHE) {gamma}-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 ({approx}0.5 hr) performed on 2010 June 17. The MAGIC detection coincides with high-energy MeV/GeV {gamma}-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 {proportional_to} E {sup -}{Gamma} with a photon index {Gamma} = 3.75 {+-} 0.27{sub stat} {+-} 0.2{sub syst}. The averaged integral flux above 100 GeV is (4.6 {+-} 0.5) x 10{sup -10} cm{sup -2} s{sup -1} ({approx}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 {gamma}-ray emission region to lie outside the broad-line region, which would otherwise absorb the VHE {gamma}-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.

• OSTI ID: 21560407
• Journal Information: Astrophysical Journal Letters, Vol. 730, Issue 1; Other Information: DOI: 10.1088/2041-8205/730/1/L8; ISSN 2041-8205
• Country of Publication: United States
• Language: English

Related Subjects

79 ASTROPHYSICS
COSMOLOGY AND ASTRONOMY
BACKGROUND RADIATION
COSMIC RADIATION
EMISSION
GAMMA RADIATION
QUASARS
COSMIC RADIO SOURCES
ELECTROMAGNETIC RADIATION
IONIZING RADIATIONS
RADIATIONS