AGILE, Fermi, Swift, and GASP/WEBT multi-wavelength observations of the high-redshift blazar 4C +71.07 in outburst^⋆

¹ INAF, Osservatorio Astronomico di Brera, Via Emilio Bianchi 46, 23807 Merate, LC, Italy
e-mail: stefano.vercellone@inaf.it
² INAF, Istituto di Astrofisica e Planetologia Spaziale, Via Fosso del Cavaliere 100, 00133 Roma, Italy
³ ASI, Via del Politecnico, 00133 Roma, Italy
⁴ UAB, Universitat Autonòma de Barcelona, Departament de Física Edifici C, 08193 Bellaterra, Cerdanyola del Vallès, Spain
⁵ INAF, Osservatorio Astronomico di Torino, Via Osservatorio 20, 10025 Pino Torinese, Italy
⁶ ASI Space Science Data Center, Via del Politecnico, 00133 Roma, Italy
⁷ INAF, Osservatorio Astronomico di Roma, Via Frascati 33, 00078 Monte Porzio Catone, Italy
⁸ INAF, Osservatorio di Astrofisica e Scienza dello Spazio, Via Piero Gobetti 93/3, 40129 Bologna, Italy
⁹ Dip. di Fisica, Univ. di Roma “Tor Vergata”, Via della Ricerca Scientifica 1, 00133 Roma, Italy
¹⁰ Gran Sasso Science Institute, Viale Francesco Crispi 7, 67100 L’Aquila, Italy
¹¹ Instituto de Astrofísica de Canarias (IAC), 38205 La Laguna, Tenerife, Spain
¹² Departamento de Astrofísica, Universidad de La Laguna, 38206 La Laguna, Tenerife, Spain
¹³ Instituto de Astrofísica de Andalucía (CSIC), Apartado 3004, 18080 Granada, Spain
¹⁴ Pulkovo Observatory, St.-Petersburg, Russia
¹⁵ Max-Planck-Insitut für Radioastronomie, Auf dem Hügel 69, 53121 Bonn, Germany
¹⁶ Institute of Astronomy and National Astronomical Observatory, Bulgarian Academy of Sciences, 72, Tsarigradsko Shose Blvd., 1784 Sofia, Bulgaria
¹⁷ Crimean Astrophysical Observatory RAS, P/O Nauchny 298409, Russia
¹⁸ Astronomical Observatory, Volgina 7, 11060 Belgrade, Serbia
¹⁹ INAF, Istituto di Radioastronomia, Via Piero Gobetti 93/2, 40129 Bologna, Italy
²⁰ Dip. di Fisica e Astronomia, Università di Bologna, Viale Berti Pichat 6/2, 40127 Bologna, Italy
²¹ Sternberg Astronomical Institute, M.V. Lomonosov Moscow State University, Universitetskij prosp.13, Moscow 119991, Russia
²² Ulugh Beg Astronomical Institute, Maidanak Observatory, Uzbekistan
²³ Astron. Inst., St.-Petersburg State Univ., Russia
²⁴ Aalto University Metsähovi Radio Observatory, Metsähovintie 114, 02540 Kylmälä, Finland
²⁵ Aalto University Department of Electronics and Nanoengineering, PO Box 13000, 00076 Aalto, Finland
²⁶ Abastumani Observatory, Mt. Kanobili, 0301 Abastumani, Georgia
²⁷ Engelhardt Astronomical Observatory, Kazan Federal University, Tatarstan, Russia
²⁸ Center for Astrophysics, Guangzhou University, Guangzhou 510006, PR China
²⁹ Key Laboratory of Optical Astronomy, National Astronomical Observatories, Chinese Academy of Sciences, Beijing 100012, PR China
³⁰ INFN, Sezione di Pavia, Via Agostino Bassi, 6, 27100 Pavia, Italy
³¹ School of Physics, University of the Witwatersrand, 1 Jan Smuts Avenue, Braamfontein, 2000 Johannesburg, South Africa
³² INFN, Sezione di Trieste, Via Valerio 2, 34127 Trieste, Italy
³³ Dipartimento di Fisica, Università degli Studi di Trieste, Via Valerio 2, 34127 Trieste, Italy
³⁴ INFN, Sezione di Roma Tor Vergata, Via della Ricerca Scientifica 1, 00133 Roma, Italy
³⁵ East Windsor RSD, 25a Leshin Lane, Hightstown, NJ 08520, USA

Received: 22 December 2017
Accepted: 9 November 2018

Abstract

Context. The flat-spectrum radio quasar 4C +71.07 is a high-redshift (z = 2.172), γ-loud blazar whose optical emission is dominated by thermal radiation from the accretion disc.

Aims. 4C +71.07 has been detected in outburst twice by the AGILE γ-ray satellite during the period from the end of October to mid-November 2015, when it reached a γ-ray flux of the order of F(E >  100 MeV)=(1.2 ± 0.3)×10⁻⁶ photons cm⁻² s⁻¹ and F(E > 100 MeV)=(3.1 ± 0.6)×10⁻⁶ photons cm⁻² s⁻¹, respectively, allowing us to investigate the properties of the jet and the emission region.

Methods. We investigated its spectral energy distribution by means of almost-simultaneous observations covering the cm, mm, near-infrared, optical, ultraviolet, X-ray, and γ-ray energy bands obtained by the GASP-WEBT Consortium and the Swift, AGILE, and Fermi satellites.

Results. The spectral energy distribution of the second γ-ray flare (whose energy coverage is more dense) can be modelled by means of a one-zone leptonic model, yielding a total jet power of about 4 × 10⁴⁷ erg s⁻¹.

Conclusions. During the most prominent γ-ray flaring period our model is consistent with a dissipation region within the broad-line region. Moreover, this class of high-redshift, flat-spectrum radio quasars with high-mass black holes might be good targets for future γ-ray satellites such as e-ASTROGAM.