Multi-frequency monitoring of γ-ray loud blazars
I. Light curves and spectral energy distributions
INAF – Osservatorio Astronomico di Torino, via Osservatorio 20, 10025 Pino Torinese (TO), Italy e-mail: firstname.lastname@example.org
2 Osservatorio Astronomico, Università di Perugia, via B. Bonfigli, 06126 Perugia, Italy
3 INAF – Osservatorio Astrofisico di Catania, via S. Sofia 78, 95123 Catania, Italy
4 Astronomical Institute, St. Petersburg State University, Universitetsky pr. 28, Petrodvoretz, 198504 St. Petersburg, Russia
5 INAF – Istituto di Radioastronomia, Sezione di Noto, C.da Renna Bassa – Loc. Case di Mezzo C.P. 141, 96017 Noto, Italy
6 Pulkovo Astronomical Observatory of the Russian Academy of Sciences, Russia
7 Agrupació Astronòmica de Sabadell, PO Box 50, 08200 Sabadell, Spain
8 INAF – Osservatorio Astronomico di Roma, via di Frascati 33, 00040 Monte Porzio Catone, Italy
9 INAF – Osservatorio Astronomico di Collurania Teramo, via Maggini snc, 64100 Teramo, Italy
10 Ulugh Beg Astronomical Institute, 33 Astronomical Str., Tashkent 700052, Uzbekistan
11 Abastumani Astrophysical Observatory, 383762 Abastumani, Georgia
12 INAF – Istituto di Radioastronomia, Sezione di Medicina, via Fiorentina 3508/B, 40059 Medicina, Italy
Accepted: 14 November 2006
Context.Being dominated by non-thermal emission from aligned relativistic jets, blazars allow us to elucidate the physics of extragalactic jets, and, ultimately, how the energy is extracted from the central black hole in radio-loud active galactic nuclei.
Aims.Crucial information is provided by broad-band spectral energy distributions (SEDs), their trends with luminosity and correlated multi-frequency variability. With this study we plan to obtain a database of contemporaneous radio-to-optical spectra of a sample of blazars, which are and will be observed by current and future high-energy satellites.
Methods.Since December 2004 we are performing a monthly multi-frequency radio monitoring of a sample of 35 blazars at the antennas in Medicina and Noto. Contemporaneous near-IR and optical observations for all our observing epochs are organised.
Results.Until June 2006 about 4000 radio measurements and 5500 near-IR and optical measurements were obtained. Most of the sources show significant variability in all observing bands. Here we present the multi-frequency data acquired during the first eighteen months of the project, and construct the SEDs for the best-sampled sources.
Key words: galaxies: active / galaxies: BL Lacertae objects: general / galaxies: jets / galaxies: quasars: general
© ESO, 2007