The Most Powerful Flaring Activity from the NLSy1 PMN J0948+0022

• Published in: Monthly notices of the Royal Astronomical Society Vol. 446; no. 3; p. 2456
• Main Authors: D'Ammando, F., Orienti, M., Finke, J., Raiteri, C. M., Hovatta, T., Larsson, J., Max-Moerbeck, W., Perkins, J., Readhead, A. C. S., Richards, J. L.
• Format: Journal Article
• Language: English
• Published: Goddard Space Flight Center Monthly Notices of the Royal Astronomical Society 2015; Oxford University Press; Royal Astronomical Society
• Subjects: Arrays; Astronomy; ASTRONOMY AND ASTROPHYSICS; Astroparticle Physics; Astropartikelfysik; Energy; Flares; Flux; galaxies: active; galaxies: individual: PMN J0948+0022; galaxies: nuclei; galaxies: Seyfert; gamma-rays: general; Luminosity; Monitoring; Radio; Scattering; Scientific imaging; Space telescopes; Spectral energy distribution; Stars & galaxies; Symbols; Telescopes; USA, California, Owens Valley; Flaring; Activity; Powerful
• ISSN: 0035-8711; 1365-2966; 1365-2966
• DOI: 10.1093/mnras/stu2251

We report on multifrequency observations performed during 2012 December-2013 August of the first narrow-line Seyfert 1 galaxy detected in gamma rays, PMN J0948+0022 (z equal to 0.5846). A gamma-ray flare was observed by the Large Area Telescope on board Fermi during 2012 December-2013 January, reaching a daily peak flux in the 0.1-100 GeV energy range of (155 plus or minus 31)×10(exp −8) ph cm (exp −2) s (exp −1) on 2013 January 1, corresponding to an apparent isotropic luminosity of approximately 1.5×10)exp 48) erg s(exp −1). The gamma-ray flaring period triggered Swift and VERITAS observations in addition to radio and optical monitoring by OVRO, MOJAVE, and CRTS. A strong flare was observed in optical, UV, and X- rays on 2012 December 30, quasi-simultaneously to the gamma-ray flare, reaching a record flux for this source from optical to gamma rays. VERITAS observations at very high energy (E greater than 100 GeV) during 2013 January 6-17 resulted in an upper limit of F(sub greater than 0.2 TeV) less than 4.0 × 10(exp −12) ph cm(exp −2) s(exp −1). We compared the spectral energy distribution (SED) of the flaring state in 2013 January with that of an intermediate state observed in 2011. The two SEDs, modelled as synchrotron emission and an external Compton scattering of seed photons from a dust torus, can be modelled by changing both the electron distribution parameters and the magnetic field.