The most powerful flaring activity from the NLSy1 PMN J0948+0022

Abstract

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 ($z$ = 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 $\pm$ 31) $\times$10${}^{-8}$ ph cm${}^{-2}$ s${}^{-1}$ on 2013 January 1, corresponding to an apparent isotropic luminosity of about 1.5$\times$10${}^{48}$ erg s${}^{-1}$. 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 > 100 GeV) during 2013 January 6-17 resulted in an upper limit of F (> 0.2 TeV) < 4.0$\times$10${}^{-12}$ ph cm${}^{-2}$ s${}^{-1}$. 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.

13 pages, 5 Figures, 5 Tables. Accepted for publication in Monthly Notices of the Royal Astronomical Society

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• The first gamma-ray detection of the narrow-line Seyfert 1 FBQS J1644+2619
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• The awakening of the gamma-ray narrow-Line Seyfert 1 galaxy PKS 1502+036
• The first GeV flare of the radio-loud narrow-line Seyfert 1 galaxy PKS 2004-447
• Radio jet structures at ~100 parsec and larger scales of the $\gamma$-ray-emitting narrow-line Seyfert 1 galaxy PMN J0948+0022
• Broadband X-ray observations of four gamma-ray narrow-line Seyfert 1 galaxies
• Gamma-ray-emitting narrow-line Seyfert 1 galaxies: the Swift view
• Multiwavelength variability of gamma-ray emitting narrow-line Seyfert 1 galaxies
• Modelling the variable emission states of $\gamma$-ray emitting Narrow-Line Seyfert 1 galaxies
• A γ-ray emitting NLS1 galaxy SDSS J095909.51+460014.3 identified by multiwavelength contemporaneous brightening
• Short time-scale variability of $\gamma$-ray-emitting narrow-line Seyfert 1 galaxies in optical and UV bands
• Relativistic Jets in Gamma-Ray-Emitting Narrow-Line Seyfert 1 Galaxies
• High-energy and Very High-energy Constraints from Log-parabolic Spectral Models in Narrow-line Seyfert 1 Galaxies