Multifrequency studies of the narrow-line Seyfert 1 galaxy SBS 0846+513
The narrow-line Seyfert 1 galaxy SBS 0846+513 was first detected by the Large Area Telescope on board Fermi in 2011 June–July when it underwent a period of flaring activity. Since then, as Fermi continues to accumulate data on this source, its flux has been monitored on a daily basis. Two further γ-ray flaring episodes from SBS 0846+513 were observed in 2012 May and August, reaching a daily peak flux integrated above 100 MeV of (50 ± 12) × 10^(−8) ph cm^(−2) s^(−1), and (73 ± 14) × 10^(−8) ph cm^(−2) s^(−1) on May 24 and August 7, respectively. Three outbursts were detected at 15 GHz by the Owens Valley Radio Observatory 40 m telescope in 2012 May, 2012 October and 2013 January, suggesting a complex connection with the γ-ray activity. The most likely scenario suggests that the 2012 May γ-ray flare may not be directly related to the radio activity observed over the same period, while the two γ-ray flaring episodes may be related to the radio activity observed at 15 GHz in 2012 October and 2013 January. The γ-ray flare in 2012 May triggered Swift observations that confirmed that SBS 0846+513 was also exhibiting high activity in the optical, UV and X-ray bands, thus providing a firm identification between the γ-ray source and the lower energy counterpart. We compared the spectral energy distribution (SED) of the flaring state in 2012 May with that of a quiescent state. The two SEDs, modelled as an external Compton component of seed photons from a dust torus, could be fitted by changing the electron distribution parameters as well as the magnetic field. No significant evidence of thermal emission from the accretion disc has been observed. Interestingly, in the 5 GHz radio luminosity versus synchrotron peak frequency plot SBS 0846+513 seems to lie in the flat spectrum radio quasar part of the so-called 'blazar sequence'.
Additional Information© 2013 The Authors. Published by Oxford University Press on behalf of the Royal Astronomical Society. Accepted 2013 August 16. Received 2013 August 4; in original form 2013 May 30. First published online: September 16, 2013. The Fermi LAT Collaboration acknowledges generous ongoing support from a number of agencies and institutes that have supported both the development and the operation of the LAT as well as scientific data analysis. These include the National Aeronautics and Space Administration and the Department of Energy in the United States, the Commissariat à l'Energie Atomique and the Centre National de la Recherche Scientifique/Institut National de Physique Nucléaire et de Physique des Particules in France, the Agenzia Spaziale Italiana and the Istituto Nazionale di Fisica Nucleare in Italy, the Ministry of Education, Culture, Sports, Science and Technology (MEXT), High Energy Accelerator Research Organization (KEK) and Japan Aerospace Exploration Agency (JAXA) in Japan, and the K. A. Wallenberg Foundation, the Swedish Research Council and the Swedish National Space Board in Sweden. Additional support for science analysis during the operations phase is gratefully acknowledged from the Istituto Nazionale di Astrofisica in Italy and the Centre National d'Études Spatiales in France. We thank the Swift team for making these observations possible, the duty scientists and science planners. The OVRO 40 m monitoring programme is supported in part by NASA grants NNX08AW31G and NNX11A043G, and NSF grants AST-0808050 and AST-1109911. This paper is partly based on observations with the 100 m telescope of the Max-Planck-Institut für Radioastronomie (MPIfR) at Effelsberg and the Medicina telescope operated by INAF–Istituto di Radioastronomia. We acknowledge A. Orlati, S. Righini and the Enhanced Single-dish Control System (ESCS) Development Team. FD, MO, MG, CR acknowledge financial contribution from grant PRIN-INAF-2011. This research has made use of data from the MOJAVE data base that is maintained by the MOJAVE team (Lister et al. 2009). IM and VK were supported for this research through a stipend from the International Max Planck Research School (IMPRS) for Astronomy and Astrophysics at the University of Bonn and Cologne. We thank D. Horan, P. Bruel and S. Digel for helpful comments and suggestions.
Published - MNRAS-2013-D'Ammando-191-201.pdf
Published - MNRAS-2013-D=0027Ammando-191-201.pdf
Submitted - 1308.3709v1.pdf