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 (LAT) 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
gamma-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)x10^-8
ph/cm^2/s, and (73+/-14)x10^-8 ph/cm^2/s 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 gamma-ray activity. The most likely scenario
suggests that the 2012 May gamma-ray flare may not be directly related to the
radio activity observed over the same period, while the two gamma-ray flaring
episodes may be related to the radio activity observed at 15 GHz in 2012
October and 2013 January. The gamma-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 gamma-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 vs. synchrotron peak frequency plot SBS 0846+513
seems to lie in the flat spectrum radio quasar part of the so-called `blazar
sequence'.
