Study of the radio spectra evolution of Narrow-line Seyfert 1 galaxies with RATAN-600

Abstract

We present the radio properties of narrow-line Seyfert 1 (NLS1) galaxies, obtained using quasi-simultaneous measurements with the radio telescope RATAN-600 in the frequency range 1 . 2–22 . 3 GHz. The sample of 95 NLS1s includes both galaxies emitting and not emitting 𝛾 -rays. Generally, 𝛾 -ray emitting NLS1s are more radio luminous and radio-loud than those not emitting 𝛾 -rays. The other difference is the more intensive spectral evolution for 𝛾 -ray emitters: the repet-itive change of the spectral index sign on a time scale of months and a high level of variability, on average 26–37% at 4.7–11.2 GHz. The obtained differences between 𝛾 -ray emitting and non-emitting NLS1s can be caused by an evolving flare component in the 𝛾 -ray emitters, while for the NLS1s not emitting 𝛾 -rays a quiescent spectral component is predominant. Universe: Theory Observations