The ordinary life of the -ray emitting narrow-line Seyfert 1 galaxy PKS 1502+036

We report on multifrequency observations of the γ -ray emitting narrow-line Seyfert 1 galaxy PKS 1502+036 performed from radio to γ -rays during 2008 August-2012 November by Fermi-Large Area Telescope (LAT), Swift (X-ray Telescope and Ultraviolet/Optical Telescope), Owens Valley Radio Observatory, Very Long Baseline Array (VLBA) and Very Large Array. No significant variability has been observed in γ -rays, with 0.1-100 GeV flux that ranged between (3-7) × 10-8 ph cm-2 s-1 using 3-month time bins. The photon index of the LAT spectrum (Γ = 2.60 ± 0.06) and the apparent isotropic γ -ray luminosity (L0.1-100 GeV = 7.8 × 1045 erg s-1) over 51 months are typical of a flat spectrum radio quasar. The radio spectral variability and the one-sided structure, in addition to the observed γ -ray luminosity, suggest a relativistic jet with a high Doppler factor. In contrast to SBS 0846+513, the VLBA at 15 GHz did not observe superluminal motion for PKS 1502+036. Despite having the optical characteristics typical of a narrow-line Seyfert 1 galaxy, radio and γ -ray properties of PKS 1502+036 are found to be similar to those of a blazar at the low end of the black hole mass distribution for blazars. This is in agreement with what has been found in the case of the other γ -ray emitting narrow-line Seyfert 1 SBS 0846+513. © 2013 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society.