2018MNRAS.478L..66D

The detection of γ-ray emission from narrow-line Seyfert 1 galaxies (NLSy1) has challenged the idea that large black hole (BH) masses (>=10⁸ M_☉) are needed to launch relativistic jets. We present near-infrared imaging data of the γ-ray-emitting NLSy1 PKS 1502+036 obtained with the Very Large Telescope. Its surface brightness profile, extending to ∼20 kpc, is well described by the combination of a nuclear component and a bulge with a Sersic index n = 3.5, which is indicative of an elliptical galaxy. A circumnuclear structure observed near PKS 1502+036 may be the result of galaxy interactions. A BH mass of ∼7 x 10⁸ M_☉ has been estimated by the bulge luminosity. The presence of an additional faint disc component cannot be ruled out with the present data, but this would reduce the BH mass estimate by only ∼30 per cent. These results, together with analogous findings obtained for FBQS J1644+2619, indicate that the relativistic jets in γ-ray-emitting NLSy1 are likely produced by massive black holes at the centre of elliptical galaxies.