Interaction of the relativistic jet and the narrow-line region of PMN J0948+0022

¹ European Southern Observatory (ESO), Alonso de Córdova 3107, Vitacura Santiago, Chile
² Università degli Studi dell’Insubria, Via Valleggio 11, Como 22100, Italy
³ Osservatorio Astronomico di Brera, Istituto Nazionale di Astrofisica (INAF), Via E. Bianchi 46, Merate (LC) 23807, Italy
⁴ Università degli Studi di Padova, Vicolo dell’Osservatorio 3, Padova 35122, Italy
⁵ Scuola Normale Superiore, Piazza dei Cavalieri 7, Pisa 56126, Italy
⁶ Osservatorio Astrofisico di Arcetri, Istituto Nazionale di Astrofisica (INAF), Largo E. Fermi 5, Firenze 50125, Italy
⁷ School of Physics, University of Melbourne, Parkville, Victoria 3010, Australia
⁸ Osservatorio Astronomico di Padova, Istituto Nazionale di Astrofisica (INAF), Vicolo dell’Osservatorio, 5 Padova (PD) 35122, Italy

^⋆ Corresponding author.

Received: 30 September 2024
Accepted: 17 May 2025

Abstract

We analyzed publicly available optical spectra of PMN J0948+0022 obtained with the Sloan Digital Sky Survey, the X-shooter, and the Multi Unit Spectroscopic Explorer (MUSE). Initially, PMN J0948+0022 was classified as a jetted narrow-line Seyfert 1 galaxy, but X-shooter and MUSE observations, which have a better spectral resolution, revealed a different profile for the Hβ line: from a Lorentzian to a composite one (a combination of a broad and a narrow Gaussian), which is more typical of intermediate Seyfert galaxies. According to the unified model, intermediate Seyferts are viewed at larger angles. However, we show that, in this case, the composite line profile results from the interaction of the powerful relativistic jet with the narrow-line region. The jet transfers part of its kinetic energy to the narrow-line region, producing flux changes in the Hβ narrow component (a drop by a factor of 3.4 from SDSS to X-shooter), the [O III]λ5007 core component (which nearly doubled from X-shooter to MUSE), and its blue wing (Δv ∼ 200 km s⁻¹), which we interpret as evidence of an outflow. We also recalculated the physical parameters of this AGN, obtaining a black hole mass of 10^7.8 M_⊙ and an Eddington ratio of ∼0.21 (weighted mean).