Spectral Variation of NLS1 Galaxy PMN J0948+0022

TL;DR

This study analyzes four spectral energy distributions of NLS1 galaxy PMN J0948+0022 using a combined model to understand jet physics and spectral variations, revealing correlations between luminosity, peak frequency, and bulk motion effects.

Contribution

It introduces a detailed spectral modeling approach to investigate the physical parameters and spectral variability of PMN J0948+0022, emphasizing the role of external photon fields.

Findings

Spectral variations correlate with luminosity and peak frequency shifts.

External photon field magnification influences spectral changes.

Inverse Compton bump dominated by external Compton process.

Abstract

Four well-sampled spectral energy distributions (SEDs) of PMN J0948+0022 are fitted with the syn+SSC+EC model to derive the physical parameters of its jets and to investigate the spectral variations of its SEDs. A tentative correlation between the peak luminosity L_c and peak frequency nu_c of its inverse Compton (IC) bump is found in both the observer and co-moving frames, indicating that the variations of luminosity are accompanied with the spectral shift. A correlation between L_c and delta is found, and thus the magnification of the external photon field by the bulk motion of the radiation regions is an essential reason for the spectral variation since the IC bump of PMN J0948+0022 is dominated by the EC process.