A Rare Gamma-ray Flaring episode of the Narrow-Line Seyfert 1 Galaxy 1H 0323+342

Abstract

Gamma-ray-emitting narrow-line Seyfert 1 ($γ$-NLSy1) galaxies represent an enigmatic class of active galactic nuclei (AGNs) bridging populations of radio-quiet and radio-loud AGNs. Here we report the multi-wavelength investigation of a rare $γ$-ray flaring episode of an NLSy1 galaxy, 1H 0323+342 ($z=0.063$), using data from Fermi-Large Area Telescope, Swift, and Nuclear Spectroscopic Telescopic Array. The source exhibited a significant enhancement in $γ$-ray flux along with rapid variability on $\sim$sub-hour timescales in both $γ$-ray and hard X-ray wavelengths, hinting that the energy dissipation is happening from a compact region close to the central supermassive black-hole. The time-resolved X-ray spectral study revealed a transition between a jet-dominated and a mixed jet+corona emission state. Reproducing the broadband spectral energy distribution with a one-zone leptonic model suggested that the high-energy emission is mainly produced by external Compton scattering of the accretion disc and broad line region photons. The inferred jet power reaches values of the order of $10^{46}$ erg s$^{-1}$ comparable to those of powerful flat-spectrum radio quasars, suggesting that even low black-hole mass systems can occasionally produce powerful $γ$-ray outbursts.