Unraveling the mysteries of Jets in peculiar NLSy1 galaxies through multi-wavelength variability

TL;DR

This study investigates the variability in radio-quiet NLSy1 galaxies across optical and MIR wavelengths, revealing evidence of weak or intermittent jets influencing their emission, challenging the traditional thermal emission dominance assumption.

Contribution

It provides a comprehensive multi-wavelength variability analysis and SED modeling that uncovers jet contributions in RQ-NLSy1 galaxies, a novel insight into their emission mechanisms.

Findings

Significant long-term optical variability with shorter wavelengths showing larger amplitudes.

Detection of MIR variability and optical-MIR lags indicating non-thermal processes.

Evidence of weak or intermittent jets contributing to galaxy emission.

Abstract

Radio-quiet narrow-line Seyfert 1 galaxies (RQ-NLSy1s) are generally considered to be dominated by thermal emission from the accretion disk. However, recurring 37 GHz radio flares detected from seven RQ-NLSy1s by the Metsahovi Radio Observatory suggest that non-thermal processes may also contribute to their emission. We present a systematic optical and mid-infrared (MIR) variability study combined with broadband SED modeling to investigate the origin of their flux variations and assess the relative contributions of accretion disk and possible jet-related components. High-cadence optical light curves in the g, r, and i bands were obtained from ZTF, while long-term MIR light curves in the W1 and W2 bands were taken from WISE. Optical variability was quantified using the FAGN-test, peak-to-peak variability amplitude, and fractional variability, while MIR variability was characterized using redshift-corrected intrinsic variability amplitudes. Optical variability was examined from intra-night to long-term timescales, and MIR variability on long-term timescales. All RQ-NLSy1s show statistically significant long-term optical variability, with amplitudes increasing toward shorter wavelengths. Three sources exhibit bluer-when-brighter trends and increasing variability amplitudes across the optical bands, indicating a non-thermal contribution. Intrinsic MIR variability is detected in three of the four sources. Significant optical-MIR and MIR intra-band lags are observed, while optical intra-band lags are insignificant. Optical variability amplitudes are anti-correlated with the Eddington ratio and positively correlated with black hole mass. These results suggest that a subset of RQ-NLSy1s hosts weak or intermittent jets contributing to their optical and MIR emission, supported by SED modeling. Coordinated multi-wavelength monitoring is required to better constrain the origin of these variations.