A Possible Optical Quasi-periodic Oscillation of 134~day in the Radio-loud Narrow-line Seyfert 1 Galaxy TXS 1206+549 at $z=1.34$

Abstract: Here we report an optical quasi-periodic oscillation (QPO) with a period of $\sim$134~day detected in g- and r-band light curves of a narrow-line Seyfert 1 galaxy TXS 1206+549 at redshift of 1.34 with the data from the Zwicky Transient Facility (ZTF) observations. After considering the trial factor, the significance levels in the two bands are 3.1 $\sigma$ and 2.6 $\sigma$, respectively. The QPO signal presents about 10 cycles ranging from 2018 March to 2021 December lasting $\sim$4 year. A near-sinusoidal profile also appears in the folded light curves by a phase-resolved analysis. Interestingly, in the simultaneous light curve as the time scale of ZTF observations, a potential periodic signal with similar period is detected in the o-band light curve from the Asteroid Terrestrial-Impact Last Alert System data, additionally a weak peak is also detected at the similar period in the gamma-ray light curve obtained from the \emph{Fermi} Gamma-ray Space Telescope data. Some potential origins of periodicities in active galactic nuclei are discussed for the QPO reported here.