A Possible Optical Quasiperiodic Oscillation of 134 days in the Radio-loud Narrow-line Seyfert 1 Galaxy TXS 1206+549 at z = 1.34

Abstract

Here we report an optical quasiperiodic oscillation (QPO) with a period of ∼134 days detected in g - and r -band light curves of the narrow-line Seyfert 1 galaxy TXS 1206+549 at a redshift of 1.34 with data from observations at the Zwicky Transient Facility (ZTF). After considering the trial factor, the significance levels in the two bands are 3.1 σ and 2.6 σ , respectively. The QPO signal presents about 10 cycles ranging from 2018 March to 2021 December, thus lasting ∼4 yr. A nearly sinusoidal profile also appears in the folded light curves by using a phase-resolved analysis. Interestingly, in the simultaneous light curve with the timescale of ZTF observations, a potential periodic signal with a similar period is detected in the o -band light curve from Asteroid Terrestrial-impact Last Alert System data; additionally, a weak peak is also detected at a similar period in the γ -ray light curve obtained from Fermi Gamma-ray Space Telescope data. Some potential origins of periodicities in active galactic nuclei are discussed for the QPO reported here.

Keywords

• Active galactic nuclei
• Time series analysis
• Period search