Multiple periodic oscillations in the radio light curves of NRAO 530

TL;DR

This study uses the CLEANest method to identify multiple periodicities in the radio light curves of blazar NRAO 530 over three decades, confirming previous findings and revealing additional shorter-term oscillations.

Contribution

The paper applies the CLEANest time series analysis to radio light curves of NRAO 530, identifying multiple periodicities and discussing their physical origins, which advances understanding of blazar variability.

Findings

Two main periodicities of about 6.3 and 9.5 years confirmed across frequencies.

Additional shorter periodicities of 5.0, 4.2, 3.4, and 2.8 years detected.

Physical mechanisms for the oscillations are discussed.

Abstract

In this paper, the time series analysis method CLEANest is employed to search for characteristic periodicities in the radio light curves of the blazar NRAO 530 at 4.8, 8.0 and 14.5 GHz over a time baseline of three decades. Two prominent periodicities on time scales of about 6.3 and 9.5 yr are identified at all three frequencies, in agreement with previous results derived from different numerical techniques, confirming the multiplicity of the periodicities in NRAO 530. In addition to these two significant periods, there is also evidence of shorter-timescale periodicities of about 5.0 yr, 4.2 yr, 3.4 yr and 2.8 yr showing lower amplitude in the periodograms. The physical mechanisms responsible for the radio quasi-periodic oscillations and the multiplicity of the periods are discussed.