Periodic Radio Variability in NRAO 530: Phase Dispersion Minimization Analysis

TL;DR

This study identifies two persistent radio periodicities of approximately 6 and 10 years in NRAO 530 across multiple frequencies using an improved phase dispersion minimization method, confirmed by simulations.

Contribution

The paper introduces an enhanced PDM technique for periodicity analysis and applies it to NRAO 530, revealing consistent long-term periodicities validated by multiple methods.

Findings

Two main periodicities at ~6 and ~10 years detected across frequencies

Results confirmed with Lomb-Scargle and wavelet Z-transform methods

High confidence levels established through Monte Carlo simulations

Abstract

In this paper, a periodicity analysis of the radio light curves of the blazar NRAO 530 at 14.5, 8.0, and 4.8 GHz is presented employing an improved Phase Dispersion Minimization (PDM) technique. The result, which shows two persistent periodic components of $ \sim 6$ and $ \sim 10$ years at all three frequencies, is consistent with the results obtained with the Lomb-Scargle periodogram and weighted wavelet Z-transform algorithms. The reliability of the derived periodicities is confirmed by the Monte Carlo numerical simulations which show a high statistical confidence. (Quasi-)Periodic fluctuations of the radio luminosity of NRAO 530 might be associated with the oscillations of the accretion disk triggered by hydrodynamic instabilities of the accreted flow. \keywords{methods: statistical -- galaxies: active -- galaxies: quasar: individual: NRAO 530}