USING LEAKED POWER TO MEASURE INTRINSIC AGN POWER SPECTRA OF RED-NOISE TIME SERIES

• Published in: The Astrophysical journal Vol. 825; no. 1; p. 56
• Main Authors: Zhu, S. F., Xue, Y. Q.
• Format: Journal Article
• Language: English
• Published: United States The American Astronomical Society 01.07.2016
• Subjects: Active galactic nuclei; Aliasing; ASTROPHYSICS, COSMOLOGY AND ASTRONOMY; Broadband; Computer simulation; COMPUTERIZED SIMULATION; DATA ANALYSIS; EMISSION; Estimating; GALAXIES; galaxies: active; GALAXY NUCLEI; Leakage; methods: data analysis; methods: numerical; methods: statistical; MONTE CARLO METHOD; Monte Carlo methods; NOISE; Nuclear power generation; SPECTRA; SPECTRAL DENSITY; VARIATIONS
• ISSN: 0004-637X; 1538-4357
• DOI: 10.3847/0004-637X/825/1/56

ABSTRACT Fluxes emitted at different wavebands from active galactic nuclei (AGNs) fluctuate at both long and short timescales. The variation can typically be characterized by a broadband power spectrum, which exhibits a red-noise process at high frequencies. The standard method of estimating the power spectral density (PSD) of AGN variability is easily affected by systematic biases such as red-noise leakage and aliasing, in particular when the observation spans a relatively short period and is gapped. Focusing on the high-frequency PSD that is strongly distorted due to red-noise leakage and usually not significantly affected by aliasing, we develop a novel and observable normalized leakage spectrum (NLS), which sensitively describes the effects of leaked red-noise power on the PSD at different temporal frequencies. Using Monte Carlo simulations, we demonstrate how an AGN underlying PSD sensitively determines the NLS when there is severe red-noise leakage, and thereby how the NLS can be used to effectively constrain the underlying PSD.