Identification of periodicities with arbitrary shapes in AGN light curves

Fuente: arXiv
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Auteurs principaux: Bertassi, Lorenzo, Charisi, Maria, Buscicchio, Riccardo, Rigamonti, Fabio, Runnoe, Jessie, Dotti, Massimo
Format: Preprint
Publié: 2025
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author Bertassi, Lorenzo
Charisi, Maria
Buscicchio, Riccardo
Rigamonti, Fabio
Runnoe, Jessie
Dotti, Massimo
author_facet Bertassi, Lorenzo
Charisi, Maria
Buscicchio, Riccardo
Rigamonti, Fabio
Runnoe, Jessie
Dotti, Massimo
contents Massive black hole binaries are expected to be observable as periodic AGN in time-domain photometric surveys. Periodicities may originate from different physical processes, including the intermittent gas feeding of the black holes caused by the time-varying non-axisymmetric binary potential, the Doppler boosting of the flux emitted by individual accretion discs bound to the orbiting BHs, and the gravitational lensing of the accretion disc of one black hole due to the presence of the other. Only the Doppler boost scenario applied to circular binaries with non-modulated accretion predicts a sinusoidal light curve, while in the general case, binary signals are expected to show more complex periodic patterns. Current searches for massive black hole binaries rely on techniques tailored to quasi-sinusoidal light curves, but fail to identify the more complex periodicities predicted. We present an alternative method that leverages Gaussian processes, making use of a generic periodic kernel flexible enough for the identification of arbitrary periodicities in unevenly sampled light curves with realistic quasar noise. We demonstrate that it outperforms previously proposed strategies in identifying general periodicities by analysing mock light curves with different baselines. Specifically, we find that our analysis can detect non-sinusoidal periodicities (e.g., sawtooth-shaped) and retrieves a higher fraction of true periodicities when compared to periodogram analysis or Gaussian processes analysis with less flexible periodic kernels. Furthermore, by comparing the retrieved fraction of periodicities between mock PTF light curves and mock LSST light curves, we find that our analysis is most sensitive to the number of observed cycles. The application of this analysis has the potential to greatly increase the scientific return of current and upcoming large time-domain photometric surveys.
format Preprint
id arxiv_https___arxiv_org_abs_2512_13688
institution arXiv
publishDate 2025
record_format arxiv
spellingShingle Identification of periodicities with arbitrary shapes in AGN light curves
Bertassi, Lorenzo
Charisi, Maria
Buscicchio, Riccardo
Rigamonti, Fabio
Runnoe, Jessie
Dotti, Massimo
Astrophysics of Galaxies
Massive black hole binaries are expected to be observable as periodic AGN in time-domain photometric surveys. Periodicities may originate from different physical processes, including the intermittent gas feeding of the black holes caused by the time-varying non-axisymmetric binary potential, the Doppler boosting of the flux emitted by individual accretion discs bound to the orbiting BHs, and the gravitational lensing of the accretion disc of one black hole due to the presence of the other. Only the Doppler boost scenario applied to circular binaries with non-modulated accretion predicts a sinusoidal light curve, while in the general case, binary signals are expected to show more complex periodic patterns. Current searches for massive black hole binaries rely on techniques tailored to quasi-sinusoidal light curves, but fail to identify the more complex periodicities predicted. We present an alternative method that leverages Gaussian processes, making use of a generic periodic kernel flexible enough for the identification of arbitrary periodicities in unevenly sampled light curves with realistic quasar noise. We demonstrate that it outperforms previously proposed strategies in identifying general periodicities by analysing mock light curves with different baselines. Specifically, we find that our analysis can detect non-sinusoidal periodicities (e.g., sawtooth-shaped) and retrieves a higher fraction of true periodicities when compared to periodogram analysis or Gaussian processes analysis with less flexible periodic kernels. Furthermore, by comparing the retrieved fraction of periodicities between mock PTF light curves and mock LSST light curves, we find that our analysis is most sensitive to the number of observed cycles. The application of this analysis has the potential to greatly increase the scientific return of current and upcoming large time-domain photometric surveys.
title Identification of periodicities with arbitrary shapes in AGN light curves
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2512.13688