Year: 2026
Type: article
Abstract: The Vera C. Rubin Observatory’s Legacy Survey of Space and Time (LSST) is expected to obtain observations of over ten million quasars. The survey’s exceptional cadence and sensitivity will enable a significant fraction of these objects to be monitored in the ugrizy bands, spanning observed wavelengths of approximately 0.3 − 1.0 μm. The unprecedented number of sources makes spectroscopic follow-up for the vast majority of them unfeasible in the near future, so most studies will have to rely on photometric redshift estimates which are traditionally much less reliable for Active Galactic Nuclei (AGNs) than for inactive galaxies. This work presents a novel methodology to constrain the photometric redshift of AGNs that leverages the effects of cosmological time dilation, and of the luminosity and wavelength dependence of AGN variability. Specifically, we assume that the variability can be modeled as a damped random walk (DRW) process, and we adopted a parametric model to characterize the DRW timescale (τ) and asymptotic amplitude of the variability (SF∞) based on the redshift, the rest-frame wavelength, and the AGN luminosity. We constructed variability-based photometric redshift (photo-z) priors by modeling the observed variability using the expected DRW parameters at a given redshift. These variability-based photo-z (VAR-PZ) priors were then combined with traditional spectral energy distribution (SED) fitting to improve the redshift estimates from SED fitting. Validation was performed using observational data from the Sloan Digital Sky Survey (SDSS), demonstrating significant reduction in catastrophic outliers by more than 10% in comparison with SED fitting techniques and improvements in redshift precision. The simulated light curves with both SDSS and LSST-like cadences and baselines confirm that VAR-PZ will be able to constrain the photometric redshifts of SDSS-like AGNs by bringing the outlier fractions down to below 15% from 32% (SED alone) at the end of the survey.
Authors: S. Satheesh-Sheeba, R. J. Assef, T. Anguita, P. Sánchez-Sáez, R. Shirley, T. T. Ananna, F. E. Bauer, A. Bobrick, C. G. Bornancini, S. E. I. Bosman, W. N. Brandt, D. De Cicco, B. Czerny, M. Fatović, K. Ichikawa, D. Ilić, A. B. Kovačević, G. Li, M. Liao, A. Rojas-Lilayú, M. Marculewicz, D. Marsango, C. Mazzucchelli, T. Mkrtchyan, S. Panda, A. Peca, B. Rani, C. Ricci, G. T. Richards, M. Salvato, D. P. Schneider, M. J. Temple, F. Tombesi, W. Yu, I. Yoon, F. Zou
Institutions: Universidad Andrés Bello, Millennium Institute of Astrophysics, European Southern Observatory, Wayne State University, University of Tarapacá, ARC Centre of Excellence for Gravitational Wave Discovery, Monash University, Waseda University, Tohoku University, Frontier Research Institute for Interdisciplinary Sciences, Tohoku University, Universität Hamburg, University of Belgrade, Peking University, Universidad Diego Portales, International Gemini Observatory, Yale University, Eureka Scientific, Goddard Space Flight Center, University of Maryland, Baltimore County, University of Geneva, Drexel University, Max Planck Institute for Extraterrestrial Physics, Excellence Cluster Origins, Bishop's University, National Radio Astronomy Observatory, University of Virginia, University of Michigan
Language: English
Subfield: Astronomy and Astrophysics
Field: Physics and Astronomy
Domain: Physical Sciences
Open Access status: green
Funders: National Science Foundation, U.S. Department of Energy, National Aeronautics and Space Administration, Alfred P. Sloan Foundation, Princeton University, Ohio State University, University of Washington, Johns Hopkins University, University of Pittsburgh, Case Western Reserve University, Drexel University, Universität Basel, University of Portsmouth, New Mexico State University, Universidad Nacional de Córdoba, UK Research and Innovation, Royal Astronomical Society, Deutsche Forschungsgemeinschaft, Schweizerischer Nationalfonds zur Förderung der Wissenschaftlichen Forschung, Coordenação de Aperfeiçoamento de Pessoal de Nível Superior, Chinese Academy of Sciences, Consejo Nacional de Investigaciones Científicas y Técnicas, Ministero dell’Istruzione, dell’Università e della Ricerca, Max-Planck-Gesellschaft, Agencia Nacional de Investigación y Desarrollo, Max-Planck-Institut für Astronomie, U.S. Naval Observatory, Fermilab, Los Alamos National Laboratory
Awards: INSTITUTO MILENIO DE ASTROFISICA, EXTREME SUPERMASSIVE BLACK HOLE ACCRETION, AGNS THROUGH COSMIC TIME HOT DUST OBSCURED GALAXIES AND THE RUBIN LSST, G2329447088, G2428672771, Understanding the Stellar Mass and Environmental Dependences of Cosmic Black-Hole Growth, G3010137097, G4231707589, A PANCHROMATIC VIEW OF RADIO-LOUD QUASARS IN THE EARLY UNIVERSE, LENSED AGN FROM EUCLID AND LSST OPTIMIZING SAMPLES FOR COSMOGRAPHY AND THE PHYSICAL STRUCTURE OF HIGH-Z AGN., G5834573078, SPECTRO-TEMPORAL STUDIES OF AGN POPULATIONS, The Many Facets of Sustainable Development, CENTRO DE ASTROFISICA Y TECNOLOGIAS AFINES (CATA)
OpenAlex ID: W7133125336
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