paper

Beyond Traditional Diagnostics: Identifying Active Galactic Nuclei with Spectral Energy Distribution Fitting in DESI Data

arXiv:2506.09143 · doi:10.1051/0004-6361/202555463

Abstract

Active galactic nuclei (AGN) are typically identified through their distinctive X-ray or radio emissions, mid-infrared (MIR) colors, or emission lines. However, each method captures different subsets of AGN due to signal-to-noise (SNR) limitations, redshift coverage, and extinction effects, underscoring the necessity for a multi-wavelength approach for comprehensive AGN samples. This study explores the effectiveness of spectral energy distribution (SED) fitting as a robust method for AGN identification. Using {\tt CIGALE} optical-MIR SED fits on DESI Early Data Release galaxies, we compare SED-based AGN selection ({\tt AGNFRAC} ) with traditional methods including BPT diagrams, WISE colors, X-ray, and radio diagnostics. SED fitting identifies of narrow/broad-line AGN and 87\% of WISE-selected AGN. Incorporating high SNR WISE photometry reduces star-forming galaxy contamination from 62\% to 15\%. Initially, of SED-AGN candidates are undetected by standard methods, but additional diagnostics classify of these sources, revealing LINERs and retired galaxies potentially representing evolved systems with weak AGN activity. Further spectroscopic and multi-wavelength analysis will be essential to determine the true AGN nature of these sources. SED fitting provides complementary AGN identification, unifying multi-wavelength AGN selections. This approach enables more complete -- albeit with some contamination -- AGN samples essential for upcoming large-scale surveys where spectroscopic diagnostics may be limited.

accepted for publication in A&A

References in corpus (99)

Cited by in corpus (1)