2007/03/12 by Rogério Riffel, R. Riffel, M. G. Pastoriza +4 · 3 citations
Physics and Astronomy · #Active galactic nucleus #Astronomy #Astrophysical Phenomena and Observations #Astrophysics #Context (archaeology) #Emission spectrum #Equivalent width #Galaxies: Formation, Evolution, Phenomena #Galaxy #Geology #Infrared #Line (geometry) #Physics #Spectral line #Spectral signature #Star formation #Stars #Stellar, planetary, and galactic studies #astro-ph
paper · pdf · doi:10.1086/517999
Accepted for publication in The Astrophysical Journal Letters. 4 pages, 3 figures
arxiv created 2007/03/12 · openalex publication_date 2007/03/20 · arxiv updated 2009/12/01 · openalex created_date 2025/10/10 · openalex updated_date 2026/08/05
We present the first detection of the near-infrared CN absorption band in the nuclear spectra of active galactic nuclei (AGNs). This feature is a recent star formation tracer, being particularly strong in carbon stars. The equivalent width of the CN line correlates with that of the CO at 2.3 μm as expected in stellar populations (SPs) with ages between ~0.2 and ~2 Gyr. The presence of the 1.1 μm CN band in the spectra of the sources is taken as unambiguous evidence of the presence of young/intermediate SPs close to the central source of the AGNs. Near-infrared bands can be powerful age indicators for star formation connected to AGNs, the understanding of which is crucial in the context of galaxy formation and AGN feedback.