• DOI:10.1086/382217
• Corpus ID: 119101213

Stellar Population in LLAGN.I: Ground-based observations

@inproceedings{Fernandes2004StellarPI,
  title={Stellar Population in LLAGN.I: Ground-based observations},
  author={Roberto Cid Fernandes and Rosa M. Gonz{\'a}lez Delgado and Henrique R. Schmitt and Thaisa Storchi-Bergmann and Lucimara P. Martins and Enrique P{\'e}rez and Timothy M. Heckman and Claus Leitherer and Daniel Schaerer},
  year={2004}
}

• R. C. Fernandes, R. Delgado, +6 authors D. Schaerer
• Published 21 January 2004
• Physics

(Abridge): We present a spectroscopic study of the stellar populations of Low Luminosity AGN (LLAGN). Our main goal is to determine whether the stars who live in the innermost (100 pc-scale) regions of these galaxies are in some way related to the emission line properties, which would imply a link between the stellar population and the ionization mechanism. High signal to noise, ground based long-slit spectra in the 3500--5500 A interval were collected for 60 galaxies.Our main findings are: (1) Few LLAGN have a detectable young (<10 Myr) starburst component, indicating that very massive stars do not contribute significantly to the optical continuum. In particular, no features due to Wolf-Rayet stars were convincingly detected. (2) High Order Balmer absorption lines of HI (HOBLs), on the other hand, are detected in 40% of LLAGN. These features, which are strongest in 100 Myr--1 Gyr intermediate age stellar populations, are accompanied by diluted metal absorption lines and bluer colors than other objects in the sample. (3) These intermediate age populations are very common (50 %) in LLAGN with relatively weak [OI] emission, but rare (10 %) in LLAGN with stronger [OI]. This is intriguing since LLAGN with weak [OI] have been previously hypothesized to be ``transition objects'' in which both an AGN and young stars contribute to the emission-line excitation. Massive stars, if present, are completely outshone by intermediate age and old stars in the optical. This happens in at least a couple of objects where independent UV spectroscopy detects young starbursts not seen in the optical. (4) Objects with predominantly old stars span the whole range of [OI]/Halpha values, but (5) sources with significant young and/or intermediate age populations are nearly all (90%) weak [OI] emitters.