CAAUL Seminar - LINERs and Lyman continuum photon escape - 17 fevereiro 2014

Polychronis Papaderos

CAUP

Abstract / Resumo

An ongoing investigation of 32 early-type galaxies (ETGs) from the Calar Alto Legacy Integral Field spectroscopy Area survey (CALIFA) reveals the presence of faint nebular emission several kpc away from the ETG nuclei. The nature of the dominant excitation mechanism of this extended ionized gas component will be discussed in the light of the observed radial distribution of diagnostic line ratios and H-alpha equivalent width. We find that in more than half of the sample galaxies, 70-90% of the Lyman continuum (LyC) photon output from post-AGB stars (consequently, from any other discrete or diffuse ionizing source) escapes into the intergalactic space without being reprocessed into nebular emission. We argue that, because of extensive LyC photon leakage, nuclear emission-line luminosities and equivalent widths in these systems are reduced by at least one order of magnitude. Consequently, the line weakness of these ETGs, all of which show LINER-specific spectroscopic properties, is by itself no compelling evidence for their containing merely "weak" (sub-Eddington accreting) active galactic nuclei.

17 de fevereiro de 2014 | 15:30

Local

OAL - Observatório Astronómico de Lisboa

Seminar room at 15:30 with coffee, tea and biscuits from 15:15