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LINERs and their Physical Mechanisms

Alexei V. Filippenko
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Abstract

I review the basic properties of low-ionization nuclear emission-line regions (LINERs), as well as the main ionization mechanisms thus far proposed for them. There is substantial heterogeneity among LINERs, especially those with extended kpc-scale emission. An extensive survey by Ho, Filippenko, & Sargent quantifies with unprecedented accuracy the optical emission-line intensity ratios in the nuclei of a complete sample of 486 nearby, bright galaxies. Over 40% of all early-type galaxies in the sample can be classified as LINERs or LINER/H II transition objects. A nonstellar continuum is detected in many LINERs, suggesting that they are genuine AGNs powered by accretion onto a compact object. Broad H alpha emission similar to that of Seyfert 1 nuclei is seen in many LINERs. In some LINERs, the broad H alpha emission has two well-separated peaks, probably indicative of an accretion disk.

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Alexei V. Filippenko. 2003-07-08. LINERs and their Physical Mechanisms. https://arxiv.org/abs/astro-ph/0307137

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