Skip to main content Accessibility help
×
Home
Hostname: page-component-99c86f546-7c2ld Total loading time: 0.451 Render date: 2021-12-01T22:44:41.621Z Has data issue: true Feature Flags: { "shouldUseShareProductTool": true, "shouldUseHypothesis": true, "isUnsiloEnabled": true, "metricsAbstractViews": false, "figures": true, "newCiteModal": false, "newCitedByModal": true, "newEcommerce": true, "newUsageEvents": true }

Book contents

Stellar Ionization of Low-Luminosity Active Galactic Nuclei

Published online by Cambridge University Press:  10 November 2010

G. Tenorio-Tagle
Affiliation:
Instituto de Astrofísica de Canarias, Tenerife
Joseph C. Shields
Affiliation:
Steward Observatory, University of Arizona, Tucson, AZ 85721, USA
Get access

Summary

Low-Ionization Nuclear Emission-Line Regions (LINERs) are a common constituent of galaxies, and are often regarded as a weak form of Seyfert activity. LINERs have emission-line luminosities that are similar to those of giant HII regions, however, and recent theoretical work suggests that their nebular properties can be reproduced in many cases with photoionization by normal O stars. In an extension of this scenario, energetic phenomena such as non-thermal radio emission, broad Hα features, and substantial X-ray luminosity seen in some LINERs might be attributable to supernovae. In this review I consider the empirical evidence bearing on an interpretation of LINERs as stellar-powered sources. While stellar phenomena appear capable of matching LINERs of modest luminosity in terms of broad-band energetics, some important differences remain in detailed spectral characteristics, particularly at X-ray energies. A certain amount of anomalous behavior on the part of stars within galaxy nuclei (e.g. in terms of the initial mass function) is required if LINERs result from stellar ionization.

Introduction

Spectroscopic surveys indicate that ∼ 30% or more of bright galaxies contain weak emission-line nuclei that are classified as LINERs (Low-Ionization Nuclear Emission-Line Regions; Heckman 1980b, hereafter H80b). The intensity ratios of low-ionization optical lines relative to recombination features are characteristically higher in LINERs than in HII regions, causing LINERs to be regarded as “active” nuclei subject to unusual energetic processes. The luminosities of LINERs and giant HII regions are comparable, however, with typical Hα luminosity ∼ 1040 erg s−1 or somewhat less.

Type
Chapter
Information
Violent Star Formation
From 30 Doradus to QSOs
, pp. 353 - 364
Publisher: Cambridge University Press
Print publication year: 1994

Access options

Get access to the full version of this content by using one of the access options below. (Log in options will check for institutional or personal access. Content may require purchase if you do not have access.)

Send book to Kindle

To send this book to your Kindle, first ensure no-reply@cambridge.org is added to your Approved Personal Document E-mail List under your Personal Document Settings on the Manage Your Content and Devices page of your Amazon account. Then enter the ‘name’ part of your Kindle email address below. Find out more about sending to your Kindle.

Note you can select to send to either the @free.kindle.com or @kindle.com variations. ‘@free.kindle.com’ emails are free but can only be sent to your device when it is connected to wi-fi. ‘@kindle.com’ emails can be delivered even when you are not connected to wi-fi, but note that service fees apply.

Find out more about the Kindle Personal Document Service.

Available formats
×

Send book to Dropbox

To send content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Dropbox.

Available formats
×

Send book to Google Drive

To send content items to your account, please confirm that you agree to abide by our usage policies. If this is the first time you use this feature, you will be asked to authorise Cambridge Core to connect with your account. Find out more about sending content to Google Drive.

Available formats
×