The incidence of nuclear activity in galaxy pairs with different morphologies (E+E), (E+S) and (S+S)

DOI: 
10.1093/mnras/stw480
Publication date: 
01/06/2016
Main author: 
Hernández-Ibarra, Francisco J.
IAA authors: 
del Olmo, Ascensión;Perea, Jaime
Authors: 
Hernández-Ibarra, Francisco J.;Krongold, Yair;Dultzin, Deborah;del Olmo, Ascensión;Perea, Jaime;González, Jesús;Mendoza-Castrejón, Sandro;Bitsakis, Theodoros
Journal: 
Monthly Notices of the Royal Astronomical Society
Refereed: 
Yes
Publication type: 
Article
Volume: 
459
Pages: 
291-309
Abstract: 
We analysed 385 Sloan Digital Sky Survey Data Release 7 (SDSS-DR7) galactic spectra that belong to the catalogue of isolated pairs of galaxies by Karachentsev. The spectra correspond to physical pairs of galaxies defined by a difference in velocity ≤1200 km s<SUP>-1</SUP> and a pair separation ≤100 kpc. We study the incidence of nuclear activity, both star formation and non-thermal - active galactic nuclei (AGNs). After a careful extraction of the nuclear spectra, we use diagnostic diagrams and find that the incidence of AGNs is 48 per cent in emission line paired galaxies and 40 per cent for the total sample (as compared to ̃43 per cent and 41 per cent, respectively, in a sample of isolated galaxies). These results remain after dissecting the effects of morphological type and galactic stellar mass (with only a small, non significant, enhancement of the AGN fraction in galaxy pairs). These results suggest that weak interactions are not necessary and/or sufficient to trigger low-luminosity AGN. Since the fraction of AGN is predominant in early-type spiral galaxies, we conclude that the role of a bulge, and a large gas reservoir are both essential for the triggering of nuclear activity. The most striking result is that Type 1 nuclei are absent from the AGN sample. This result is in conflict with the Unified Model, and suggests that high accretion rates are essential to form the broad line region in active galaxies.
Database: 
ADS
SCOPUS
WOK
SCOPUS
URL: 
https://ui.adsabs.harvard.edu/#abs/2016MNRAS.459..291H/abstract
ADS Bibcode: 
2016MNRAS.459..291H
Keywords: 
galaxies: active;galaxies: evolution;galaxies: interactions;Astrophysics - Astrophysics of Galaxies