J/MNRAS/434/336 Nuclear activity in isolated galaxies (Hernandez-Ibarra+, 2013)
Nuclear activity in isolated galaxies.
Hernandez-Ibarra F.J., Dultzin D., Krongold Y., del Olmo A., Perea J.,
Gonzalez J.
<Mon. Not. R. Astron. Soc., 434, 336-346 (2013)>
=2013MNRAS.434..336H 2013MNRAS.434..336H
ADC_Keywords: Galaxy catalogs ; Abundances
Keywords: galaxies: active - galaxies: evolution - galaxies: interactions
Abstract:
We present a spectroscopic study of the incidence of active galactic
nucleus (AGN) nuclear activity in two samples of isolated galaxies.
Our results show that the incidence of non-thermal nuclear activity is
about 43 and 31 percent for galaxies with emission lines and 40 and 27
percent for the total sample, respectively. For the first time we have
a large number of bona fide isolated galaxies (513 objects), with
statistically significant number of all morphological types. A large
fraction (∼70%) of elliptical galaxies or early-type spirals have an
AGN and ∼70% of them are low-ionization nuclear emission-line regions.
We find a larger fraction of AGN in early morphological types, as also
found in the general population of galaxies. Only 3% of the AGN show
the presence of broad lines (not a single one can be classified as
type 1 AGN). This is an important result which is at odds with the
unified model even if we consider warped or clumpy tori. Finally, we
interpret the large fraction of AGN in isolated galaxies as the result
of secular accretion.
Description:
We used two samples of rigorously defined isolated galaxies: the
photometric catalogue of isolated galaxies (CIG) by Karachentseva
(1973, Cat. VII/82) and the northern isolated disc galaxies compiled
by Varela et al. (2004, Cat. J/A+A/420/873).
We examined all of the spectra looking if emission lines were present.
Within the spectral range covered by the SDSS spectra, we searched for
Hβ, [OIII] λ5007Å, [OI] λ6300Å,
[NII] λλ6548, 6584Å, Hα and the two sulphur
([SII] λλ6717, 6731Å) lines.
File Summary:
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FileName Lrecl Records Explanations
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ReadMe 80 . This file
table6.dat 86 349 Logarithm intensity ratios with their errors and
AGN type for the CIG sample (VII/82)
table7.dat 86 81 Logarithm intensities ratios and their errors
for the Varela's sample (J/A+A/420/873)
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See also:
VII/82 : Catalogue of Isolated Galaxies (Karachentseva+ 1986)
J/A+A/420/873 : Properties of isolated disk galaxies (Varela+, 2004)
Byte-by-byte Description of file: table6.dat table7.dat
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Bytes Format Units Label Explanations
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1- 2 A2 --- T Galaxy type (E, S, Sa, Sb, Sc, Sm)
4- 11 A8 --- Object Object name
13- 17 A5 --- MType Morphological type (1)
19- 25 F7.4 [-] [OIII/Hb] Logarithm intensity ratio [OIII]/Hβ
27- 32 F6.4 [-] e_[OII/Hb] rms uncertainty on [[OIII]/Hb]
34- 41 F8.5 [-] [NII/Ha] Logarithm intensity ratio [NII]/Hα
43- 48 F6.4 [-] e_[NII/Ha] rms uncertainty on [[NII]/Ha]
50- 56 F7.4 [-] [SII/Ha] Logarithm intensity ratio [SII]/Hα
58- 63 F6.4 [-] e_[SII/Ha] rms uncertainty on [[SII]/Ha]
65- 71 F7.4 [-] [OI/Ha] ?=- Logarithm intensity ratio [OI]/Hα
73- 78 F6.4 [-] e_[OI/Ha] ? rms uncertainty on [[OI]/Ha]
80- 84 A5 --- Type Type of galaxy (2)
86 A1 --- n_Type [+*] Note on type (3)
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Note (1): AGN classification denotes those galaxies that are AGN according
to the [NII] diagrams but not to the [SII] and/or [OI].
Note (2): Types are:
AGN = Active Galaxy Nucleus
HII = HII galaxy
Sy = Seyfert (active) galaxy
LINER = Low-Ionization Nuclear Emission-line Region
L-S = LINER, close to a Seyfert galaxy
S-L = Seyfert galaxy, close of a LINER
Note (3): Notes as follows:
+ = L-S classification means that galaxies fall in the separation line
for Seyfert and LINER according to [SII] and [OI] diagrams
* = Type with weak broad component in permitted lines. Seyfert quantitative
classification according to Winkler (1992MNRAS.257..677W 1992MNRAS.257..677W).
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History:
From electronic version of the journal
(End) Patricia Vannier [CDS] 29-Jul-2014