Photometric characterization of a well-defined sample of isolated galaxies in the context of the AMIGA project

Durbala, A.; Sulentic, J. W.; Buta, Ronald J.; Verdes–Montenegro, L.

doi:10.1111/j.1365-2966.2008.13713.x

Cited by 46 publications

(96 citation statements)

References 106 publications

(166 reference statements)

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“…The rate of AGN candidates, derived from IRAS colors and radio continuum emission of the AMIGA galaxies is lowest compared to similar studies from the literature . Optical photometric analysis of Sb-Sc galaxies in the AMIGA sample showed that most galaxies have pseudo-bulges instead of classical bulges, and a comparison with samples of spiral galaxies selected without isolation criteria revealed that the isolated galaxies tend to host larger bars, are more symmetric, less concentrated and less clumpy (Durbala et al 2008). These findings strongly support that the AMIGA sample represents the most isolated galaxies in the local Universe where secular evolution is dominant.…”

Section: Introductionsupporting

confidence: 69%

The AMIGA sample of isolated galaxies

Lisenfeld

Espada

Verdes–Montenegro

et al. 2011

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Aims. We characterize the molecular gas content (ISM cold phase) using CO emission of a redshift-limited subsample of isolated galaxies from the AMIGA (Analysis of the interstellar Medium of Isolated GAlaxies) project in order to provide a comparison sample for studies of galaxies in different environments. Methods. We present the 12 CO(1-0) data for 273 AMIGA galaxies, most of them (n = 186) from our own observations with the IRAM 30 m and the FCRAO 14 m telescopes and the rest from the literature. We constructed a redshift-limited sample containing galaxies with 1500 km s −1 < v < 5000 km s −1 and excluded objects with morphological evidence of possible interaction. This sample (n = 173) is the basis for our statistical analysis. It contains galaxies with molecular gas masses, M H 2 , in the range of ∼10 8 −10 10 M . It is dominated, both in absolute number and in detection rate, by spiral galaxies of type T = 3-5 (Sb-Sc). Most galaxies were observed with a single pointing towards their centers. Therefore, we performed an extrapolation to the total molecular gas mass expected in the entire disk based on the assumption of an exponential distribution. We then studied the relationships between M H 2 and other galactic properties The molecular and the atomic gas masses of our sample show no strong correlation. We find a low mean value, log(M H 2 /M HI ) = −0.7 (for T = 3-5), and a strong decrease in this ratio with morphological type. The molecular gas column density and the surface density of the star formation rate (the Kennicutt-Schmidt law) show a tight correlation with a rough unity slope. We compare the relations of M H 2 with L B and L K found for AMIGA galaxies to samples of interacting galaxies from the literature and find an indication for an enhancement of the molecular gas in interacting galaxies of up to 0.2-0.3 dex.

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Section: Introductionsupporting

confidence: 69%

The AMIGA sample of isolated galaxies

Lisenfeld

Espada

Verdes–Montenegro

et al. 2011

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“…Our studies suggest that the most isolated galaxies show different properties than less isolated field samples. AMIGA early-type galaxies are usually fainter than late-types in the B-band and most spirals in our sample appear to host pseudo-bulges and not classical bulges (Verdes-Montenegro et al 2005;Sulentic et al 2006;Durbala et al 2008b). AMIGA spiral galaxies are redder than similar type galaxies in close pairs, showing a Gaussian distribution of the (g − r) colours with a smaller median absolute deviation (almost half) compared to galaxies in wide and close pairs.…”

Section: Introductionmentioning

confidence: 94%

The AMIGA sample of isolated galaxies

Sabater

Verdes–Montenegro

Léon

et al. 2012

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Context. This paper is part of a series involving the AMIGA project (Analysis of the Interstellar Medium of Isolated GAlaxies), which identifies and studies a statistically significant sample of the most isolated galaxies in the northern sky. Aims. We present a catalogue of nuclear activity, traced by optical emission lines, in a well-defined sample of the most isolated galaxies in the local Universe, which will be used as a basis for studying the effect of the environment on nuclear activity. Methods. We obtained spectral data from the 6th Data Release of the Sloan Digital Sky Survey, which were inspected in a semiautomatic way. We subtracted the underlying stellar populations from the spectra (using the software Starlight) and modelled the nuclear emission features. Standard emission-line diagnostics diagrams were applied, using a new classification scheme that takes into account censored data, to classify the type of nuclear emission. Results. We provide a final catalogue of spectroscopic data, stellar populations, emission lines and classification of optical nuclear activity for AMIGA galaxies. The prevalence of optical active galactic nuclei (AGN) in AMIGA galaxies is 20.4%, or 36.7% including transition objects. The fraction of AGN increases steeply towards earlier morphological types and higher luminosities. We compare these results with a matched analysis of galaxies in isolated denser environments (Hickson Compact Groups). After correcting for the effects of the morphology and luminosity, we find that there is no evidence for a difference in the prevalence of AGN between isolated and compact group galaxies, and we discuss the implications of this result. Conclusions. We find that a major interaction is not a necessary condition for the triggering of optical AGN.

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“…The original CIG contains 1051 items, but one of the compiled objects is a globular cluster (CIG 781;Verdes-Montenegro et al 2005) so the size of the sample considered in the rest of this paper is N = 1050. The AMIGA project also started several multiwavelength studies for galaxies in the CIG: characterisation of the B-band luminosity function (Sulentic et al 2006); Fourier photometric decomposition, optical asymmetry, and photometric clumpiness and concentration (Durbala et al 2008(Durbala et al , 2009); characterisation of the FIR luminosity function (Lisenfeld et al 2007), radiocontinuum ), molecular gas (Lisenfeld et al A9, page 2 of 14 2012), and atomic gas (Espada et al 2011); characterisation of nuclear activity (Sabater et al , 2012; optical colours (Fernández Lorenzo et al 2012); and optical study of the stellar mass-size relation (Fernández Lorenzo et al 2013). …”

Section: Amiga Projectmentioning

confidence: 99%

“…It is a first step in trying to identify and better understand isolated galaxies in the local Universe. Durbala et al (2008) used a subsample of 100 typical CIG galaxies (Sb, Sbc, and Sc) and found that most of them have a bulge-to-total luminosity ratio B/T < 0.1. If B/T is a measure of environmental dynamical processing (MacArthur et al 2010), galaxies in the CIG sample appear to be very little affected by it.…”

Section: Introductionmentioning

confidence: 99%

The AMIGA sample of isolated galaxies

Argudo-Fernández

Verley

Bergond

et al. 2013

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Context. To understand the evolution of galaxies, it is necessary to have a reference sample where the effect of the environment is minimized and quantified. In the framework of the AMIGA project (Analysis of the interstellar Medium of Isolated GAlaxies), we present a revision of the environment for galaxies in the Catalogue of Isolated Galaxies (CIG, Karachentseva 1973, Astrof. Issledovaniia Byu. Spec. Ast. Obs., 8, 3) using the ninth data release of the Sloan Digital Sky Survey (SDSS-DR9). Aims. The aims of this study are to refine the photometric-based AMIGA sample of isolated galaxies and to provide an improvement of the quantification of the isolation degree with respect to previous works, using both photometry and spectroscopy. Methods. We developed an automatic method to search for neighbours within a projected area of 1 Mpc radius centred on each primary galaxy to revise the CIG isolation criteria introduced by Karachentseva (1973). The local number density at the fifth nearest neighbour and the tidal strength affecting the CIG galaxy were estimated to quantify the isolation degree. Results. Of the 636 CIG galaxies considered in the photometric study, 426 galaxies fulfil the CIG isolation criteria within 1 Mpc, taking into account projected neighbours. Of the 411 CIG galaxies considered in the spectroscopic study, 347 galaxies fulfil the CIG isolation criteria when a criterion about redshift difference is added. The available redshifts allow us to reject background neighbours and thus improve the photometric assessment. On average, galaxies in the AMIGA sample show lower values in the local number density and the tidal strength parameters than galaxies in denser environments such as pairs, triplets, compact groups, and clusters. Conclusions. For the first time, the environment and the isolation degree of AMIGA galaxies are quantified using digital data. The use of the SDSS database permits one to identify fainter and smaller-size satellites than in previous AMIGA works. The AMIGA sample is improved by this study, because we reduced the sample of isolated galaxies used in previous AMIGA works by about 20%. The availability of the spectroscopic data allows us to check the validity of the CIG isolation criteria, which is not fully efficient. About 50% of the neighbours considered as potential companions in the photometric study are in fact background objects. We also find that about 92% of the neighbour galaxies that show recession velocities similar to the corresponding CIG galaxy are not considered by the CIG isolation criteria as potential companions, which may have a considerable influence on the evolution of the central CIG galaxy.

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Photometric characterization of a well-defined sample of isolated galaxies in the context of the AMIGA project

Cited by 46 publications

References 106 publications

The AMIGA sample of isolated galaxies

The AMIGA sample of isolated galaxies

The AMIGA sample of isolated galaxies

The AMIGA sample of isolated galaxies

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