The Nature of the Activity in Hickson Compact Groups of Galaxies

Coziol, R.; Ribeiro, André; Carvalho, R. R. de; Capelato, H. V.

doi:10.1086/305160

Cited by 63 publications

(133 citation statements)

References 19 publications

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“…Coziol et al (1998) classified the nuclear region of HCG 22a as a dwarf Seyfert 2 and Gallagher et al (2008) did not find evidence for any excess mid-infrared emission in this object. Verdes-Montenegro et al (1998) gave upper limits for the IR luminosities of HCG 22b and HCG 22c (log L IR < 8.55 L and log L IR = 8.88 L respectively).…”

Section: Hcg 22mentioning

confidence: 93%

“…Bournaud & Duc (2006) performed simulations in order to relate TDGs and Allam et al (1996), Verdes-Montenegro et al (1998) and Gallagher et al (2008). The indicator "Central Activity" was taken from: Shimada et al (2000), de Carvalho et al (1997), Coziol et al (1998 and Xu et al (2003). b The disagreement between optical and kinematic position angle could be associated with the presence of a bar.…”

Section: Ultraviolet Light As An Evolutionary Diagnosticmentioning

confidence: 99%

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Star formation in the intragroup medium and other diagnostics of the evolutionary stages of compact groups of galaxies

Torres-Flores

Oliveira²,

Mello

et al. 2009

A&A

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Context. Compact groups of galaxies are entities that have high densities of galaxies and serve as laboratories to study galaxy interactions, intergalactic star formation and galaxy evolution. Aims. The main goal of this study is to search for young objects in the intragroup medium of seven compact groups of galaxies: HCG 2, 7, 22, 23, 92, 100 and NGC 92 as well as to evaluate the stage of interaction of each group. Methods. We used Fabry-Perot velocity fields and rotation curves together with GALEX NUV and FUV images and optical R-band and HI maps. Results. (i) HCG 7 and HCG 23 are in early stages of interaction; (ii) HCG 2 and HCG 22 are mildly interacting; and (iii) HCG 92, HCG 100 and NGC 92 are in late stages of evolution. We find that all three evolved groups contain populations of young blue objects in the intragroup medium, consistent with ages < 100 Myr, of which several are younger than <10 Myr. We also report the discovery of a tidal dwarf galaxy candidate in the tail of NGC 92. These three groups, besides containing galaxies that have peculiar velocity fields, also show extended HI tails. Conclusions. Our results indicate that the advanced stage of evolution of a group, together with the presence of intragroup HI clouds, may lead to star formation in the intragroup medium. A table containing all intergalactic HII regions and tidal dwarf galaxies confirmed to date is appended.

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Section: Hcg 22mentioning

confidence: 93%

Section: Ultraviolet Light As An Evolutionary Diagnosticmentioning

confidence: 99%

Star formation in the intragroup medium and other diagnostics of the evolutionary stages of compact groups of galaxies

Torres-Flores

Oliveira²,

Mello

et al. 2009

A&A

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“…Spectroscopy study results, in particular, were found to be different from expectations based on the common assumptions that the main effects of dynamical interactions on galaxies in CG should be a direct enhancement of their star formation and activation of supermassive black holes (SMBHs) at their centers. Although emission-line galaxies are remarkably frequent in CG, involving more than 50% of the galaxies (Coziol et al 1998(Coziol et al , 2000(Coziol et al , 2004Martínez et al 2008Martínez et al , 2010, this activity seems mostly nonthermal, in the form of Seyfert 2, low-ionization nuclear emission-line region (LINER), and numerous low-luminosity active galactic nuclei (AGN). Luminous AGN with typical broad line regions are relatively rare in CG (Coziol et al 1998(Coziol et al , 2004Ribeiro et al 1996;Martínez et al 2008Martínez et al , 2010.…”

Section: Introductionmentioning

confidence: 99%

“…Although emission-line galaxies are remarkably frequent in CG, involving more than 50% of the galaxies (Coziol et al 1998(Coziol et al , 2000(Coziol et al , 2004Martínez et al 2008Martínez et al , 2010, this activity seems mostly nonthermal, in the form of Seyfert 2, low-ionization nuclear emission-line region (LINER), and numerous low-luminosity active galactic nuclei (AGN). Luminous AGN with typical broad line regions are relatively rare in CG (Coziol et al 1998(Coziol et al , 2004Ribeiro et al 1996;Martínez et al 2008Martínez et al , 2010. Nuclear star formation, although mildly enhanced in some groups (e.g., Ribeiro et al 1996;Iglesias-Páramo & Vílchez 1997), is generally low (Rubin et al 1991;Zepf et al 1991;Moles et al 1994; Article published by EDP Sciences A48, page 1 of 13 Pildis et al 1995;Menon 1995;Ribeiro et al 1996;Coziol et al 1998Coziol et al , 2000Verdes-Montenegro et al 1998;Allam et al 1999;Iglesias-Páramo & Vílchez 1999;Martínez et al 2010).…”

Section: Introductionmentioning

confidence: 99%

“…Indeed, it is difficult to explain how an elliptical galaxy, or even the massive bulge of an early-type spiral galaxy, can build up after star formation is quenched in the disk of a late-type spiral galaxy by gas stripping (Dressler 1980), unless one assumes that these galaxies can build massive bulges later by dry mergers (Plauchu-Frayn & Coziol 2010b). However, neither can gas stripping explain the many AGN observed in CG (e.g., Coziol et al 1998Coziol et al , 2000Martínez et al 2010). These AGN are related to the formation of numerous early-type galaxies through tidal triggering, a mechanism that funnels gas down directly into the center of galaxies, starting a sequence of bursts of star formation that increase the mass of the bulges, and forming, or feeding, a SMBH at their centers (Merritt 1983(Merritt , 1984Byrd & Valtonen 1990;Henriksen & Byrd 1996;Fujita 1998).…”

Section: Introductionmentioning

confidence: 99%

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The star formation histories of Hickson compact group galaxies

Plauchu-Frayn

Olmo

Coziol

et al. 2012

A&A

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Aims. We study the star formation fistory (SFH) of 210 galaxy members of 55 Hickson compact groups (HCG) and 309 galaxies from the Catalog of Isolated Galaxies (CIG). The SFH traces the variation of star formation over the lifetime of a galaxy, and consequently yields a snapshot picture of its formation. Comparing the SFHs in these extremes in galaxy density allows us to determine the main effects of compact groups (CG) on the formation of galaxies. Methods. We fit our spectra using the spectral synthesis code STARLIGHT and obtained the stellar population contents and mean stellar ages of HCG and CIG galaxies in three different morphological classes: early-type galaxies (EtG), early-type spirals (EtS), and late-type spirals (LtS). Results. We find that EtG and EtS galaxies in HCG show higher contents of old and intermediate stellar populations as well as an important deficit of the young stellar population, which clearly implies an older average stellar age in early galaxies in HCG. For LtS galaxies we find similar mean values for the stellar content and age in the two samples. However, we note that LtS can be split into two subclasses, namely old and young LtS. In HCG we find a higher fraction of young LtS than in the CIG sample, in addition, most of these galaxies belong to groups in which most of the galaxies are also young and actively forming stars. The specific star formation rate (SSFR) of spiral galaxies in the two samples differ. The EtS in HCG show lower SSFR values, while LtS peak at higher values compared with their counterparts in isolation. We also measured the shorter star formation time scale (SFTS) in HCG galaxies, which indicates that they have a shorter star formation activity than CIG galaxies. We take these observations as evidence that galaxies in CG have evolved more rapidly than galaxies in isolation, regardless of their morphology. Our observations are consistent with the hierarchical galaxy formation model, which states that CGs are structures that formed recently from primordial small-mass density fluctuations. From the systematic difference in SFTS we deduce that the HCG have most probably formed ∼3 Gyr in the past. The galaxies in the HCG are not in equilibrium state, but merging without gas (i.e., under dissipationless conditions), which may explain their relatively long lifetime.

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Low Luminosity Activity in Hickson Compact Groups

Martínez

Olmo

Perea

et al. 2007

Groups of Galaxies in the Nearby Universe

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With the aim of studying the influence of environment on the nuclear activity of galaxies, we have selected a well defined sample of 65 Compact Groups of galaxies with concordant redshift in the Hickson Catalog. In this proceeding, we present the results of the classification of nuclear activity for 42 galaxies, based on newly obtained spectral observations. In this subsample, 71% of the galaxies turned out to have emission lines in their nuclei. 73% of these emission-line galaxies were found to have characteristics consistent with low luminosity AGN (LLAGN), which makes compact groups extremely rich in such objects.Comment: 5 pages with 5 figure, submitted to the proceedings of the ESO workshop "Groups of Galaxies in the Nearby Universe

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The Nature of the Activity in Hickson Compact Groups of Galaxies

Cited by 63 publications

References 19 publications

Star formation in the intragroup medium and other diagnostics of the evolutionary stages of compact groups of galaxies

Star formation in the intragroup medium and other diagnostics of the evolutionary stages of compact groups of galaxies

The star formation histories of Hickson compact group galaxies

Low Luminosity Activity in Hickson Compact Groups

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