Are compact groups hostile towards faint galaxies?

Zandivarez, Ariel; Díaz-Giménez, Eugenia; Oliveira, C. Mendes de; Gubolin, Henrique

doi:10.1051/0004-6361/201424677

Cited by 10 publications

(7 citation statements)

References 46 publications

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“…Despite the relative proximity, there have been no detailed studies on its LSB dwarf galaxy population, as most attention has been paid to the group's bright and/or ultra-compact dwarf (UCD) (de Ribeiro et al 1994;Da Rocha et al 2011), and giant galaxies. This avenue of study is ripe for investigation, as other HCGs have been shown to host faint dwarfs (Campos et al 2004;Carrasco et al 2006;Krusch et al 2006;Konstantopoulos et al 2013), which are to be expected from theoretical considerations, despite the dynamically more hostile environments in these systems (Zandivarez et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Faint dwarf galaxies in Hickson Compact Group 90

Órdenes-Briceño

Taylor

Puzia

et al. 2016

Mon. Not. R. Astron. Soc.

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We report the discovery of a very diverse set of five low-surface brightness (LSB) dwarf galaxy candidates in Hickson Compact Group 90 (HCG 90) detected in deep U-and I-band images obtained with VLT/VIMOS. These are the first LSB dwarf galaxy candidates found in a compact group of galaxies. We measure spheroid half-light radii in the range 0.7 r eff /kpc 1.5 with luminosities of −11.65 M U −9.42 and −12.79 M I −10.58 mag, corresponding to a color range of (U−I) 0 1.1−2.2 mag and surface brightness levels of µ U 28.1 mag/arcsec 2 and µ I 27.4 mag/arcsec 2 . Their colours and luminosities are consistent with a diverse set of stellar population properties. Assuming solar and 0.02 Z metallicities we obtain stellar masses in the range M * | Z 10 5.7−6.3 M and M * | 0.02 Z 10 6.3−8 M . Three dwarfs are older than 1 Gyr, while the other two significantly bluer dwarfs are younger than ∼ 2 Gyr at any mass/metallicity combination. Altogether, the new LSB dwarf galaxy candidates share properties with dwarf galaxies found throughout the Local Volume and in nearby galaxy clusters such as Fornax. We find a pair of candidates with ∼ 2 kpc projected separation, which may represent one of the closest dwarf galaxy pairs found. We also find a nucleated dwarf candidate, with a nucleus size of r eff 46−63 pc and magnitude M U,0 = −7.42 mag and (U−I) 0 = 1.51 mag, which is consistent with a nuclear stellar disc with a stellar mass in the range 10 4.9−6.5 M .

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Section: Introductionmentioning

confidence: 99%

Faint dwarf galaxies in Hickson Compact Group 90

Órdenes-Briceño

Taylor

Puzia

et al. 2016

Mon. Not. R. Astron. Soc.

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“…They also demonstrated the incompleteness of the Hickson sample. Recently, and using similar semi-analytical tools, a new analysis of the influence of these extreme environments on their faint galaxy population has been performed by Zandivarez et al (2014b). These authors reported that when compared with suitable control group samples, the compact group environment is not hostile enough to modify the distribution and density of the faint galaxy population that resides in the group and in their surroundings.…”

Section: Introductionmentioning

confidence: 99%

Where are compact groups in the local Universe?

Díaz-Giménez¹,

Zandivarez²

2015

A&A

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Aims. The purpose of this work is to perform a statistical analysis of the location of compact groups in the Universe from observational and semi-analytical points of view. Methods. We used the velocity-filtered compact group sample extracted from the Two Micron All Sky Survey for our analysis. We also used a new sample of galaxy groups identified in the 2M++ galaxy redshift catalogue as tracers of the large-scale structure. We defined a procedure to search in redshift space for compact groups that can be considered embedded in other overdense systems and applied this criterion to several possible combinations of different compact and galaxy group subsamples. We also performed similar analyses for simulated compact and galaxy groups identified in a 2M++ mock galaxy catalogue constructed from the Millennium Run Simulation I plus a semi-analytical model of galaxy formation. Results. We observed that only ∼27% of the compact groups can be considered to be embedded in larger overdense systems, that is, most of the compact groups are more likely to be isolated systems. The embedded compact groups show statistically smaller sizes and brighter surface brightnesses than non-embedded systems. No evidence was found that embedded compact groups are more likely to inhabit galaxy groups with a given virial mass or with a particular dynamical state. We found very similar results when the analysis was performed using mock compact and galaxy groups. Based on the semi-analytical studies, we predict that 70% of the embedded compact groups probably are 3D physically dense systems. Finally, real space information allowed us to reveal the bimodal behaviour of the distribution of 3D minimum distances between compact and galaxy groups. Conclusions. The location of compact groups should be carefully taken into account when comparing properties of galaxies in environments that are a priori different.

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“…We identify these systems using a FoF algorithm in real space at 𝑧 = 0 using a longer linking length 𝑟 0 appropriate to obtain virialized loose galaxy groups. Following previous studies (Eke et al 2004;Berlind et al 2006;Zandivarez et al 2014), we adopt 𝑏 𝑓 = 0.14, and using the relations quoted in the eqs. 1 and 2, we compute the values of 𝑟 0 to identify the samples of FoF-LGs in each SAM.…”

Section: Global Isolation: Non-embedded Dense Systemsmentioning

confidence: 99%

Compact groups from semi-analytical models of galaxy formation -- III: purity and completeness of Hickson-like catalogues

Taverna,

Diaz-Gimenez,

Zandivarez

et al. 2022

Preprint

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Many catalogues of isolated compact groups of galaxies (CGs) have been extracted using Hickson's criteria to identify isolated, dense systems of galaxies, with at least three or four galaxies concordant in magnitude and redshift. But is not clear to what extent the catalogues of CGs are complete and reliable, relative to 3D truly isolated, dense groups. Using five different semi-analytical models of galaxy formation (SAMs), we identify isolated dense groups in 3D real space, containing at least three galaxies. We then build mock redshift space galaxy catalogues and run a Hickson-like CG finder. We find that the Hickson-like algorithm in redshift space is poor at recovering 3D CGs of at least 3 galaxies, with a purity of ∼ 10% and a completeness of ∼ 22%. Among the ∼ 90% of spurious systems, typically 60% are dense structures that failed the 3D isolation criteria, while the remaining 40% are chance alignments of galaxies along the line of sight, nearly all of which are within regular groups, with some variation with the SAM used for the analysis. In other words, while only 10% of CGs are isolated dense groups, as intended, half are dense structures embedded within larger groups, and one-third are chance alignments within larger groups. The low completeness of the extracted CG sample is mainly due to the flux limits of the selection criteria. Our results suggest that a new observational algorithm to identify compact groups in redshift space is required to obtain dense isolated galaxy systems.

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Are compact groups hostile towards faint galaxies?

Cited by 10 publications

References 46 publications

Faint dwarf galaxies in Hickson Compact Group 90

Faint dwarf galaxies in Hickson Compact Group 90

Where are compact groups in the local Universe?

Compact groups from semi-analytical models of galaxy formation -- III: purity and completeness of Hickson-like catalogues

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