Luminosity function of galaxies in groups in the Sloan Digital Sky Survey Data Release 7: the dependence on mass, environment and galaxy type

Zandivarez, Ariel; Martínez, H.

doi:10.1111/j.1365-2966.2011.18878.x

Cited by 56 publications

(70 citation statements)

References 89 publications

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“…This can affect the result, since in some of the four magnitude-gap bins we could be dominated by massive clusters, while in others the dominant systems could be groups. Differences can be found in the literature between the Schechter parameters of clusters and groups (e.g., Zandivarez & Martínez 2011). To test this aspect, we ran a Kolmogorov-Smirnov test, which confirmed that the distributions of σ v (which is a mass proxy, as suggested by Munari et al (2013), and it has been obtained from L X ) for the four subsamples that are not different.…”

Section: Caveats Of the Resultsmentioning

confidence: 88%

Fossil group origins

Zarattini

Aguerri

Sánchéz-Janssen

et al. 2015

A&A

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Context. In nature we observe galaxy aggregations that span a wide range of magnitude gaps between the two first-ranked galaxies of a system (Δm 12 ). Thus, there are systems with gaps close to zero (e.g., the Coma cluster), and at the other extreme of the distribution, the largest gaps are found among the so-called fossil systems. The observed distribution of magnitude gaps is thought to be a consequence of the orbital decay of M * galaxies in massive halos and the associated growth of the central object. As a result, to first order the amplitude of this gap is a good statistical proxy for the dynamical age of a system of galaxies. Fossil and non-fossil systems could therefore have different galaxy populations that should be reflected in their luminosity functions. Aims. In this work we study, for the first time, the dependence of the luminosity function parameters on Δm 12 using data obtained by the fossil group origins (FOGO) project. Methods. We constructed a hybrid luminosity function for 102 groups and clusters at z ≤ 0.25 using both photometric data from the SDSS-DR7 and redshifts from the DR7 and the FOGO surveys. The latter consists of ∼1200 new redshifts in 34 fossil system candidates. We stacked all the individual luminosity functions, dividing them into bins of Δm 12 , and studied their best-fit Schechter parameters. We additionally computed a "relative" luminosity function, expressed as a function of the central galaxy luminosity, which boosts our capacity to detect differences -especially at the bright end. Results. We find trends as a function of Δm 12 at both the bright and faint ends of the luminosity function. In particular, at the bright end, the larger the magnitude gap, the fainter the characteristic magnitude M * . The characteristic luminosity in systems with negligible gaps is more than a factor three brighter than in fossil-like ones. Remarkably, we also find differences at the faint end. In this region, the larger the gap, the flatter the faint-end slope α. Conclusions. The differences found at the bright end support a dissipationless, dynamical friction-driven merging model for the growth of the central galaxy in group-and cluster-sized halos. The differences in the faint end cannot be explained by this mechanism. Other processes -such as enhanced tidal disruption due to early infall and/or prevalence of eccentric orbits -may play a role. However, a larger sample of systems with Δm 12 > 1.5 is needed to establish the differences at the faint end.

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Section: Caveats Of the Resultsmentioning

confidence: 88%

Fossil group origins

Zarattini

Aguerri

Sánchéz-Janssen

et al. 2015

A&A

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“…The solid line is the luminosity function for semi-analytical galaxies in groups with virial masses higher than 10 13.5 h −1 M and whose brightest galaxy is an elliptical galaxy. Grey region show the results for galaxies in groups in the SDSS DR7 obtained by Zandivarez & Martínez (2011). Upper and lower arrows represent the faint end slope of the luminosity function obtained by Popesso et al (2005) and Zarattini et al (2015), while middle arrow correspond to the value obtained in this work.…”

Section: Fossil Groupsmentioning

confidence: 99%

“…2. The grey region was built from the best-fitting Schechter parameters of the luminosity function of galaxies in groups identified in the SDSS DR7 by Zandivarez & Martínez (2011) 1 . These fits were obtained only for galaxies brighter than M r − 5 log(h) = −17.…”

Section: Fossil Groupsmentioning

confidence: 99%

Fossil groups in the Millennium simulation

Kanagusuku

Díaz-Giménez

Zandivarez

2016

A&A

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Aims. We investigate the evolution of bright and faint galaxies in fossil and non-fossil groups. Methods. We used mock galaxies constructed based on the Millennium run simulation II. We identified fossil groups at redshift zero according to two different selection criteria, and then built reliable control samples of non-fossil groups that reproduce the fossil virial mass and assembly time distributions. The faint galaxies were defined as having r-band absolute magnitudes in the range [−16, −11]. We analysed the properties of the bright and faint galaxies in fossil and non-fossil groups during the past 8 Gyr.Results. We observed that the brightest galaxy in fossil groups is typically brighter and more massive than their counterparts in control groups. Fossil groups developed their large magnitude gap between the brightest galaxies around 3.5 Gyr ago. The brightest galaxy stellar masses of all groups show a notorious increment at that time. By analysing the behaviour of the magnitude gap between the first and the second, third, and fourth ranked galaxies, we found that at earlier times, fossil groups comprised two large brightest galaxies with similar magnitudes surrounded by much fainter galaxies, while in control groups these magnitude gaps were never as large as in fossils. At early times, fossil groups in the faint population were denser than non-fossil groups, then this trend reversed, and finally they became similar at the present day. The mean number of faint galaxies in non-fossil systems increases in an almost constant rate towards later times, while this number in fossil groups reaches a plateau at z ∼ 0.6 that lasts ∼2 Gyr, and then starts growing again more rapidly. Conclusions. The formation of fossil groups is defined at the very beginning of the groups according to their galaxy luminosity sampling, which could be determined by their merging rate at early times.

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“…The catalogue of ZM11 comprises 15,961 groups with more than 4 members, adding up to 103,342 galaxies. We refer the reader to Zandivarez & Martínez (2011) and references therein for further details of group identification.…”

Section: The Samplesmentioning

confidence: 99%

“…Just et al (2015) found evidences of preprocessing of galaxies in the infall region of clusters in the redshift range 0.4 < z < 0.8. These authors found that at z ∼ 0.6, the fraction of red galaxies in the infall region is larger than in the field (see also Moran et al 2007 andPatel et al 2011) In this paper, we study the population of galaxies in the infalling region of massive groups taken from Zandivarez & Martínez (2011). We distinguish between galaxies infalling into groups along filaments and those that are in the infalling region but outside filaments, which we refer to as isotropic infalling galaxies.…”

Section: Introductionmentioning

confidence: 99%

Galaxies infalling into groups: filaments versus isotropic infall

Martínez

Muriel

Coenda

2015

Mon. Not. R. Astron. Soc.

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We perform a comparative analysis of the properties of galaxies infalling into groups classifying them accordingly to whether they are: falling along filamentary structures; or they are falling isotropically. For this purpose, we identify filamentary structures connecting massive groups of galaxies in the SDSS. We perform a comparative analysis of some properties of galaxies in filaments, in the isotropic infall region, in the field, and in groups. We study the luminosity functions (LF) and the dependence of the specific star formation rate (SSFR) on stellar mass, galaxy type, and projected distance to the groups that define the filaments. We find that the LF of galaxies in filaments and in the isotropic infalling region are basically indistinguishable between them, with the possible exception of late-type galaxies. On the other hard, regardless of galaxy type, their LFs are clearly different from that of field or group galaxies. Both of them have characteristic absolute magnitudes and faint end slopes in between the field and group values. More significant differences between galaxies in filaments and in the isotropic infall region are observed when we analyse the SSFR. We find that galaxies in filaments have a systematically higher fraction of galaxies with low SSFR as a function of both, stellar mass and distance to the groups, indicating a stronger quenching of the star formation in the filaments compared to both, the isotropic infalling region, and the field. Our results suggest that some physical mechanisms that determine the differences observed between field galaxies and galaxies in systems, affect galaxies even when they are not yet within the systems.

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Luminosity function of galaxies in groups in the Sloan Digital Sky Survey Data Release 7: the dependence on mass, environment and galaxy type

Cited by 56 publications

References 89 publications

Fossil group origins

Fossil group origins

Fossil groups in the Millennium simulation

Galaxies infalling into groups: filaments versus isotropic infall

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