Deep spectroscopic luminosity function of Abell 85: no evidence for a steep upturn of the faint-end slope

Agulli, I.; Aguerri, J. A. L.; Sánchéz-Janssen, R.; Barrena, R.; Diaferio, Antonaldo; Serra, Ana Laura; Méndez-Abreu, J.

doi:10.1093/mnrasl/slu108

Cited by 42 publications

(73 citation statements)

References 47 publications

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“…There are only a handful of deep, spectroscopic observations of nearby clusters, in which cluster-to-cluster variations of the shape of the LF are observed: Virgo and Abell 2199 LFs do not show any upturn at the faint end (Rines & Geller 2008), unlike A 85 (Agulli et al 2014). Moreover, the radial analysis of Rines & Geller (2008) does not present a significant dependence of the LF on clustercentric radius, but opposite trends in the radial variation of M * between Virgo and Abell 2199.…”

Section: Environmental Influence On Dwarfsmentioning

confidence: 94%

“…We computed the total spectroscopic LF of A 85 following the prescription in Agulli et al (2014). The LF is given by: φ(Mr) = N phot (Mr) × fm(Mr)/(∆Mr × A), where N phot is the number of photometric targets (see section 2.2), fm the fraction of cluster members defined in section 2.3, A the surveyed area and ∆mr = 0.5 the magnitude bin size used.…”

Section: Spectroscopic Lf Of a 85mentioning

confidence: 99%

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Deep spectroscopy of nearby galaxy clusters – I. Spectroscopic luminosity function of Abell 85

Agulli¹,

Aguerri²,

Sánchéz-Janssen³

et al. 2016

Mon. Not. R. Astron. Soc.

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We present a new deep spectroscopic catalogue for Abell 85, within 3.0 × 2.6 Mpc 2 and down to M r ∼ M * r +6. Using the Visible Multi-Object Spectrograph at the Very Large Telescope and the AutoFiber 2 at the William Herschel Telescope, we obtained almost 1430 new redshifts for galaxies with m r ≤ 21 mag and µ e,r ≤ 24 mag arcsec −2 . These redshifts, together with SDSS-DR6 and NED spectroscopic information, result in 460 confirmed cluster members. This data set allows the study of the luminosity function (LF) of the cluster galaxies covering three orders of magnitudes in luminosities. The total and radial LFs are best modelled by a double Schechter function. The normalized LFs show that their bright (M r ≤ −21.5) and faint (M r ≥ −18.0) ends are independent of clustercentric distance and similar to the field LFs unlike the intermediate luminosity range (−21.5 ≤ M r ≤ −18.0). Similar results are found for the LFs of the dominant types of galaxies: red, passive, virialized and early-infall members. On the contrary, the LFs of blue, star-forming, non-virialized and recent-infall galaxies are well described by a single Schechter function. These populations contribute to a small fraction of the galaxy density in the innermost cluster region. However, in the outskirts of the cluster, they have similar densities to red, passive, virialized and early-infall members at the LF faint end. These results confirm a clear dependence of the colour and star formation of Abell 85 members in the cluster centric distance.

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Section: Environmental Influence On Dwarfsmentioning

confidence: 94%

Section: Spectroscopic Lf Of a 85mentioning

confidence: 99%

Deep spectroscopy of nearby galaxy clusters – I. Spectroscopic luminosity function of Abell 85

Agulli¹,

Aguerri²,

Sánchéz-Janssen³

et al. 2016

Mon. Not. R. Astron. Soc.

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“…Nevertheless, it requires a large amount of observational time and generally larger telescope apertures than the photometric one. This method has mainly been applied to the study of nearby individual clusters (e.g., Rines & Geller 2008;Agulli et al 2014). The photometric method requires less observing time and consists in computing the galaxy number counts, as a function of magnitude, within the system region and in a region of the sky in which no structure is present.…”

Section: Luminosity Functions Of Individual Systemsmentioning

confidence: 99%

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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“…Within this framework, the progenitors of early-type dwarf galaxies would be dwarf systems with active star formation that was quenched by the sweeping out of their cold gas content by the interaction of the galaxy with the hot intracluster medium (see Boselli et al 2008;Gavazzi et al 2010). The lines of observational evidence for this argument include (i) the similar faint-end slope of the galaxy luminosity function observed in nearby galaxy clusters and the field (see e.g., Boselli et al 2011;Agulli et al 2014); (ii) the relation of the gas content, colour, and environment found in clusters (e.g. Sánchez-Janssen et al 2008;Gavazzi et al 2013); (iii) the age and metallicity spread observed in dwarf galaxies of nearby clusters, together with the correlation between age, metallicity, and clustercentric distance (see Boselli et al 2008;Smith et al 2009;Toloba et al 2009;Koleva et al 2013); the globular cluster content (see Sánchez-Janssen & Aguerri 2012); and the different kinematics properties between galaxies located in the inner and the outermost regions of the clusters (see Toloba et al 2009).…”

Section: Introductionmentioning

confidence: 96%

“…In contrast, red dwarf galaxies dominate in number the faint end of the luminosity function of galaxies in nearby clusters (e.g. De Propris et al 2003;Popesso et al 2006;Agulli et al 2014).…”

Section: Introductionmentioning

confidence: 99%

Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

Aguerri

2016

A&A

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Context. The surface brightness distribution of ∼30-40% of the early-type dwarf galaxies with −18 ≤ M B ≤ −15 in the Virgo and the Coma clusters is fitted by models that include two structural components (Sérsic + exponential) as for bright disc galaxies. Aims. The goal of the present study is to determine whether early-type dwarf galaxies with a two-component stellar structure in the Virgo and the Coma clusters are low-luminosity copies of bright disc galaxies or are the remnants of bright galaxies strongly transformed by cluster environmental effects. Methods. I analysed the location of bright disc galaxies and early-type dwarfs in the r b,e /h-n plane. The location in this plane of the two-component dwarf galaxies was compared with the remnants of tidally disrupted disc galaxies reported by numerical simulations. Results. Bright unbarred disc galaxies show a strong correlation in the r b,e /h-n plane. Galaxies with larger Sérsic shape parameters show a higher r b,e /h ratio. In contrast, two-component early-type dwarf galaxies do not follow the same correlation. A fraction (∼55%) of them are located outside the locus defined in this plane by having 95% of bright disc galaxies. This distribution indicates that they are not a low-mass replica of bright disc galaxies. The different location in the r b,e /h-n plane of two-component early-type dwarfs and bright galaxies can be qualitatively explain whether the former are remnants of disc galaxies strongly transformed by tidal processes. Conclusions. The progenitors of ∼20−25% of early-type dwarf galaxies with −18 ≤ M B ≤ −15 in the Virgo and Coma clusters could be bright disc galaxies transformed by effects of the environment. These tidally transformed galaxies can be selected according to their location in the r b,e /h-n plane.

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Deep spectroscopic luminosity function of Abell 85: no evidence for a steep upturn of the faint-end slope

Cited by 42 publications

References 47 publications

Deep spectroscopy of nearby galaxy clusters – I. Spectroscopic luminosity function of Abell 85

Deep spectroscopy of nearby galaxy clusters – I. Spectroscopic luminosity function of Abell 85

Fossil group origins

Early-type dwarf galaxies with multicomponent stellar structure: Are they remnants of disc galaxies strongly transformed by their environment?

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