Compact stellar systems around NGC 1399

Firth, P.; Drinkwater, Michael J.; Evstigneeva, E. A.; Gregg, Michael D.; Karick, A. M.; Jones, Bryn; Phillipps, S.

doi:10.1111/j.1365-2966.2007.12474.x

Cited by 38 publications

(52 citation statements)

References 49 publications

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“…The provided errors on R eff and n are those given by GALFIT, which should be taken with caution because close to the resolution limit these errors might be underestimated. The alternative object names from the literature are from the following sources: for UCDx Firth et al (2007), X − xxx Mieske et al (2002Mieske et al ( , 2004, Yxxx references Richtler et al (2008). Some of these objects were also presented in Richtler et al (2005) with the following names: (a) Notes.…”

Section: Surface Brightness Analysismentioning

confidence: 99%

“…We compiled a sample of 313 UCDs and GCs in the Fornax cluster with stellar masses above M = 10 6 M (Firth et al 2007;Mieske et al 2002Mieske et al , 2004Dirsch et al 2004;Richtler et al 2008;Schuberth et al 2010), which all are confirmed Fornax members according to their radial velocities. To determine their stellar masses consistently for the full sample, we used their V-band magnitudes and (V − I) colors and calculated their V-band massto-light ratios from the simple stellar population models (SSP) of Maraston (2005).…”

Section: Surface Brightness Analysismentioning

confidence: 99%

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Globular cluster clustering and tidal features around ultra-compact dwarf galaxies in the halo of NGC 1399

Voggel¹,

Hilker²,

Richtler³

2016

A&A

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We present a novel approach to constrain the formation channels of ultra-compact dwarf galaxies (UCDs). They most probably are an inhomogeneous class of objects, composed of remnants of tidally stripped dwarf elliptical galaxies and star clusters that occupy the high mass end of the globular cluster luminosity function. We use three methods to unravel their nature: 1) we analyzed their surface brightness profiles; 2) we carried out a direct search for tidal features around UCDs; and 3) we compared the spatial distribution of GCs and UCDs in the halo of their host galaxy. Based on FORS2 observations under excellent seeing conditions, we studied the detailed structural composition of a large sample of 97 UCDs in the halo of NGC 1399, the central galaxy of the Fornax cluster, by analyzing their surface brightness profiles. We found that 13 of the UCDs were resolved above the resolution limit of 23 pc and we derived their structural parameters fitting a single Sérsic function. When decomposing their profiles into composite King and Sérsic profiles, we find evidence for faint stellar envelopes at µ =∼ 26 mag arcsec −2 , surrounding the UCDs up to an extension of 90 pc in radius. We also show new evidence for faint asymmetric structures and tidal tail-like features surrounding several of these UCDs, a possible tracer of their origin and assembly history within their host galaxy halos. In particular, we present evidence for the first discovery of a significant tidal tail with an extension of ∼350 pc around UCD-FORS 2. Finally, we studied the local overdensities in the spatial distribution of globular clusters within the halo of NGC 1399 out to 110 kpc to see if they are related to the positions of the UCDs. We found a local overabundance of globular clusters on a scale of ≤1 kpc around UCDs, when we compared it to the distribution of globulars from the host galaxy. This effect is strongest for the metal-poor blue GCs. We discuss how likely it is that these clustered globulars were originally associated with the UCD, either as globular cluster systems of a nucleated dwarf galaxy that was stripped down to its nucleus, or as a surviving member of a merged super star cluster complex.

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Section: Surface Brightness Analysismentioning

confidence: 99%

Section: Surface Brightness Analysismentioning

confidence: 99%

Globular cluster clustering and tidal features around ultra-compact dwarf galaxies in the halo of NGC 1399

Voggel¹,

Hilker²,

Richtler³

2016

A&A

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“…Hilker et al 1999;Drinkwater et al 2000Drinkwater et al , 2003Phillipps et al 2001;Mieske et al 2004Mieske et al , 2007Mieske et al , 2009Haşegan et al 2005;Jones et al 2006;Firth et al 2007;Gregg et al 2009;Price et al 2009;Chiboucas et al 2010;Madrid et al 2010). Recently, UCDs have also been identified in several group environments (e.g.…”

Section: Introductionmentioning

confidence: 99%

A large population of ultra-compact dwarf galaxies in the Hydra I cluster

Misgeld

Mieske

Hilker

et al. 2011

A&A

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Aims. We performed a large spectroscopic survey of compact, unresolved objects in the core of the Hydra I galaxy cluster (Abell 1060), with the aim of identifying ultra-compact dwarf galaxies (UCDs) and investigating the properties of the globular cluster (GC) system around the central cD galaxy NGC 3311. Methods. We obtained VIMOS medium-resolution spectra of about 1200 candidate objects with apparent magnitudes 18.5 < V < 24.0 mag, covering both the bright end of the GC luminosity function and the luminosity range of all known UCDs. Results. By means of spectroscopic redshift measurements, we identified 118 cluster members, from which 52 are brighter than M V = −11.0 mag, and can therefore be termed UCDs. The brightest UCD in our sample has an absolute magnitude of M V = −13.4 mag (corresponding to a mass of 5 × 10 7 M ) and a half-light radius of 25 pc. This places it among the brightest and most massive UCDs ever discovered. Most of the GCs/UCDs are both spatially and dynamically associated to the central cD galaxy. The overall velocity dispersion of the GCs/UCDs is comparable to what is found for the cluster galaxies. However, when splitting the sample into a bright and a faint part, we observe a lower velocity dispersion for the bright UCDs/GCs than for the fainter objects. At a dividing magnitude of M V = −10.75 mag, the dispersions differ by more than 200 km s −1 and up to 300 km s −1 for objects within 5 around NGC 3311. Conclusions. We interpret these results in the context of different UCD formation channels, and conclude that interaction-driven formation seems to play an important role in the centre of Hydra I.

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“…In spite of the lack of such very bright UCDs, there is now a total of eight confirmed UCDs with M V < −12 mag in Centaurus (this paper, Mieske et al 2007), comparable to the numbers in Virgo/Fornax (Jones et al 2006;Firth et al 2007). Seven of those eight sources belong to the main cluster Cen30.…”

Section: Resultsmentioning

confidence: 95%

“…A new class of compact stellar systems called "ultra-compact dwarf galaxies" (UCDs, Phillipps et al 2001) has been established (Hilker et al 1999;Drinkwater et al 2000Drinkwater et al , 2003Hasegan et al 2005;Jones et al 2006;Mieske et al 2007;Firth et al 2007;Misgeld et al 2008). UCDs are characterised by typical luminosities of −13.5 < M V < −11.0 mag, half-light radii of 10 < r h < 100 pc, and masses of 2 × 10 6 < m < 10 8 M .…”

Section: Introductionmentioning

confidence: 99%

A search for massive ultra-compact dwarf galaxies in the Centaurus galaxy cluster

Mieske¹,

Hilker

Misgeld

et al. 2009

A&A

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Context. In a previous paper, we initiated a search for ultra-compact dwarf galaxies (UCDs) in the Centaurus galaxy cluster, resulting in the discovery of 27 compact objects with −12.2 < M V < −10.9 mag. Our overall survey completeness was 15-20% within 120 kpc projected clustercentric distance. Aims. To constrain the luminosity distribution of the brightest UCDs in Centaurus in a more accurate way, we continue our search by improving substantially our survey completeness specifically for brightnesses of M V < −12 mag (V 0 < 21.3 mag). Methods. Using VIMOS at the VLT, we obtained low resolution spectra of 400 compact objects with 19.3 < V 0 < 21.3 mag (−14 < M V < −12 mag at the Centaurus distance) in the central 25 of the Centaurus cluster, which corresponds to a projected radius of ∼150 kpc. Our survey had complete area coverage within a radius of ∼120 kpc. Results. For 94% of the sources included in the masks, we measure successfully a redshift. Because of incompleteness in the slit assignment, our final completeness in the area surveyed is 52%. Among our targets, we find three new UCDs in the magnitude range −12.2 < M V < −12 mag, hence at the faint limit of our survey. For one of these targets HST WFPC2 imaging is available, yielding a size estimate of r h < ∼ 8−9 pc. At 95% confidence, we can reject the hypothesis that in the area surveyed there are more than 2 massive UCDs with M V < −12.2 mag and r eff < ∼ 70 pc. Hence our survey confirms the extreme rarity of massive UCDs. We find that the radial distributions of Centaurus and Fornax UCDs with respect to their host clusters' centres agree within the 2σ level.

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Compact stellar systems around NGC 1399

Cited by 38 publications

References 49 publications

Globular cluster clustering and tidal features around ultra-compact dwarf galaxies in the halo of NGC 1399

Globular cluster clustering and tidal features around ultra-compact dwarf galaxies in the halo of NGC 1399

A large population of ultra-compact dwarf galaxies in the Hydra I cluster

A search for massive ultra-compact dwarf galaxies in the Centaurus galaxy cluster

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