Globular cluster systems in fossil groups: NGC 6482, NGC 1132, and ESO 306-017

Álamo-Martínez, Karla; West, Michael J.; Blakeslee, John P.; González-Lópezlira, Rosa A.; Jordán, Andrés; Gregg, Michael D.; Côté, Patrick; Drinkwater, Michael J.; Bergh, Sidney van den

doi:10.1051/0004-6361/201219285

Cited by 18 publications

(18 citation statements)

References 92 publications

(114 reference statements)

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“…This result is consistent with the general picture of the GC system being spatially more extended than the host galaxy (Harris 1991;Harris et al 2000;Forbes et al 2006;Alamo-Martínez et al 2012;Kartha et al 2014).…”

Section: Surface Density Profilessupporting

confidence: 91%

VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems

Cantiello¹,

Capaccioli

Napolitano

et al. 2015

A&A

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We present a study of globular clusters (GCs) and other small stellar systems (SSSs) in the field of NGC 3115, observed as part of the ongoing wide-field imaging survey VEGAS, carried out with the 2.6 m VST telescope. We used deep g and i observations of NGC 3115, a well-studied lenticular galaxy that is covered excellently well in the scientific literature. This is fundamental to test the methodologies, verify the results, and probe the capabilities of the VEGAS-SSS. Leveraging the large field of view of the VST allowed us to accurately study the distribution and properties of SSSs as a function of galactocentric distance, well beyond ∼20 galaxy effective radii, in a way that is rarely possible. Our analysis of colors, magnitudes, and sizes of SSS candidates confirms the results from existing studies, some of which were carried out with 8-10 m class telescopes, and further extends them to previously unreached galactocentric distances with similar accuracy. In particular, we find a color bimodality for the GC population and a de Vaucouleurs r 1/4 profile for the surface density of GCs similar to the galaxy light profile. The radial color gradient of blue and red GCs previously found, for instance, by the SLUGGS survey with Subaru and Keck data, is further extended out to the largest galactocentric radii inspected, ∼65 kpc. In addition, the surface density profiles of blue and red GCs taken separately are well approximated by a r 1/4 density profile, with the fraction of blue GCs being slightly larger at larger radii. We do not find hints of a trend for the red GC subpopulation and for the GC turnover magnitude to vary with radius, but we observe a ∼0.2 mag difference in the turnover magnitude of the blue and red GC subpopulations. Finally, from inspecting SSS sizes and colors, we obtain a list of ultracompact dwarf galaxies and GC candidates suitable for future spectroscopic follow-up. In conclusion, our study shows i) the reliability of the methodologies developed to study SSSs in the field of bright early-type galaxies; and ii) the great potential of the VEGAS survey to produce original results on SSSs science, mainly thanks to the wide-field imaging adopted.

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Section: Surface Density Profilessupporting

confidence: 91%

VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems

Cantiello¹,

Capaccioli

Napolitano

et al. 2015

A&A

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“…Its Sérsic n = 2.82 ± 0.03 -the light concentration parameter -is rather small for such a giant elliptical galaxy, given that a Sérsic n = 4 represents the typical de Vaucouleurs profile. In particular it is smaller than reported by Alamo-Martínez et al (2012) who find values of ∼3.9 in gand z-band. However, smaller values of n for fossil group central galaxies were already reported by the FOGO collaboration (Aguerri et al 2011;Méndez-Abreu et al 2012), who obtain a mean Sérsic index of n ∼ 3 for a sample of 21 FGs.…”

Section: The Brightest Group Galaxy Ngc 6482contrasting

confidence: 74%

“…Such a red color was also found for NGC 6482 by Alamo-Martínez et al (2012) (g−z = 1.85 at r 50 ). Another finding of our study is the relatively low Sérsic index of n ∼ 2.82 for NGC 6482, in agreement with the studies of the FOGO group, who find Sérsic indices around n ∼ 3 for FGs (Aguerri et al 2011;Méndez-Abreu et al 2012).…”

Section: Brightest Group Galaxysupporting

confidence: 72%

“…Bender (1988) and Khochfar & Burkert (2005) find that disky isophotes of giant elliptical galaxies are the result of wet, gas-rich mergers, i.e., mergers with participation of spiral or irregular galaxies. We clearly see disky isophotes in the BGG (a 4 /a ∼ 0.05) and Alamo-Martínez et al (2012) identify a dust lane in their HST images of NGC 6482 -favoring the merger scenario of our FG as originally claimed by Ponman et al (1994). But that does not necessarily disfavor the "failed group" scenario of Mulchaey & Zabludoff (1999).…”

Section: Brightest Group Galaxysupporting

confidence: 57%

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A normal abundance of faint satellites in the fossil group NGC 6482

Lieder¹,

Mieske²,

Sánchéz-Janssen³

et al. 2013

A&A

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A fossil group is considered the end product in a galaxy group's evolution. It is a massive central galaxy that dominates the luminosity budget of the group, and is the outcome of efficient merging between intermediate-luminosity members. Little is known, however, about the faint satellite systems of fossil groups. Here we present a Subaru/Suprime-Cam wide-field, deep imaging study in the B− and R−bands of the nearest fossil group NGC 6482 (M tot ∼ 4 × 10 12 M ), covering the virial radius out to 310 kpc. We performed detailed completeness estimations and selected group member candidates by a combination of automated object detection and visual inspection. A fiducial sample of 48 member candidates down to M R ∼ −10.5 mag is detected, making this study the deepest of a fossil group to now. We investigate the photometric scaling relations, the color-magnitude relation, and the luminosity function of our galaxy sample. We find evidence of recent and ongoing merger events among bright group galaxies. The color-magnitude relation is comparable to that of nearby galaxy clusters, and it exhibits significant scatter at the faintest luminosities. The completeness-corrected luminosity function is dominated by early-type dwarfs and is characterized by a faint end slope α = −1.32 ± 0.05. We conclude that the NGC 6482 fossil group shows photometric properties consistent with those of regular galaxy clusters and groups, including a normal abundance of faint satellites.

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“…which gives a good analytical description of the completeness, and which has been used for many GC studies (e.g., McLaughlin et al 1994;Fleming et al 1995;Wehner et al 2008;Alamo-Martínez et al 2012). The free parameters α and m 50 indicate the speed at which the detection rate falls at the faint level and the 50% completeness, respectively.…”

Section: Photometry Completenessmentioning

confidence: 99%

Isolated ellipticals and their globular cluster systems

Salinas

Alabi

Richtler

2015

A&A

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As tracers of star formation, galaxy assembly, and mass distribution, globular clusters have provided important clues to our understanding of early-type galaxies. But their study has been mostly constrained to galaxy groups and clusters where early-type galaxies dominate, leaving the properties of the globular cluster systems (GCSs) of isolated ellipticals as a mostly uncharted territory. We present Gemini-South/GMOS g i observations of five isolated elliptical galaxies: NGC 3962, NGC 2865, IC 4889, NGC 2271, and NGC 4240. Photometry of their GCSs reveals clear color bimodality in three of them, but remains inconclusive for the other two. All the studied GCSs are rather poor with a mean specific frequency S N ∼ 1.5, independently of the parent galaxy luminosity. Considering information from previous work as well, it is clear that bimodality and especially the presence of a significant, even dominant, population of blue clusters occurs at even the most isolated systems, which casts doubts on a possible accreted origin of metal-poor clusters, as suggested by some models. Additionally, we discuss the possible existence of ultra-compact dwarfs around the isolated elliptical NGC 3962.

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Globular cluster systems in fossil groups: NGC 6482, NGC 1132, and ESO 306-017

Cited by 18 publications

References 92 publications

VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems

VEGAS-SSS. A VST early-type galaxy survey: analysis of small stellar systems

A normal abundance of faint satellites in the fossil group NGC 6482

Isolated ellipticals and their globular cluster systems

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