The SLUGGS survey★: the globular cluster systems of three early-type galaxies using wide-field imaging

Kartha, Sreeja S.; Forbes, Duncan A.; Spitler, Lee R.; Romanowsky, Aaron J.; Arnold, Jacob A.; Brodie, Jean P.

doi:10.1093/mnras/stt1880

Cited by 77 publications

(149 citation statements)

References 95 publications

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“…Considering a similar mass range, the opposite trend is seen for the Virgo GCSs (already discussed by Peng et al 2008). IEs with log M > 11.4 show a diverse behavior, while NGC 3962 follows the trend of less massive galaxies, NGC 720 (S N = 3 ± 0.2, Kartha et al 2014) and NGC 7796 (S N = 2.5 ± 0.5, Richtler et al 2015) show an increased S N , although still lower than Virgo ellipticals of similar mass.…”

Section: Specific Frequency Of Clusters In Low-and High-density Envirmentioning

confidence: 63%

“…Figure 6 (upper panel) contains a comparison between our results with the sample of Cho et al (2012) of ten low-density early-type galaxies and galaxies from the ACS Virgo Cluster Survey (ACSVCS, Peng et al 2008). Additionally, we include the S N of five more isolated or low-density ellipticals, NGC 3585, NGC 5812 (Lane et al 2013), NGC 7507 (Caso et al 2013), NGC 720 (Kartha et al 2014) and NGC 7796 (Richtler et al 2015). Figure 6 (upper left panel) presents S N as a function of stellar mass.…”

Section: Specific Frequency Of Clusters In Low-and High-density Envirmentioning

confidence: 99%

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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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Section: Specific Frequency Of Clusters In Low-and High-density Envirmentioning

confidence: 63%

Section: Specific Frequency Of Clusters In Low-and High-density Envirmentioning

confidence: 99%

Isolated ellipticals and their globular cluster systems

Salinas

Alabi

Richtler

2015

A&A

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“…Dirsch, Schuberth & Richtler 2005;Hargis & Rhode 2014), while others have more decoupled components (e.g. Strader et al 2011;Kartha et al 2014). Moreover, in a number of nearby ETGs the kinematics of bGCs have been found to be significantly distinct from those of the stellar component and the rGCs (e.g.…”

Section: What Is the Origin Of Gc Metallicity Bimodality?mentioning

confidence: 99%

“…Strader et al 2005;. In general, rGCs seem to be linked with the host galaxy bulge's stellar population, having similar spatial distribution, kinematics and metallicity, while bGCs seem to share several properties with the galaxy halo component (e.g., Faifer et al 2011;Strader et al 2011;Arnold et al 2011;Forbes et al 2011;Forbes, Ponman & O'Sullivan 2012;Pota et al 2013;Peacock et al 2015;Kartha et al 2014;Pota et al 2015).…”

Section: Introductionmentioning

confidence: 99%

The SLUGGS survey: combining stellar and globular cluster metallicities in the outer regions of early-type galaxies

Pastorello

Forbes

Usher

et al. 2015

Monthly Notices of the Royal Astronomical Society

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The outer halo regions of early-type galaxies carry key information about their past accretion history. However, spectroscopically probing the stellar component at such galactocentric radii is still challenging. Using Keck/DEIMOS, we have been able to measure the metallicities of the stellar and globular cluster components in 12 early-type galaxies out to more than 10 R e . We find similar metallicity gradients for the metalpoor and metal-rich globular cluster subpopulations, suggesting a common formation process for the two subpopulations. This is in conflict with most current theoretical predictions, where the metal-poor globular clusters are thought to be purely accreted and metal-rich globular clusters mostly formed in-situ. Moreover, we find that the globular cluster metallicity gradients show a trend with galaxy mass, being steeper in lower-mass galaxies than in higher-mass galaxies. This is similar to what we find for the outermost galaxy stars and suggests a more active accretion history, with a larger role played by major mergers, in the most massive galaxies. This conclusion is qualitatively consistent with expectations from two-phase galaxy assembly models. Finally, we find that the small difference in metallicity between galaxy stars and metal-rich globular clusters at 1 R e may correlate with galaxy mass. The origin of this difference is not currently clear.

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“…In the last decade, Hubble Space Telescope (HST) and ground-based wide-field imaging of hundreds of GC systems has provided us with very detailed information on bimodality (e.g. Dirsch et al 2003;Bassino et al 2006;Peng et al 2006;Harris et al 2006Harris et al , 2013Forbes et al 2011;Kartha et al 2014).…”

Section: Colour Magnitude Relation Of Extragalactic Globular Clustersmentioning

confidence: 99%

The colour–magnitude relation of globular clusters in Centaurus and Hydra

Fensch

Mieske

Müller-Seidlitz

et al. 2014

A&A

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Aims. We investigate the colour-magnitude relation of metal-poor globular clusters, the so-called blue tilt, in the Hydra and Centaurus galaxy clusters and constrain the primordial conditions for star cluster self-enrichment. Methods. We analyse U, I photometry for about 2500 globular clusters in the central regions of Hydra and Centaurus, based on VLT/FORS1 data. We measure the relation between mean colour and luminosity for the blue and red subpopulation of the globular cluster samples. We convert these relations into mass-metallicity space and compare the obtained GC mass-metallicity relation with predictions from the star cluster self-enrichment model by Bailin & Harris (2009, ApJ, 695, 1082. For this we include effects of dynamical and stellar evolution and a physically well motivated primordial mass-radius scaling. Results. We obtain a mass-metallicity scaling of Z ∝ M 0.27 ± 0.05 for Centaurus GCs and Z ∝ M 0.40 ± 0.06 for Hydra GCs, consistent with the range of observed relations in other environments. We find that the GC mass-metallicity relation already sets in at present-day masses of a few 10 5 M and is well established in the luminosity range of massive MW clusters like ω Centauri. The inclusion of a primordial mass-radius scaling of star clusters significantly improves the fit of the self-enrichment model to the data. The selfenrichment model accurately reproduces the observed relations for average primordial half-light radii r h ∼ 1−1.5 pc, star formation efficiencies f ∼ 0.3−0.4, and pre-enrichment levels of [Fe/H] − 1.7 dex. The slightly steeper blue tilt for Hydra can be explained either by a ∼30% smaller average r h at fixed f ∼ 0.3, or analogously by a ∼20% smaller f at fixed r h ∼ 1.5 pc. Within the selfenrichment scenario, the observed blue tilt implies a correlation between GC mass and width of the stellar metallicity distribution. We find that this implied correlation matches the trend of width with GC mass measured in Galactic GCs, including extreme cases like ω Centauri and M 54. Conclusions. First, we found that a primordial star cluster mass-radius relation provides a significant improvement to the selfenrichment model fits. Second we show that broadened metallicity distributions as found in some massive MW globular clusters may have arisen naturally from self-enrichment processes, without the need of a dwarf galaxy progenitor.

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The SLUGGS survey★: the globular cluster systems of three early-type galaxies using wide-field imaging

Cited by 77 publications

References 95 publications

Isolated ellipticals and their globular cluster systems

Isolated ellipticals and their globular cluster systems

The SLUGGS survey: combining stellar and globular cluster metallicities in the outer regions of early-type galaxies

The colour–magnitude relation of globular clusters in Centaurus and Hydra

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