Globular clusters of NGC 3115 in the near-infrared

Cantiello, M.; Blakeslee, John P.; Raimondo, Gabriella; Chies-Santos, Ana L.; Jennings, Zachary G.; Norris, Mark A.; Küntschner, H.

doi:10.1051/0004-6361/201323272

Cited by 32 publications

(36 citation statements)

References 37 publications

(43 reference statements)

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“…The GCs of NGC3115 show a clear separation between metal-poor and rich GCs, yet GCs still lie along with our models. As suggested by Cantiello et al (2014), several metal-rich GCs in NGC3115 prefer the younger-age model (cyan lines), which explains the presence of a group of metal-rich GCs with small offsets from models. In the same vein, the metal-rich GCs in NGC4494 can be also explained by younger-age stellar populations (Foster et al 2011).…”

Section: Comparison With Observationsmentioning

confidence: 63%

Nonlinear Color–metallicity Relations of Globular Clusters. Vi. On Calcium Ii Triplet Based Metallicities of Globular Clusters in Early-Type Galaxies

Chung

Yoon²,

Lee

et al. 2016

ApJ

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The metallicity distribution function of globular clusters (GCs) in galaxies is a key to understanding galactic formation and evolution. The calcium II triplet (CaT) index has recently become a popular metal abundance indicator thanks to its sensitivity to GC metallicity. Here we revisit and assess the reliability of CaT as a metallicity indicator using our new stellar population synthesis simulations based on empirical high-resolution fluxes. The model shows that the CaT strength of old (>10 Gyr) GCs is proportional to [Fe/H] below −0.5. In the modest metal-rich regime, however, CaT does not increase anymore with [Fe/H] due to the little contribution from coolest red giant stars to the CaT absorption. The nonlinear nature of the color-CaT relation is confirmed by the observations of GCs in nearby early-type galaxies. This indicates that the CaT should be used carefully when deriving metallicities of metal-rich stellar populations. Our results offer an explanation for the observed sharp difference between the color and CaT distributions of GCs in the same galaxies. We take this as an analogy to the view that metallicity-color and metallicity-Lick index nonlinearity of GCs is primarily responsible for their observed "bimodal" distributions of colors and absorption indices.

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Section: Comparison With Observationsmentioning

confidence: 63%

Nonlinear Color–metallicity Relations of Globular Clusters. Vi. On Calcium Ii Triplet Based Metallicities of Globular Clusters in Early-Type Galaxies

Chung

Yoon²,

Lee

et al. 2016

ApJ

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“…Because of its proximity, the galaxy and its satellites were targeted by many photometric and spectroscopic studies (Hanes & Harris 1986;Capaccioli et al 1987;Kundu & Whitmore 1998;Puzia et al 2000Puzia et al , 2002Norris et al 2006;Arnold et al 2011;Usher et al 2012). Moreover, we recall that the GC system of the galaxy is the first system beyond the Local Group with a confirmed bimodal metallicity distribution, as shown by Brodie et al (2012) from calcium triplet analysis and by Cantiello et al (2014) using optical to near-IR photometry (see also Blakeslee et al 2010;Yoon et al 2011). The paper is organized as follows: the next section briefly describes the observations and data reduction procedures.…”

Section: Introductionmentioning

confidence: 68%

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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“…In many galaxies, a long-standing empirical feature of the MDF is its bimodal nature, with a canonical metal-poor (MP) "blue" sequence centered near [ ]  á ñ -Fe H 1.5 and a metal-rich (MR) "red" sequence near [ ]  á ñ -Fe H 0.5. Many authors have adopted the view that this two-part structure of the MDF is evidence of two major and perhaps distinct starforming epochs in the formation histories of large galaxies, a view that has persisted for many years (e.g., Zepf & Ashman 1993;Forbes et al 1997Forbes et al , 2011Arnold et al 2011;Blom et al 2012b;Brodie et al 2014;Cantiello et al 2014;Kartha et al 2016, among many others). However, bimodal MDFs are not characteristic of the field-halo stars in their parent galaxies, in the few cases where it has been possible to directly compare the GCs and halo stars in the same galaxy (e.g., Harris et al 2007;Durrell et al 2010;Rejkuba et al 2011Rejkuba et al , 2014Monachesi et al 2016).…”

Section: Metallicity and Color Distributionsmentioning

confidence: 99%

“…The extensive literature that reveals clearly bimodal CDFs for many galaxies therefore continues to be important (e.g., Geisler et al 1996;Neilsen & Tsvetanov 1999;Kundu & Whitmore 2001;Larsen et al 2001;Rhode & Zepf 2004;Bassino et al 2006;Peng et al 2006;Harris 2009aHarris , 2009bFaifer et al 2011;Cantiello et al 2014;Jennings et al 2014;Kartha et al 2014, among many others). At the same time, some galaxies are better described as trimodal, unimodal, or simply broad without matching a simple Gaussian-type model (for specific examples, see Larsen et al 2001Larsen et al , 2005Peng et al 2006;Kundu & Zepf 2007;Blom et al 2012b;Usher et al 2012).…”

Section: Metallicity and Color Distributionsmentioning

confidence: 99%

Globular Cluster Systems in Brightest Cluster Galaxies. Iii. Beyond Bimodality

Harris

Ciccone

Eadie

et al. 2017

ApJ

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We present new deep photometry of the rich globular cluster (GC) systems around the Brightest Cluster Galaxies UGC 9799 (Abell 2052) and UGC 10143 (Abell 2147), obtained with the Hubble Space Telescope (HST) ACS and WFC3 cameras. For comparison, we also present new reductions of similar HST/ACS data for the Coma supergiants NGC 4874 and 4889. All four of these galaxies have huge cluster populations (to the radial limits of our data, comprising from 12,000 to 23,000 clusters per galaxy). The metallicity distribution functions (MDFs) of the GCs can still be matched by a bimodal-Gaussian form where the metal-rich and metalpoor modes are separated by 0.8 dex, but the internal dispersions of each mode are so large that the total MDF becomes very broad and nearly continuous from [Fe/H];−2.4 to solar. There are, however, significant differences between galaxies in the relative numbers of metal-rich clusters, suggesting that they underwent significantly different histories of mergers with massive gas-rich halos. Last, the proportion of metal-poor GCs rises especially rapidly outside projected radii  R R 4 eff , suggesting the importance of accreted dwarf satellites in the outer halo. Comprehensive models for the formation of GCs as part of the hierarchical formation of their parent galaxies will be needed to trace the systematic change in structure of the MDF with galaxy mass, from the distinctly bimodal form in smaller galaxies up to the broad continuum that we see in the very largest systems.

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Globular clusters of NGC 3115 in the near-infrared

Cited by 32 publications

References 37 publications

Nonlinear Color–metallicity Relations of Globular Clusters. Vi. On Calcium Ii Triplet Based Metallicities of Globular Clusters in Early-Type Galaxies

Nonlinear Color–metallicity Relations of Globular Clusters. Vi. On Calcium Ii Triplet Based Metallicities of Globular Clusters in Early-Type Galaxies

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

Globular Cluster Systems in Brightest Cluster Galaxies. Iii. Beyond Bimodality

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