THE SLUGGS SURVEY:<i>HST</i>/ACS MOSAIC IMAGING OF THE NGC 3115 GLOBULAR CLUSTER SYSTEM

Jennings, Zachary G.; Strader, Jay; Romanowsky, Aaron J.; Brodie, Jean P.; Arnold, Jacob A.; Lin, Dacheng; Irwin, Jimmy A.; Sivakoff, G. R.; Wong, Ka-Wah

doi:10.1088/0004-6256/148/2/32

Cited by 30 publications

(64 citation statements)

References 83 publications

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“…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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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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“…These colours are obtained from HST /ACS, Subaru/Suprime-Cam and CFHT/MegaCam photometry. As per Jennings et al (2014), we convert Pota et al (2015) colours into total metallicities [Z/H] using equation B1 in Usher et al (2012).…”

Section: 6mentioning

confidence: 99%

“…In the literature there are several massive ETGs for which both the rGCs and bGCs in the inner regions show a significant colour/metallicity gradient, while in the outer regions such gradients flatten (Forte et al 2001;Harris 2009a,b;Forbes et al 2011;Arnold et al 2011;Liu et al 2011;Jennings et al 2014;Hargis & Rhode 2014;Pota et al 2015). While this strongly supports a common in-situ formation for the two GC subpopulations in the inner regions, the metallicities have been obtained from photometric colours.…”

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

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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“…However, the latter procedure affects the shape of slightly extended objects, which makes it unsuitable for the purposes of the present study. obtained with the ACS camera onboard of the Hubble Space Telescope (HST; Jennings et al 2014). The ACS study relies on data with similar wavelength coverage and g-band depth as the data used here.…”

Section: Introductionmentioning

confidence: 99%

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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THE SLUGGS SURVEY:HST/ACS MOSAIC IMAGING OF THE NGC 3115 GLOBULAR CLUSTER SYSTEM

Cited by 30 publications

References 83 publications

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

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

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

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

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