Globular Clusters as Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474

Lim, Sungsoon; Peng, Eric W.; Duc, Pierre–Alain; Fensch, Jérémy; Durrell, Patrick R.; Harris, William E.; Cuillandre, Jean-Charles; Gwyn, Stephen; Lançon, A.; Sánchéz-Janssen, R.

doi:10.3847/1538-4357/835/2/123

Cited by 31 publications

(27 citation statements)

References 45 publications

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“…Using the galaxy mass-metallicity relation from Gallazzi et al (2005), the outer shell's mass-weighted metallicity of [Z/H]= −0.03 dex suggests that the disrupted galaxy had a stellar mass of log(M * /M ) ≥ 9.6. This estimate agrees well with the conclusion made by Lim et al (2017) that the disrupted galaxy is overmassive for a dwarf galaxy but still sub-L * . Kim et al (2012), using Spitzer imaging, already reported that the shells in NGC 474 are ∼6 − 10 percent as luminous as the underlying galaxy light (see their Table 4).…”

Section: Discussionsupporting

confidence: 91%

NGC 474 as viewed with KCWI: diagnosing a shell galaxy

Alabi

Ferré-Mateu

Forbes

et al. 2020

Monthly Notices of the Royal Astronomical Society

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Abstract We present new spectra obtained using Keck/KCWI and perform kinematics and stellar population analyses of the shell galaxy NGC 474, from both the galaxy centre and a region from the outer shell. We show that both regions have similarly extended star formation histories although with different stellar population properties. The central region of NGC 474 is dominated by intermediate-aged stars (8.3 ± 0.3 Gyr) with subsolar metallicity ([Z/H]=−0.24 ± 0.07 dex) while the observed shell region, which hosts a substantial population of younger stars, has a mean luminosity-weighted age of 4.0 ± 0.5 Gyr with solar metallicities ([Z/H]=−0.03 ± 0.09 dex). Our results are consistent with a scenario in which NGC 474 experienced a major to intermediate merger with a log$(M_*/\rm M_\odot )\mathord {\sim }10$ mass satellite galaxy at least $\mathord {\sim }2$ Gyr ago which produced its shell system. This work shows that the direct spectroscopic study of low-surface brightness stellar features, such as shells, is now feasible and opens up a new window to understanding galaxy formation and evolution.

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Section: Discussionsupporting

confidence: 91%

NGC 474 as viewed with KCWI: diagnosing a shell galaxy

Alabi

Ferré-Mateu

Forbes

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…The number of galaxies that were counted in in these histograms and the total number of galaxies in the sample are noted in the corners. some collisional features for one system is presented in Lim et al (2017) and Fensch et al 2020 (submitted ). In principle, it will be possible to estimate the dynamical mass of the galaxies in our sample from the number of their GCs (e.g., Harris et al 2015;Forbes et al 2018) or kinematics (e.g., Samurović 2014;Bílek et al 2019b) after measuring the radial velocities of the GCs.…”

Section: The Matlas Surveymentioning

confidence: 99%

Census and classification of low-surface-brightness structures in nearby early-type galaxies from the MATLAS survey

Bílek

Duc

Cuillandre

et al. 2020

Monthly Notices of the Royal Astronomical Society

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The morphology of galaxies gives essential constraints on the models of galaxy evolution. The morphology of the features in the low-surface-brightness regions of galaxies has not been fully explored yet because of observational difficulties. Here we present the results of our visual inspections of very deep images of a large volume-limited sample of 177 nearby massive early-type galaxies (ETGs) from the MATLAS survey. The images reach a surface-brightness limit of 28.5 − 29 mag arcsec−2 in the g′ band. Using a dedicated navigation tool and questionnaire, we looked for structures at the outskirts of the galaxies such as tidal shells, streams, tails, disturbed outer isophotes or peripheral star-forming disks, and simultaneously noted the presence of contaminating sources, such as Galactic cirrus. We also inspected internal sub-structures such as bars and dust lanes. We discuss the reliability of this visual classification investigating the variety of answers made by the participants. We present the incidence of these structures and the trends of the incidence with the mass of the host galaxy and the density of its environment. We find an incidence of shells, stream and tails of approximately 15%, about the same for each category. For galaxies with masses over 1011 M⊙, the incidence of shells and streams increases about 1.7 times. We also note a strong unexpected anticorrelation of the incidence of Galactic cirrus with the environment density of the target galaxy. Correlations with other properties of the galaxies, and comparisons to model predictions, will be presented in future papers.

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“…Keller et al 2012), and in external galaxies (e.g. Whitmore et al 1993;Lim et al 2017). Violent galaxy interactions such as major mergers are known to leave morphological signatures for as long as a few Gyr (∼ 2-3 Gyr for a major merger; e.g.…”

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confidence: 99%

The Next Generation Virgo Cluster Survey (NGVS). XXXII. A Search for Globular Cluster Substructures in the Virgo Galaxy Cluster Core

Powalka¹,

Puzia

Lançon³

et al. 2018

ApJ

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Substructure in globular cluster (GC) populations around large galaxies is expected in galaxy formation scenarios that involve accretion or merger events, and it has been searched for using direct associations between GCs and structure in the diffuse galaxy light, or with GC kinematics. Here, we present a search for candidate substructures in the GC population around the Virgo cD galaxy M87 through the analysis of the spatial distribution of the GC colors. The study is based on a sample of ∼ 1800 bright GCs with high-quality u, g, r, i, z, K s photometry, selected to ensure a low contamination by foreground stars or background galaxies. The spectral energy distributions of the GCs are associated with formal estimates of age and metallicity, which are representative of its position in a 4-D color-space relative to standard single stellar population models. Dividing the sample into broad bins based on the relative formal ages, we observe inhomogeneities which reveal signatures of GC substructures. The most significant of these is a spatial overdensity of GCs with relatively young age labels, of diameter ∼ 0.1 deg (∼ 30 kpc), located to the south of M87. The significance of this detection is larger than about 5σ after accounting for estimates of random and systematic errors. Surprisingly, no large Virgo galaxy is present in this area, that could potentially host these GCs. But candidate substructures in the M87 halo with equally elusive hosts have been described based on kinematic studies in the past. The number of GC spectra available around M87 is currently insufficient to clarify the nature of the new candidate substructure.

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Globular Clusters as Tracers of Fine Structure in the Dramatic Shell Galaxy NGC 474

Cited by 31 publications

References 45 publications

NGC 474 as viewed with KCWI: diagnosing a shell galaxy

NGC 474 as viewed with KCWI: diagnosing a shell galaxy

Census and classification of low-surface-brightness structures in nearby early-type galaxies from the MATLAS survey

The Next Generation Virgo Cluster Survey (NGVS). XXXII. A Search for Globular Cluster Substructures in the Virgo Galaxy Cluster Core

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