Deep imaging of the shell elliptical galaxy NGC 3923 with MegaCam

Bílek, Michal; Cuillandre, Jean-Charles; Gwyn, Stephen; Ebrová, Ivana; Bartošková, Kateřina; Jungwiert, Bruno; Jílková, Lucie

doi:10.1051/0004-6361/201526608

Cited by 27 publications

(33 citation statements)

References 22 publications

(36 reference statements)

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“…We have identified 23 strong shells in common with [5]. Eleven shells are classified as uncertain, and eight shells from [5] are not detected. No new shells have been detected yet, but analysis is ongoing.…”

Section: Shellsmentioning

confidence: 92%

“…The galaxy subtraction was done using a two-Sersic model with Imfit image-fitting code [23]. We also enhanced the shell edges in the inner regions by applying an erosion filter edge detection algorithm [5]. The results are given in Figure 5.…”

Section: Shellsmentioning

confidence: 99%

“…NGC 3923 is one of the most studied shell galaxies because it has the largest number of detected shells. Different studies have identified between 22 and 42 shells [5,6]. Therefore, new, deeper data will help determine the true number of shells and look for additional shells at larger radii.…”

Section: Introductionmentioning

confidence: 99%

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The Extended Baryonic Halo of NGC 3923

et al. 2017

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Galaxy halos and their globular cluster systems build up over time by the accretion of small satellites. We can learn about this process in detail by observing systems with ongoing accretion events and comparing the data with simulations. Elliptical shell galaxies are systems that are thought to be due to ongoing or recent minor mergers. We present preliminary results of an investigation of the baryonic halo-light profile, globular clusters, and shells/streams-of the shell galaxy NGC 3923 from deep Dark Energy Camera (DECam) g and i-band imaging. We present the 2D and radial distributions of the globular cluster candidates out to a projected radius of about 185 kpc, or ∼ 37R e , making this one of the most extended cluster systems studied. The total number of clusters implies a halo mass of M h ∼ 3 × 10 13 M . Previous studies had identified between 22 and 42 shells, making NGC 3923 the system with the largest number of shells. We identify 23 strong shells and 11 that are uncertain. Future work will measure the halo mass and mass profile from the radial distributions of the shell, N-body models, and line-of-sight velocity distribution (LOSVD) measurements of the shells using the Multi Unit Spectroscopic Explorer (MUSE).

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Section: Shellsmentioning

confidence: 92%

Section: Shellsmentioning

confidence: 99%

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The Extended Baryonic Halo of NGC 3923

et al. 2017

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“…Good examples of type-I systems include NGC 3923 and NGC7600. The former is extensively reviewed by Carter et al (1998) (also see Bílek et al 2016), and a visual replica of the latter has been reproduced via mergers, by Cooper et al (2011), using cosmological simulations.…”

Section: Introductionmentioning

confidence: 99%

The Next Generation Virgo Cluster Survey. Xxii. Shell Feature Early-Type Dwarf Galaxies in the Virgo Cluster*

Paudel

Smith

Duc

et al. 2017

ApJ

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The Next Generation Virgo Cluster Survey is a deep (with a 2σ detection limit μ g =29 mag arcsec −2 in the g-band) optical panchromatic survey targeting the Virgo cluster from its core to virial radius, for a total areal coverage of 104 square degrees. As such, the survey is well suited for the study of galaxies' outskirts, haloes, and low surface brightness features that arise from dynamical interactions within the cluster environment. We report the discovery of extremely faint (μ g >25 mag arcsec−2 ) shells in three Virgo cluster early-type dwarf galaxies: VCC1361, VCC1447, and VCC1668. Among them, VCC1447 has an absolute magnitude M g =−11.71 mag and is the least massive galaxy with a shell system discovered to date. We present a detailed study of these low surface brightness features. We detect between three and four shells in each of our galaxies. Within the uncertainties, we find no evidence of a color difference between the galaxy main body and shell features. The observed arcs of the shells are located up to several effective radii of the galaxies. We further explore the origin of these low surface brightness features with the help of idealized numerical simulations. We find that a near equal mass merger is best able to reproduce the main properties of the shells, including their quite symmetric appearance and their alignment along the major axis of the galaxy. The simulations provide support for a formation scenario in which a recent merger, between two near-equal mass, gas-free dwarf galaxies, forms the observed shell systems.

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“…The shape of the shell, especially in the case of narrow cones, adds useful information that can be then used to tighten the constraints on the initial configuration, relative masses, and velocities (Hernquist & Quinn 1988;Ebrová et al 2012), although significant degeneracies exist. Also, color information and gradients, if seen, might add information relevant for a population synthesis of the shell stars and the system's history (e.g., Sikkema et al 2007;Bílek et al 2016).…”

Section: Introductionmentioning

confidence: 99%

Strong Lensing Analysis of the Galaxy Cluster Macs J1319.9+7003 and the Discovery of a Shell Galaxy

Zitrin

2016

ApJ

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We present a strong-lensing (SL) analysis of the galaxy cluster MACS J1319.9+7003 (z=0.33, also known as Abell 1722), as part of our ongoing effort to analyze massive clusters with archival Hubble Space Telescope (HST) imaging. We spectroscopically measured with Keck/Multi-Object Spectrometer For Infra-Red Exploration (MOSFIRE) two galaxies multiply imaged by the cluster. Our analysis reveals a modest lens, with an effective Einstein radius of q = =   z 2 12 1 e ( ) , enclosing 2.1 0.3 10 13 M e . We briefly discuss the SL properties of the cluster, using two different modeling techniques (see the text for details), and make the mass models publicly available (ftp://wise-ftp.tau.ac.il/pub/adiz/MACS1319/). Independently, we identified a noteworthy, young shell galaxy (SG) system forming around two likely interacting cluster members, 20″ north of the brightest cluster galaxy. SGs are rare in galaxy clusters, and indeed, a simple estimate reveals that they are only expected in roughly one in several dozen, to several hundred, massive galaxy clusters (the estimate can easily change by an order of magnitude within a reasonable range of characteristic values relevant for the calculation). Taking advantage of our lens model best-fit, mass-to-light scaling relation for cluster members, we infer that the total mass of the SG system is~1.3 10 11  M , with a host-to-companion mass ratio of about 10:1. Despite being rare in high density environments, the SG constitutes an example to how stars of cluster galaxies are efficiently redistributed to the intra-cluster medium. Dedicated numerical simulations for the observed shell configuration, perhaps aided by the mass model, might cast interesting light on the interaction history and properties of the two galaxies. An archival HST search in galaxy cluster images can reveal more such systems.

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Deep imaging of the shell elliptical galaxy NGC 3923 with MegaCam

Cited by 27 publications

References 22 publications

The Extended Baryonic Halo of NGC 3923

The Extended Baryonic Halo of NGC 3923

The Next Generation Virgo Cluster Survey. Xxii. Shell Feature Early-Type Dwarf Galaxies in the Virgo Cluster*

Strong Lensing Analysis of the Galaxy Cluster Macs J1319.9+7003 and the Discovery of a Shell Galaxy

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