Ubiquitous signs of interactions in early-type galaxies with prolate rotation

Ebrová, Ivana; Bílek, Michal; Vudragović, A.; Yıldız, Mustafa K.; Duc, Pierre–Alain

doi:10.1051/0004-6361/202140588

Cited by 11 publications

(12 citation statements)

References 122 publications

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“…Concentricity -From numerical simulations, shells are usually formed as concentric structures (e.g., Pop et al 2018;Ebrová et al 2021;Bílek et al 2021), a prediction we can directly test with our observations. To compute the concentricity, we assume that the curved line defining the shell is a circular arc, and we compute its center 18 .…”

Section: Concentricity and Radiimentioning

confidence: 67%

“…Hence, the study of the position of a shell relatively to the center of its primary galaxy is important, as comparisons with simulations can give us hints about the merger that triggered the shells, as well as its age (e.g., Ebrová et al 2021;Bílek et al 2021). Shell radii are useful also for investigating the gravitational fields of galaxies (e.g., Hernquist & Quinn 1987;Bílek et al 2013).…”

Section: Distance Between Shells and The Primary Galaxymentioning

confidence: 99%

“…They have the main advantage of providing the ground truth when interpreting the results. Indeed, it is possible to track the merger trees of LSB hosting galaxies and their 3D information to follow the LSB structures wrapping around galaxies (e.g., Hendel & Johnston 2015;Pop et al 2018;Mancillas et al 2019;Ebrová et al 2021;Bílek et al 2021).…”

Section: Introductionmentioning

confidence: 99%

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Characterization of low surface brightness structures in annotated deep images

Sola

Duc

Richards

et al. 2022

A&A

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Context. The identification and characterization of low surface brightness (LSB) stellar structures around galaxies such as tidal debris of ongoing or past collisions is essential to constrain models of galactic evolution. So far most efforts have focused on the numerical census of samples of varying sizes, either through visual inspection or more recently with deep learning. Detailed analyses including photometry have been carried out for a small number of objects, essentially because of the lack of convenient tools able to precisely characterize tidal structures around large samples of galaxies. Aims. Our goal is to characterize in detail, and in particular obtain quantitative measurements, of LSB structures identified in deep images of samples consisting of hundreds of galaxies. Methods. We developed an online annotation tool that enables contributors to delineate the shapes of diffuse extended stellar structures with precision, as well as artifacts or foreground structures. All parameters are automatically stored in a database which may be queried to retrieve quantitative measurements. We annotated LSB structures around 352 nearby massive galaxies with deep images obtained with the Canada-France-Hawaii Telescope as part of two large programs: Mass Assembly of early-Type GaLAxies with their fine Structures (MATLAS) and Ultraviolet Near Infrared Optical Northern Survey (UNIONS)/Canada-France Imaging Survey (CFIS). Each LSB structure was delineated and labeled according to its likely nature: stellar shells, streams associated with a disrupted satellite, tails that formed in major mergers, ghost reflections, or cirrus. Results. From our database containing 8441 annotations, the area, size, median surface brightness, and distance to the host of 228 structures were computed. The results confirm the fact that tidal structures defined as streams are thinner than tails, as expected by numerical simulations. In addition, tidal tails appear to exhibit a higher surface brightness than streams (by about 1 mag), which may be related to different survival times for the two types of collisional debris. We did not detect any tidal feature fainter than 27.5 mag arcsec −2 , while the nominal surface brightness limits of our surveys range between 28.3 and 29 mag arcsec −2 , a difference that needs to be taken into account when estimating the sensitivity of future surveys to identify LSB structures. Conclusions. We compiled an annotation database of observed LSB structures around nearby massive galaxies including tidal features that may be used for quantitative analysis and as a training set for machine learning algorithms.

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Section: Concentricity and Radiimentioning

confidence: 67%

Section: Distance Between Shells and The Primary Galaxymentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Characterization of low surface brightness structures in annotated deep images

Sola

Duc

Richards

et al. 2022

A&A

Self Cite

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show abstract

“…To gauge the scatter in the abundance and age properties might tell us more about galaxy assembly than measuring grand averages. Spatially resolved galaxy observations would reveal radial profiles in abundance ratios, and these may not be smooth, but may display substructure that could then be used to decipher galaxy histories on an individual basis (Statler 2001;Statler et al 1996;Bender & Surma 1992;Ebrová et al 2021;Omori & Takeuchi 2021;Taylor et al 2019).…”

Section: Discussionmentioning

confidence: 99%

Individual element sensitivity for stellar evolutionary isochrones

Worthey,

Shi,

Pal

et al. 2022

Preprint

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Stellar evolution calculations with variable abundance ratios were used to gauge the effects on temperatures, luminosities, and lifetimes in various phases. Individual elements C, N, O, Mg, Si, and Fe were included. Most of the effect relevant to integrated light models is contained in the temperature variable, as opposed to the timescale or luminosity. We derive a recipe for including abundance-sensitive temperature effects that is applicable to existing isochrone grids. The resultant enhanced isochrones are incorporated into composite stellar population models and compared with galaxy data from the Sloan Digital Sky Survey. A severe oxygen-age degeneracy is apparent, 2 -3 Gyr per 0.1 dex in [O/R], where R represents a heavy element such as Fe. Over the range of early-type galaxy velocity dispersion, the spans of all abundance ratios are reduced but the age range increases, systematically older. Allowing Fe-peak elements the freedom to vary accentuates this increase of age span. Overall, these results sharpen the age-mass correlation known as downsizing but decrease the steepness of abundance ratio gradients. Both of these observations, in turn, imply a more robust contribution from gas free mergers in the histories of typical elliptical galaxies.

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Section: Identification Of Tidal Featuresmentioning

confidence: 99%

Characterization of Low Surface Brightness structures in annotated deep images

Sola,

Duc,

Richards

et al. 2022

Preprint

Self Cite

View full text Add to dashboard Cite

Context. The identification and characterization of Low Surface Brightness (LSB) stellar structures around galaxies such as tidal debris of on-going or past collisions is essential to constrain models of galactic evolution. So far most efforts have focused on the numerical census of samples of varying sizes, either through visual inspection or more recently with deep learning. Detailed analysis including photometry has been carried out for a small number of objects, essentially because of the lack of convenient tools able to precisely characterize tidal structures around large samples of galaxies. Aims. Our goal is to characterize in detail, and in particular obtain quantitative measurements, of LSB structures identified in deep images of samples consisting of hundreds of galaxies. Methods. We developed an online annotation tool that enables contributors to delineate with precision the shapes of diffuse extended stellar structures, as well as artefacts or foreground structures. All parameters are automatically stored in a database which may be queried to retrieve quantitative measurements. We annotated LSB structures around 352 nearby massive galaxies with deep images obtained with the Canada-France-Hawaii Telescope as part of two large programs: MATLAS and UNIONS/CFIS. Each LSB structure was delineated and labeled according to its likely nature: stellar shells, streams associated to a disrupted satellite, tails formed in major mergers, ghost reflections or cirrus. Results. From our database containing 8441 annotations, the area, size, median surface brightness and distance to the host of 228 structures were computed. The results confirm the fact that tidal structures defined as streams are thinner than tails, as expected by numerical simulations. In addition, tidal tails appear to exhibit a higher surface brightness than streams (by about 1 mag), which may be related to different survival times for the two types of collisional debris. We did not detect any tidal feature fainter than 27.5 mag arcsec −2 , while the nominal surface brightness limits of our surveys range between 28.3 and 29 mag arcsec −2 , a difference that needs to be taken into account when estimating the sensitivity of future surveys to identify LSB structures. Conclusions. We compiled an annotation database of observed LSB structures around nearby massive galaxies including tidal features that may be used for quantitative analysis and as a training set for machine learning algorithms.

show abstract

Ubiquitous signs of interactions in early-type galaxies with prolate rotation

Cited by 11 publications

References 122 publications

Characterization of low surface brightness structures in annotated deep images

Characterization of low surface brightness structures in annotated deep images

Individual element sensitivity for stellar evolutionary isochrones

Characterization of Low Surface Brightness structures in annotated deep images

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