The combined and respective roles of imaging and stellar kinematics in identifying galaxy merger remnants

Abstract

One of the central challenges to establishing the role of mergers in galaxy evolution is the selection of pure and complete merger samples in observations. In particular, while large and reasonably pure interacting galaxy pair samples can be obtained with relative ease via spectroscopic criteria, automated selection of post-coalescence merger remnants is restricted to the physical characteristics of remnants alone. Furthermore, such selection has predominantly focused on imaging data -- whereas kinematic data may offer a complimentary basis for identifying merger remnants. Therefore, we examine the theoretical utility of both the morphological and kinematic features of merger remnants in distinguishing galaxy merger remnants from other galaxies. Deep classification models are calibrated and evaluated using idealized synthetic images and line-of-sight stellar velocity maps of a heterogeneous population of galaxies and merger remnants from the TNG100 cosmological hydrodynamical simulation. We show that even idealized stellar kinematic data has limited utility compared to imaging and under-performs by $2.1\%\pm 0.5\%$ in completeness and $4.7\%\pm 0.4\%$ in purity for our fiducial model architecture. Combining imaging and stellar kinematics offers a small boost in completeness (by $1.8\%\pm 0.4\%$, compared to $92.7\%\pm 0.2\%$ from imaging alone) but no change in purity ($0.1\%\pm 0.3\%$ improvement compared to $92.7\%\pm 0.2\%$, evaluated with equal numbers of merger remnant and non-remnant control galaxies). Classification accuracy of all models is particularly sensitive to physical companions at separations $\lesssim 40$ kpc and to time-since-coalescence. Taken together, our results show that the stellar kinematic data has little to offer in compliment to imaging for merger remnant identification in a heterogeneous galaxy population.

MNRAS accepted; 20 pages, 12 figures and 2 tables; data available upon request

References in corpus (69)

• Cold streams in early massive hot haloes as the main mode of galaxy formation
• Overview of the SDSS-IV MaNGA Survey: Mapping Nearby Galaxies at Apache Point Observatory
• A Cosmological Framework for the Co-Evolution of Quasars, Supermassive Black Holes, and Elliptical Galaxies: I. Galaxy Mergers & Quasar Activity
• Properties of galaxies reproduced by a hydrodynamic simulation
• Introducing the Illustris Project: the evolution of galaxy populations across cosmic time
• The MUSE second-generation VLT instrument
• The SAURON project -- IX. A kinematic classification for early-type galaxies
• Galaxy Zoo: the dependence of morphology and colour on environment
• Galaxy Pairs in the Sloan Digital Sky Survey I: Star Formation, AGN Fraction, and the Luminosity/Mass-Metallicity Relation
• The SAMI Galaxy Survey: instrument specification and target selection
• The effect of galaxy mass ratio on merger--driven starbursts
• Galaxy Merger Morphologies and Time-Scales from Simulations of Equal-Mass Gas-Rich Disc Mergers
• Tracing Galaxy Formation with Stellar Halos II: Relating Substructure in Phase- and Abundance-Space to Accretion Histories
• Kinematic Structure of Merger Remnants
• Sunrise: Polychromatic Dust Radiative Transfer in Arbitrary Geometries
• Kinemetry of SINS High-Redshift Star-Forming Galaxies: Distinguishing Rotating Disks from Major Mergers
• Galaxy pairs in the Sloan Digital Sky Survey - IX: Merger-induced AGN activity as traced by the Wide-field Infrared Survey Explorer
• Clumpy Galaxies in CANDELS. I. The Definition of UV Clumps and the Fraction of Clumpy Galaxies at 0.5<z<3
• The Redshift Evolution of Wet, Dry, and Mixed Galaxy Mergers from Close Galaxy Pairs in the DEEP2 Galaxy Redshift Survey
• Bursting and Quenching in Massive Galaxies without Major Mergers or AGNs
• Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey
• A definitive merger-AGN connection at z~0 with CFIS: mergers have an excess of AGN and AGN hosts are more frequently disturbed
• Morphology and star formation in IllustrisTNG: the build-up of spheroids and discs
• Observational constraints on the merger history of galaxies since $z\approx 6$: Probabilistic galaxy pair counts in the CANDELS fields
• The Millennium Galaxy Catalogue: The connection between close pairs and asymmetry; implications for the galaxy merger rate
• The Luminosity Dependence of the Galaxy Merger Rate
• Interacting galaxies on FIRE-2: The connection between enhanced star formation and interstellar gas content
• AGNs and galaxy interactions
• 2-Dimensional Kinematics of Simulated Disc Merger Remnants
• Dissipationless Mergers of Elliptical Galaxies and the Evolution of the Fundamental Plane
• AEGIS: Enhancement of Dust-enshrouded Star Formation in Close Galaxy Pairs and Merging Galaxies up to z ~ 1
• Deep learning predictions of galaxy merger stage and the importance of observational realism
• The mass-metallicity relation of interacting galaxies
• Galaxy And Mass Assembly (GAMA): Refining the Local Galaxy Merger Rate using Morphological Information
• Spatially resolved star formation and fuelling in galaxy interactions
• The Canada-France Imaging Survey: First results from the u-band component
• Lopsided Spiral Galaxies
• Galaxies in the Illustris simulation as seen by the Sloan Digital Sky Survey - II: Size-luminosity relations and the deficit of bulge-dominated galaxies in Illustris at low mass
• Galaxy Merger Rates up to z $\sim$ 3 using a Bayesian Deep Learning Model $-$ A Major-Merger classifier using IllustrisTNG Simulation data
• Identifying Galaxy Mergers in Observations and Simulations with Deep Learning
• On the lifetime of merger features of equal-mass disk mergers
• Convolutional neural network identification of galaxy post-mergers in UNIONS using IllustrisTNG
• A Surprisingly High Pair Fraction for Extremely Massive Galaxies at z ~ 3 in the GOODS NICMOS Survey
• Interacting galaxies in the IllustrisTNG simulations -- I: Triggered star formation in a cosmological context
• Interacting galaxies in the IllustrisTNG simulations -- II: Star formation in the post-merger stage
• Galaxy mergers in EAGLE do not induce a significant amount of black hole growth yet do increase the rate of luminous AGN
• Distinguishing Mergers and Disks in High Redshift Observations of Galaxy Kinematics
• What shapes a galaxy? - Unraveling the role of mass, environment and star formation in forming galactic structure
• The relationship between fine galaxy stellar morphology and star formation activity in cosmological simulations: a deep learning view
• Bulge plus disc and Sérsic decomposition catalogues for 16,908 galaxies in the SDSS Stripe 82 co-adds: A detailed study of the $ugriz$ structural measurements
• Galaxy Evolution in all Five CANDELS Fields and IllustrisTNG: Morphological, Structural, and the Major Merger Evolution to $z\sim 3$
• The neutral gas content of post-merger galaxies
• Kinematic decomposition of IllustrisTNG disk galaxies: morphology and relation with morphological structures
• DeepMerge II: Building Robust Deep Learning Algorithms for Merging Galaxy Identification Across Domains
• Interacting galaxies in the IllustrisTNG simulations -- III: (the rarity of) quenching in post-merger galaxies
• Galaxies in the Illustris simulation as seen by the Sloan Digital Sky Survey - I: Bulge+disc decompositions, methods, and biases
• Kinematic classifications of local interacting galaxies: implications for the merger/disk classifications at high-z
• Galaxy interactions in IllustrisTNG-100, I: The power and limitations of visual identification
• The SAMI Galaxy Survey: Asymmetry in Gas Kinematics and its links to Stellar Mass and Star Formation
• SDSS-IV MaNGA: Kinematic Asymmetry as An Indicator of Galaxy Interaction in Paired Galaxies
• Nearby Clumpy, Gas Rich, Star Forming Galaxies: Local Analogs of High Redshift Clumpy Galaxies
• Accurate Identification of Galaxy Mergers with Stellar Kinematics
• Probing Asymmetric Structures in the Outskirts of Galaxies
• What is Important? Morphological Asymmetries are Useful Predictors of Star Formation Rates of Star-forming Galaxies in SDSS Stripe 82
• Gas fractions and depletion times in galaxies with different degrees of interaction
• The Effects of Interactions on the Structure and Morphology of Elliptical/Lenticular galaxies in Pairs
• BVRI Surface Photometry of Isolated Spiral Galaxies
• On the relationship between gas content, star-formation, and global HI asymmetry of galaxies on the star-forming main-sequence
• Properties of galaxies with an offset between the position angles of the major kinematic and photometric axes

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• Galaxy mergers can rapidly shut down star formation
• IllustrisTNG in the HSC-SSP: image data release and the major role of mini mergers as drivers of asymmetry and star formation
• The merger fraction of post-starburst galaxies in UNIONS
• ERGO-ML I: Inferring the assembly histories of IllustrisTNG galaxies from integral observable properties via invertible neural networks
• Star formation characteristics of CNN-identified post-mergers in the Ultraviolet Near Infrared Optical Northern Survey (UNIONS)
• Machine Learning for Observational Cosmology
• AGN in post-mergers from the Ultraviolet Near Infrared Optical Northern Survey
• Machine learning detects multiplicity of the first stars in stellar archaeology data
• The observability of galaxy merger signatures in nearby gas-rich spirals
• The interconnection between galaxy mergers, AGN activity and rapid quenching of star formation in simulated post-merger galaxies
• The SAMI Galaxy Survey: Using Tidal Streams and Shells to Trace the Dynamical Evolution of Massive Galaxies
• Molecular gas and star formation in nearby starburst galaxy mergers
• The origin of double-peak emission-line galaxies: rotating discs, bars or galaxy mergers?
• ERGO-ML: Towards a robust machine learning model for inferring the fraction of accreted stars in galaxies from integral-field spectroscopic maps
• Automated Detection of Double Nuclei Galaxies using GOTHIC and the Discovery of a Large Sample of Dual AGN
• SDSS-IV MaNGA: Unveiling Galaxy Interaction by Merger Stages with Machine Learning
• Galaxy pairs in The Three Hundred simulations II: studying bound ones and identifying them via machine learning
• IllustrisTNG in the HSC-SSP: No Shortage of Thin Disk Galaxies in TNG50
• Galaxy 3D Shape Recovery using Mixture Density Network
• A Simulation Driven Deep Learning Approach for Separating Mergers and Star Forming Galaxies: The Formation Histories of Clumpy Galaxies in all the CANDELS Fields