Real galaxy mergers from galaxy pair catalogs

Abstract

Mergers of galaxies are extremely violent events shaping their evolution. Such events are thought to trigger starbursts and, possibly, black hole accretion. Nonetheless, it is still not clear how to know the fate of a galaxy pair from the data available at a given time, limiting our ability to constrain the exact role of mergers. In this paper we use the lightcone of the Horizon-AGN simulation, for which we know the fate of each pair, to test three selection processes aiming at identifying true merging pairs. We find that the simplest one (selecting objects within two thresholds on projected distance $d$ and redshift difference $\Delta z$) gives similar results than the most complex one (based on a neural network analyzing $d$, $\Delta z$, redshift of the primary, masses/star formation rates/aspect ratio of both galaxies). Our best thresholds are $d_{\mathrm{th}}\sim 100\mathrm{kpc}$ and $\Delta z_{\mathrm{th}}\sim 10^{-3}$, in agreement with recent results.

submitted to MNRAS

References in corpus (20)

• Introducing the Illustris Project: Simulating the coevolution of dark and visible matter in the Universe
• The effect of galaxy mass ratio on merger--driven starbursts
• Building Merger Trees from Cosmological N-body Simulations
• Dissipation and Extra Light in Galactic Nuclei: II. 'Cusp' Ellipticals
• Growth and activity of black holes in galaxy mergers with varying mass ratios
• Galaxy Interactions Trigger Rapid Black Hole Growth: an unprecedented view from the Hyper Suprime-Cam Survey
• Observational constraints on the merger history of galaxies since $z\approx 6$: Probabilistic galaxy pair counts in the CANDELS fields
• Off the Beaten Path: A New Approach to Realistically Model The Orbital Decay of Supermassive Black Holes in Galaxy Formation Simulations
• Dissipation and Extra Light in Galactic Nuclei: III. 'Core' Ellipticals and 'Missing' Light
• The erratic dynamical life of black hole seeds in high-redshift galaxies
• High-redshift major mergers weakly enhance star formation
• Massive Close Pairs Measure Rapid Galaxy Assembly in Mergers at High Redshift
• The SAMI Galaxy Survey: First detection of a transition in spin orientation with respect to cosmic filaments in the stellar kinematics of galaxies
• Mergers drive spin swings along the cosmic web
• Major mergers are not significant drivers of star formation or morphological transformation around the epoch of peak cosmic star formation
• The birth of a supermassive black hole binary
• A Physical Approach to the Identification of High-z Mergers: Morphological Classification in the Stellar Mass Domain
• Merger induced clump formation in distant infrared luminous starburst galaxies
• An artificial neural network to discover Hypervelocity stars: Candidates in Gaia DR1/TGAS
• Weak lensing in the Horizon-AGN simulation lightcone. Small scale baryonic effects