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The Formation Mechanisms of Galaxy Tails: A Statistical and Case Study

Using a hydrodynamical smoothed particle hydrodynamics (SPH) zoom-in simu lation of a galaxy group, we present a set of tail identification methods, and study
the statistical properties of galaxy tails and their correlations with their expected
formation mechanisms. We have a sample of 4548 M > 108 M⊙ galaxies across 58
snapshots from z = 0.67 to z = 0. For each galaxy, we apply a series of velocity and
density cuts to identify the tail. We observed no significant correlations between
galaxy tail mass and ram pressure, though we note some issues with our sampling.
Tracking four visually identified jellyfish galaxies over time showed some evidence
of increased ram pressure driving ISM mass loss, as well as spikes in tail mass pre ceding spikes in ram pressure with temporal offsets ranging from 500 Myr to 2 Gyr.
No correlation was found between ISM mass and tail mass. We track the tail gas
of a particularly well defined jellyfish galaxy 3.2 Gyrs back in time. We find that
a lower bound of 30% of the tail gas was never in the ISM. Distinguishing between
former ISM tail material and never ISM-accreted tail material, we see evidence of
temperature mixing with the IGM in the former. Velocity and radial trajectory
maps show a sharp impulse of ∆v ≈ 50 km s−1 over 4 snapshots, affecting both
the never ISM-accreted tail material and CGM material, with the former showing
evidence of momentum mixing onto the former ISM material. Combined with ob servations of CGM stripping, we propose that a significant portion of galaxy tails
consists of stripped CGM that got swept up into the stripped ISM / Thesis / Master of Science (MSc)

Identiferoai:union.ndltd.org:mcmaster.ca/oai:macsphere.mcmaster.ca:11375/27817
Date January 2022
CreatorsLu, Hong Yi
ContributorsWadsley, James, Parker, Laura, Physics and Astronomy
Source SetsMcMaster University
LanguageEnglish
Detected LanguageEnglish
TypeThesis

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