Merge and Strip II: Imprint of galaxy formation physics and viscosity on baryon-dominated dwarf galaxies

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Main Authors: Ivleva, Anna, Dolag, Klaus, Remus, Rhea-Silvia, Forbes, Duncan A., Marin-Gilabert, Tirso
Format: Preprint
Published: 2026
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author Ivleva, Anna
Dolag, Klaus
Remus, Rhea-Silvia
Forbes, Duncan A.
Marin-Gilabert, Tirso
author_facet Ivleva, Anna
Dolag, Klaus
Remus, Rhea-Silvia
Forbes, Duncan A.
Marin-Gilabert, Tirso
contents Motivated by the discovery of peculiar dwarf galaxies inside galaxy clusters such as blue candidates (BCs), dark galaxies and ultra-diffuse galaxies (UDGs), we present hydrodynamic simulations of galaxy mergers in cluster environments. We vary the viscosity and stellar feedback prescriptions, realistically modelling possible conditions for hydrodynamic drag and fluid instabilities, as well as internal destabilization through stellar feedback-driven heating and gas loss. We find that long-lived tidal dwarf galaxies (TDGs) can form throughout all viscosity values applicable to galaxy clusters if stellar feedback is moderate. Our results expand on studies of cloud crushing simulations, investigating the entrainment problem in intracluster medium ambience. The smallest clouds have gas masses on the order of $M_\text{gas} \sim 10^7 \text{ M}_\odot$ and reach relatively low final drift velocities of $\sim 100 \text{ km/s}$. The lowest possible Reynolds number acting on this class of clouds is $Re \sim 1$ for full Spitzer viscosity. Almost all TDGs display elevated star formation rates of $0.01-0.1 \text{ M}_\odot / \text{yr}$, which are stable across several Gyr. Based on their matching properties, we support that BCs observed in the Virgo cluster are likely stripped TDGs. Similar features are also found in comparison with dark galaxies and baryon-dominated UDGs, implying that a subsample of these objects are also long-lived TDGs. This work provides robust evidence that stripping from galaxy mergers is a viable channel for the formation of stable cold gas clouds and dark matter-deficient galaxies observed in galaxy clusters.
format Preprint
id arxiv_https___arxiv_org_abs_2605_00984
institution arXiv
publishDate 2026
record_format arxiv
spellingShingle Merge and Strip II: Imprint of galaxy formation physics and viscosity on baryon-dominated dwarf galaxies
Ivleva, Anna
Dolag, Klaus
Remus, Rhea-Silvia
Forbes, Duncan A.
Marin-Gilabert, Tirso
Astrophysics of Galaxies
Motivated by the discovery of peculiar dwarf galaxies inside galaxy clusters such as blue candidates (BCs), dark galaxies and ultra-diffuse galaxies (UDGs), we present hydrodynamic simulations of galaxy mergers in cluster environments. We vary the viscosity and stellar feedback prescriptions, realistically modelling possible conditions for hydrodynamic drag and fluid instabilities, as well as internal destabilization through stellar feedback-driven heating and gas loss. We find that long-lived tidal dwarf galaxies (TDGs) can form throughout all viscosity values applicable to galaxy clusters if stellar feedback is moderate. Our results expand on studies of cloud crushing simulations, investigating the entrainment problem in intracluster medium ambience. The smallest clouds have gas masses on the order of $M_\text{gas} \sim 10^7 \text{ M}_\odot$ and reach relatively low final drift velocities of $\sim 100 \text{ km/s}$. The lowest possible Reynolds number acting on this class of clouds is $Re \sim 1$ for full Spitzer viscosity. Almost all TDGs display elevated star formation rates of $0.01-0.1 \text{ M}_\odot / \text{yr}$, which are stable across several Gyr. Based on their matching properties, we support that BCs observed in the Virgo cluster are likely stripped TDGs. Similar features are also found in comparison with dark galaxies and baryon-dominated UDGs, implying that a subsample of these objects are also long-lived TDGs. This work provides robust evidence that stripping from galaxy mergers is a viable channel for the formation of stable cold gas clouds and dark matter-deficient galaxies observed in galaxy clusters.
title Merge and Strip II: Imprint of galaxy formation physics and viscosity on baryon-dominated dwarf galaxies
topic Astrophysics of Galaxies
url https://arxiv.org/abs/2605.00984