Bibcode
Jiang, Fangzhou; Dekel, Avishai; Freundlich, Jonathan; Romanowsky, Aaron J.; Dutton, Aaron A.; Macciò, Andrea V.; Di Cintio, Arianna
Bibliographical reference
Monthly Notices of the Royal Astronomical Society, Volume 487, Issue 4, p.5272-5290
Advertised on:
8
2019
Citations
120
Refereed citations
108
Description
We study ultra-diffuse galaxies (UDGs) in zoom in cosmological
simulations, seeking the origin of UDGs in the field versus galaxy
groups. We find that while field UDGs arise from dwarfs in a
characteristic mass range by multiple episodes of supernova feedback (Di
Cintio et al.), group UDGs may also form by tidal puffing up and they
become quiescent by ram-pressure stripping. The field and group UDGs
share similar properties, independent of distance from the group centre.
Their dark-matter haloes have ordinary spin parameters and centrally
dominant dark-matter cores. Their stellar components tend to have a
prolate shape with a Sérsic index n ˜ 1 but no significant
rotation. Ram pressure removes the gas from the group UDGs when they are
at pericentre, quenching star formation in them and making them redder.
This generates a colour/star-formation-rate gradient with distance from
the centre of the dense environment, as observed in clusters. We find
that ˜20 per cent of the field UDGs that fall into a massive halo
survive as satellite UDGs. In addition, normal field dwarfs on highly
eccentric orbits can become UDGs near pericentre due to tidal puffing
up, contributing about half of the group-UDG population. We interpret
our findings using simple toy models, showing that gas stripping is
mostly due to ram pressure rather than tides. We estimate that the
energy deposited by tides in the bound component of a satellite over one
orbit can cause significant puffing up provided that the orbit is
sufficiently eccentric. We caution that while the simulations produce
UDGs that match the observations, they under-produce the more compact
dwarfs in the same mass range, possibly because of the high threshold
for star formation or the strong feedback.
Related projects
Numerical Astrophysics: Galaxy Formation and Evolution
How galaxies formed and evolved through cosmic time is one of the key questions of modern astronomy and astrophysics. Cosmological time- and length-scales are so large that the evolution of individual galaxies cannot be directly observed. Only through numerical simulations can one follow the emergence of cosmic structures within the current
Claudio
Dalla Vecchia
Traces of Galaxy Formation: Stellar populations, Dynamics and Morphology
We are a large, diverse, and very active research group aiming to provide a comprehensive picture for the formation of galaxies in the Universe. Rooted in detailed stellar population analysis, we are constantly exploring and developing new tools and ideas to understand how galaxies came to be what we now observe.
Ignacio
Martín Navarro