NIHAO - XI. Formation of ultra-diffuse galaxies by outflows

By A. Cintio, C. Brook, A. Dutton, A. Macciò, A. Obreja, A. Dekel. 2016

183 citations recorded by the source corpus.

We address the origin of Ultra-Diffuse Galaxies (UDGs), which have stellar masses typical of dwarf galaxies but effective radii of Milky Way-sized objects. Their formation mechanism, and whether they are failed $\rm L_{\star}$ galaxies or diffuse dwarfs, are challenging issues. Using zoom-in cosmological simulations from the NIHAO project, we show that UDG analogues form naturally in medium-mass haloes due to episodes of gas outflows associated with star formation. The simulated UDGs live in isolated haloes of masses $10^{10-11}\rm M_{\odot}$, have stellar masses of $10^{7-8.5}\rm M_{\odot}$, effective radii larger than 1 kpc and dark matter cores. They show a broad range of colors, an average Sersic index of 0.83, a typical distribution of halo spin and concentration, and a non-negligible HI gas mass of $10^{7-9}\rm M_{\odot}$, which correlates with the extent of the galaxy. Gas availability is crucial to the internal processes that form UDGs: feedback driven gas outflows, and subsequent dark matter and stellar expansion, are the key to reproduce faint, yet unusually extended, galaxies. This scenario implies that UDGs represent a dwarf population of low surface brightness galaxies and should exist in the field. The largest isolated UDGs should contain more HI gas than less extended dwarfs of similar $\rm M_{\star}$.

Subfields: Astronomy and Astrophysics, Instrumentation

View Paper: https://www.semanticscholar.org/paper/c3a7a57b962f82ce3481b0331a5fa6027c4c48bd

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Citations in the corpus

Ultra-diffuse galaxies outside clusters: clues to their formation and evolution (2016, methodology): “The existence of UDGs in the field has also been motivated theoretically by Di Cintio et al. (2017).”
(Almost) Dark Galaxies in the ALFALFA Survey: Isolated H i-bearing Ultra-diffuse Galaxies (2017, methodology): “If, as Di Cintio et al. (2017) suggest, UDGs have bursty SF histories, we may be observing the HUDS during a period of significant gas infall, before they experience a significant increase in their star formation rate.”
The hidden giant: discovery of an enormous Galactic dwarf satellite in Gaia DR2 (2018, background): “Powerful bursty gaseous outflows have been shown to be able to ‘drag’ many of the constituent stars to much larger radii overall, thus creating noticeably diffuse dwarf galaxies (see e.g. El-Badry et al. 2016; Di Cintio et al. 2017; Chan et al. 2018).”
The Local Group on FIRE: dwarf galaxy populations across a suite of hydrodynamic simulations (2018, background): “If ultra-diffuse galaxies (UDGs) are prevalent in the field (as predicted by Di Cintio et al. 2017 and Chan et al. 2017), with central surface brightnesses 24–26 mag arcsec−2 (van Dokkum et al. 2015), then some of this incompleteness may even arise at M∗ ∼ 107 M .”