Reignition of star formation in dwarf galaxies

Wright, Anna C.; Brooks, Alyson; Weisz, Daniel R.; Christensen, Charlotte

doi:10.1093/mnras/sty2759

Cited by 67 publications

(67 citation statements)

References 87 publications

(127 reference statements)

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“…The metal-rich stars continue forming until the gas is depleted in this galaxy. Such interactions have been previously noted by Benítez-Llambay et al (2013) and Wright et al (2019). We show this passage through the cosmic filaments in greater detail in Fig.…”

Section: Ram Pressure-induced Star Formationsupporting

confidence: 80%

“…Another plausible formation path has been suggested by Wright et al (2019). These authors identified ram pressure as a mechanism for the reignition of star formation in field dwarf galaxies of stellar mass in the range 9.2×10 8 -8.4×10 9 M , and in which the star formation history has a prolonged gap.…”

Section: Introductionmentioning

confidence: 89%

“…A successful scenario for the formation of dwarfs with two stellar metallicity populations would need to explain both the difference in the age/metallicity of the two populations as well as the difference in their spatial extent. Whilst the works of Benítez-Llambay et al (2016) and Wright et al (2019) have been able to achieve this, neither have considered satellite dwarfs in a Local Group-like environment. In this work we analyse the assembly histories of both field and satellite dwarf galaxies with stellar masses spanning the range 10 6 -10 9 M in five high-resolution hydrodynamical simulations of environments resembling that of the Local Group.…”

Section: Introductionmentioning

confidence: 99%

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The distinct stellar metallicity populations of simulated Local Group dwarfs

Genina

Frenk

Benitez-Llambay

et al. 2019

Monthly Notices of the Royal Astronomical Society

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ABSTRACT A number of Local Group dwarf galaxies are known to have two spatially segregated stellar metallicity populations, a centrally concentrated metal-rich population, and a more extended metal-poor population. In this work we discuss mechanisms that lead to the formation of two spatially segregated metallicity populations. Using a set of high-resolution hydrodynamical simulations of Local Group-like environments, we select a sample of satellite and field galaxies, spanning the stellar mass range 106–109 M⊙, that exhibit bimodality in their metallicity distributions. Among those, we identify a subsample with a strong spatial segregation in the two populations. We find three distinct mechanisms for their formation. In field dwarfs and in a small fraction of satellites, a merger causes the metal-poor stars to migrate to larger radii and encourages the available gas to sink to the centre of the dwarf. Most of the gas is subsequently blown out of the halo through star formation feedback, but the remaining gas is consumed in the formation of a metal-rich population. In the exclusive case of satellites that have retained some of their gas at infall, it is the compression of this gas by ram pressure near pericentre that triggers the formation of metal-rich stars, whilst simultaneously preventing star formation at larger radii through stripping. Additionally, in a small number of field and satellite dwarfs, interactions with gaseous filaments and other galaxies can result in the formation of a metal-rich population. Regardless of the formation mechanism, a history of mergers typically enhances the spatial segregation.

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Section: Ram Pressure-induced Star Formationsupporting

confidence: 80%

Section: Introductionmentioning

confidence: 89%

Section: Introductionmentioning

confidence: 99%

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The distinct stellar metallicity populations of simulated Local Group dwarfs

Genina

Frenk

Benitez-Llambay

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…residual star formation can be fuelled by the galaxy's existing gas reservoir so as to produce SFHs similar to those observed for UFDs (Oñorbe et al 2015;Wheeler et al 2015). Additionally, reignition of star formation after initial suppression via reionization may produce short and late periods of star formation (Ledinauskas & Zubovas 2018;Wright et al 2019), such as that observed in Carina by Weisz et al (2014b). Observations in the Local Volume also broadly suggest that the mass scale at which quenching via reionization dominates is approximately M ∼ 10 5 M (e.g.…”

Section: Quenching On the Smallest Scalesmentioning

confidence: 74%

The suppression of star formation on the smallest scales: what role does environment play?

Wimberly

Cooper

Fillingham

et al. 2018

Monthly Notices of the Royal Astronomical Society

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The predominantly ancient stellar populations observed in the lowest mass galaxies (i.e. ultrafaint dwarfs) suggest that their star formation was suppressed by reionization. Most of the well-studied ultra-faint dwarfs, however, are within the central half of the Milky Way dark matter halo, such that they are consistent with a population that was accreted at early times and thus potentially quenched via environmental processes. To study the potential role of environment in suppressing star formation on the smallest scales, we utilize the Exploring the Local Volume in Simulations suite of N-body simulations to constrain the distribution of infall times for low-mass subhaloes likely to host the ultra-faint population. For the ultra-faint satellites of the Milky Way with star formation histories inferred from Hubble Space Telescope imaging, we find that environment is highly unlikely to play a dominant role in quenching their star formation. Even when including the potential effects of pre-processing, there is a 0.1 per cent probability that environmental processes quenched all of the known ultra-faint dwarfs early enough to explain their observed star formation histories. Instead, we argue for a mass floor in the effectiveness of satellite quenching at roughly M ∼ 10 5 M , below which star formation in surviving galaxies is globally suppressed by reionization. We predict a large population of quenched ultra-faint dwarfs in the Local Field (1 < R/R vir < 2), with as many as ∼250 to be discovered by future wide-field imaging surveys.

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“…Indeed, modern hydrodynamic simulations of dwarf galaxies (e.g., Brooks & Zolotov 2014;Shen et al 2014;Oñorbe et al 2015;Wheeler et al 2015;Fitts et al 2017) have achieved great success in reproducing the observed properties, such as stellar mass content (e.g., Behroozi et al 2013;Moster et al 2013;Brook et al 2014;Garrison-Kimmel et al 2014;Read et al 2017;Jethwa et al 2018), cold gas content, star formation history (e.g., Tolstoy et al 2009;Weisz et al 2011Weisz et al , 2014Brown et al 2014), mass-metallicity relationship (e.g., McConnachie 2012; Kirby et al 2013Kirby et al , 2014, and stellar, gas kinematics, and morphological properties (e.g., McConnachie 2012) in field and satellite dwarf galaxies in the local Universe. With ever increasing resolution, simulations are now capable of probing the formation of ultra-faint dwarf galaxies (UFDs) and can be used to make predictions for upcoming deep surveys from telescopes such as the Vera C. Rubin Observatory (e.g., Fitts et al 2017;Revaz & Jablonka 2018;Wheeler et al 2019;Wright et al 2019a;Munshi et al 2019;Agertz et al 2020;Applebaum et al, in prep.). All these simulations have confirmed that, at least in the regime of classical dwarfs (M vir ∼ 10 10 M ), galactic outflows driven by stellar feedback are of critical importance to suppress star formation, reduce the stellar bulge-to-disc ratio, lower the intestellar medium (ISM) metallicity, and enrich the CGM.…”

Section: Introductionmentioning

confidence: 99%

The baryon cycle of Seven Dwarfs with superbubble feedback

Mina

Shen

Keller

et al. 2021

A&A

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We present results from a high-resolution, cosmological, ΛCDM simulation of a group of field dwarf galaxies with the “superbubble” model for clustered SN feedback, accounting for thermal conduction and cold gas evaporation. We compared our results to a previous simulation which has the same initial condition and galaxy formation physics (other than SN feedback), but adopts a delayed-cooling model for supernova. The simulated luminous galaxies have blue colors, low star formation efficiencies and metallicities, and high cold gas content, reproducing the observed scaling relations of dwarf galaxies in the Local Volume. Bursty star formation histories and superbubble-driven outflows lead to the formation of kpc-size dark matter (DM) cores when stellar masses reaches M* > 106 M⊙, similar to previous findings. However, the superbubble model appears more effective in destroying DM cusps than the delayed-cooling model in the previous study, reflecting a higher coupling efficiency of SN energy with the ISM. On larger scale, superbubble-driven outflows have a more moderate impact: galaxies have higher gas content, more extended stellar discs, and a smaller metal-enriched region in the circumgalactic medium (CGM). The two halos with Mvir ∼ 109 M⊙, which formed ultra-faint dwarf galaxies with the delayed-cooling mode, remain dark due to the different impact of metal-enriched galactic winds from two nearby luminous galaxies, indicating that the formation of faint dwarfs is highly dependent on feedback and environmental effects. The column density distributions of H I, Si II, C IV and O VI as a function of the scaled impact parameter (b/Rvir) are in good agreement with recent observations of CGM around isolated dwarf galaxies. While H I is ubiquitous with a covering fraction of unity within the CGM, low and intermediate ions like Si II and C IV are less extended (typically confined within 0.2 − 0.3 Rvir), and non-detections are common. O VI is more extended with column density N(O VI) ≳ 1013.5 cm−2 within Rvir, but its mass is only 11% of the total CGM oxygen budget, as the diffuse CGM is highly ionised by the UV background. Superbubble feedback produces C IV and O VI column densities that are an order of magnitude higher than those in the previous study using delayed-cooling feedback. Thus, the CGM and DM cores are most sensitive probes of feedback mechanisms.

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Reignition of star formation in dwarf galaxies

Cited by 67 publications

References 87 publications

The distinct stellar metallicity populations of simulated Local Group dwarfs

The distinct stellar metallicity populations of simulated Local Group dwarfs

The suppression of star formation on the smallest scales: what role does environment play?

The baryon cycle of Seven Dwarfs with superbubble feedback

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