Are ancient dwarf satellites the building blocks of the Galactic halo?

Spitoni, E.; Vincenzo, Fiorenzo; Matteuccí, F.; Romano, D.

doi:10.1093/mnras/stw519

Cited by 29 publications

(37 citation statements)

References 68 publications

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“…(vii) Comparing the abundances of UFD stars with the Galactic ones, we suggest that at least a fraction of UFDs could not be the building blocks of the halo given the different [α/Fe] trends observed for UFDs and the Galactic halo. To draw firmer conclusions more data about UFDs are necessary and more elements should be studied such as barium (Spitoni et al 2016).…”

Section: Discussionmentioning

confidence: 99%

“…With the discovery of a large number of smaller satellite galaxies, the interest has been shifthed on these systems, the UFDs. Spitoni et al (2016) modeled the chemical evolution of the Galactic halo both assuming it to be formed from the accretion of disrupted satellites as well as from the infall of pre-enriched gas. They ruled out the possibility that the Galactic halo was entirely originated by the merging of current dSphs and UFDs ancestors.…”

Section: Introductionmentioning

confidence: 99%

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Chemical evolution of ultrafaint dwarf galaxies: testing the IGIMF

Lacchin

Matteuccí

Vincenzo

et al. 2020

Monthly Notices of the Royal Astronomical Society

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We test the integrated galactic initial mass function (IGIMF) on the chemical evolution of 16 ultra-faint dwarf (UFD) galaxies discussing in detail the results obtained for three of them: Boötes I, Boötes II and Canes Venatici I, taken as prototypes of the smallest and the largest UFDs. These objects have very small stellar masses (∼ 10 3 − 10 4 M ) and quite low metallicities ([Fe/H]< −1.0 dex). We consider three observational constraints: the present-day stellar mass, the [α/Fe] vs. [Fe/H] relation and the stellar metallicity distribution function. Our model follows in detail the evolution of several chemical species (H, He, α-elements and Fe). We take into account detailed nucleosynthesis and gas flows (in and out). Our results show that the IGIMF, coupled with the very low star formation rate predicted by the model for these galaxies (∼ 10 −4 − 10 −6 M yr −1 ), cannot reproduce the main chemical properties, because it implies a negligible number of core-collapse SNe and even Type Ia SNe, the most important polluters of galaxies. On the other hand, a constant classical Salpeter IMF gives the best agreement with data. We suggest for all the UFDs studied a very short infall time-scale and high galactic wind efficiencies. Comparing with Galaxy data we suggest that UFDs could not be the building blocks of the entire Galactic halo, although more data are necessary to draw firmer conclusions.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Chemical evolution of ultrafaint dwarf galaxies: testing the IGIMF

Lacchin

Matteuccí

Vincenzo

et al. 2020

Monthly Notices of the Royal Astronomical Society

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“…In our work, we do not consider galaxy interactions. Several chemical evolution papers have demonstrated that interactions can be simulated by enriched gas infall from a companion galaxy (Spitoni 2015;Spitoni et al 2016). In Spitoni (2015) is shown that external, primordial infall is more important than enriched one, especially in the early phases of galaxy evolution.…”

Section: Chemical Evolution Models Including Dustmentioning

confidence: 99%

Galactic Archaeology at High Redshift: Inferring the Nature of GRB Host Galaxies from Abundances

Palla

Matteuccí

Calura

et al. 2020

ApJ

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We identify the nature of high redshift long Gamma-Ray Bursts (LGRBs) host galaxies by comparing the observed abundance ratios in the interstellar medium with detailed chemical evolution models accounting for the presence of dust. We compare abundance data from long Gamma-Ray Bursts afterglow spectra to abundance patterns as predicted by our models for different galaxy types. We analyse [X/F e] abundance ratios (where X is C, N , O, M g, Si, S, N i, Zn) as functions of [F e/H]. Different galaxies (irregulars, spirals, spheroids) are, in fact, characterised by different star formation histories, which produce different [X/F e] vs. [F e/H] relations ("time-delay model"). This allows us to identify the star formation history of the host galaxies and to infer their age (i.e. the time elapsed from the beginning of star formation) at the time of the GRB events. Unlike previous works, we use newer models in which we adopt updated stellar yields and prescriptions for dust production, accretion and destruction. We consider a sample of seven LGRB host galaxies. Our results suggest that two of them (GRB 050820, GRB 120815A) are star forming spheroids, two (GRB 081008, GRB 161023A) are spirals and three (GRB 090926A, GRB 050730, GRB 120327A) are irregulars. The inferred ages of the considered host galaxies span from 10 M yr to slightly more than 1 Gyr.

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“…The novelty of Spitoni et al (2016) is to take into account in a self-consistent way time dependent abundances. The gas infall law is the same as in the 2IM or 2IMW models and it is only considered a time dependent chemical composition of the infall gas mass.…”

Section: The Enriched Infall Of Gasmentioning

confidence: 99%

“…In Spitoni et al (2016) we test the hypothesis that dSph and UfD galaxies have been the building blocks of the Galactic halo, by assuming that the halo formed by accretion of stars belonging to these galaxies. Moreover, extending the results of Spitoni (2015) to detailed chemical evolution models in which the IRA is relaxed, we explored the scenario, in which the Galactic halo formed by accretion of chemically enriched gas originating from dSph and UfD galaxies.…”

Section: Introductionmentioning

confidence: 99%

The connection between the Galactic halo and ancient Dwarf Satellites

Spitoni¹,

Vincenzo²,

Matteuccí³

et al. 2017

Proceedings of Frontier Research in Astrophysics – II — PoS(FRAPWS2016)

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We explore the hypothesis that the classical and ultra-faint dwarf spheroidal satellites of the Milky Way have been the building blocks of the Galactic halo by comparing their [O/Fe] [O/Fe] ratios. Moreover, we show the effects of an enriched infall of gas with the same chemical abundances as the matter ejected and/or stripped from dwarf satellites of the Milky Way on the chemical evolution of the Galactic halo. We find that the resulting chemical abundances of the halo stars depend on the assumed infall time scale, and the presence of a threshold in the gas for star formation.

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Are ancient dwarf satellites the building blocks of the Galactic halo?

Cited by 29 publications

References 68 publications

Chemical evolution of ultrafaint dwarf galaxies: testing the IGIMF

Chemical evolution of ultrafaint dwarf galaxies: testing the IGIMF

Galactic Archaeology at High Redshift: Inferring the Nature of GRB Host Galaxies from Abundances

The connection between the Galactic halo and ancient Dwarf Satellites

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