XMP gas-rich dwarfs in nearby voids: results of SALT spectroscopy

Pustilnik, S. A.; Knyazev, A. Yu.; Perepelitsyna, Y. A.; Egorova, E. S.

doi:10.1093/mnras/staa215

Cited by 17 publications

(10 citation statements)

References 57 publications

(77 reference statements)

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“…The XMP galaxies are the most relevant for measurements constraining Y p ; however, historically, the searches for these galaxies have had very low yields (see discussion in Sánchez Almeida et al [69]). Fortunately, in recent years, there have been a number of discoveries of XMP galaxies [58,[87][88][89][90][91][92][93][94][95]. Although many of these XMP galaxies are too low in emission line surface brightness to be viable for precise He abundance measurements, future observations of the most promising of these galaxies, with quality comparable to the observations of Leo P presented here, represents a very desirable goal.…”

Section: The Primordial Helium Abundancementioning

confidence: 63%

Improving Helium Abundance Determinations with Leo P as a Case Study

Aver,

Berg,

Olive

et al. 2020

Preprint

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Currently, the primordial helium abundance is best estimated through spectroscopic observations of H II regions in metal-poor galaxies. However these determinations are limited by several systematic uncertainties which ultimately limit our ability to accurately ascertain the primordial abundance. In this study, we improve the methodologies for solving for the reddening, the emission contributions from collisional excitation of the H I atoms, the effects underlying absorption in the H I and He I emission lines, and the treatment of the blended H I and He I emission at λ3889 with the aim of lowering the systematic uncertainties in helium abundance determinations. To apply these methods, we have obtained observations of the He I λ10830 emission line in the brightest H II region in the extremely metal-poor (3% Z ⊙ ) galaxy Leo P with the LUCI1 instrument on the LBT. We combine this measurement with previous MODS/LBT observations to derive an improved helium abundance. In doing so, our present analysis results in a decrease in the uncertainty in the helium abundance of Leo P by approximately 70%. This result is combined with data from other observations to estimate the primordial helium mass fraction, Y p = 0.2453 ± 0.0034.

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Section: The Primordial Helium Abundancementioning

confidence: 63%

Improving Helium Abundance Determinations with Leo P as a Case Study

Aver,

Berg,

Olive

et al. 2020

Preprint

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“…Here we follow the more restrictive definition by [33]. XMPs are quite rare galaxies, but because of their interest they are currently being actively searched for by several groups [e.g., 38,46,47,[94][95][96][97][98][99][100][101][102][103][104].…”

Section: Extremely Metal-poor Galaxiesmentioning

confidence: 99%

Chemical and stellar properties of star-forming dwarf galaxies

Annibali,

Tosi

2022

Preprint

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Dwarf galaxies are the least massive, most abundant, and most widely distributed type of galaxies. Hence, they are key to testing theories of galaxy and Universe evolution. Dwarf galaxies sufficiently close to have their gas and stellar components studied in detail are of particular interest, because their properties and their evolution can be inferred with accuracy. This Review summarizes what is known of the stellar and chemical properties of star-forming dwarf galaxies closer than ∼20 Mpc. Given their low metallicity, high gas content and ongoing star formation, these objects are supposed to resemble the first galaxies that formed at the earliest epochs, and may thus represent a window on the distant, early Universe. We describe the major results obtained in the past decade on the star formation histories, chemical abundances, galaxy formation and evolution of star-forming dwarfs, and the uncertainties still affecting these results.

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“…This would allow us to identify LSBGs in our galaxy population in a way more closely comparable to observational results, while continuing to benefit from the reproducibility and modularity of the pipeline presented in this work. The inclusion of metallicity evolution, in particular that of O/H, would allow comparison with the populations of extremely metal-poor gas-rich, dwarf galaxies that seem to characterise a difference between void and non-void galaxy formation (Pustilnik et al 2020).…”

Section: Future Extensionsmentioning

confidence: 99%

The role of the elaphrocentre in void galaxy formation

Marius

Roukema

2021

Monthly Notices of the Royal Astronomical Society

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Voids may affect galaxy formation via weakening mass infall or increasing disk sizes, which could potentially play a role in the formation of giant low surface brightness galaxies (LSBGs). If a dark matter halo forms at the potential hill corresponding to a void of the cosmic web, which we denote the “elaphrocentre” in contrast to a barycentre, then the elaphrocentre should weaken the infall rate to the halo when compared to infall rates towards barycentres. We investigate this hypothesis numerically. We present a complete software pipeline to simulate galaxy formation, starting from a power spectrum of initial perturbations and an N-body simulation through to merger-history-tree based mass infall histories. The pipeline is built from well-established, free-licensed cosmological software packages, and aims at highly portable long-term reproducibility. We find that the elaphrocentric accelerations tending to oppose mass infall are modest. We do not find evidence of location in a void or elaphrocentric position weakening mass infall towards a galaxy. However, we find indirect evidence of voids influencing galaxy formation: while void galaxies are of lower mass compared to galaxies in high density environments, their spin parameters are typically higher. For a fixed mass, the implied disk scale length would be greater. Tangential accelerations in voids are found to be high and might significantly contribute to the higher spin parameters. We find significantly later formation epochs for void galaxies; this should give lower matter densities and may imply lower surface densities of disk galaxies. Thus, void galaxies have higher spin parameters and later formation epochs; both are factors that may increase the probability of forming LSBGs in voids.

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XMP gas-rich dwarfs in nearby voids: results of SALT spectroscopy

Cited by 17 publications

References 57 publications

Improving Helium Abundance Determinations with Leo P as a Case Study

Improving Helium Abundance Determinations with Leo P as a Case Study

Chemical and stellar properties of star-forming dwarf galaxies

The role of the elaphrocentre in void galaxy formation

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