Rapid Chemical Enrichment by Intermittent Star Formation in GN-z11

Kobayashi, Chiaki; Ferrara, Andrea

doi:10.3847/2041-8213/ad1de1

Cited by 13 publications

(1 citation statement)

References 65 publications

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“…This is far too rapid for enrichment by AGB stars. Previous studies suggest that either WR, super massive stars, tidal disruption events, or active galactic nuclei environments could be responsible for the high nitrogen abundances (e.g., Matsuoka et al 2017;Cameron et al 2023;Kobayashi & Ferrara 2024). However, the nitrogen and carbon lines observed within GN-z11 are rarely detected in local star-forming galaxies, such that a complete understanding of the production and origin of these features has not fully been revealed.…”

Section: Introductionmentioning

confidence: 99%

CHAOS. VIII. Far-ultraviolet Spectra of M101 and the Impact of Wolf–Rayet Stars*

Berg,

Skillman,

Chisholm

et al. 2024

ApJ

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We investigate the stellar and nebular properties of nine H ii regions in the spiral galaxy M101 with far-ultraviolet (FUV; ∼900–2000 Å) and optical (∼3200–10,000 Å) spectra. We detect significant C iii] λλ1907,1909 nebular emission in seven regions, but O iii] λ1666 only in the lowest-metallicity region. We produce new analytic functions of the carbon ionization correction factors as a function of metallicity in order to perform a preliminary C/O abundance analysis. The FUV spectra also contain numerous stellar emission and P-Cygni features that we fit with luminosity-weighted combinations of single-burst Starburst99 and BPASS models. We find that the best-fit Starburst99 models closely match the observed very-high-ionization P-Cygni features, requiring very hot, young (≲3 Myr), metal-enriched massive stars. The youngest stellar populations are strongly correlated with broad He ii emission, nitrogen Wolf–Rayet (WR) FUV and optical spectral features, and enhanced N/O gas abundances. Thus, the short-lived WR phase may be driving excess emission in several N P-Cygni wind features (λ955, λ991, λ1720) that bias the stellar continuum fits to higher metallicities relative to the gas-phase metallicities. Accurate characterization of these H ii regions requires additional inclusion of WR stars in the stellar population synthesis models. Our FUV spectra demonstrate that the ∼900–1200 Å FUV can provide a strong test bed for future WR atmosphere and evolution models.

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Section: Introductionmentioning

confidence: 99%

CHAOS. VIII. Far-ultraviolet Spectra of M101 and the Impact of Wolf–Rayet Stars*

Berg,

Skillman,

Chisholm

et al. 2024

ApJ

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Explaining the high nitrogen abundances observed in high-z galaxies via population III stars of a few thousand solar masses

Nandal,

Regan,

Woods

et al. 2024

A&A

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Efforts to understand the origin and growth of massive black holes observed in the early Universe have spurred a strong interest in the evolution and fate of rapidly-accreting primordial (metal-free) stars. Here, we investigate the evolution of such Population III (Pop III) stars under variable accretion rates, focusing on the thermal response and stellar structure, the impact of the luminosity wave encountered early in the evolution of these stars, and the influence of accretion on their physical parameters. We employ the Geneva stellar evolution code and simulate ten models with varying accretion histories, covering a final mass range from 491 to 6127 Our findings indicate that the critical accretion rate delineating the red and blue supergiant regimes during the pre-main sequence evolution is approximately $2.5 Once core hydrogen burning commences, the value of this critical accretion rate drops to $7.0 Moreover, we also confirm that the Kelvin-Helmholtz timescale in the outer surface layers is the more relevant timescale for determining the transition between red and blue phases. Regarding the luminosity wave, we find that it affects only the early pre-main sequence phase of evolution and does not directly influence the transition between red and blue phases, which primarily depends on the accretion rate. Finally, we demonstrate that variable accretion rates significantly impact the physical parameters of our models, including their lifetimes and time spent in the red phase. Our study provides a comprehensive understanding of the intricate evolutionary patterns of Pop III stars subjected to variable accretion rates.

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Super-early JWST galaxies, outflows, and Lyαvisibility in the Epoch of Reionization

Ferrara

2024

A&A

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The overabundance of super-early (redshift $z>10$) luminous ($M_ UV < -20$) blue galaxies detected by JWST has been explained as being due to negligible dust attenuation in these systems. We show that this model correctly reproduces the UV luminosity function at $z>10$ and the star formation rate (SFR) density evolution. The model also predicts, in agreement with data, that the cosmic specific SFR (sSFR) grows as $ sSFR $. At $z 10$, the cosmic sSFR crosses the critical value $ sSFR^ $, and approximately $45$<!PCT!> of the galaxies become super-Eddington, driving outflows reaching velocities of $ where $ and $f_M$ are the star formation efficiency and fraction of the halo gas expelled in the outflow, respectively. This prediction is consistent with the outflow velocities measured in 12 super-Eddington galaxies of the JWST /JADES sample. Such outflows clear the dust, thus boosting the galaxy luminosity. They also dramatically enhance the visibility of the Lyalpha line from $z>10$ galaxies by introducing a velocity offset. The observed Lyalpha properties in GN-z11 ($z=10.6$) are simultaneously recovered by the outflow model if $ HI 20.1$, implying that the outflow is largely ionized. We make analogous predictions for the Lyalpha visibility of other super-early galaxies, and we compare the model with Lyalpha surveys at $z>7$, finding that essentially all super-Eddington (sub-Eddington) galaxies are (not) detected in Lyalpha . Finally, the sSFR positively correlates with the LyC escape fraction, as outflows carve ionized transparent channels through which LyC photons leak.

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Rapid Chemical Enrichment by Intermittent Star Formation in GN-z11

Cited by 13 publications

References 65 publications

CHAOS. VIII. Far-ultraviolet Spectra of M101 and the Impact of Wolf–Rayet Stars*

CHAOS. VIII. Far-ultraviolet Spectra of M101 and the Impact of Wolf–Rayet Stars*

Explaining the high nitrogen abundances observed in high-z galaxies via population III stars of a few thousand solar masses

Super-early JWST galaxies, outflows, and Lyαvisibility in the Epoch of Reionization

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