Discovery of the most metal-poor damped Lyman-α system

Cooke, Ryan; Steidel, Charles C.

doi:10.1093/mnras/stx037

Cited by 61 publications

(74 citation statements)

References 97 publications

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“…Three out of the four absorbers show significantly subsolar [C/O] ratios. The [C/O] ratios found in these z ∼ 5 absorbers are similar to the typical value of −0.28 ± 0.12 for the very metal-poor (VMP) DLAs (Cooke et al 2011(Cooke et al , 2017. Two out of four of our z ∼ 5 absorbers show strong depletion of Fe relative to O.…”

Section: Dust Depletionsupporting

confidence: 83%

Early metal enrichment of gas-rich galaxies at z ∼ 5

Poudel

Kulkarni

Morrison

et al. 2017

Monthly Notices of the Royal Astronomical Society

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We present abundance measurements of elements O, C, Si and Fe for three gas-rich galaxies at z∼5 using observations from the Very Large Telescope (VLT) and the Keck telescope in order to better constrain the early chemical enrichment of gas-rich galaxies. These galaxies show strong Lyman-α absorption in the spectra of background quasars, with neutral hydrogen column densities log N H I (cm −2 ) = 20.10±0.15, 20.10±0.15, and 20.80±0.15. Using the undepleted element O, we find the metallicities [O/H] to be in the range of −2.51 to −2.05 dex. Our study has doubled the existing sample of measurements of undepleted elements at z > 4.5. Combining our measurements with those from the literature, we find that the N H I -weighted mean metallicity of z∼5 absorbers is consistent with the prediction based on z < 4.5 DLAs. Thus, we find no significant evidence of a sudden drop in metallicity at z > 4.7 as reported by some prior studies. We also determine the extent of dust depletion using a combination of both the volatile element O and the refractory elements Si and/or Fe. Some of the absorbers show evidence of depletion of elements on dust grains, e.g. low [Si/O] or [Fe/O]. The relative abundances of these absorbers along with other z∼5 absorbers from the literature show some peculiarities, e.g. low [C/O] in several absorbers and high [Si/O] in one absorber. Finally, we find that the metallicity vs. velocity dispersion relation of z∼5 absorbers may be different from that of lower-redshift absorbers.

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Section: Dust Depletionsupporting

confidence: 83%

Early metal enrichment of gas-rich galaxies at z ∼ 5

Poudel

Kulkarni

Morrison

et al. 2017

Monthly Notices of the Royal Astronomical Society

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“…In contrast to this, a similar analysis performed by Grimmett et al (2018) found that the abundance patterns of EMP halo stars are best described by the yields of (5 − 10) × 10 51 erg explosions (i.e hypernovae). This preference towards enrichment by a population of high energy SNe was also reported by Cooke et al (2017) and Ishigaki et al (2018). Furthermore, the observed overabundance of [Zn/Fe] in the most metal-poor halo stars (Primas et al 2000;Cayrel et al 2004), is thought to be due to enrichment by a population of hypernovae (Umeda & Nomoto 2002).…”

Section: Explosion Energysupporting

confidence: 75%

“…To isolate the chemical signature of the first stars, we should restrict our analysis to the most metal-deficient DLAs, ideally, those with [O/H] < −3. Currently, there are not enough systems known within this regime to implement such an analysis -only one system, J0903+2628, has been found with an oxygen abundance [O/H] < −3 (Cooke et al 2017).…”

Section: Slopementioning

confidence: 99%

Modelling the chemical enrichment of Population III supernovae: The origin of the metals in near-pristine gas clouds.

Welsh

Cooke

Fumagalli

2019

Monthly Notices of the Royal Astronomical Society

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The most metal-poor, high redshift damped Lyman α systems (DLAs) provide a window to study some of the first few generations of stars. In this paper, we present a novel model to investigate the chemical enrichment of the near-pristine DLA population. This model accounts for the mass distribution of the enriching stellar population, the typical explosion energy of their supernovae, and the average number of stars that contribute to the enrichment of these DLAs. We conduct a maximum likelihood analysis of these model parameters using the observed relative element abundances ([C/O], [Si/O], and [Fe/O]) of the 11 most metal-poor DLAs currently known. We find that the mass distribution of the stars that have enriched this sample of metal-poor DLAs can be well-described by a Salpeter-like IMF slope at M > 10 M and that a typical metal-poor DLA has been enriched by 72 massive stars (95 per cent confidence), with masses 40 M . The inferred typical explosion energy (Ê exp = 1.8 +0.3 −0.2 × 10 51 erg) is somewhat lower than that found by recent works that model the enrichment of metal-poor halo stars. These constraints suggest that some of the metal-poor DLAs in our sample may have been enriched by Population II stars. Using our enrichment model, we also infer some of the typical physical properties of the most metal-poor DLAs. We estimate that the total stellar mass content is log 10 (M /M ) = 3.5 +0.3 −0.4 and the total gas mass is log 10 (M gas / M ) = 7.0 +0.3 −0.4 for systems with a relative oxygen abundance [O/H] ≈ −3.0.

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“…Population III star are imprinted on the observed DLA, indicating that such systems could be the predecessors of UFDs (Cooke et al 2017). All these avenues promise to offer fundamental insights into the nature of the first generation of stars and into the metal enrichment history of the early universe.…”

Section: Discussionmentioning

confidence: 96%

Connecting the First Galaxies with Ultrafaint Dwarfs in the Local Group: Chemical Signatures of Population III Stars

Jeon

Besla

Bromm

2017

ApJ

142

183

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We investigate the star formation history (SFH) and chemical evolution of isolated analogs of Local Group (LG) ultrafaint dwarf galaxies (UFDs; stellar mass range of) and gas-rich, low-mass dwarfs (Leo P analogs; stellar mass range of). We perform a suite of cosmological hydrodynamic zoom-in simulations to follow their evolution from the era of the first generation of stars down to z=0. We confirm that reionization, combined with supernova (SN) feedback, is primarily responsible for the truncated star formation in UFDs. Specifically, halos with a virial mass of ´ M M 2 10 vir 9form 90% of stars prior to reionization. Our work further demonstrates the importance of PopulationIII stars, with their intrinsically high [ ] C Fe yields and the associated external metal enrichment, in producing low-metallicity stars (  -[ ] Fe H 4) and carbon-enhanced metal-poor (CEMP) stars. We find that UFDs are composite systems, assembled from multiple progenitor halos, some of which hosted only PopulationII stars formed in environments externally enriched by SNe in neighboring halos, naturally producing extremely low metallicity Population II stars. We illustrate how the simulated chemical enrichment may be used to constrain the SFHs of true observed UFDs. We find that Leo P analogs can form in halos with~´ M M 4 10 vir 9(z = 0). Such systems are less affected by reionization and continue to form stars until z=0, causing higher-metallicity tails. Finally, we predict the existence of extremely low metallicity stars in LG UFD galaxies that preserve the pure chemical signatures of Population III nucleosynthesis.

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Discovery of the most metal-poor damped Lyman-α system

Cited by 61 publications

References 97 publications

Early metal enrichment of gas-rich galaxies at z ∼ 5

Early metal enrichment of gas-rich galaxies at z ∼ 5

Modelling the chemical enrichment of Population III supernovae: The origin of the metals in near-pristine gas clouds.

Connecting the First Galaxies with Ultrafaint Dwarfs in the Local Group: Chemical Signatures of Population III Stars

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