A survey of extremely metal-poor gas at cosmic noon: evidence of elevated [O/Fe]

arXiv - PHYS - Astrophysics of Galaxies Pub Date : 2024-09-11 DOI:arxiv-2409.07525

Louise Welsh, Ryan Cooke, Michele Fumagalli, Max Pettini, Gwen C. Rudie

{"title":"A survey of extremely metal-poor gas at cosmic noon: evidence of elevated [O/Fe]","authors":"Louise Welsh, Ryan Cooke, Michele Fumagalli, Max Pettini, Gwen C. Rudie","doi":"arxiv-2409.07525","DOIUrl":null,"url":null,"abstract":"We aim to study the high-precision chemical abundances of metal-poor gas\nclouds at cosmic noon (2<z<4) and investigate the associated enrichment\nhistories. We analyse the abundances of four newly discovered metal-poor gas\nclouds utilising observations conducted with Keck/HIRES and VLT/UVES. These\nsystems are classified as very metal-poor (VMP), with [Fe/H]<-2.57, and one\nsystem qualifies as an extremely metal-poor (EMP) Damped Lyman-alpha (DLA)\nsystem with [Fe/H]=-3.13+/-0.06. In combination with new high-resolution data\nof two previously known EMP DLAs and 2 systems reported in the literature, we\nconduct a comprehensive analysis of eight of the most metal-poor gas clouds\ncurrently known. We focus on high-precision abundance measurements using the\nelements: C, N, O, Al, Si, and Fe. Our findings indicate increasing evidence of\nelevated [O/Fe] abundances when [Fe/H]<-3. EMP DLAs are well-modelled with a\nmean value of [O/Fe]=+0.50 +/- 0.04 and an intrinsic scatter of\n$\\sigma_{int,[O/Fe]}=0.13^{+0.06}_{-0.04}$. While VMP DLAs are well-modelled\nwith [O/Fe]=+0.40 +/- 0.02 and $\\sigma_{int,[O/Fe]}$=0.06 +/- 0.02. We further\nfind tentative evidence of a redshift evolution of [C/O] across these most\nmetal-poor DLAs with lower redshift systems showing elevated [C/O] ratios.\nUsing the measured abundances, combined with a stochastic chemical enrichment\nmodel, we investigate the properties of the stellar population responsible for\nenriching EMP gas at cosmic noon. We find that the chemistry of these systems\nis best explained via the enrichment of just two massive progenitors,\nN_*=2+/-1, that ended their lives as core collapse SNe with a typical explosion\nenergy E_exp=(1.6 +/- 0.6)x10$^{51}$ erg. These progenitors formed obeying a\nSalpeter-like power-law IMF, where all stars of mass greater than\nM_max=32$^{+10}_{-4}$ M_sun collapse directly to black holes and do not\ncontribute to the metal enrichment.","PeriodicalId":501187,"journal":{"name":"arXiv - PHYS - Astrophysics of Galaxies","volume":"396 1","pages":""},"PeriodicalIF":0.0000,"publicationDate":"2024-09-11","publicationTypes":"Journal Article","fieldsOfStudy":null,"isOpenAccess":false,"openAccessPdf":"","citationCount":"0","resultStr":null,"platform":"Semanticscholar","paperid":null,"PeriodicalName":"arXiv - PHYS - Astrophysics of Galaxies","FirstCategoryId":"1085","ListUrlMain":"https://doi.org/arxiv-2409.07525","RegionNum":0,"RegionCategory":null,"ArticlePicture":[],"TitleCN":null,"AbstractTextCN":null,"PMCID":null,"EPubDate":"","PubModel":"","JCR":"","JCRName":"","Score":null,"Total":0}