%0 Generic %1 wang2022strong %A Wang, Xin %A Cheng, Cheng %A Ge, Junqiang %A Meng, Xiao-Lei %A Daddi, Emanuele %A Yan, Haojing %A Jones, Tucker %A Malkan, Matthew A. %A Haro, Pablo Arrabal %A Brammer, Gabriel %A Oguri, Masamune %D 2022 %K library %T A strong He II $łambda$1640 emitter with extremely blue UV spectral slope at $z=8.16$: presence of Pop III stars? %U http://arxiv.org/abs/2212.04476 %X Cosmic hydrogen reionization and cosmic production of first metals are major phase transitions of the Universe occurring during the first billion years after the Big Bang, but still poorly explored observationally. Using the JWST NIRSpec prism spectroscopy, we report the discovery of a sub-$L_\ast$ galaxy at $z_spec=8.1623_-0.0008^+0.0007$, dubbed RXJ2129-z8HeII, via the detection of a series of strong rest-frame UV/optical nebular emission lines and the clear Lyman break. A strong He II $łambda$1640 emission is present, the highest redshift He II line currently known. Its high rest-frame equivalent width (EW $=19.4\pm3.2$ Angstrom) and extreme flux ratios with respect to UV metal lines and Balmer lines raise the possibility that part of RXJ2129-z8HeII's stellar populations could be Pop III-like. RXJ2129-z8HeII also shows a pronounced UV continuum with an extremely steep (i.e. blue) spectral slope of $\beta=-2.50\pm0.08$, the steepest amongst all spectroscopically confirmed galaxies at $z\gtrsim7$, in support of its very hard ionizing spectrum that could lead to a significant leakage of its ionizing flux. Therefore, RXJ2129-z8HeII is representative of the key galaxy population driving the cosmic reionization. To date, this is also the most compelling case where trace Pop III stars might coexist with more metal-enriched stars.

@misc{wang2022strong, abstract = {Cosmic hydrogen reionization and cosmic production of first metals are major phase transitions of the Universe occurring during the first billion years after the Big Bang, but still poorly explored observationally. Using the JWST NIRSpec prism spectroscopy, we report the discovery of a sub-$L_{\ast}$ galaxy at $z_{\rm spec}=8.1623_{-0.0008}^{+0.0007}$, dubbed RXJ2129-z8HeII, via the detection of a series of strong rest-frame UV/optical nebular emission lines and the clear Lyman break. A strong He II $\lambda$1640 emission is present, the highest redshift He II line currently known. Its high rest-frame equivalent width (EW $=19.4\pm3.2$ Angstrom) and extreme flux ratios with respect to UV metal lines and Balmer lines raise the possibility that part of RXJ2129-z8HeII's stellar populations could be Pop III-like. RXJ2129-z8HeII also shows a pronounced UV continuum with an extremely steep (i.e. blue) spectral slope of $\beta=-2.50\pm0.08$, the steepest amongst all spectroscopically confirmed galaxies at $z\gtrsim7$, in support of its very hard ionizing spectrum that could lead to a significant leakage of its ionizing flux. Therefore, RXJ2129-z8HeII is representative of the key galaxy population driving the cosmic reionization. To date, this is also the most compelling case where trace Pop III stars might coexist with more metal-enriched stars.}, added-at = {2022-12-09T08:49:31.000+0100}, author = {Wang, Xin and Cheng, Cheng and Ge, Junqiang and Meng, Xiao-Lei and Daddi, Emanuele and Yan, Haojing and Jones, Tucker and Malkan, Matthew A. and Haro, Pablo Arrabal and Brammer, Gabriel and Oguri, Masamune}, biburl = {https://www.bibsonomy.org/bibtex/2ee3fc8c4ef1ce7c8addc758a71d44a8d/gpkulkarni}, description = {A strong He II $\lambda$1640 emitter with extremely blue UV spectral slope at $z=8.16$: presence of Pop III stars?}, interhash = {10851fa645fd1ce456ca9ffef2814a7e}, intrahash = {ee3fc8c4ef1ce7c8addc758a71d44a8d}, keywords = {library}, note = {cite arxiv:2212.04476Comment: Submitted}, timestamp = {2022-12-09T08:49:31.000+0100}, title = {A strong He II $\lambda$1640 emitter with extremely blue UV spectral slope at $z=8.16$: presence of Pop III stars?}, url = {http://arxiv.org/abs/2212.04476}, year = 2022 }