JWST-JADES. Possible Population III signatures at z=10.6 in the halo of GN-z11

Understand

Finding the first generation of stars formed out of pristine gas in the early Universe, known as Population III (PopIII) stars, is one of the most important goals of modern astrophysics.

• Recent models have suggested that PopIII stars may form in pockets of pristine gas in the halo of more evolved galaxies.
• We present NIRSpec integral field spectroscopy and micro-shutter array spectroscopic observations of the region around GN-z11, an exceptionally luminous galaxy at z=10.6, that reveal a greater than 5 sigma detection of a feature consistent with being HeII1640 emission at the redshift of GN-z11.
• The very high equivalent width of the putative HeII emission in this clump (log(EW_rest(HeII)/A) = 1.79) and a lack of metal lines can be explained in terms of photoionisation by PopIII stars, while photoionisation by PopII stars is inconsistent with the data.