The hyperfine transition of 3He+ as a probe of the intergalactic medium

We explore the prospects of using the hyperfine transition of 3He+ as a probe of the intergalactic medium. The emission signal from ionized regions during reionization is expected to be anti-correlated with 21cm maps. The predicted emission signal from Lyman-alpha blobs at lower redshifts is detectable with future radio observatories.