Even stronger abundance enhancements, #92;deltaY#95;p#47;Y#95;p ~ a few 10#123;-3#125;, may arise at much later, post-reionization epochs, z ~ 2, in protogroups of galaxies (#92;sim 10#123;13#125;M#95;#123;#92;odot#125;) as a result of accretion of warm-hot intergalactic medium with T ~ 10^6 K.
Source: wiktionary