>>62
>（1の3乗根が含まれるか否かは、別の議論が必要でしょ）

下記の議論が、参考になると思う
（細かいところは、殆ど読めてないけどｗ）

https://arxiv.org/pdf/2202.00219.pdf
Approximating Absolute Galois Groups
Gunnar Carlsson, Roy Joshua
February 2, 2022

P4
where S1 denotes the circle group,

Proposition 2.3 The construction A → A＾ satisfies the following properties.
1. The＾-construction defines an equivalence of categories from the category of compact topological
abelian groups to the opposite of the category of discrete abelian groups. The＾-construction is
its own inverse.
2. For a profinite group G, G＾ is isomorphic to Homc(G, μ∞), where μ∞ ⊆ S1 is the group of
all roots of unity, isomorphic to Q/Z. If G is a p-profinite group, then μ∞ can be replaced by
μp∞, the group of all p-power roots of unity, isomorphic to Z[1/p]/Z.
3. The functor A → A＾ is exact.
4. For G a profinite abelian group, G is torsion free if and only if G＾ is divisible. Similarly for
“p-torsion free” and “p-divisible”.

Proof: Statement (1) is one version of the statement of the Pontrjagin duality theorem, (2) is an
immediate consequence, and (3) follows immediately from (1). It remains to prove (4). To prove
(4), we note that G is torsion free if and only if the sequence 0 → G ー(×n) -→ G is exact. The exactness
proves that this occurs if and only if G＾
G＾ ×n ー(×n) -→G＾-→ 0 is exact, so ×n is surjective. This is the result.

We now have the main result of this section.
Theorem 2.1 Let F be any field containing all roots of unity. Then the absolute Galois group GF
of F is totally torsion free.
Remark 2.3 Class field theory shows, for example, that one cannot expect this result to hold for
absolute Galois groups of number fields, so that some condition on the field is necessary.
(引用終り)
以上