I recently got an automated email from Twitter with the following subject (except with real user names):
username さん、username さん、username さんをご存じですか?
My question is about
を paired with
ご存じですか. As I understand it,
を normally marks the direct object of a verb. Therefore, I expect it to be followed by a transitive verb; if there is no verb, I expect one to be implied. However, this sentence ends with a noun and copula instead, so I can't make grammatical sense of it.
I assume this phrase is grammatical, as I got it in an email that was likely to be proofread, and I can find plenty of uses online on websites that I think are likely to contain standard Japanese.
So how does it work grammatically? The only explanation I can come up with is that
ご存じです is functioning as a transitive verb, like a polite/honorific form of
存じる. Is there a better explanation?