Has Bhrgu an IE etymology? Is it from *bHleg- "to burn, shine" or *bHerg- "white" ?
Is it analogous to Rbhu. Rbhu is akin to ON alfr; R.bhu < *h2LbHus, alfr < *h2elbHos.
By analogy, we can propose a *bHRgu- / *bHergos alternation?
Manu could fit in this form (zero grade + u = adjective?)
Manu < *mnu, *mnHu-, *mNnu- *mMnu - ????
Joao SL