I had a question about Tech Priest. I'm new to the 40K universe, so I wondering if any could answer a question about if a group of Rogue Traders "acquire" suits of power armor, would Space Marines be able to detect Space Marine Power Armor on the Rogue Trader's ship.

Just FYI, I think your post's subject is off.

If the power armour is originally from space marines, then I might actually say yes, they could probably at least detect the fusion power packs, and possibly that their machine spirits are working within the tolerances used by the Astartes.

Now, just to point out, regular humans don't wear Astartes power armour, so some significant changes would have to made to the suits themselves to accommodate "normal" people. So much so that in fact, the properties of the suit could show up different on the auger arrays.