Varnias Tybalt said:
Of course, you could use that for a story idea. The Rogue Traders, while exploring the Koronus Expanse, discover a small warp anomaly. On further investigation, they discover that it seemingly doesn't lead anywhere. Then they're hailed by a tiny ship of unknown design.
"This is the USS Enterprise. Unknown vessel, please identify yourselves."
Yes, they've appeared in the Alpha Quadrant; it's where the Segmentum Obscurus is in the Star Trek galaxy.
Here's a pretty acurate description of a Star Trek/Warhammer 40.000 crossover:
Not really. I doubt they'd skip straight to Purging, especially if it's a human that's the Captain. A Rogue Trader certainly wouldn't; he'd realize that he's dealing with heathens who are allied with Xenos and promptly attempt to work out some way to get more Profit out of it, and maybe attempt to conquer them for his own wealth and glory. Even the Inquisition wouldn't skip straight to Purging, though; that's the last step of the process. They'd need to investigate to determine how widespread the rot is first, at the very least.