I have a 2004 audi s4
6 speed
130000 miles


while driving I started hearing a loud rattle coming from my car, I looked later that day and found some loose bolts that had come from this part of the car, does anyone know what part this is, I found about 3 bolts sitting in the area above the oil pan.

I have included 2 photos, one is just a bit closer up

 

It is the drive shaft for the A/C compressor. These are shaft driven on this engine instead of the traditional belt driven type. You need to get those bolts back in and tightened down before that shaft gets loose and flops around messing things up.