ArcMap EMF files - anthonyblackham/GIS-Wiki GitHub Wiki
If you want logos and icons to be scalable with your maps then you'll want something vector based. One way to do this is with an EMF file.
Adding an EMF file to arcmap:
Customize>Style Manager> C:\Users\USERNAME\AppData\Roaming\ESRI\Desktop10.x\Arcmap\USERNAME.style North arrows> New>symbol>edit symbol>type: Picture Marker Symbol Size: 80?