The bar is clamped in a metal vise, so the vise is very slightly heated and that side of the bar is much cooler.
Taken using the Topdon Android attachment.
I agree with the other commenter about why the saw has an arched back. It's not thermals. That blade is thin steel which is a poor path for heat. The temperature profile is mostly due to radiation and convection to the environment (semi-infinite) and has little to do with the bounds.