Reciprocal System Research Society

"This was particularly intriguing because radio pulses don't come from an X-ray binary and the X-ray source has to be long gone before radio signals can emerge."

Read more at: http://phys.org/news/2013-09-jekyll-hyd ... radio.html

Once you understand that radio pulses occur when matter is accelerated FTL, and X-rays when it drops back to sublight speeds, this situation makes a lot more sense. It probably does not have anything to do with the companion star, if you look at Larson's analysis of nova (not supernova).

Remember that these white dwarf/neutron stars are just moving more in 3D time than in 3D space, so they are cooling and expanding, and have an inverse density gradient--so all the light matter is on the inside. When gas pressure causes that internal matter to erupt, the extremely hot surface will accelerate it to FTL speeds, just as our own sun does when it flares. That acceleration will produce radio pulses, and once it diminishes, you'll be back to X-rays.