A method of definitely distinguishing a neutron star from a possible stellar black hole is that it produces X-ray bursts, which have a sharp rise time and may last for an extended period. I had previously thought these occurred when hydrogen fell to the surface and was immediately fused to helium, but I've now learned that bursts are thought to occur when an amount of helium has built up and undergoes further fusion in a chain reaction. It occurs to me that this type of burst might therefore not be possible if the neutron star were sufficiently massive that the falling hydrogen was already sufficiently energetic to fuse beyond helium at a rate sufficient to prevent any build-up. I don't know the details of the required energy, but it seems that this could mean that neutron stars above some mass threshold might not produce X-ray flashes, making it difficult to tell the difference from a black hole. Is it known whether this burst suppression might actually occur within the range of masses expected for neutron stars, and if so can anyone point me to any further information on the subject?