Rotating Radio Transient - Possible Pulse Mechanisms

Possible Pulse Mechanisms

In order to explain the irregularity of RRAT pulses, we note that most of the pulsars which have been labelled as RRATs are entirely consistent with pulsars which have regular underlying emission which is simply undetectable due to the low intrinsic brightness or large distance of the sources. However, assuming that when we do not detect pulses from these pulsars that they are truly 'off', several authors have proposed mechanisms whereby such sporadic emission could be explained. For example, as pulsars gradually lose energy, they approach what is called the pulsar "death valley," a theoretical area in pulsar pulsar period - period derivative space, where the pulsar emission mechanism is thought to fail but may become sporadic as pulsars approach this region. However although this is consistent with some of the behavior of RRATs, the RRATs with known periods and period derivatives do not lie near canonical death regions. Another suggestion is that asteroids might form in the debris of the supernova that formed the neutron star, and infall of these debris in to the light cone of RRATs and some other types of pulsars might cause some of the irregular behavior observed. To confirm this would require directly observing the debris surrounding a neutron star, which is presently not possible, but may be possible in the future with the Square Kilometer Array. Nevertheless, as more RRATs are detected by observatories such as Arecibo, the Green Bank Telescope, and the Parkes Observatory at which RRATs were first discovered, some of the characteristics of RRATs may become clearer.