Glitch (astronomy)
Encyclopedia
A glitch is a sudden increase (up to 1 part in 106) in the rotational frequency
of a rotation-powered pulsar, which usually decreases steadily due to braking provided by the emission of radiation and high-energy particles. It is unknown whether or not they are related to the timing noise
which all pulsars exhibit. Following a glitch is a period of gradual recovery where the observed periodicity
slows to a period close to that observed before the glitch. These gradual recovery periods have been observed to last from days to years. Currently, only multiple glitches of the Crab
and Vela
pulsars have been observed and studied extensively
core to the crust, which are usually decoupled. This brief coupling transfers angular momentum from core to the surface, which causes an increase in the measured periodicity. It is thought that the coupling could be caused by a breaking of the pulsar's magnetic dipole, which would apply a torque to the crust causing a brief coupling between the two parts.
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
of a rotation-powered pulsar, which usually decreases steadily due to braking provided by the emission of radiation and high-energy particles. It is unknown whether or not they are related to the timing noise
Timing noise
Timing noise is the name for rotational irregularities observed in all pulsars. This timing noise is observable as random wandering in the pulse frequency or phase. It is unknown whether timing noise is related to pulsar glitches....
which all pulsars exhibit. Following a glitch is a period of gradual recovery where the observed periodicity
Frequency
Frequency is the number of occurrences of a repeating event per unit time. It is also referred to as temporal frequency.The period is the duration of one cycle in a repeating event, so the period is the reciprocal of the frequency...
slows to a period close to that observed before the glitch. These gradual recovery periods have been observed to last from days to years. Currently, only multiple glitches of the Crab
Crab Pulsar
The Crab Pulsar is a relatively young neutron star. The star is the central star in the Crab Nebula, a remnant of the supernova SN 1054, which was widely observed on Earth in the year 1054...
and Vela
Vela Pulsar
The Vela Pulsar is a radio, optical, X-ray and gamma-emitting pulsar associated with Vela Supernova Remnant, in the constellation of Vela.- Supernova origins :...
pulsars have been observed and studied extensively
Cause
While the exact cause of glitches is unknown, they are thought to be caused by an internal process within the pulsar. This differs from the steady decrease in the star's rotational frequency which is caused by external processes. Although the details of the glitch process are unknown, it is thought that the resulting increase in the pulsar's rotational frequency is caused by a brief coupling of the pulsar's faster-spinning superfluidSuperfluid
Superfluidity is a state of matter in which the matter behaves like a fluid without viscosity and with extremely high thermal conductivity. The substance, which appears to be a normal liquid, will flow without friction past any surface, which allows it to continue to circulate over obstructions and...
core to the crust, which are usually decoupled. This brief coupling transfers angular momentum from core to the surface, which causes an increase in the measured periodicity. It is thought that the coupling could be caused by a breaking of the pulsar's magnetic dipole, which would apply a torque to the crust causing a brief coupling between the two parts.