Anomalous X-ray pulsar
Encyclopedia
Anomalous X-ray Pulsars are now widely believed to be magnetar
Magnetar
A magnetar is a type of neutron star with an extremely powerful magnetic field, the decay of which powers the emission of copious high-energy electromagnetic radiation, particularly X-rays and gamma rays...

s—young, isolated, highly magnetized neutron star
Neutron star
A neutron star is a type of stellar remnant that can result from the gravitational collapse of a massive star during a Type II, Type Ib or Type Ic supernova event. Such stars are composed almost entirely of neutrons, which are subatomic particles without electrical charge and with a slightly larger...

s. These energetic X-ray pulsar
X-ray pulsar
X-ray pulsars or accretion-powered pulsars are a class of astronomical objects that are X-ray sources displaying strict periodic variations in X-ray intensity...

s are characterized by slow rotation periods of ~2–12 seconds and large magnetic field
Magnetic field
A magnetic field is a mathematical description of the magnetic influence of electric currents and magnetic materials. The magnetic field at any given point is specified by both a direction and a magnitude ; as such it is a vector field.Technically, a magnetic field is a pseudo vector;...

s of ~1013–1015 gauss
Gauss (unit)
The gauss, abbreviated as G, is the cgs unit of measurement of a magnetic field B , named after the German mathematician and physicist Carl Friedrich Gauss. One gauss is defined as one maxwell per square centimeter; it equals 1 tesla...

 (1 to 100 gigateslas). There are currently 9 known and 1 candidate AXPs. The identification of AXPs with magnetars was motivated by their similarity to another enigmatic class of sources, the soft gamma repeater
Soft gamma repeater
A soft gamma repeater is an astronomical object which emits large bursts of gamma-rays and X-rays at irregular intervals. It is conjectured that they are a type of magnetar or, alternatively, neutron stars with fossil disks around them....

s.
A list of AXP candidates and their estimated rotation period in seconds, as of 2003, follows:
AXP 1E 2259+586  6.98  
AXP 1E 1048-59
AXP 1E 1048-59
Anomalous X-ray pulsar 1E 1048.1-5937 was the first AXP ever observed to emit an SGR-like X-ray burst....

 
6.45  
AXP 4U 0142+61  8.69  
AXP 1RXS 1708-40  11.0  
AXP 1E 1841-045  11.8  
AXP AXJ1844-0258  6.97  
AXP CXJ0110-7211 5.44  
Please note that the second, fourth, and last names were abbreviated

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