X-ray pulsar

A Röntgenpulsar is a neutron star, the rotation produced by a strictly periodic modulated signal in the field of X-ray radiation with a period length of milliseconds to 1000 seconds. Röntgenpulsare are divided on the cause of the emitted electromagnetic radiation in akkretionsangetriebene, rotationally driven and unusual Röntgenpulsare.

Akkretionsangetriebene Röntgenpulsare

Akkretionsangetriebene Röntgenpulsare (English accretion powered X -ray pulsars ) are always part of an X-ray binary star. The observed period values ​​fall within the range of a few milliseconds to 1000 seconds. It is also reported extreme periods of up to a few hours, they must still be confirmed. After the type of the companion of the neutron star, the X-ray binaries in High Mass X -ray binaries ( HMXB ) in which the companion is an early giant, or divided in Low Mass X -ray binaries ( LMXB ) with an accompanying late main sequence star. The LMXBs matter from companion by Roche- border river flows to the compact star, while the accretion occurs at the HMXBs over the stellar wind of the massive star. X-rays produced upon impingement of the ionized material on the magnetic poles of the neutron star, wherein the material heats up, and the energy is emitted through Bremsstrahlung and synchrotron radiation. The periodic modulation of the radiation is a result of the rotation of the star, whereby the inclined against the rotation axis of the magnetic poles are intermittently visible or invisible.

Rotation Driven Röntgenpulsare

Rotation Driven Röntgenpulsare (English rotationally powered X -ray pulsars ) are identical to the radio pulsars. Examples are the Vela pulsar and the pulsar in the Crab Nebula, which emit pulsed radio emission in addition to periodically modulated optical, UV, X-ray and gamma radiation. The pulse profile in the field of X-ray radiation, in contrast to the long-wavelength emission is often a double maximum per rotation period. The observed periods in the rotationally driven X-ray pulsars are between 1.5 milliseconds and 5 seconds, with long-period pulsars are weak emitters in the field of X-ray radiation. The pulsed component of the X-ray radiation is generated as the radio emission by synchrotron radiation in the rotating magnetic field of the neutron star. In young rotation- powered X-ray pulsars, thermal and non-modulated component is still present, which is interpreted as blackbody radiation of several million degrees warm surface of the neutron star. The luminosity of pulsars decreases with time, with the maximum values ​​in the range of 1034-1036 erg / s.

Rotation Driven Röntgenpulsare send their signals from permanently and with great temporal predictability. These properties can be used to make a local determination with an accuracy of five kilometers in interplanetary space. The function corresponds to the Global Positioning System, can be calculated at runtime from the differences of the pulsed signals of the place.

Unusual Röntgenpulsare

Unusual Röntgenpulsare (English anomaleous X -ray pulsars, short AXPs ) are a small group of pulsating X-ray sources with periods of 2-12 seconds. They show strong outbursts with luminosities of 1042-1044 erg per eruption. Your spin-down age is about 10,000 to 100,000 years. Most AXPs repeat their eruptions at a distance of a few years and are closely related to the soft gamma repeaters, whose eruptions and pulsations was detected in the area of ​​soft gamma radiation. Between the two groups there is probably no difference, since some AXPs can also be detected in the area of ​​gamma radiation. Today, they are interpreted as manifestations of magnetars. Magnetars are neutron stars with the strongest known magnetic flux densities of 1014-1016 Gauss. The eruptions are interpreted as the energy that is released in a short circuit of magnetic flux lines at the surface of the neutron stars.

A small group of unusual Röntgenpulsare, which are called low magnetic field magnetars, are characterized by a very low deceleration of the rotation with deceleration rates of 10-13 s / s The properties of these Röntgenpulsare can also be described by rotating white dwarfs with magnetic field densities of 108 Gauss. In particular, the observed Periodenspünge are more compatible with the assumption of a massive white dwarf as a neutron star.

Relationship between akkretionsangetriebene and rotationally driven X-ray pulsars

For a long time it is assumed that akkretionsangetriebene Röntgenpulsare are the precursors of the rotationally driven Millisekundenpulsare. Due to the accretion of matter and angular momentum is transferred to the neutron star, which increases the rotational frequency. IGR J18245 - 2452 with a transfer system has been observed, which can be detected as a time and at other times as Radiomillisekundenpulsar akkretionsangetriebene Röntgenpulsar. The matter is accreted even temporarily, can be confirmed on the basis of thermonuclear bursts.


  • Pulsar
  • Ray binary