Fallback Disks, Magnetars and Other Neutron Stars

Abstract

The presence of matter with angular momentum, in the form of a fallback disk around a young isolated neutron star will determine its evolution. This leads to an understanding of many properties of different classes of young neutron stars, in particular a natural explanation for the period clustering of AXPs, SGRs and XDINs. The spindown or spinup properties of a neutron star are determined by the dipole component of the magnetic field. The natural possibility that magnetars and other neutron stars may have different strengths of the dipole and higher multipole components of the magnetic field is now actually required by observations on the spindown rates of some magnetars. This talk gives a broad overview and some applications of the fallback disk model to particular neutron stars. Salient points are: (i) A fallback disk has already been observed around the AXP 4U 0142+61 some years ago. (ii) The low observed spindown rate of the SGR 0418+5729 provides direct evidence that the dipole component of the field is in the $10^{12}G$ range. All properties of the SGR 0418+5729 at its present age can be explained by spindown under torques from a fallback disk. (iii) The anomalous braking index of PSR J1734-3333 can also be explained by the fallback disk model which gives the luminosity, period, period derivative and the period second derivative at the present age. (iv) These and all applications to a variety of other sources employ the same disk physics and evolution, differing only in the initial conditions of the disk.

7 pages, 2 figures. Invited talk, Proceedings of IAU Symposium 290, "Feeding Compact Objects: Accretion on All Scales", C. M. Zhang, T. Belloni, M. Mendez & S. N. Zhang (eds.), Beijing, China, 20-24 August 2012 (Typo corrected in version 2)

References in corpus (7)

• A Debris Disk Around An Isolated Young Neutron Star
• 1E 1547.0-5408: a radio-emitting magnetar with a rotation period of 2 seconds
• Distances to Anomalous X-ray Pulsars using Red Clump Stars
• Anomalous X-ray pulsars: Persistent States with Fallback Disks
• A Mid-Infrared Counterpart to the Magnetar 1E 2259+586
• On the X-Ray Light Curve, Pulsed-Radio Emission, and Spin Frequency Evolution of the Transient Anomalous X-Ray Pulsar Xte J1810--197 During its X-Ray Outburst
• On the X-ray Outbursts of Transient Anomalous X-ray Pulsars and Soft Gamma-ray Repeaters

Cited by in corpus (4)

• Long-period Pulsars as Possible Outcomes of Supernova Fallback Accretion
• The origin of the high-mass X-ray binary 4U 2206+54/BD +53 2790
• Searching for Debris Disks around Isolated Pulsars
• Do we see accreting magnetars in X-ray pulsars?