ON THE EVOLUTION OF YOUNG NEUTRON STARS WITH FALLBACK DISKS
Physics, Ph.D. Dissertation, 2012
Assoc. Prof. Ünal Ertan (Thesis supervisor), Prof. Dr. Mehmet Ali Alpar, Assoc. Prof. Mehmet Hakan Erkut, Prof. Dr. Ersin Göğüş, Assoc. Prof. Mehmet Keskinöz
Date &Time: 22.01.2013 - 10:00
Place: FENS G035
Keywords: neutron stars, pulsars, fallback disks, accretion, bursts
In the last decades, developments in observational techniques led to the discovery of new young isolated neutron star populations. Despite distinguishing differences, these young systems also have striking similarities, which suggest possible evolutionary links between them. The emergence of these different populations is likely to be due to their different initial conditions. Understanding the nature of these neutron stars in a single coherent picture requires a detailed investigation of individual properties of the sources that belong to different classes. The properties and emergence of these young neutron stars as distinct populations could be explained if absence, presence and properties of fallback disks are included in the initial conditions in addition to magnetic moment and initial period (Alpar 2001). Pursuing this idea, we investigate the properties of AXP/SGRs and the radio pulsar PSR J1734−3333. We show that: (i) persistent optical/infrared emission of AXP/SGRs can be fit by the emission from the disk surface, (ii) X-ray enhancement light curves of AXP/SGRs can be produced by the relaxation of the disk that has been pushed back by a soft gamma- ray burst, (iii) Luminosity and rotational properties of SGR 0418+5729 can be achieved simultaneously by a neutron star evolving with a fallback disk, and (iv) rotational properties, including the anomalous breaking index and X-ray luminosity of PSR J1734−3333 can be produced simultaneously in the fallback disk model. The model we use is self-consistent in that we use the same basic disk parameters and do not require special assumptions in any of these explanations.