Population study of radio-quiet and thermally emitting isolated neutron stars

• Grant number: 09/18499-6
• Support Opportunities: Scholarships in Brazil - Post-Doctoral
• Start date: March 01, 2010
• End date: December 31, 2010
• Field of knowledge: Physical Sciences and Mathematics - Astronomy - Stellar Astrophysics
• Principal Investigator: Eduardo Janot Pacheco
• Grantee: Adriana Mancini Pires
• Host Institution: Instituto de Astronomia, Geofísica e Ciências Atmosféricas (IAG). Universidade de São Paulo (USP). São Paulo , SP, Brazil

Abstract

The observed population of neutron stars is dominated by radio pulsars. In recent years, however, different observational manifestations of isolated neutron stars (INSs) have been discovered, which include magnetars, X-ray dim isolated neutron stars (XDINS) and rotating radio transients (RRATs). While fewer in number, they certainly have a signicant impact on our understanding of the physical properties of matter at extreme conditions of gravity and magnetic field. XDINS constitute a homogeneous group of seven nearby, cooling INSs displaying unique properties. Their long spin periods, high magnetic fields, soft thermal X-ray radiation, no significant magnetospheric activity and lack of radio emission make them stand apart from ordinary rotation-powered radio pulsars. Striking evidence relates them to other peculiar groups ofINSs - in particular those of magnetars and RRATs. Moreover, it is presently inferred that both XDINS and RRATs outnumber active radio pulsars. If such is the case, the Galactic rate of core-collapse supernovae cannot account for all different INS groups without invoking either evolutionary relations or geometrical effects between them. Multiwavelength investigations of individual sources are therefore important not only to characterise neutron star properties and evolutionary state but also to unveil clues relating the different subgroups of INSs. Similarly, the discovery of new thermally emitting sources is mandatory to understand their properties as a population and to constrain their contribution to the total number of neutron stars in the Milky Way.