Matter in extreme conditions
Neutron stars represent the final evolutionary phase of massive stars (between 8 and 25 times the mass of the Sun) that end their lives as core-collapse supernovae. All the physical conditions in these objects are extreme, and for this reason they represent ideal laboratories for the exploration of the properties of matter in extreme conditions, not accessible to terrestrial experiments and not found in other astrophysical contexts. Isolated neutron stars (INSs), that is, not belonging to binary systems, are of particular interest. Explaining their physics can provide a complete understanding of the final stage of evolution of massive stars.
In recent years, the Italian scientific community has contributed at a very high level to research in the field of isolated neutron stars. The researchers operate in an international context with large collaborations, and the quality of the work benefits from the synergy that has long existed between the observational and theoretical groups active in Italy. The principal research directions include multi-wavelength observations (from the infrared to gamma-rays) of Anomalous X-ray Pulsars (AXPs) and Soft Gamma-Ray Repeaters (SGRs) and the associated modeling, optical and X-ray observations of X-ray Dim Isolated Neutron Stars (XDINSs) and of Central Compact Objects (CCOs) and the construction of detailed models of their surface emission, radio and X-ray observations of Rotating Radio Transients (RRaTs) and of transient magnetars, and the comparative study of these sources in relation to the other classes of Isolated Neutron Stars (INSs).
In an international context, as part of the study of RRaTs, the most important experiment in forthcoming years will be the HITRUN survey at the Parkes radio telescope, with an important Italian contribution. On a national scale, INAF participates in the research on isolated neutron stars in the following projects: Spectral and Timing Properties of Isolated Neutron Stars, Magnetars and Related Objects and the Study of Periodic and Aperiodic Variability of Cosmic X-ray Sources: Data mining in a Decade of Chandra/RXTE/Swift/XMM Databases.
These projects involve satellite observations in the X-ray band with XMM-Newton, Swift, Chandra, Suzaku and Rossi XTE; in the gamma-ray band with Integral; with the optical telescopes, VLT, Gemini and HST and finally in the radio with Parkes, GBT and the GMRT.