Speaker
Description
Advanced timing studies of archival data from ASCA, Suzaku, NuSTAR, and XMM-Newton are opening several novel aspects of magnetars. (1a) Representative 7 magnetars were found to be axially deformed to 10^{-4}, and performs free precession. (1b) The deformation is due to internal magnetic pressure, with the internal (toroidal) magnetic fields reaching 10^{16} G (Makishima+24a, 24b). (2a) The toroidal (Bt) to dipole (Bd) magnetic-field ratios of the 7 magnetars increase towards older objects; their Bt lasts longer than their Bd (Makishima+24a). (2b) Considering the Bd decay, magnetars could dominate new-born neutron stars (Nakano+15). (2d) There may be a large population of old magnetars with weak Bd but strong Bt. (2e) The very long periods (e.g., 6.7 hours) of some Central Compact Objects in supernova remnants are not their rotational periods, but are the slip periods of their free precession. Their true rotation period may reside at about 1 second. (3a) Magnetars are also found in binaries, such as X-Persei (via MAXI observations; Yatabe+18) and the gamma-ray binary LS 5039 (Yoneda+20, Makishima+23). (3b) As in LS 5039, magnetars can steadily accelerate particles up to TeV energies, probably via induced electric fields. (3c) The magnetars in binaries allow first measurements of the mass of magnetars. As indicated by X-Persei and LS 5039, magnetars could have a higher mass (~2.0 Msun) than the ordinary neutron stars.
