We propose that the bimodal nature of the kick velocity distribution of radio pulsars is connected to the dichotomy between hadronic stars (i.e. neutron stars with no quark matter content) and quark stars. Bimodality can appear due to different mechanisms of explosion which lead to the formation of two types of compact stars or due to two different sets of parameters driving a particular kick mechanism. The low velocity maximum (at similar to100 km s(-1)) is associated with hadronic star formation, whereas the second peak corresponds to quark stars. In the model of delayed collapse of hadronic stars to quark stars (Berezhiani et al. 2003) quark deconfinement leads to a second energy release, and to a second kick, in addition to the kick imparted to the newly formed hadronic star during the supernova explosion. If the electromagnetic rocket mechanism can give a significant contribution to pulsar kicks, then the high velocity peak can be associated with the shorter initial spin periods of quark stars with respect to hadronic stars. We discuss these scenarios.
On the nature of the bimodal initial velocity distribution of neutron stars RID B-6368-2008
BOMBACI, IGNAZIO;
2004-01-01
Abstract
We propose that the bimodal nature of the kick velocity distribution of radio pulsars is connected to the dichotomy between hadronic stars (i.e. neutron stars with no quark matter content) and quark stars. Bimodality can appear due to different mechanisms of explosion which lead to the formation of two types of compact stars or due to two different sets of parameters driving a particular kick mechanism. The low velocity maximum (at similar to100 km s(-1)) is associated with hadronic star formation, whereas the second peak corresponds to quark stars. In the model of delayed collapse of hadronic stars to quark stars (Berezhiani et al. 2003) quark deconfinement leads to a second energy release, and to a second kick, in addition to the kick imparted to the newly formed hadronic star during the supernova explosion. If the electromagnetic rocket mechanism can give a significant contribution to pulsar kicks, then the high velocity peak can be associated with the shorter initial spin periods of quark stars with respect to hadronic stars. We discuss these scenarios.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
