Laboratory study of the initial stages of quasi-parallel collisionless shocks relevant to supernova remnants (SNR)

Collisionless shocks are ubiquitous in astrophysics and a possible source of the highest-energy cosmic rays in our universe. Over the last decade, experimental and numerical efforts have shown that ion-Weibel instability is a leading candidate mechanism for collisionless shock formation in unmagnetized astrophysical objects. In a magnetized environment, ion streaming instabilities, such as the non-resonant instability (NRI), can dominate the dynamics and mediate the development of collisionless shocks. This mediation occurs in a quasi-parallel configuration, meaning that the plasma flow is parallel to the ambient magnetic field.

Laser experiments offer a unique capability to study SNR-relevant collisionless shock in a laboratory. Due to the high velocity of the laser-driven plasma (> 1500 km/s), the ion-ion mean free path is larger than the system. Therefore, the system is weakly magnetized, i.e., M_A ~ 150 when applying a 10-T external magnetic field. A novel platform has been developed at OMEGA-EP to study the formation of parallel collisionless shocks relevant to SNRs. The results show the growth of the NRI and ion-Weibel instability, though the NRI appears to dominate at early times. Hybrid-PIC and FLASH simulations will be presented, supporting the experimental observations.