Laboratory study of stationary accretion shock relevant to astrophysical systems

Abstract

Accretion processes play a crucial role in a wide variety of astrophysical systems. Of particular interest are magnetic cataclysmic variables, where, plasma flow is directed along the star’s magnetic field lines onto its poles. A stationary shock is formed, several hundred kilometres above the stellar surface; a distance far too small to be resolved with today’s telescopes. Here, we report the results of an analogous laboratory experiment which recreates this astrophysical system. The dynamics of the laboratory system are strongly influenced by the interplay of material, thermal, magnetic and radiative effects, allowing a steady shock to form at a constant distance from a stationary obstacle. Our results demonstrate that a significant amount of plasma is ejected in the lateral direction; a phenomenon that is under-estimated in typical magnetohydrodynamic simulations and often neglected in astrophysical models. This changes the properties of the post-shock region considerably and has important implications for many astrophysical studies.

Enhanced X-ray emission arising from laser-plasma confinement by a strong transverse magnetic field

“…The investigation of the dynamics of strongly magnetized high-energy-density (HED) plasmas is a topic that has been recently the subject of significant effort by many groups. Permitted by the advent of new experimental facilities capable of developing strong magnetic fields 1 – 3 , such investigations have led to major progress in diverse fields such as laboratory astrophysics 4 – 12 or inertial confinement fusion (ICF). As for the latter, for example, via a reduction in electron thermal conductivity, it was shown that magnetization could increase the fuel ion temperature in ICF targets 13 .…”

Laboratory Study of Bilateral Supernova Remnants and Continuous MHD Shocks

“…These distances were sufficiently far away from the laser-plasma interaction so as to prevent any significant amount of carbon ablated from the target from entering the detector's field of view. The entire experimental setup was placed in a coil which was driven by a pulsed power machine in order to create a spatially uniform magnetic field of 10.2 T (Albertazzi et al 2018;Mabey et al 2019). The magnetic field remains constant (less than 2% vari-ation) for a period of several microseconds, much larger than the timescales considered in this experiment.…”

“…can now be produced in the laboratory (Albertazzi et al 2013). Studies have been performed to investigate expanding volumes of plasma (Collette & Gekelman 2010;Bonde et al 2018), diamagnetic bubbles (Niemann et al 2013), accretion columns (Albertazzi et al 2018;Mabey et al 2019), interpenetrating plasma flows (Shaikhislamov et al 2015) and particle dynamics in collisionless shocks (Schaeffer et al 2017(Schaeffer et al , 2019. Nevertheless, many topics, such as the structure of MHD shocks, the energy partitioning between electrons and ions across collisionless shocks, or the propagation of supernova remnants through a magnetized ISM, still remain poorly understood.…”

New Class of Laboratory Astrophysics Experiments: Application to Radiative Accretion Processes around Neutron Stars

“…Furthermore, although numerical simulations continue to be the only means to study these phenomena, their validity remains to be assessed. The framework for scaling astrophysical phenomena to the laboratory (Ryutov et al 1999;Falize et al 2011a) has been the basis for many high-energy density plasma experiments, such as those studying physical processes relevant to accretion shocks (Falize et al 2012;Krauland et al 2012Krauland et al , 2013Cross et al 2016;Revet et al 2017;Van Box Som et al 2018;Mabey et al 2019), magnetized stellar jets (Lebedev et al 2005;Ciardi et al 2007Ciardi et al , 2009Ciardi et al , 2013Albertazzi et al 2014;Revet et al 2021), supernova remnants (Kuranz et al 2018;Rigon et al 2019;Albertazzi et al 2020), or accretion disks (Valenzuela-Villaseca et al 2022). However, these similarity concepts require experiments to reach the same physical regime as found in astrophysics, as well as to keep the microphysics of the two systems similar.…”