Cosmic Jets

Prof. Kazunari Shibata

Recent progress of astronomical observations of our universe in radio waves, X-rays, and so on, has revealed amazing view of our universe that collimated high-speed jets are ubiquitous on various different scales in the universe.
Well-known jets on galactic scales are jets ejected from active galactic nuclei (AGN) such as quasars. These jets often extend to a length of a few million light years, exceeding the size of galaxies. Their velocity is extremely high, sometimes amount to 99.9 percent of the light speed.
Similar relativistic jets are found on much smaller scales such as in close binary systems containing black holes or neutron stars. Since these jets appear to be miniature version of AGN jets, they are sometimes called micro quasars.
It has also been revealed that similar jets are ejected from young stellar objects (YSOs) but on even smaller scales. Although these jets show morphology similar to those of AGN jets, their velocities are much slower than those of AGN jets, about a few 100 km/s.
More recent observations have revealed various different kinds of jets, such as pulsar jets, planetary nebula jets, gamma ray bursts, and so on, and it has been found that even our Sun, especially the solar corona, is full of jets !
Why is our universe full of jets ?
What are the formation mechanism of these cosmic jets ?
What is the role of these jets in the evolution of stars, galaxies, and life ?
A hint is found from solar observations, which tells us that magnetic field plays important role for the formation of solar jets.
How are solar jets formed with the help of magnetic field ?
Are cosmic jets formed by similar magnetic mechanism operating in the solar corona ?
I will talk about these amazing views of cosmic jets revealed by recent astronomical observations, and will try to discuss our present understanding of these enigmatic cosmic jets, based on solar research and computer simulations of cosmic jets.