How to have a blast like a black hole

Date:
September 8, 2020
Source:
Osaka University
Summary:
Scientists have created magnetized-plasma conditions similar to
those near a black hole using very intense laser pulses. This work
may help show how X-rays can be produced by astronomical objects.



FULL STORY ========================================================================== Laser Engineering at Osaka University have successfully used short, but extremely powerful laser blasts to generate magnetic field reconnection
inside a plasma. This work may lead to a more complete theory of X-ray
emission from astronomical objects like black holes.


==========================================================================
In addition to being subjected to extreme gravitational forces, matter
being devoured by a black hole can be also be pummeled by intense heat
and magnetic fields. Plasmas, a fourth state of matter hotter than
solids, liquids, or gasses, are made of electrically charged protons
and electrons that have too much energy to form neutral atoms. Instead,
they bounce frantically in response to magnetic fields. Within a plasma, magnetic reconnection is a process in which twisted magnetic field lines suddenly "snap" and cancel each other, resulting in the rapid conversion
of magnetic energy into particle kinetic energy. In stars, including
our sun, reconnection is responsible for much of the coronal activity,
such as solar flares. Owing to the strong acceleration, the charged
particles in the black hole's accretion disk emit their own light,
usually in the X-ray region of the spectrum.

To better understand the process that gives rise to the observed X-rays
coming from black holes, scientists at Osaka University used intense
laser pulses to create similarly extreme conditions on the lab. "We were
able to study the high-energy acceleration of electrons and protons
as the result of relativistic magnetic reconnection," Senior author
Shinsuke Fujioka says. "For example, the origin of emission from the
famous black hole Cygnus X-1, can be better understood." This level of
light intensity is not easily obtained, however. For a brief instant,
the laser required two petawatts of power, equivalent to one thousand
times the electric consumption of the entire globe. With the LFEX laser,
the team was able to achieve peak magnetic fields with a mind-boggling
2,000 telsas. For comparison, the magnetic fields generated by an MRI
machine to produce diagnostic images are typically around 3 teslas, and
Earth's magnetic field is a paltry 0.00005 teslas. The particles of the
plasma become accelerated to such an extreme degree that relativistic
effects needed to be considered.

"Previously, relativistic magnetic reconnection could only be studied
via numerical simulation on a supercomputer. Now, it is an experimental
reality in a laboratory with powerful lasers," first author King Fai
Farley Law says. The researchers believe that this project will help
elucidate the astrophysical processes that can happen at places in the
Universe that contain extreme magnetic fields.


========================================================================== Story Source: Materials provided by Osaka_University. Note: Content may
be edited for style and length.


========================================================================== Journal Reference:
1. K. F. F. Law, Y. Abe, A. Morace, Y. Arikawa, S. Sakata, S. Lee, K.

Matsuo, H. Morita, Y. Ochiai, C. Liu, A. Yogo, K. Okamoto,
D. Golovin, M.

Ehret, T. Ozaki, M. Nakai, Y. Sentoku, J. J. Santos, E. d'Humie`res,
Ph.

Korneev, S. Fujioka. Relativistic magnetic reconnection in laser
laboratory for testing an emission mechanism of hard-state
black hole system. Physical Review E, 2020; 102 (3) DOI:
10.1103/PhysRevE.102.033202 ==========================================================================

Link to news story: https://www.sciencedaily.com/releases/2020/09/200908101638.htm

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