Computational astrophysics team uncloaks magnetic fields of cosmic events

January 5, 2018 by Rob Mitchum, University of Chicago
Computational astrophysicists describe a new method for acquiring information on experiments using laser beams to reproduce cosmic conditions. Credit: Lawrence Livermore National Laboratory

The development of ultra-intense lasers delivering the same power as the entire U.S. power grid has enabled the study of cosmic phenomena such as supernovae and black holes in earthbound laboratories. Now, a new method developed by computational astrophysicists at the University of Chicago allows scientists to analyze a key characteristic of these events: their powerful and complex magnetic fields.

In the of high-energy density physics, or HEDP, scientists study a wide range of astrophysical objects—stars, at the center of galaxies and galaxy clusters—with laboratory experiments as small as a penny and lasting only a few billionths of a second. By focusing powerful lasers on a carefully designed target, researchers can produce plasmas that reproduce conditions observed by astronomers in our sun and distant galaxies.

Planning these complex and expensive experiments requires large-scale, high-fidelity computer simulation beforehand. Since 2012, the Flash Center for Computational Science of the Department of Astronomy & Astrophysics at UChicago has provided the leading open computer code, called FLASH, for these HEDP simulations, enabling researchers to fine-tune experiments and develop analysis methods before execution at sites such as the National Ignition Facility at Lawrence Livermore National Laboratory or the OMEGA Laser Facility in Rochester, N.Y.

"As soon as FLASH became available, there was kind of a stampede to use it to design experiments," said Petros Tzeferacos, research assistant professor of astronomy and astrophysics and associate director of the Flash Center.

During these experiments, laser probe beams can provide researchers with information about the density and temperature of the plasma. But a key measurement, the , has remained elusive. To try and tease out magnetic field measurements from extreme plasma conditions, scientists at MIT developed an experimental diagnostic technique that uses charged particles instead, called .

In a new paper for the journal Review of Scientific Instruments, Flash Center scientists Carlo Graziani, Donald Lamb and Tzeferacos, with MIT's Chikang Li, describe a new method for acquiring quantitative, high-resolution information about these magnetic fields. Their discovery, refined using FLASH simulations and real experimental results, opens new doors for understanding .

"We chose to go after experiments motivated by astrophysics where magnetic fields were important," said Lamb, the Robert A. Millikan Distinguished Service Professor Emeritus in Astronomy & Astrophysics and director of the Flash Center. "The creation of the code plus the need to try to figure out how to understand what magnetic fields are created caused us to build this software, that can for the first time quantitatively reconstruct the shape and strength of the magnetic field."

Skyrocketing experiments

In proton radiography, energetic protons are shot through the magnetized plasma towards a detector on the other side. As the protons pass through the magnetic field, they are deflected from their path, forming a complex pattern on the detector. These patterns were difficult to interpret, and previous methods could only make general statements about the field's properties.

"Magnetic fields play important roles in essentially almost every astrophysical phenomena. If you aren't able to actually look at what's happening, or study them, you're missing a key part of almost every astrophysical object or process that you're interested in," said Tzeferacos.

By conducting simulated experiments with known magnetic fields, the Flash Center team constructed an algorithm that can reconstruct the field from the proton radiograph pattern. Once calibrated computationally, the method was applied to experimental data collected at laser facilities, revealing new insights about astrophysical events.

The combination of the FLASH code, the development of the proton radiography diagnostic, and the ability to reconstruct magnetic fields from the experimental data, are revolutionizing laboratory plasma astrophysics and HEDP. "The availability of these tools has caused the number of HEDP experiments that study magnetic fields to skyrocket," said Lamb.

The new software for magnetic field reconstruction, called PRaLine, will be shared with the community both as part of the next FLASH code release and as a separate component available on GitHub. Lamb and Tzeferacos said they expect it to be used for studying many astrophysics topics, such as the annihilation of magnetic fields in the solar corona; astrophysical jets produced by young stellar objects, the Crab Nebula pulsar, and the supermassive black holes at the center of galaxies; and the amplification of magnetic fields and acceleration of cosmic rays by shocks in supernova remnants.

"The types of experiments HEDP scientists perform now are very diverse," said Tzeferacos. "FLASH contributed to this diversity, because it enables you to think outside the box, try different simulations of different configurations, and see what plasma conditions you are able to achieve."

The paper, "Inferring Morphology and Strength of Magnetic Fields From Proton Radiographs," was published online by Review of Scientific Instruments.

Explore further: Scaled laboratory experiments explain the kink behaviour of the Crab Nebula jet

More information: Carlo Graziani et al. Inferring morphology and strength of magnetic fields from proton radiographs, Review of Scientific Instruments (2017). DOI: 10.1063/1.5013029

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11 comments

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cantdrive85
1.5 / 5 (8) Jan 05, 2018
"Magnetic fields play important roles in essentially almost every astrophysical phenomena. If you aren't able to actually look at what's happening, or study them, you're missing a key part of almost every astrophysical object or process that you're interested in," said Tzeferacos.

You're also missing a key part of almost every astrophysical object or process if you aren't considering the electric currents and electric fields which create these magnetic fields.
Captain Stumpy
4.5 / 5 (8) Jan 05, 2018
You're also missing a key part of almost every astrophysical objectblah blah stupidity coated in lie and delusion blah.
@cd the pseudoscience idiot

repeating a lie doesn't make it truer

it makes you a religious idiot
Merrit
4.6 / 5 (10) Jan 05, 2018
Pretty sure cantdrive doesn't even really understand how electric fields work
Bookperson
1 / 5 (4) Jan 07, 2018
The science of plasma physics has been around at least 80 years. It hasn't been readily accepted because it competes with the nebular (gravitational) theory of the formation of the universe. It has none of the theoretical problems that nebular theory has, and may provide answers for many other cosmological phenomenon. But it also presents serious challenges to philosophical naturalism and the related issues of deep time and the evolution of the cosmos, as plasma induced processes in the laboratory can create miniature galaxies in just a few moments.
Bookperson
1.8 / 5 (5) Jan 07, 2018
Captain Stumpy and Merrit,

I guess I don't understand where your comments are coming from. Would you please enlighten us as to how what cantdrive said doesn't make sense to you? Electric currents and fields ARE related to magnetic fields.

What makes it a lie, and why do you call him a religious idiot? (Name calling is never the sign of an intelligent argument.)

Thanks
Captain Stumpy
5 / 5 (2) Jan 07, 2018
@bookperson
I guess I don't understand where your comments are coming from...(Name calling is never the sign of an intelligent argument.)
don't jump to conclusions

cd is a known promiscuous acolyte for the electric universe [typically referred to here as the "eu"] and has a long history of posting blatant lies here on PO

read his post, especially the part that states "You're also missing a key part"

... at this point, he is repeating an oft-told lie of the eu that astrophysicists don't consider:
1- plasma physics because they don't know or even learn "proper" plasma physics
2- electric/magnetic fields/currents (demonstrably a lie per the above study)

he inferred that the eu is the only source of "science" and yet (still) cannot produce any proof from a reputable source that isn't personal or known pseudoscience

this is a years long battle where he spreads misinformation and pseudoscience
Captain Stumpy
5 / 5 (3) Jan 07, 2018
@bookperson cont'd
What makes it a lie, and why do you call him a religious idiot?
as stated above: it's a lie because he repeatedly and often states astrophysicists don't consider electric fields etc

This is part of the mantra of the eu

a religion per merriam-webster is: a personal set or institutionalized system of religious attitudes, beliefs, and practices
OED 1.2 has a similar definition

clearly, it is a codified set of rules which are used to judge others in order to classify non-believers for whatever purpose

this means that, because cd has ignored empirical evidence that directly refutes his/her claims that come from his/her own sources at times, then it is a belief that isn't based upon empirical evidence (ergo, it is a faith)

as such said belief is restated regardless of the evidence, making it a religious practice, not a science or even reality

there are several long term studies periodically stimulating these acolytes to elicit data
Captain Stumpy
5 / 5 (2) Jan 07, 2018
@book last
It hasn't been readily accepted because it competes with the nebular (gravitational) theory of the formation of the universe
and this is where you are completely and utterly wrong

Plasma physics are an integral part of astrophysics that cannot be untangled from it

this is demonstrable in many places, but here is a good start: http://www.pppl.gov/

note that astrophysicists and engineers (plasma physics, electrical and many others as well) work together to not only define the processes that are observed, but also to research new ideas

Any person who considers it separate from astrophysics is someone who is not studying recent data - which I suggest you glean from original sources (like reputable journals) rather than random web-pages, regardless of the person posting because (this is important): there are no authorities in science - there is only evidence

use google scholar, not google
you can get education free: https://ocw.mit.edu/index.htm
Whydening Gyre
not rated yet Jan 07, 2018
"Magnetic fields play important roles in essentially almost every astrophysical phenomena. If you aren't able to actually look at what's happening, or study them, you're missing a key part of almost every astrophysical object or process that you're interested in," said Tzeferacos.

You're also missing a key part of almost every astrophysical object or process if you aren't considering the electric currents and electric fields which create these magnetic fields.

No.. They Amplify them.
In actuality, you cannot have one without the other...
milnik
1 / 5 (1) Jan 08, 2018
From almost all the previous explanations of the behavior of some celestial bodies, it seems that science does not know what magnetism is, how it arises, and who causes it in general in the universe.
The same situation with gravity. What scientists see as "coming out" from black holes is evidence that they do not know what the black holes are and how they form. Trying to form plasma lasers is not the right path of research. It is again evidence that it does not know how the plasma is produced and who provokes it.
rrwillsj
5 / 5 (1) Jan 08, 2018
Well, here I sit,
broken hearted.
Awaiting the arrival
of any of the EU fool
With their thunderfarted
of magical drool

Still waiting for any of them to produce a physical item based on their EU gibberish.

........

Still waiting...

"Yawn..."

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