Measuring temperatures similar to those occurring in star collisions in the lab

Measuring temperatures similar to those occurring in star collisions in the lab
Simulations of nuclear matter in collisions yielding extreme conditions of density and temperature. Credit: The HADES Collaboration.

Collisions between neutron stars are fascinating cosmic events that lead to the formation of numerous chemical elements. Temperatures during these collisions are exponentially high, typically reaching up to hundreds of billions of degrees Celsius.

The HADES collaboration, a large team of researchers working at different universities worldwide, has recently gathered the very first measurement of the thermal electromagnetic radiation produced during star collisions, known as black-body radiation, in a laboratory setting. Their study, outlined in a paper published in Nature Physics, has led to the observation of temperatures of approximately 800 billion degrees Celsius, which are comparable to those occurring during star collisions.

"In our study, we smashed nuclei (e.g. gold nuclei) at relativistic energies head on," Joachim Stroth, spokesperson for the HADES collaboration, told "This produces forms of matter under conditions not existing normally. Only neutron reach such densities (or even higher) and when merge, their temperature can get as high as in our experiment. That is why we can form a cosmic type of matter in the laboratory."

In their study, Stroth and his colleagues used the HADES detector system at the GSI/FAIR accelerator center in in Darmstadt to gather new insight into the collisions of two heavy nuclei at relativistic energies. This allowed them to gather in-depth lab observations of the microscopic properties of extreme, cosmic-like states of matter.

The researchers specifically created quantum chromodynamics (QCD) matter as a transient state by colliding heavy ions at relativistic energies. This type of matter can exist in different phases depending on a series of factors, including temperature, pressure and baryochemical potential.

By observing the states of QCD matter, the researchers hoped to gain a better understanding of neuron star matter and collisions. A key question that they set out to investigate was whether the constituents of nuclei, which are essentially the building blocks of matter, can change their properties under extreme conditions.

"We measured the electromagnetic radiation thereby emitted from the fireballs formed in the collision," Stroth explained. This radiation can tell us a lot about the properties of the constituents. However, this is a difficult measurement to attain, as the fireballs live for very short time (10-22 s) and the radiation is rarely emitted."

Hadrons are composite particles made of three quarks (baryon) of an antiquark and a quark (meson) held together by the strong force. When these particles decay, they sometimes produce virtual photons, which are photons that cannot directly be detected because their existence violates conservation of energy and momentum.

These , which carry all information about the decayed subatomic particles, also immediately decay into pairs of electrons (i.e. an electron and a positron). In their study, Stroth and his colleagues detected these particles using a spectrometer.

"We observed that the temperature in the zone can reach 800 billion degrees and the density can be as high as three times nuclear saturation density," Stroth said. "We find that under such condition the building blocks of matter are substantially modified. This also means that the matter properties are much different, as if the building blocks just retain their properties."

The HADES collaboration is the first research team to successfully measure temperatures similar to those occurring during star collisions in a laboratory setting. This team's findings could significantly enhance the current scientific understanding of neutron star merger events, while also shedding light on the production of matter from elementary quarks and gluons.

"We are currently building a successor experiment for HADES which will be operated at the new FAIR facility starting in 2025," Stroth said. "With this detector we will be able to extend the measurements to and density."

Explore further

Merging neutron stars: How cosmic events give insight into fundamental properties of matter

More information: Probing dense baryon-rich matter with virtual photons, Nature Physics (2019). DOI: 10.1038/s41567-019-0583-8
Journal information: Nature Physics

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Aug 20, 2019
800 billion degrees Celsius!!!

I wonder if they can use these findings to determine the relative temperatures involved in a neutron star and black hole collision

Aug 21, 2019
This experiment and the information gleaned from these ion collisions is important for high speed particle physics and, among other uses, will eventually have real world application for ion engine propelled spacecraft traveling at near light speed (where collision with even a mote of dust could be devastating) but it may not provide significant information regarding the inside of a neutron star merger.

The inner areas of the merger of neutron stars would maintain the incredibly high pressures and temperatures for much longer times than the ultra tiny fraction of a second of the collision of the ions. Significant differences are likely to result from maintaining the high pressures at those temperatures versus having the pressure released (and temperature dropped) almost instantly as the collision between the charged atoms ends and the particles disperse. Including differences in the type and duration of any released radiation.

Aug 21, 2019
Is there an upper limit Temperature?

As absolute zero is 0°K
Implies an absolute maximum ?°K
Collisions between neutron stars
Lead to the formation of numerous chemical elements
Where temperatures during these collisions
Rise to hundreds of billions of degrees Kelvin

At above 5,000°K all matter is plasma
There are no elements
Just simply ionic protons

At a 100 billion degrees Kelvin there will only be this primordial soup – certainly not new elements

Aug 21, 2019
Is there an upper limit Temperature? As absolute zero is 0°K This Implies an absolute maximum ?°K
Temperature, just like 'Time', is an abstracted/derived value based on the observed average motional speeds/rates of matter/energy quanta. And, just as the motional 'lightspeed limit' applies to the derived/abstracted Time "values", so also does that same motional 'lightspeed limit' apply to the abstracted/derived Temperature "values" possible. So, yes, there must be an "absolute" for "Temperature value' greater than applying when matter/energy quanta reaches motional 'lightspeed limit' state; just as there must also be an "absolute" for 'Timing value' greater than that applying when material/energy quanta likewise reaches motional 'lightspeed limit' state. By the way, since the universal process is 'always on' (ie, motion never stops, no matter how cold) then there can be NO ABSOLUTE ZERO state/value for MOTIONALLY abstracted/derived Temperature OR Timing. :)

Aug 21, 2019

1) " "absolute" for "Temperature value' greater than..."

should have read:

" "absolute" for 'Temperature value' NO greater than that..."

2) " "absolute" for 'Timing value' greater than that..."

should have read:

" "absolute" for 'Timing value' NO greater than that..."

Thanks. Apologies. :)

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