Max Planck Institute for Nuclear Physics

How Gamma Rays Track the Velocity of the Galactic Microquasar SS 433’s Jets and Uncover Highly Efficient Particle Acceleration.

Quantum electrodynamics put to the test

The Max Planck Society honours Daniel Zajfman with the Harnack Medal in recognition of his remarkable contributions to the advancement of science and German-Israeli cooperation
 

Four scientists can look forward to additional funding in this year's ERC Advanced Grants

In future it will be possible to incorporate data from deep space telescopes into the underlying atomic models with a high degree of reliability

Black holes, pulsars, remnants of exploded stars – these celestial bodies accelerate particles to enormous energies and emit high-energy gamma radiation. The two observatories known as H.E.S.S. and MAGIC, whose construction was supervised by the Max Planck Institutes for Nuclear Physics in Heidelberg and Physics in Munich, make this extreme spectral region accessible.

Neutrinos are particles with seemingly magical powers: the different types are able to transform into one another, and thus have a mass. This discovery earned two scientists the 2015 Nobel Prize for Physics. A quarter of a century ago, these ghostly particles also attracted the attention of researchers at the Max Planck Institute for Nuclear Physics in Heidelberg for the first time. While conducting their Gallex experiment to hunt for them, they looked deep into the furnace of the Sun.

If cosmologists are correct, there is a form of matter in the universe that is six times moreabundant than the matter we know. It is invisible, which is why it’s called dark matter.Postulated for the first time 80 years ago, it has yet to be detected directly. Researchers atthe Max Planck Institute for Physics in Munich and the Max Planck Institute for NuclearPhysics in Heidelberg want to solve this cosmic mystery in the next few years.

Earth is subjected to continuous bombardment. At any point in time, somewhere in the depths of the universe, a star explodes or a black hole ejects gigantic gas clouds from the core of a distant galaxy. These aggressive events are heralded by gamma rays, whichtravel straight through the universe and eventually impact on the Earth’s atmosphere. But this is the end of the line – fortunately for all life, as the energy dose would be lethal in the long term. However, the gamma light doesn’t vanish completely into thin air – a lucky break for astronomers, who can then use it to investigate the cosmic messengers. The radiation leaves its traces in a cascade of particles high above the ground. In the process, a large number of elementary particles are created, which generate Cherenkov radiation – blue flashes that last only one billionth of a second and can’t be seen with the naked eye.In order to record this celestial light, researchers built the four H.E.S.S. telescopes in the Khomas Highland in Namibia several years ago – and they are now converting this quartet into a quintet. H.E.S.S. II is the name of the new dish, which our picture shows bathed in moonlight as it stretches upward like a steel pyramid into the night sky. With a diameter of 28 meters, it roughly corresponds to the area of two tennis courts. And this giant weighs in at no fewer than 580 tons; its camera eye alone weighs three tons. The five scouts of the High Energy Stereoscopic System record the blue flashes with all the tricks of the astronomical observation trade. Securing the evidence in the data then leads to the scene of the crime, as it were: to the source of the radiation. Thus, the astronomers at the Max Planck Institute for Nuclear Physics in Heidelberg, which played an important role in the development and design of H.E.S.S. II as well as coordinating the installation work, also play the role of detectives. Their efforts will soon enable us to better understand the cosmic particle catapults, such as supernovae and black holes.

Researchers use clever methods to weigh even tiny atomic nuclei; and in doing so, help to shed light on key questions in physics.

Astrophysicists use laboratory equipment to simulate chemical reactions that take place in distant interstellar clouds.

Energetic ionizing radiation can act on biological tissue in more ways than previously assumed. In addition to the direct ionization of biomolecules excess energy stored therein can be transferred to neighboring molecules. This produces several charged molecular fragments and free electrons, which give rise to further reactions in the immediate vicinity. Therefore, the biological impact of this so called intermolecular Coulombic decay is high and it can give rise to irreparable damage for instance in the genetic material (DNA). Such reactions can play an important role in radiation biology.

Liquid Crystals (LCs) represent a benchmark material to study phenomena which occur across different states of matter, occupying a spot between solids and liquids. They self-assemble, giving rise to new phases of matter in which they show no positional order but long range orientational order. In 2015 we demonstrated that very short optical pulses can excite the weakly bound electron clouds in LCs producing a modulation of their refractive index in the picosecond time scale. This is our starting point for a deeper understanding of the ultrafast dynamics in LCs.

After more than a decade of searching for very-high energy gamma-rays from the afterglows of Gamma-Ray Bursts, detection at these photon energies are at last a reality. Observing these distant sources is challenging due to the reduced transparency of the universe to such energetic photons over cosmological distances. Yet since our first detection in 2018, several more have followed in quick succession. The findings put the standard model under the microscope, revealing potential cracks. These developments ensure a bright future for Gamma-Ray Burst studies at very-high energies. 

The discovery of a Higgs-like particle at the CERN Large Hadron Collider (LHC) represents one of the biggest findings of the last decades. Notwithstanding, its small mass is in conflict with general physical arguments. Most of the models that can address this issue, by considering the Higgs particle to be composed of more fundamental states, however predict light partner particles of the top quark, which have not been found yet at the LHC. A novel mechanism of symmetry breaking could resolve this tension.

Is there anything older than our Universe? Surely not, but billions of years appear as a blink of an eye compared to some extremely slow processes. Physicists of the XENON1T collaboration detected such a process. It is the radioactive decay of the xenon-124 atomic nucleus, the slowest decay process ever measured. The half-life of this extremely rare nuclear transformation is for unimaginably long 1.8 × 10²² years. This corresponds to about a trillion times the age of the Universe!