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Introduction There are some few physical scenarios in the Universe with extreme high density and/or temperature matter conditions, much higher than in any terrestrial environment. These scenarios are challenging our current understanding of how matter behaves and interacts in these situations, and has attracted the interest of both large experimental and theoretical communities of nuclear and particle physics, as well as of astrophysicists and cosmologists. The matter of the universe some few microseconds after the Big Bang was made up of a mixture or soup of quarks and gluons, the so called quark gluon plasma. The temperature then was so high that not only the atoms, but also all the protons and neutrons were melted into their fundamental constituents. This thermal period of the Universe is recreated in terrestrial accelerators, such as the Relativistic Heavy Ion Collider (RHIC) in Brookhaven National Laboratory (USA), the Large Hadron Collider (LHC) of CERN (Switzerland) or the Facility for Antiproton and Ion Research (FAIR) in Darmstadt (Germany). There are still manypuzzles to understand, as the experimental data extracted from these accelerators does not entirely match the initial predicted behavior. Matter under extreme dense conditions can also be found in compact stars. Neutron stars are supposed to be composed by neutrons, protons and electrons, although they might also contain unconfined quark matter in their core. High-precision X-ray astronomy from future space missions, such as NICER (Neutron star Interior Composition ExploreR) or eXTP (enhanced X-ray Timing and Polarimetry Mission), is expected to offer precise measurements of masses and radii and, thus, help us in understanding the microscopic composition of neutron stars. Focus The research of the group of Nuclear and Particle Astrophysics aims at understanding the behavior of matter under extreme density and/or matter conditions. We mainly focus on understanding the physics of compact stellar objects from its tiniest constituents, thus connecting present knowledge of the physics of subatomic particles at extreme conditions of densities with astrophysical observations. Our topics of research include the - equation of state of dense phases in compact stellar objects (which allows us to constrain the mass/ratio relation of the star), including the interplay of dense matter with dark matter - transport properties inside neutron stars (which allows us to understand the behavior of their hydrodynamical modes, rotational properties, and cooling) - magnetic fields We also study matter at extreme large temperatures, as those occurring few microseconds after the Big Bang. Our topics of research include - The properties of quarks and hadrons in hot and dense matter - Effective descriptions of the dynamics of the hot quark-gluon plasma which are studied in present particle accelerators, such as the FAIR/GSI, LHC/CERN or RHIC/BNL. Senior Institute members involved Manuel , L. Tolos
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ZNANSTVENICI američkog Nacionalnog laboratorija Brookhaven u ponedjeljak su objavili da su u akceleratoru čestica stvorili novo stanje materije vruću i gustu tekućinu sastavljenu od subatomskih čestica koja, kako tvrde, pokazuje kako je rani svemir izgledao u jednom kratkom trenutku nakon "Velikog praska". Djelić sekunde nakon "Velikog praska", kada se rodio svemir, sva je materija bila u obliku tekućine koja se naziva kvark-gluon plazma, rekli su znanstvenici. "Dobili smo novo stanje materije", kazao je Sam Aronson, pomoćnik direktora laboratorija za visoku energiju i nuklearnu fiziku u Nacionalnom laboratoriju Brookhaven. "Mislimo da gledamo u svemir kakav je bio prije 13 milijardi godina kada su se slobodni kvarkovi i gluoni hladili u čestice kakve mi poznajemo danas", rekao je Aronson na konferenciji za novinare. Kvark-gluon plazma je stvorena u Relativistic Heavy Ion Collideru (RHIC) - moćnom akceleratoru čestica u Brookhaven laboratoriju u Uptonu u saveznoj državi New York. Neočekivano, kvark gluon plazma se ponašala kao savršena tekućina kvarkova umjesto kao plin. Za svoj su eksperiment znanstvenici sudarili dva iona zlata pri vrlo velikoj brzini, bliskoj brzini svjetlosti. Sudar je bio tako jak da je inače jaka sila koja kvarkove veže u protone i neutrone oslabila dopuštajući kvarkovima da slobodno lutaju. Normalno su kvarkovi, temeljne čestice koje čine materiju, povezani i ne može ih se izravno mjeriti. Na temperaturi većoj i do 10.000 puta od temperature izmjerene na Suncu i sa samo nekoliko tisuća čestica, nuklearni fizičari su očekivali da će kvarkovi letjeti okolo slobodni poput plina. Međutim, kvarkovi su se ponašali kao savršena tekućina, lebdeći zajedno poput jata riba bez turbulencija i nasumičnih pokreta. Suprotno tomu, kap vode koja sadrži isti broj čestica neće se uopće ponašati kao tekućina. "To je kretanje tekućine koje je gotovo savršeno", kazao je Aronson. "Stvarno začuđujuće otkriće u RHIC-u da je novo stanje materije nastalo sudarom dvaju iona zlata više nalik tekućini nego plinu daje nam dubok uvid u najranije trenutke svemira", rekao je Raymond Orbach, direktor energetskog odjela za znanost koji financira RHIC.