Johann Rafelski
We discuss properties and evolution of quark-gluon plasma in the early Universe and compare to laboratory heavy ion experiments. We describe how matter and antimatter emerged from a primordial soup of quarks and gluons. We focus our discussion on similarities and differences between the early Universe and the laboratory experiments.
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We study bottom flavor abundance in the early Universe near to a temperature $T_\mathrm{H}\simeq150\,\mathrm{MeV}$, the condition for hadronization of deconfined quark-gluon plasma (QGP). We show bottom flavor abundance nonequilibrium lasting microseconds. In our study we use that in both QGP, and the hadronic gas phase (HG) $b$ and $\bar b$ quarks near $T_\mathrm{H}$ are bound in B-mesons and antimesons subject to $CP$ violating weak decays. A coincident non-equilibrium abundance of bottom flavor can lead to matter genesis at required strength: a) The specific thermal yield per entropy is $n_…
Short Note on Spin Magnetization in QGP
本文提出利用自旋磁化理论解释宇宙早期磁场起源，发现夸克气体可产生超强磁场，且所需极化随温度升高而减小，并可将磁场传递至夸克禁闭之后。
The effective number of neutrinos, $N_{\text{eff}}$, obtained from CMB fluctuations accounts for all effectively massless degrees of freedom present in the Universe, including but not limited to the three known neutrinos. Using a lattice-QCD derived QGP equation of state, we constrain the observed range of $N_{\text{eff}}$ in terms of the the freeze-out of unknown degrees of freedom near to quark-gluon hadronization. We explore limits on the coupling of these particles, applying methods of kinetic theory. We present bounds on the coupling of such particles and discuss the implications of a con…
Experimental studies of the Quark-Gluon Plasma (QGP) focus on two, in practice distinct, regimes: one in which the baryonic chemical potential $μ_B$ is essentially zero, the other in which it is of the same order of magnitude as the temperature. The cosmic QGP which dominates the early Universe after reheating is normally assumed to be of the first kind, but recently it has been suggested that it might well be of the second: this is the case in the theory of "Little Inflation". If that is so, then it becomes a pressing issue to fix the trajectory of the Universe, as it cools, through the quark…
Inflation and dark energy are two of the most relevant aspects of modern cosmology. These different epochs provide the universe is passing through accelerated phases soon after the Big-Bang and at present stage of its evolution. In this review paper, we discuss that both eras can be, in principle, described by a geometric picture, under the standard of $f(R)$ gravity. We give the fundamental physics motivations and outline the main ingredients of $f(R)$ inflation, quintessence and cosmography. This wants to be a quick summary of $f(R)$ paradigm without claiming of completeness.
A short survey of matter-antimatter evolution in the primordial universe
本文综述了原始宇宙中物质-反物质演化，基于Λ-CDM模型和已知重子不对称性，重点讨论了QGP、中微子自由流、μ子消失、电子-正电子磁性及BBN等关键时期，并展望了相关方法在磁星和GRB研究中的应用。
We consider a non-singular origin for the Universe starting from an Einstein static Universe, the so called "emergent universe" scenario, in the framework of a theory which uses two volume elements $\sqrt{-{g}}d^{4}x$ and $Φd^{4}x$, where $Φ$ is a metric independent density, used as an additional measure of integration. Also curvature, curvature square terms and for scale invariance a dilaton field $ϕ$ are considered in the action. The first order formalism is applied. The integration of the equations of motion associated with the new measure gives rise to the spontaneous symmetry breaking (S.…
We demonstrate that the dynamics of neural networks trained with gradient descent and the dynamics of scalar fields in a flat, vacuum energy dominated Universe are structurally profoundly related. This duality provides the framework for synergies between these systems, to understand and explain neural network dynamics and new ways of simulating and describing early Universe models. Working in the continuous-time limit of neural networks, we analytically match the dynamics of the mean background and the dynamics of small perturbations around the mean field, highlighting potential differences in…
Abridged: The golden age of astrophysics is upon us with both grand discoveries (extra-solar planets, dark matter, dark energy) and precision cosmology. Fundamental understanding of the working of stars and galaxies is within reach, thanks to newly available precision measurements. We highlight the importance of distances and model independent distances and masses. Distances are fundamental in astrophysics and their knowledge can change our perception of phenomena dramatically: e.g., in antiquity, the Heliocentric model was rejected because the predicted stellar parallaxes were not observed. D…
If the Hartle-Hawking wave function is the correct boundary condition of our universe, the history of our universe will be well approximated by an instanton. Although this instanton should be classicalized at infinity, as long as we are observing a process of each history, we may detect a non-classicalized part of field combinations. When we apply it to a dark energy model, this non-classicalized part of fields can be well embedded to a quintessence and a phantom model, i.e., a quintom model. Because of the property of complexified instantons, the phantomness will be naturally free from a big …
The cosmographic approach is gaining considerable interest as a model-independent technique able to describe the late expansion of the universe. Indeed, given only the observational assumption of the cosmological principle, it allows to study the today observed accelerated evolution of the Hubble flow without assuming specific cosmological models. In general, cosmography is used to reconstruct the Hubble parameter as a function of the redshift, assuming an arbitrary fiducial value for the current matter density, $Ω_m$, and analysing low redshift cosmological data. Here we propose a different s…
In this Letter, we present a model connecting the cosmic star formation rate (CSFR) to the growth of supermassive black holes. Considering that the evolution of the massive black hole is dominated by accretion (Soltan's argument) and that the accretion process can be described by a probabilistic function directly regulated by the CSFR, we obtain the evolution of the black hole mass density. Then using the quasar luminosity function, we determine both the functional form of the radiative efficiency and the evolution of the quasar duty-cycle as functions of the redshift. We analyze four differen…
We investigate the evolution of dust content in galaxies from redshifts z=0 to z=9.5. Using empirically motivated prescriptions, we model galactic-scale properties -- including halo mass, stellar mass, star formation rate, gas mass, and metallicity -- to make predictions for the galactic evolution of dust mass and dust temperature in main sequence galaxies. Our simple analytic model, which predicts that galaxies in the early Universe had greater quantities of dust than their low-redshift counterparts, does a good job at reproducing observed trends between galaxy dust and stellar mass out to z~…
We discuss status of the singularity problem in General Relativity and argue that the requirement that a physical solution must be completely free of singularities may be too strong. As an example, we consider properties of the integrable singularities and show that they represent light horizons separating T-regions of black and white holes. Connecting an astrophysical black hole to a white hole, they lead to a natural mechanism of generating new universes. Under favorable conditions the new universes will also contain black holes which, in their turn, will give rise to another generation of u…
(Abridged) The contemporary discoveries of galaxies and gamma ray bursts (GRBs) at high redshift have supplied the first direct information on star formation when the universe was only a few hundred million years old. The probable origin of long duration GRBs in the deaths of massive stars would link the universal GRB rate to the redshift-dependent star formation rate density, although exactly how is currently unknown. As the most distant GRBs and star-forming galaxies probe the reionization epoch, the potential rewards of understanding the redshift-dependent ratio Psi(z) of the GRB rate to st…
Connecting the growth of galaxies to the large-scale environment in a massive node of the Cosmic Web at z~3
本文利用 MUSE、JWST 等多波段观测研究 z≈3.25 超亮类星体 MQN01 周围的超密星系环境，发现星系恒星形成仍遵循主序关系但大质量端恒星质量函数显著抬升，并揭示该超密结构可能延伸至数十共动 Mpc。
Intensity mapping of the neutral hydrogen (HI) is a new observational tool that can be used to efficiently map the large-scale structure of the Universe over wide redshift ranges. The power spectrum of the intensity maps contains cosmological information on the matter distribution and probes galaxy evolution by tracing the HI content of galaxies at different redshifts and the scale-dependence of HI clustering. The cross-correlation of intensity maps with galaxy surveys is a robust measure of the power spectrum which diminishes systematics caused by instrumental effects and foreground removal. …
Connecting Early Dark Energy to Late Dark Energy by the Diluting Matter Potential
本文研究了一种具有两种标量场的标量不变引力理论，其中包含尘埃粒子和一个与度量无关的度量定义。通过整合定义度量的自由度，自发破除了标量对称性，使我们处于爱因斯坦框架中，有效势依赖于粒子的密度。该势包含三个平坦区域，一个用于膨胀，另一个用于早期暗能量，第三个用于晚期暗能量。当物质稀释时，从早期暗能量到晚期暗能量的隧穿可以开始高效进行。这种机制自然缓解了观测到的哈勃张力，通过修改再结合前的声学 horizon 而不破坏晚期宇宙学。此外，该模型的预测与减少的 CMB、BAO 和局部 H₀ 测量一致，提供了宇宙的统一描述。在此背景下，这些数据集的贝叶斯分析证实了我们场景的可行性，最佳拟合参数表明在红移 z′=5000 处早期暗能量分数约为 f_{NEDE}≈0.3。该初步估计，通过减少的 CMB 数据集获得，预计在考虑完整 CMB 可能性时会更加精确。
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