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# 物理代写|天文学代写Astronomy代写|PHY105 OUTLOOK

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## 物理代写|天文学代写Astronomy代写|PARTICLES BEYOND THE GZK CUTOFF

Since we do not observe the expected GZK cutoff, we need to look for particles which defy the interaction with the microwave background or for a source distribution which reduces the time for interaction with the microwave background substantially.

Here we emphasize those concepts which can explain the events beyond the $\mathrm{GZK}$ cutoff; these proposals do not necessarily also explain those particles below the expected cutoff. A source distribution which is closely patterned after the decay of primordial relics, with an energy of $10^{24} \mathrm{eV}$. actual galaxy distribution in the nearby universe greatly Such a decay produces a large number of highly enerenhances the expected flux of events near the GZK cutoff getic neutrinos, photons, and only $3 \%$ of ultimately proand may allow an interpretation of the observed events tons. Since these protons start with a much flatter spectrum given a properly biased version of the galaxy distribution than normal cosmic rays, and also have such extreme iniand a source population like a special class of galaxies. thal energies, the lack of a GZK cuotff can be understood. However, the data are also compatible with a spectrum There is, however, a strong prediction: The large numwhich suggests a rise beyond the expected GZK cutoff, ber of photons produced yields a cascade that gives rise and this strongly hints at a totally different and new event to a strong contribution to the gamma ray background. class. This supports an interpretation as the result of the This gamma ray background adds to all the gamma rays produced by active galactic nuclei. It is not finally resolved whether observations exclude this option because of an excessive gamma ray background or whether the actual spectrum of the gamma ray background in fact supports it.

## 物理代写|天文学代写Astronomy代写|OUTLOOK

The origin of cosmic rays with observed particle energies to $300 \mathrm{EeV}$ remains an unsolved problem.

A number of efforts related to cosmic rays will surely help our understanding:

• The determination of gamma ray spectra and maps of the Galaxy at high energy.
• More information on stellar evolution including rotation and magnetic fields. Are massive stars all converging to a small set of final states, which includes the magnetic field?
• The search to determine the strength and structure of cosmic magnetic fields, both in the halo of galaxies and in the web of the cosmological galaxy distribution. Clearly this is the key to understand the propagation of high-energy cosmic rays.
• The search for possible correlations in arrival directions of high-energy cosmic rays with astronomical sources. If there were such a subset of events, it would provide very strong constraints on the nature of the particles, as already is the case with some events near $\mathrm{EeV}$ energies. At higher energies it might provide new constraints on models for the fundamental properties of particles.
Progress in our understanding of cosmic rays will be mainly determined by much better data:
• Very accurate spectra, at low energies, such as now available from the first AMS data.
• Very accurate data on antimatter, positrons, antiprotons, and antinuclei, also from AMS and extended campaigns of balloon flights.
• Very accurate data on isotopic ratios, from a new generation of balloon flights.
• Accurate chemical composition near the knee and beyond.
• Accurate spectra, sky distribution, and information on the nature of particles in the three energy ranges from the knee to the ankle, through the energy range from $3 \mathrm{EeV}$ to $50 \mathrm{EeV}$, the expected GZK cutoff, and beyond.
The search for the origin of cosmic rays promises to remain at the focus of research in physics in the 21st century.

## 物理代写|天文学代写ASTRONOMY代写|OUTLOOK

• 伽马射线光谱和高能星系图的测定。
• 有关恒星演化的更多信息，包括自转和磁场。大质量恒星是否都汇聚成一小组最终状态，包括磁场？
• 寻找确定宇宙磁场强度和结构的研究，包括星系晕和宇宙星系分布网。显然，这是理解高能宇宙射线传播的关键。
• 寻找高能宇宙射线到达方向与天文源的可能相关性。如果有这样的事件子集，它将对粒子的性质提供非常强的约束，就像附近的一些事件一样和和在能量。在更高的能量下，它可能为粒子基本特性的模型提供新的约束。
我们对宇宙射线理解的进展将主要取决于更好的数据：
• 非常准确的光谱，在低能量下，例如现在可以从第一个 AMS 数据中获得。
• 反物质、正电子、反质子和反核的非常准确的数据，也来自 AMS 和气球飞行的扩展活动。
• 来自新一代气球飞行的非常准确的同位素比率数据。
• 膝盖附近及以外的准确化学成分。
• 从膝盖到脚踝的三个能量范围内，通过能量范围从3和和在至50和和在，预期的 GZK 截止值，以及更多。
寻找宇宙射线的起源有望继续成为 21 世纪物理学研究的重点。

## Matlab代写

MATLAB 是一种用于技术计算的高性能语言。它将计算、可视化和编程集成在一个易于使用的环境中，其中问题和解决方案以熟悉的数学符号表示。典型用途包括：数学和计算算法开发建模、仿真和原型制作数据分析、探索和可视化科学和工程图形应用程序开发，包括图形用户界面构建MATLAB 是一个交互式系统，其基本数据元素是一个不需要维度的数组。这使您可以解决许多技术计算问题，尤其是那些具有矩阵和向量公式的问题，而只需用 C 或 Fortran 等标量非交互式语言编写程序所需的时间的一小部分。MATLAB 名称代表矩阵实验室。MATLAB 最初的编写目的是提供对由 LINPACK 和 EISPACK 项目开发的矩阵软件的轻松访问，这两个项目共同代表了矩阵计算软件的最新技术。MATLAB 经过多年的发展，得到了许多用户的投入。在大学环境中，它是数学、工程和科学入门和高级课程的标准教学工具。在工业领域，MATLAB 是高效研究、开发和分析的首选工具。MATLAB 具有一系列称为工具箱的特定于应用程序的解决方案。对于大多数 MATLAB 用户来说非常重要，工具箱允许您学习应用专业技术。工具箱是 MATLAB 函数（M 文件）的综合集合，可扩展 MATLAB 环境以解决特定类别的问题。可用工具箱的领域包括信号处理、控制系统、神经网络、模糊逻辑、小波、仿真等。