Constraining Axion-Like Particles (ALPs) using X-ray observations of galaxy clusters.

我的博士利用星系团的X射线观测，该项目将致力于限制轻类轴粒子（ALPs）的参数空间。在磁化等离子体的存在下，如星系团中的ICM（IntraCluster Medium）所提供的等离子体，光可以转换为给定静止质量的ALPs，并具有特定的光子耦合强度。如果处于相空间的有利位置，就会发生这种情况，这取决于这些ALP参数以及几个天体物理参数，例如光子能量和等离子体频率。在X射线能量下，对于一个合适的天体物理环境，例如由丰富星系团的ICM提供的环境，我们可以预期光子ALP振荡会引起明亮光源光谱的光谱畸变，这些光源的光穿过ICM。目前，我正致力于利用H1821+643类星体的高能透射光栅光谱数据来约束光的ALP。这个源的红移为0.3，我目前使用的数据是由钱德拉望远镜拍摄的。从长远来看，我的博士学位研究将集中于研究预计在未来十年内发射的雅典娜X射线望远镜是否能够进一步限制光ALP（即它们的参数空间）。

My Ph.D. project will focus on constraining the parameter space of light Axion-Like Particles (ALPs) using X-ray observations of galaxy clusters.In the presence of a magnetized plasma, such as that provided by the IntraCluster Medium (ICM) in galaxy clusters, light can convert into ALPs of a given rest-mass, with a specific coupling strength to photons. This will take place if in a favourable location of phase-space, which depends on both these ALPs parameters, as well as several astrophysical parameters, such as the photon energy and the plasma frequency. At X-ray energies, and for a suitable astrophysical environment such as that provided by the ICM of a rich cluster of galaxies, we could expect photon-ALP oscillations to induce spectral distortions on spectra of bright sources whose light travels through the ICM. This can be used to constrain the parameter space of ALPs.Currently, I am focussing on constraining light ALPs using High Energy Transmission Grating Spectroscopy data of the H1821+643 quasar. This source has redshift 0.3 and the data I am currently working with were taken by the Chandra telescope. In the long-term, my Ph.D. research will focus on studying whether the Athena X-ray telescope, expected to be launched in the next decade, will be able to constrain light ALPs (that is, their parameter space) further.