Microquasars (MQs) are binary systems composed by a star feeding mass to a compact object through an accretion disk. The compact object, usually a black hole, launches oppositely directed jets which are typically observed in our galaxy through their broadband electromagnetic emission. These jets are considered potential galactic neutrino sources. MQs can also have been formed by the first generations of stars in the universe, i.e., Population III (Pop III) stars, which are considered essential contributors to the ionization processes that took place during the period of “cosmic reionization”. In the present work, we develop a model that accounts for the main particle processes occurring within Pop III MQ jets, with the aim to obtain the diffuse neutrino flux at the Earth. We define different zones within the jets of Pop III MQs where particle interactions occur, and primary particles (i.e protons and electrons) are injected. We solve a transport equation for each zone, including the relevant cooling and escape processes, which include pγ and pp interactions. Once we obtain the primary particle distributions, we compute the pion and muon distributions, as well as the neutrino output produced by their decays. Finally, we obtain the diffuse neutrino flux by integration over the redshift, the line-of-sight angle, and the MQs lifetime. We find that, for a range of parameters suitable for Pop III MQ jets, the most relevant site for neutrino production in the jets is the base of the inner conical jet. Additionally, if protons accelerated at the forward shock formed at terminal jet region can escape from the outer shell, they would produce further neutrinos via pγ interactions with the cosmic microwave background (CMB). The latter contribution to the diffuse neutrino flux turns out to be dominant in the range 107GeV . Eν . 109GeV, while the neutrinos produced in the inner jet could only account for a small fraction of the IceCube flux for Eν ∼ 105 GeV. The co-produced multiwavelength photon background is also computed and it is checked to be in agreement with observations.

中文翻译：

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种群 III 微类星体中的中微子产生

微类星体（MQs）是由恒星通过吸积盘向致密物体馈送质量组成的双星系统。这个紧凑的物体，通常是一个黑洞，发射方向相反的射流，通常通过它们的宽带电磁发射在我们的星系中观察到。这些喷流被认为是潜在的银河中微子来源。MQ 也可能由宇宙中的第一代恒星形成，即第三族（Pop III）恒星，它们被认为是“宇宙再电离”期间发生的电离过程的重要贡献者。在目前的工作中，我们开发了一个模型，该模型解释了 Pop III MQ 射流中发生的主要粒子过程，目的是获得地球上的弥散中微子通量。我们在 Pop III MQ 的射流内定义了不同的区域，其中发生粒子相互作用，并注入初级粒子（即质子和电子）。我们求解每个区域的传输方程，包括相关的冷却和逃逸过程，其中包括 pγ 和 pp 相互作用。一旦我们获得初级粒子分布，我们就计算π介子和μ介子分布，以及它们衰变产生的中微子输出。最后，我们通过对红移、视线角和 MQs 寿命的积分来获得弥散中微子通量。我们发现，对于适用于 Pop III MQ 射流的一系列参数，射流中中微子产生最相关的位置是内部锥形射流的底部。此外，如果在末端喷射区域形成的前向激波加速的质子可以从外壳中逸出，它们将通过与宇宙微波背景 (CMB) 的 pγ 相互作用产生更多的中微子。后者对扩散中微子通量的贡献在 107GeV 范围内占主导地位。ε 。109GeV，而内部射流中产生的中微子只能占 Eν ∼ 105 GeV 的 IceCube 通量的一小部分。还计算了共同产生的多波长光子背景，并检查它与观察结果是否一致。