相关实验视频
Updated: Jun 16, 2025

06:14
Simulating Imaging of Large Scale Radio Arrays on the Lunar Surface
Published on: July 30, 2020
4.9K
强大的无线电喷流对星系形成的全球预防性反
Renyue Cen1,2
1Center for Cosmology and Computational Astrophysics, Institute for Advanced Study in Physics, Zhejiang University, Hangzhou 310027, China.
概括
巨大的星系中的超大质量黑洞会产生无线电叶,防止气体积聚,从而大大阻碍了早期宇宙中的恒星形成. 这种宇宙反机制解释了观测到的恒星形成率的下降.
科学领域:
- 宇宙进化的宇宙进化.
- 银河系的形成和演变.
- 天体物理学 天体物理学
背景情况:
- 拥有超大质量黑洞的大型星系会产生巨大的无线电叶.
- 这些无线电叶通过加压星际气体来产生负面反,从而抑制向更小的光环增积.
- 预计这种效应在密集的环境中更为明显,如原始集群.
研究的目的:
- 为了研究无线电叶反对巨型光环中的气体积累的影响.
- 确定这种反机制在调节宇宙恒星形成中的作用.
- 为了解释观测到的银河系的平坦化,紫外线发光率函数.
主要方法:
- 利用观测数据来建模无线电叶压力的影响.
- 分析气体积聚在不同大规模环境中的各种质量的光环上.
- 将模拟预测与观测数据进行比较,包括星系亮度函数.
主要成果:
- 由于无线电叶反,高达一定质量的哈洛体因红移[公式:参见文本]而无法显著增加气体.
- 这种反机制是全球恒星形成下降的主要贡献者,在[公式:参见文本] 2至3中观察到.
- 这项研究为银河系紫外线发光率函数在[公式:参见文本]周围的平整提供了自然解释.
结论:
- 来自巨型星系的射电叶反在调节星系生长和恒星形成方面发挥着至关重要的作用.
- 这种外部反过程对于理解宇宙恒星形成历史至关重要.
- 未来的宇宙学模拟必须纳入这种反机制,以准确预测. 与法拉第旋转测量的交叉相关性可以测试预测的磁场.
相关概念视频
Radiation Pressure: Problem Solving
340
The radiation pressure applied by an electromagnetic wave on a perfectly absorbing surface equals the energy density of the wave. The wave's momentum also gets transferred to the surface when an electromagnetic wave is entirely absorbed by it. The rate at which momentum is transmitted to an absorbing surface perpendicular to the propagation direction equals the force on the surface.
The average value of the rate of momentum transfer divided by the absorbing area represents the average force...
The average value of the rate of momentum transfer divided by the absorbing area represents the average force...
340
Generating Electromagnetic Radiations
2.7K
The German physicist Heinrich Hertz (1857–1894) was the first to generate and detect certain types of electromagnetic waves in the laboratory. Starting in 1887, he performed a series of experiments that confirmed the existence of electromagnetic waves and verified that they travel at the speed of light. Hertz used an alternating-current RLC (resistor-inductor-capacitor) circuit that resonated at a known frequency and connected it to a loop of wire. High voltages induced across the gap in...
2.7K
Effects of feedback
534
Feedback in control systems plays a critical role in shaping various operational parameters, extending beyond simple error reduction to influence stability, bandwidth, gain, impedance, and sensitivity. Understanding these effects requires examining a basic feedback system characterized by defined input, output, error, and feedback signals.
Feedback significantly modifies the gain of a control system. The gain of a system without feedback is altered by a factor of one plus GH, where G represents...
Feedback significantly modifies the gain of a control system. The gain of a system without feedback is altered by a factor of one plus GH, where G represents...
534
Momentum And Radiation Pressure
1.9K
An object absorbing an electromagnetic wave would experience a force in the direction of propagation of the wave. This force occurs because electromagnetic waves contain and transport momentum. The force accounts for the wave's radiation pressure exerted on the object. Maxwell's prediction was confirmed in 1903 by Nichols and Hull by precisely measuring radiation pressures with a torsion balance. The measuring instrument had mirrors suspended from a fiber kept inside a glass container.
1.9K
Electromagnetic Fields
2.1K
Electric fields generated by static charges, often referred to as electrostatic fields, are characteristically different from electric fields created by time-varying magnetic fields. While the former is a conservative field, implying that no net work is done on a test charge if it goes around in a complete loop in the field, the latter is, by definition, not a conservative field; net work is done, and it is proportional to the rate of change of magnetic flux.
However, the observation of...
However, the observation of...
2.1K
Detection of Black Holes
2.2K
Although black holes were theoretically postulated in the 1920s, they remained outside the domain of observational astronomy until the 1970s.
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
Their closest cousins are neutron stars, which are composed almost entirely of neutrons packed against each other, making them extremely dense. A neutron star has the same mass as the Sun but its diameter is only a few kilometers. Therefore, the escape velocity from their surface is close to the speed of light.
Not until the 1960s, when the first neutron...
2.2K

