来自一个宇宙距离的星系21厘米的气排放
M A Zwaan1, P G van Dokkum, M A Verheijen
1School of Physics, University of Melbourne, Victoria 3010, Australia. mzwaan@physics.unimelb.edu.au
概括
研究人员在阿贝尔2218星团内的一个星系中检测到中性原子 (HI),红移z = 0.18. 这表明星系团内有高效的气体去除机制,影响星系积聚率.
科学领域:
- 天文学和天体物理学
- 宇宙学的宇宙学是什么?
- 银河系的进化 银河系的进化
背景情况:
- 星系团是研究星系演变的关键环境.
- 中性原子 (HI) 是恒星形成的关键燃料,也是星系气体含量的标志物.
- 了解星团中气体去除机制对于理解星系命运至关重要.
研究的目的:
- 在星系团Abell 2218.18中检测中性原子 (HI) 辐射.
- 为了研究一个丰富的星系团环境中的星系的气体含量和积聚率.
- 测试关于星团组装的宇宙学模型.
主要方法:
- 利用韦斯特伯克合成射电望远镜 (WSRT) 进行敏感的无线电观测.
- 目标是星系团Abell 2218的红移z = 0.18.
- 分析了光谱数据,以确定中性原子 (HI) 21厘米的排放线.
主要成果:
- 成功检测到来自于位于2.0h65(-1) Mpc距离阿贝尔2218星团核心的螺旋星系的中性原子 (HI) 辐射.
- 在集群中没有其他显著的HI检测,这表明有效的气体剥离.
- 在过去的十亿年里,推断出不到三个富含气体的星系的低增长率.
结论:
- 在阿贝尔2218中有效地去除中性气体表明,星系团环境对银河系的气体含量有重大影响.
- 低的推断积累率支持低密度的宇宙学模型,其中星系团聚集在更高的红移 (z > 1) 时.
- 这项研究为密集的宇宙结构中的星系进化模型提供了观测约束.
相关概念视频
Rocket Propulsion in Empty Space - I
The driving force for the motion of any vehicle is friction, but in the case of rocket propulsion in space, the friction force is not present. The motion of a rocket changes its velocity (and hence its momentum) by ejecting burned fuel gases, thus causing it to accelerate in the direction opposite to the velocity of the ejected fuel. In this situation, the mass and velocity of the rocket constantly change along with the total mass of ejected gases. Due to conservation of momentum, the rocket's...
Rocket Propulsion In Empty Space - II
The motion of a rocket is governed by the conservation of momentum principle. A rocket's momentum changes by the same amount (with the opposite sign) as the ejected gases. As time goes by, the rocket's mass (which includes the mass of the remaining fuel) continuously decreases, and its velocity increases. Therefore, the principle of conservation of momentum is used to explain the dynamics of a rocket's motion. The ideal rocket equation gives the change in velocity that a rocket experiences by...
Escape Velocity
The escape velocity of an object is defined as the minimum initial velocity that it requires to escape the surface of another object to which it is gravitationally bound and never to return. For example, what would be the minimum velocity at which a satellite should be launched from the Earth's surface such that it just escapes the Earth's gravitational field?
To calculate the escape velocity, it is assumed that no energy is lost to any frictional forces. In practice, a satellite launched from...
To calculate the escape velocity, it is assumed that no energy is lost to any frictional forces. In practice, a satellite launched from...
Schwarzschild Radius and Event Horizon
No object with a finite mass can travel faster than the speed of light in a vacuum. This fact has an interesting consequence in the domain of extremely high gravitational fields.
The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...
The minimum speed required to launch a projectile from the surface of an object to which it is gravitationally bound so that it eventually escapes the object’s gravitational field is called the escape velocity. The escape velocity is independent of the mass of the object. Merging the idea of escape velocity with the...
Escape Velocities of Gases
To escape the Earth's gravity, an object near the top of the atmosphere at an altitude of 100 km must travel away from Earth at 11.1 km/s. This speed is called the escape velocity. The temperature at which gas molecules attain the rms speed, which is equal to the escape velocity, can be estimated by using the equation for the average kinetic energy of the gas molecules. According to the kinetic theory of gas, the average kinetic energy of the gas molecules is proportional to its temperature.
Radiation Pressure: Problem Solving
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 per...
The average value of the rate of momentum transfer divided by the absorbing area represents the average force per...


