Fingers of God

The redshift is an alternative coordinate system in cosmology, for which the observable is used instead of the real distance.

On cosmological scales, the distance measurement (such as quasars or distant clusters of galaxies ) only by measuring the redshift is possible. Therefore, one is forced to switch instead of the " natural" coordinate system of two angular coordinates and the real distance between the observer and the object in the redshift of the two angular coordinates and the Rotverschiebungsentfernung.

Would create the observed redshift z only by the cosmic expansion, the Rotverschiebungsentfernung s would be equal to the actual distance in D. However, the object has a peculiar velocity v, as a gravitationally bound cluster galaxy, then:

Where c denotes the speed of light and the Hubble constant.

In this general case, there may be distortions of the observed structures in representation in redshift space. Approximately, a roughly spherical clusters of galaxies are distorted in virialisiertem state by the peculiar velocities so that it becomes a along the direction of observation elongated ellipsoid. These phenomena astronomers call finger of god - Finger of God.

• Cosmology (Physics)