Chandra Release - February 2, 2005

Visual Description: Mkn 421

 An X-ray spectrum (that is, energy over different wavelengths) with four small dips of the quasar Mkn 421 at lower left is set against an illustration of the system. The illustration appears to be a very dark green-blue starless sky. Two series of thick, gaseous lines, that resemble ripples or waves, fork out from the bottom of the image. One bright blue source at the right has a wavy line going from it to the left, towards the viewer and across the forked shape.  This illustration shows the absorption of X-rays from the quasar Mkn 421 by two intergalactic clouds of diffuse hot gas. The Chandra spectrum of the quasar provides evidence that three separate clouds of hot gas are filtering out, or absorbing X-rays from Mkn 421.  The dips in the X-ray spectrum are produced when some of the X-rays are absorbed by ions of oxygen in the hot gas clouds which are located at various distances from Earth. The two orange dips are due to absorption in our Galaxy, or in the Local Group of galaxies. This cloud is at most a few million light years from Earth, and is not shown in the top illustration. The green and red dips are from clouds at distances of 150 million and 370 million light years, respectively.