The Cloverleaf Quasar is a single object whose image has been reproduced four times in a cloverleaf-like arrangement through a process known as gravitational lensing. The gravitational field of one or more foreground galaxies has bent and magnified the light from the quasar to produce the multiple images. The foreground galaxies are too faint to be seen in these images.


Hubble Optical Image of the Cloverleaf Quasar
One of the images (A) is brighter in both optical and X-ray light. However, the relative brightness is greater in X-ray than in optical light. Since the amount of brightening due to gravitational lensing does not vary with the wavelength, some additional effect must be magnifying the X-rays.

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Greetings from Belgium.

his picture shows the first map of the gravitational lens effect in millimeter waves obtained with the IRAM interferometer. The Cloverleaf is a quasar whose optical picture is multiple due to the presence of galaxies on the line of sight. This map shows that CO molecules are present in the host galaxy and that their emission in the millimeter range is gravitationally amplified like the optical radiation.
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