At first glance, the Universe seems barren, a place cold, dark, and empty. But the Universe as revealed in X-rays – faint thought they are – paints a different picture. Hot plasmas hundreds of thousands of degrees. Jets emanating from black holes. Ultra-high energy particles traveling at speeds surpassing 99% of the speed of light. We find the Universe is a place packed full of hot, violent worlds.

XRISM will have two instruments. The Resolve camera will make precise measurements of the “color” of X-rays. The Xtend camera will make measurements covering an area on the sky as large as the full moon. Resolve’s outstanding ability to distinguish X-ray “colors” makes it the prime feature of XRISM.

In the same way that visible light has colors, so also do X-rays.

The fireworks that decorate the summer skies come about when different metals (elements) are made to glow hot. Each metal responds to heating by emitting its own distinctive color. Chemically, this is referred to as “Flame Reaction”, and XRISM makes use of this principle.

Different chemical elements in a very hot gas will glow in X-rays of a particular “color”, each color peculiar to each element. The forte of XRISM is that it will be able to determine which elements are present, and in what state and in what amount, in these ultra-hot gasses.

XRISM will use this ability to resolve the colors of X-rays to attack current puzzles about the Universe. These puzzles may broadly be divided into three classes: (1) the “blueprint” for groups of galaxies; (2) the “recipe of the Universe”; (3) the edge of spacetime. It is going to be exciting to watch how XRISM helps to solve these puzzles!

Author: Aya Bamba
Translated from Japanese by  Chris Baluta