X-ray astronomy : The instruments behind the science
If you follow science news regularly, you will come across news of the kind " Astronomers find brightest object of the early universe " or " Black hole-powered jets plow into galaxy ". I would just like to point out that when they mean "brightest" object, they don't mean that it's the brightest object in the visible part of the electromagnetic (EM) spectrum. They mean that it's the brightest object in terms of energy emitted across the EM spectrum i.e X-ray, UV, visible, IR and microwave radiation all put together. (And just to throw in a bit of jargon, an object's brightness is quantified in terms of it's luminosity and the luminosity of an object measured across the EM spectrum is referred to as the "Bolometric" luminosity.) Coming to the specific cases mentioned above, the quasars are in fact brightest in the X-ray, UV regime of the EM spectrum and astronomers use X-ray telescopes to look at them! At this point, I would ...