Weblog
24 Could 2025
EHT, D. Pesce, A. Chael
Astronomers with the Occasion Horizon Telescope have developed a brand new technique to observe the radio sky at a number of frequencies, and it means we’ll quickly be capable of seize coloration pictures of supermassive black holes.
Colour is an attention-grabbing factor. In physics, we will say the colour of sunshine is outlined by its frequency or wavelength. The longer the wavelength, or the decrease the frequency, the extra towards the purple finish of the spectrum mild is. Transfer towards the blue finish, and the wavelengths get shorter and the frequencies greater. Every frequency or wavelength has its personal distinctive coloration.
After all, we don’t see it that approach. Our eyes see coloration with three various kinds of cones in our retina, delicate to purple, inexperienced, and blue mild frequencies. Our minds then use this knowledge to create a coloration picture. Digital cameras work equally. They’ve sensors that seize purple, inexperienced, and blue mild. Your laptop display screen then makes use of purple, inexperienced, and blue pixels, which methods our mind into seeing a coloration picture.
Whereas we will’t see radio mild, radio telescopes can see colours, generally known as bands. A detector can seize a slender vary of frequencies, generally known as a frequency band, which has similarities to the best way optical detectors seize colours. By observing the radio sky at completely different frequency bands, astronomers can create a “coloration” picture.
However this isn’t with out its issues. Most radio telescopes can solely observe one band at a time. So astronomers have to look at an object a number of instances at completely different bands to create a coloration picture. For a lot of objects, that is completely nice, however for fast-changing objects or objects with a small obvious measurement, it doesn’t work. The picture can change so rapidly that you may’t layer pictures collectively. Think about in case your telephone digital camera took a tenth of a second to seize every coloration of a picture. It could be nice for a panorama picture or selfie, however for an motion shot the completely different pictures wouldn’t line up.
That is the place this new technique is available in. The crew used a way generally known as frequency section switch (FPT) to beat atmospheric distortions of radio mild. By observing the radio sky on the 3mm wavelength, the crew can observe how the ambiance distorts mild. That is much like the best way optical telescopes use a laser to trace atmospheric adjustments. The crew demonstrated how they’ll observe the sky at each a 3mm and 1mm wavelength on the similar time and use that to right and sharpen the picture gathered by the 1mm wavelength. By correcting for atmospheric distortion on this approach, radio astronomers may seize successive pictures at completely different radio bands, then right all of them to create a high-resolution coloration picture.
This technique continues to be in its early phases, and this newest research is only a demonstration of the approach. Nevertheless it proves the tactic can work. So future tasks such because the next-generation EHT (ngEHT) and the Black Gap Explorer (BHEX) will be capable of construct on this technique. And meaning we will see black holes stay and in coloration.
