Astronomy has a blind spot in the far infrared region compared to most other wavelengths. The far-infrared space telescope can only use its full sensitivity with an actively cooled mirror at temperatures below 4 K (-269 °C). Such a telescope does not exist yet, which is why there has been little global investment in the development of the corresponding detectors.
In 2004, SRON decided to break this cycle and invest in the development of Kinetic Induction Detectors (KIDs). Now, researchers from SRON and TU Delft have achieved the highest sensitivity possible, comparable to feeling the warmth of a candle on the moon from Earth. Show their studies in Astronomy and astrophysics On the sixth of September.
In recent years, we spoiled the most beautiful images from X-ray, infrared, radio telescopes and visible light. To name a few: the image of the black hole in M87, the Hubble Deep Deep Field, or the child image of a planetary system. But in a single wavelength region, astronomy is relatively blind: far infrared, especially at wavelengths between 300 micrometers and 10 micrometers.
Most of this radiation is blocked by the Earth’s atmosphere ground-based telescopes, while space telescopes often have such a temperature that the far-infrared detectors they emit blind themselves. With so much noise, there is little incentive to allocate large sums of money to developing more sensitive far infrared detectors. And with no sensitive detectors in place, governments won’t put money into silent supercooled telescopes.
At the beginning of this century, SRON decided to break the pattern and invest in the development of Kinetic Induction Detectors (KIDs). This decision is now paying off. Together with TU Delft, SRON researchers have nearly perfected the technology by making it sensitive enough to see the universe’s permanent background radiation.
“Even a higher sensitivity will have no benefit,” says Jochem Baselmans (SRON/TU Delft). “Because you will always be limited by the background radiation noise of the universe. So our technology provides telescope builders like NASA and the European Space Agency with far-infrared detectors as sensitive as possible. We’ve already seen two proposals submitted to NASA for supercooling the telescope. These are much more expensive It’s a relatively warm telescope, but our KIDs make it worth it.”
KIDs help astronomy bridge the terahertz gap, named after the frequency of far-infrared light. Astronomers are now losing sight of the light produced by stars in the young, distant universe, leaving a gap in our knowledge of stellar evolution. Moreover, the terahertz gap is a unique opportunity for adventurous astronomers to dive into the unknown.
“You don’t know what you don’t know. The Hubble Deep Field was created by pointing the Hubble telescope at a very black piece of sky that didn’t seem to contain anything. Then, thousands of galaxies appeared, out of an area smaller than one percent of completeness.” Moon,” says Baselmans.
The sensitivity that researchers achieved with KID can best be described by a hypothetical candle on the moon. Imagine you are standing on the ground – or floating just above the atmosphere – and raise your hand to feel the warmth of the candle. Sounds like a futile exercise? Not for KID. It is even ten times more sensitive. With integration time in seconds, KID can detect less than 3*10-20 Watts.
JJA Baselmans et al, Ultra-sensitive Super-THz microwave kinetic induction detectors for future space telescopes, Astronomy and astrophysics (2022). arxiv.org/abs/2207.08647
Dutch SRON Institute for Space Research
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