You still have to get rid of waste heat, you can’t recycle it because of the second law of thermodynamics. So they’d radiate highly in the infrared.
Incidentally, there is an object in the Triangulum galaxy that’s dim in the visible and near-infrared but the most luminous thing in that galaxy in the mid-infrared.
It’s also extremely bright in total luminosity across the spectrum (including infrared) − 100,000x as bright as the Sun. Other similar objects have been seen as supernova sources in other galaxies, suggesting they are massive stars shrouded in self-produced dust which blocks visible light but lets IR through. If this is the case, various models suggest we should see the dust around this thing clear in decades to centuries—or a supernova. You can bet people are watching it closely though...
Waste heat. Sorry, my internal editor cringes at that...
As to the object, I notice something interesting. In the writeup:
Nobody had ever bothered to look at it in mid-IR before, because as a general rule things that are dim in the near-IR are also dim in the mid-IR.
And then I look at the paper—and it was submitted in December 2010, only a few years ago. Which then leads to the question—has anyone looked for things that are dim in near-infrared but bright in far-infrared? Do we actually know how much apparent dark matter is (or isn’t) pumping out waste heat all over the place?
You still have to get rid of waste heat, you can’t recycle it because of the second law of thermodynamics. So they’d radiate highly in the infrared.
Incidentally, there is an object in the Triangulum galaxy that’s dim in the visible and near-infrared but the most luminous thing in that galaxy in the mid-infrared.
It’s also extremely bright in total luminosity across the spectrum (including infrared) − 100,000x as bright as the Sun. Other similar objects have been seen as supernova sources in other galaxies, suggesting they are massive stars shrouded in self-produced dust which blocks visible light but lets IR through. If this is the case, various models suggest we should see the dust around this thing clear in decades to centuries—or a supernova. You can bet people are watching it closely though...
Waste heat. Sorry, my internal editor cringes at that...
As to the object, I notice something interesting. In the writeup:
And then I look at the paper—and it was submitted in December 2010, only a few years ago. Which then leads to the question—has anyone looked for things that are dim in near-infrared but bright in far-infrared? Do we actually know how much apparent dark matter is (or isn’t) pumping out waste heat all over the place?
(That is a very interesting page, by the way...)