Just curious since light can't escape and infrared is a type of electromagnetic radiation. What prompted the question was I was wondering if the cold spot in the CMB could actually be a region surrounding a super sized black hole?

I read black holes are probably at the center of all galaxies so eventually the galaxies may be gobbled up by the black hole and this cold spot is just a big sized black hole that has merged with a bunch of other "gobbled" up galaxies.

This question may be out of bounds and should be given to the astronomy web site.


You're correct that if you were looking at an individual black hole, it would block the radiation behind it in your line of sight and look "cold".

However, this doesn't apply to anything we see in the CMB.

That section of the CMB is slightly, but measurably cooler. It's not like a section of it is blocked. There's no way for a single object to cool a massive region of space. Because the CMB is so distant, a region we describe as large as the cold spot is incredibly large in extent. Even some unknown Ubermassive black hole would still be insignificant in size and the ability to affect such a region.

In addition the light we see from the CMB is old. While we don't yet fully understand the origins of galaxy and supermassive black hole formation, we shouldn't be looking for a solution that requires the merger of huge galaxies at a time before or just at the formation of the first galaxies.

Black holes are interesting objects, but on a galactic scale they're incredibly tiny. The region of the CMB is much, much larger than that.

  • $\begingroup$ The cold spot is indeed a mystery. You fully answered my question and explained why. $\endgroup$ – Sedumjoy May 10 '18 at 21:21

Your Answer

By clicking “Post Your Answer”, you agree to our terms of service, privacy policy and cookie policy

Not the answer you're looking for? Browse other questions tagged or ask your own question.