Kohei Inayoshi

A massive galaxy cluster acts as a giant lens. Its gravity warps the fabric of space, and the light of distant objects, bending around this curvature, is amplified and split into multiple images.

Thanks to gravitational lens — an effect predicted by Fritz Zwicky, where a galaxy cluster acts like a magnifying glass — the James Webb Space Telescope spotted two red dots in a galaxy 800 million years after the Big Bang.

Astronomers nicknamed them 'little red dots' — distant galaxies where a giant black hole hides at the center, wrapped in a thick layer of hydrogen. This packaging isn't just camouflage; it's a natural cannon. The black hole sucks in matter, but some of it is spat back out in narrow jets.

Imagine a city where a skyscraper and a huge park are being built at the same time. The skyscraper grows upward, and the park expands outward. Both processes are fast and get in each other's way, but in the end they are meant to become a single whole. That's the situation in galaxy GNz7q: a black hole grows at the center while new stars burst to life around it.

Two stars orbit a common center, accreting gas from a surrounding cloud. Rotating disks of gas form around each star and around the pair as a whole. From these disks, jets shoot out like hoses. Inside the disks, gas is constantly churned — that's the magnetorotational instability at work.

A powerful vacuum cleaner sucks in not only dust but also its own collection bag. That's roughly how a black hole behaves at the center of a 'red dot'—a distant galaxy where the glow comes not from the hole itself but from its dense gas shroud. This shroud is so thick it resembles a puffed-up cool star. And, like many stars, it has a magnetic field.

When the James Webb Space Telescope turned its gaze deep into time, astronomers expected to see familiar galaxies. Instead, the images were dotted with a scattering of bright, incredibly compact red dots.

The James Webb Space Telescope peered into the era when the expansion of the Universe stretched the light of distant objects into the red, and found a scattering of strange sources — 'little red dots'. Their spectra broke the usual patterns: they are blue in the ultraviolet, but deep red in the optical, as if seen through a cherry veil.