When it comes to the brightest, most powerful objects in the Universe, not much can beat a Quasar. A Gamma Ray Burst from a supernova might be more energetic, but doesn’t last very long. Quasars, by comparison, can churn out 1000 times the radiation of the Milky Way, and keep doing it for hundreds of millions of years.
They get all this energy from the supermassive black holes that live at the center of galaxies. As material falls towards the black hole, an accretion disk forms around it: a swirling cloud of energetic material which heats up through friction and releases electromagnetic radiation. The resulting Quasar can be so bright it drowns out the light from the rest of its galaxy from our perspective.
On April 5th, researchers announced the discovery of a rare double quasar in the early Universe. The two quasars are gravitationally bound, spiraling in towards each other. Their host galaxies are in the process of merging, and the supermassive black holes generating the quasars will also eventually collide and merge.
Black holes are the most massive objects that we know of in the Universe. Not stellar mass black holes, not supermassive black holes (SMBHs,) but ultra-massive black holes (UMBHs.) UMBHs sit in the center of galaxies like SMBHs, but they have more than five billion solar masses, an astonishingly large amount of mass. The largest black hole we know of is Phoenix A, a UMBH with up to 100 billion solar masses.
You’re looking at NGC 346, a star cluster 210 light years away that is energetically pumping out brand new stars from a dense cloud of gas and dust. Between 10 and 11 billion years ago, nearly all galaxies in the Universe underwent an era of intense star formation similar to what we see in NGC 346. This flurry of stellar birth is poetically nicknamed cosmic noon. Since then, star formation in the Universe has gradually dwindled, though it still blazes away in small pockets. By studying NGC 346 and other clusters like it, we can learn more about the era of cosmic noon and the evolution of galaxies.
To that end, researchers pointed the James Webb Space Telescope’s NIRCam infrared camera at NGC 346 last year, and they announced their preliminary findings at the American Astronomical Society’s annual meeting on January 11, 2023.
A galaxy’s main business is star formation. And when they’re young, like youth everywhere, they keep themselves busy with it. But galaxies age, evolve, and experience a slow-down in their rate of star formation. Eventually, galaxies cease forming new stars altogether, and astronomers call that quenching. They’ve been studying quenching for decades, yet much about it remains a mystery.
A new study based on the IllustrisTNG simulations has found a link between a galaxy’s quenching and its stellar size.