One little red dot caught emerging from its shroud
Prior to the launch of the JWST, we thought the first stars and their galaxies came together several hundred million years after the big bang, with hot giant stars heating up gas as SMBHs formed and AGN to blast clear anything the stars had left clouding the universe.
And then we found a mostly transparent universe full of already formed small galaxies and these weird red dots. This was not what we expected, and suddenly, we had an entirely knew kind of object to try and explain.
Little red dots, or LRDs are point like, gas rich, massive objects that shine in star-like colors, and not… as far as we knew… in high energies like X-Rays. Numerous ideas have been put forward to explain their origins, and many of these origin stories led to a final chapter that includes a black hole embedded in a dense cloud of gas that is acting like the atmosphere of a star. And just like the atmosphere of our star prevents high energy photons from the core from escaping the surface in large numbers, the atmospheres of these little red dots may prevent high energy photons created at the black holes event horizon from escaping.
Until it doesn’t, at least.
Credit: X-ray: NASA/CXC/Max Plank Inst./R. Hviding et al.; Optical/IR; NASA/ESA/STScI/HST; Image Processing: NASA/CXC/SAO/N. Wolk
In comparing the locations of newly discovered LRDs with Chandra X-Ray data, one lone LRD was found aligned with a highly variable X-Ray source. In a new paper in the Astrophysical Journal Letters, researchers led by Raphael E. Hviding postulate this could be a transition object. Classified as 3DHST-AEGIS-12014, this object is about 11.8 billion light years away. The observed variability could be the gas around the growing black hole getting blasted away by high energy light, and we’re seeing x rays through the thin section as they rotate past.
This implies one origin story for SMBH’s is a little red dot forming from primordial gas, collapsing in its core by some means, and then growing as it it’s gas until it is so big that light forming at its event horizon clears away the surrounding region, revealing a young active galactic nuclei.
This story is still a bit vague… and one object really isn’t enough to say this is more than the vague outline of a story. But… this is more than we had before, and sometimes science advances one weirdo observation at a time
And by sometimes, I mean often. Science often advances one weirdo observation at a time.
Sources
- Chandra X-Ray Observatory Press Release
- Hviding, Raphael E., et al. “The X-Ray Dot: Exotic Dust or a Late-stage Little Red Dot?.” The Astrophysical Journal Letters 1000.1 (2026): L18. DOI 10.3847/2041–8213/ae4c88
This content was originally written for the EVSN podcast. Watch video episodes and check out additional content at EVSN.tv.
