James Webb Telescope (JWST) discovered small galaxies with black holes that are not well understood. These black holes, located in galaxies with masses much smaller than those traditionally associated with supermassive black holes (SMBHs), challenge long-held beliefs about how galaxies and their central black holes evolve. The discovery of these “extreme” black holes pushes the boundaries of our knowledge, suggesting that early galaxies may be producing black holes faster than previously thought.
Unexpected Finds: The Prospects of Pelias and Neleus
The study, led by Eduardo Iani and his colleagues, and available on arXiv, reports the discovery and analysis of two small galaxies, Pelias and Neleus, located at redshifts of z ~ 0.71 and z ~ 0.75. These galaxies, despite their small size and young age, contain black holes with masses up to 60% of the total mass of galaxies. The discovery is remarkable because, in typical galaxies, the ratio of black hole mass to stellar mass is about 0.1% to 0.5%. The fact that these small galaxies have supermassive black holes suggests that their central holes grew faster than the stars around them.
Both galaxies were observed using JWST’s high-energy infrared probe, which revealed unusual spectral energy distributions (SEDs). “We report the discovery and identification of two constellations, Pelias and Neleus, at z ~ 0.71 and z ~ 0.75,” the researchers write. These constellations displayed very blue halos, indicating young, hot stars. However, their SEDs also show a sharp rise to near- and mid-infrared wavelengths, suggesting the presence of a hot, dust-covered cloud containing an active galactic nucleus (AGN) in their cores.
The Secret of Dust-Embed Active Galactic Nuclei
The presence of AGN at the heart of these galaxies was further supported by mid-infrared observations made by JWST’s MIRI tool. These observations revealed a range of mid-infrared radiation that could not be accounted for by stars or warm dust alone.
“JWST/MIRI photometry reveals strong mid-infrared excesses that cannot be explained by stellar populations or warm interstellar dust alone, requiring a naturally hot dust component associated with a deeply embedded galactic nucleus (AGN),” the authors explain.
This is an important finding because it suggests that black holes are growing rapidly in a layer hidden behind dense dust, which makes it difficult to detect with other methods.
Interestingly, research also shows that despite clear evidence of AGN, no X-ray emission has been detected in the central regions of these galaxies. “The lack of X-ray analyzes suggests that the increase may be more subtle or less obvious on X-rays,” the researchers write. This lack of X-rays can indicate that black holes are inside Super-Eddington transition phasewhere black holes consume material at rates far exceeding normal limits.
Super-Eddington Accretion: A Closer Look at the Rapid Growth of a Black Hole
The idea of Super Eddington Accretion helps explain the rapid growth of these black holes. In this scenario, black holes can grow faster than thought possible because they consume matter at extraordinary rates. According to the researchers, Super-Eddington accretion may have been an important mechanism for the growth of black holes in the early universe, especially in small low-mass galaxies such as Pelias and Neleus. “Super-Eddington phases are thought to facilitate the rapid growth of black holes, especially low-mass galaxies,” they said.
This section is mainly related to the study of small constellations. These galaxies, which contain galaxies less than 10^7 solar masses, are among the smallest known to have active nuclei. The rapid growth of the black hole seen in Pelias and Neleus shows that even small galaxies can host supermassive black holes. “In general, Pelias and Neleus show that the rapid growth of dust-covered black holes can form galaxies with only about 107 solar masses,” the authors explain.
What’s Next? The Future of Black Hole Research
The discovery of these supermassive black holes in young galaxies has opened new avenues for future research. The next step is to find other examples of constellations like Pelias and Neleus to understand how common this phenomenon is. Researchers are hopeful that future space missions, such as the Roman Telescope and Very Large Telescope (ELT)will allow more systematic investigations of low-mass, hidden AGNs. These advanced telescopes will be able to resolve the internal structure of these galaxies, providing important data to test theories of the growth of black holes during the first stages of galaxy formation.
The discovery of these galaxies highlights the power of JWST, which continues to reveal new mysteries of the universe. “In the long term, instruments such as the Roman Space Telescope and ELT-class observatories will enable systematic searches for hidden AGN masses and resolve their internal structure, providing important tests of whether the included gain component described here represents the normal path of DG evolution,” the researchers conclude.
In the coming years, we can expect many more revelations about the mysterious relationship between black holes and galaxies, which could change our understanding of the evolution of the universe and the fabric of the universe.
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