A recent study led by Colgate Assistant Professor of Physics and Astronomy Cosmin Ilie, in collaboration with Jillian Paulin '23 at the University of Pennsylvania, Andreea Petric of the Space Telescope Science Institute, and Katherine Freese of the University of Texas at Austin, provides answers to three seemingly disparate, yet pressing, cosmic dawn puzzles. Specifically, the authors show how dark stars could help explain the unexpected discovery of "blue monster" galaxies, the numerous early overmassive black hole galaxies, and the "little red dots" in images from the James Webb Space Telescope (JWST).
The first stars in the universe form in dark matter–rich environments, at the centers of dark matter microhalos. Roughly a few hundred million light-years after the Big Bang, molecular clouds of hydrogen and helium cooled sufficiently well to begin a process of gravitational collapse, which eventually led to the formation of the first stars. This phenomenon marked the beginning of the cosmic dawn era, a period offering the right conditions for the formation of stars powered by dark matter annihilations, also known as dark stars . Those objects can grow to become supermassive, and are natural seeds for supermassive black holes .
The James Webb Space Telescope (JWST) observed the most distant objects yet to be studied, and those discoveries pose significant challenges to standard models of the formation of the first stars and galaxies. Specifically, a large fraction of the most distant galaxies are now categorized as "blue monsters," i.e., extremely bright, yet ultra-compact and almost devoid of dust. The existence of such galaxies was extremely unexpected, as no pre-JWST era simulations or theoretical models of the formation of the first galaxies predicted their existence.
Moreover, the JWST data further exacerbate the problem of the seeds for larger-than-expected supermassive black holes (SMBHs) powering the most distant quasars ever observed. Lastly, JWST has observed a whole new class of objects, including "little red dots" (LRDs), which are very compact, dustless cosmic dawn sources which unexpectedly emit little to no X-ray radiation.
Those three puzzles, combined, indicate that the commonly accepted pre-JWST models for the formation of the first galaxies and first supermassive black holes require significant refinements.
"Some of the most significant mysteries posed by the JWST's cosmic dawn data are in fact features of the dark star theory," Ilie said.
While dark stars are yet to be confirmed experimentally, this recent publication adds a significant piece to the existing evidence: photometric and spectroscopic candidates, which were discovered in two separate PNAS studies published in 2023 and 2025, respectively. In addition to discussing in-depth mechanisms via which dark stars could provide solutions to the mysteries posed by the blue monsters, little red dots, and overmassive black hole galaxies, this work also presents the most up-to-date spectroscopic analysis, finding evidence for dark star smoking-gun absorption features due to helium in the spectra of JADES-GS-13-0, in addition to the one previously found for JADES-GS-14-0 .
Dark stars are some of the most exciting astrophysical objects to possibly exist, as their study would allow for a determination of the physical properties of the dark matter particle, and thus complement the vast experimental efforts for the detection of dark matter in laboratories on Earth, via direct detection or particle production.
