Nube, an almost invisible dwarf galaxy, has been identified by an international research team led by the Instituto de Astrofísica de Canarias (IAC) in collaboration with the University of La Laguna (ULL) and other institutions.
The name “Nube,” meaning “Cloud” in Spanish, was suggested by the 5-year-old daughter of one of the researchers due to the object’s diffuse and almost ghost-like appearance. The galaxy’s extremely low surface brightness had gone unnoticed in previous surveys, as its stars are widely dispersed over a large volume.
Nube exhibits unique properties, setting it apart from known objects. Estimated to be ten times fainter than typical dwarf galaxies, it is also ten times more extended. Despite being one-third the size of the Milky Way, Nube shares a comparable mass with the Small Magellanic Cloud.
Mireia Montes, the first author of the study, notes the challenge of understanding the existence of a galaxy with such extreme characteristics. Ignacio Trujillo, the second author, discovered Nube while analyzing a specific sky strip based on the Sloan Digital Sky Survey (SDSS) images.
Confirmation of Nube’s diffuse nature came from ultra-deep multicolor images obtained using the Gran Telescopio Canarias (GTC). Although determining its exact distance remains challenging due to its faintness, an observation with the Green Bank Telescope (GBT) estimated it to be 300 million light years away.
Despite Nube’s unusual properties, there are no apparent signs of interaction or explanation for its characteristics within the current cosmological model of cold dark matter. The density of stars in Nube remains consistent throughout the object, defying the typical trend seen in galaxies.
The researchers express puzzlement at Nube’s features, as cosmological simulations fail to reproduce its extreme characteristics within the cold dark matter model. The galaxy challenges the currently accepted understanding of cosmology, opening the possibility of new insights into the nature of dark matter.
A potential explanation explored by the researchers is that Nube’s unique properties could indicate extremely small-mass particles making up dark matter. If confirmed, this hypothesis would demonstrate the application of quantum physics principles on a galactic scale, providing a remarkable connection between the world of the smallest particles and the largest cosmic structures.
