Platypus galaxies seen by James Webb may challenge ideas about galaxy formation

Researchers report nine unusual objects found in archival James Webb Space Telescope data that are small and compact but lack clear signs of bright quasars or active supermassive black holes. The objects show narrow spectral lines indicating slower gas motions, and the team says more examples and follow-up data are needed to determine their nature.

Astronomers have identified a set of unusual objects in archival data from the James Webb Space Telescope that resist easy classification. The team, led by Haojing Yan of the University of Missouri, presented the findings at the 247th meeting of the American Astronomical Society and made a related preprint available on arXiv. The group adopted the informal name "platypus galaxies" because the objects combine traits not usually seen together. Researchers say additional data and more examples will be needed to clarify what these objects represent. Key observations: - Nine objects were identified in archival JWST observations and highlighted by the research team. - The objects are small and compact in images but do not appear as point-like sources typical of bright quasars. - Their spectra are described as narrow and sharp, which the team reports indicates slower gas motions than seen around many active supermassive black holes. - The researchers report no clear signs that these objects host the kind of active, luminous black holes associated with quasars. - One reported possibility is that they are a form of star-forming galaxy from the early universe, though that interpretation raises questions because of the objects' compact appearance. - The team says more galactic samples and follow-up observations are required; JWST remains in operation with a projected long observing lifetime. Summary: If these objects are a genuine new class, they could affect how astronomers think about early galaxy formation by showing unexpectedly compact, relatively calm systems. The immediate next step reported by the team is to gather more examples and deeper observations to determine their nature; the timeline for that work is undetermined at this time.