Astronomers have identified a celestial object of extraordinary brilliance and mystery within the active galaxy NGC 4945, located approximately 11 million light-years from Earth. This newly discovered entity, named 'Punctum' by the research team led by Elena Shablovinskaia of the Institute of Astrophysical Studies at the University of Diego Portales in Chile, was detected using the Atacama Large Millimeter/submillimeter Array (ALMA).
Punctum's defining characteristic is its exceptional luminosity, outshining typical magnetars by 10,000 to 100,000 times and microquasars by approximately 100 times. Its radiance is comparable only to the Crab Nebula among stellar sources within our galaxy. Intriguingly, Punctum is exclusively observable in millimeter radio wavelengths, remaining invisible in visible light or X-rays. This unique spectral signature strongly suggests the presence of a highly structured magnetic field, with its emitted radiation likely being synchrotron radiation—a phenomenon where relativistic electrons spiral through magnetic fields, producing powerful electromagnetic emissions. While initial hypotheses considered a magnetar or a supernova remnant, neither fully accounts for Punctum's observed properties. Its compact nature, combined with its intense millimeter-wavelength emission and high polarization (around 50%), points towards a potentially novel class of astrophysical bodies, previously undetectable due to technological limitations.
The discovery highlights the power of instruments like ALMA, which can probe the universe in ways that were previously impossible. ALMA is an interferometer composed of 66 antennas, capable of high-resolution imaging across millimeter and submillimeter wavelengths, filling a crucial gap in astronomical observation. Further investigation is planned with both ALMA and the James Webb Space Telescope (JWST). The JWST's superior resolution and infrared capabilities could provide decisive clues to Punctum's true nature. If detected in infrared, its superior resolution might reveal spectral lines or dust features that could illuminate its composition and origin. The discovery of Punctum underscores the vast diversity of cosmic objects and the continuous quest for deeper understanding of the universe's intricate workings, reminding us that the cosmos still holds profound secrets waiting to be unveiled.