Hubble Space Telescope observes galaxy with "forbidden" light

In space, in the middle of an incredibly energetic galactic nucleus, it is possible to observe "forbidden" light that cannot be reproduced in the laboratory and appears to violate the known laws of Physics.

This image from NASA's Hubble Space Telescope shows a bright spiral galaxy known as MCG-01-24-014, which is located about 275 million light years from Earth. Credit: ESA/Hubble and NASA, C. Kilpatrick
This image from NASA's Hubble Space Telescope shows a bright spiral galaxy known as MCG-01-24-014, which is located about 275 million light years from Earth. Credit: ESA/Hubble and NASA, C. Kilpatrick

The image above shows a bright spiral galaxy known as MCG-01-24-014, which is located about 275 million light years from Earth. In addition to being a well-defined spiral galaxy, MCG-01-24-014 has an extremely energetic core known as the active galactic nucleus (AGN) and is categorised as a Seyfert type 2 galaxy.

Seyfert galaxies, along with quasars, host one of the most common subclasses of AGN. While the precise categorisation of AGNs is nuanced, Seyfert galaxies tend to be relatively close and their central AGN does not eclipse their host, while quasars are very distant AGNs with incredible luminosities that outshine their host galaxies.

Space subclasses and quantum physics questions

There are other subclasses of both Seyfert galaxies and quasars. In the case of Seyfert galaxies, the predominant subcategories are Type 1 and Type 2. Astronomers distinguish them by their spectrum, the pattern that results when light is split into its constituent wavelengths.

The spectral lines emitted by Seyfert type 2 galaxies are associated with specific "forbidden" emission lines. To understand why light emitted from a galaxy might be forbidden, it is helpful to understand why spectra exist in the first place.

Spectra look like this because certain atoms and molecules absorb and emit light at very specific wavelengths. The reason for this is quantum physics: electrons (the small particles that orbit the nuclei of atoms and molecules) can only exist at very specific energies, and therefore electrons can only lose or gain very specific amounts. specific energy.

These very specific amounts of energy correspond to the wavelengths of light that are absorbed or emitted. According to certain rules of quantum physics, forbidden emission lines should not exist. But quantum physics is complex, and some of the rules used for its prediction were formulated under laboratory conditions here on Earth.

Under those rules, this broadcast is "prohibited"; It is so unlikely that it is not taken into account. But in space, in the midst of an incredibly energetic galactic core, those assumptions no longer make sense, and the "forbidden" light has a chance to shine toward us.

Provided by NASA Goddard Space Flight Center.