James Webb reveals the turbulent heart of the Circinus Galaxy

In a relatively nearby galaxy, a swirl of gas, dust and infrared light conceals one of the cosmos’s most extreme phenomena.

Using the James Webb Space Telescope, astronomers have pierced this veil of dust to view, in unprecedented detail, the turbulent heart of the Circinus Galaxy, one of the most active galaxies in the Milky Way’s neighbourhood.

A restless galaxy that is hard to observe

The Circinus Galaxy, also called Circinus, lies roughly 13 million light-years from Earth. On cosmic scales, it is a comparatively close neighbour. Under ideal night-time conditions, amateur astronomers can capture it with more advanced equipment. Even so, it remains an unforgiving target.

The reason is its location in the sky: the galaxy appears almost against the plane of the Milky Way, an area crowded with stars, gas and dust from our own galaxy. All this intervening clutter makes observations from ground-based telescopes more difficult.

From space, however, the situation is different. Orbiting the Sun around 1.5 million kilometres from Earth, James Webb avoids atmospheric interference and carries instruments designed specifically to see what dust obscures.

With James Webb, researchers were able, for the first time with such precision, to distinguish what produces what within the luminous chaos at the centre of the Circinus Galaxy.

The mysterious origin of the infrared light

For years, the Circinus Galaxy has intrigued astronomers because its central region emits powerful infrared radiation. Earlier observations from telescopes including Hubble had already revealed this intense emission near the supermassive black hole at the galaxy’s core.

Theoretical models proposed a dramatic explanation: some matter heated by the black hole could be being driven outwards in energetic jets. This escaping material might account for much of the observed radiation.

The new James Webb data have completely changed that interpretation. By examining the infrared light distribution in greater detail, researchers found that most of the radiation actually comes from a large dust “cocoon” surrounding the black hole, rather than from ejected matter.

The dust doughnut feeding the black hole

This cocoon takes the form of a torus, a doughnut-shaped structure made chiefly of heated dust and dense gas. Far from being merely a visual feature, this doughnut acts as a reservoir of cosmic fuel.

As the black hole’s gravity draws in this material, it creates an accretion disc: an inner ring rotating at extremely high speed, where matter is compressed, heated and shines intensely in infrared light.

Seen from Earth, this produces an excess of light that outshines many of the surrounding structures. The galaxy’s centre therefore looks like a single bright blur, concealing crucial details of how the black hole feeds and interacts with its surroundings.

According to the new analysis, around 87% of the infrared radiation comes from the dust ring surrounding and feeding the black hole, while only around 1% is directly linked to material being expelled.

The remaining 12% of infrared emission originates in more distant areas, probably associated with clouds of gas and dust that had not been fully mapped before this observation.

James Webb tests its capabilities

To disentangle this picture, scientists turned to James Webb’s greatest strength: its infrared sensitivity. Unlike Hubble, which observes primarily visible and ultraviolet light, the JWST was designed specifically to observe the wavelengths at which dust absorbs and re-emits light.

For this campaign, the team used an interferometric observing mode, combining information from different parts of the telescope to improve resolution. The key instrument was NIRISS, a spectrograph that can also operate as a specialised interferometer to block some of the intense glare from stars and bring out fainter details.

The effect is similar to holding a hand in front of the Sun in an effort to see an aeroplane passing close to the solar disc. By cutting the glare, the telescope can record subtle structures around the galactic nucleus.

• Location of the Circinus Galaxy: around 13 million light-years
• Central object: supermassive black hole
• Main infrared source: ring of dust and gas around the black hole
• Key instrument: NIRISS in interferometric mode
• Infrared-emission fractions: 87% from the dust torus, 1% from ejected material, 12% from more distant regions

A first beyond the Milky Way

The Circinus study also represents an important technical milestone: it is the first time James Webb has used this type of interferometric observation to examine a source beyond our galaxy.

The method’s success paves the way for new campaigns targeting other active galactic nuclei nearby. With a larger sample, astronomers hope to better understand how supermassive black holes grow, how much they consume, how much they return to their environment, and how this affects star formation around them.

Black holes do not simply swallow matter: the rate at which they feed sets the energetic climate of galactic nuclei.

In many cases, this process may regulate the life of an entire galaxy by heating gas and preventing it from collapsing to form new stars. In others, nuclear activity may instead compress gas clouds and trigger intense periods of star birth.

Supermassive black hole, dust and infrared: what this means in practice

For readers unfamiliar with astronomical jargon, several terms are important for understanding the discovery.

Term	Explanation
Supermassive black hole	An object with millions or billions of times the Sun’s mass, usually found at the centres of galaxies.
Infrared	A band of light with a wavelength longer than visible light, associated with heat and emission from warmed dust.
Accretion disc	A disc of matter orbiting a massive object, heated by friction and extreme gravity.
Dust torus	A thick ring-shaped region of dust and gas surrounding a galaxy’s active centre.

Together, these structures explain why investigating the nucleus of Circinus with optical telescopes alone is so difficult. Dust absorbs visible light and re-emits it in infrared wavelengths, changing the galaxy’s observed signature.

What this research may reveal about other galaxies

The findings from the Circinus Galaxy serve almost as a laboratory for other active galactic nuclei. If similar dust structures are present in a large share of galaxies with hungry black holes, many earlier measurements may need reassessment.

For instance, models estimating how much matter a black hole consumes commonly use observed radiation as an indicator. If much of that light actually comes from a dust torus rather than directly from the accretion disc, calculations may be exaggerating or misrepresenting these objects’ true feeding rate.

One possibility raised by researchers is to combine observations across different energy bands, from radio waves to X-rays, to build a more complete picture of these nuclei. James Webb is a central piece of this puzzle, precisely in the range where dust is most prominent.

Applications, risks and next steps for high-resolution astronomy

In practical research terms, the advance is not limited to understanding Circinus. Space-based interferometric techniques could become more widely used in future missions, further expanding the ability to resolve fine details in distant galaxies.

This brings technical challenges and some risks. Interferometric systems demand great precision in both optical alignment and data analysis. Small mistakes can produce artefacts that may be mistaken for real structures. The scientific community is likely to compare James Webb’s results with data from other observatories to ensure that interpretations are not being driven by instrumental effects.

At the same time, the potential benefit is substantial: understanding how supermassive black holes grow helps reconstruct the history of galaxy formation and, by extension, the Universe’s own history. Observations such as those of the Circinus Galaxy suggest that we are only at the beginning of a period in which formerly invisible details are becoming part of science news.