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A new study reveals a dust-reddened quasar from a time when the universe was less than a billion years old. Located at a redshift of 6.5488, the object J1440+0019 contains a rapidly accreting supermassive black hole with a mass of about 1.1 billion suns. The paper was posted to the arXiv preprint server on Oct. 9.
Dusty quasarsCosmic reionization is estimated to have happened roughly between 600 million and a billion years (redshifts 6 to 8) after the Big Bang. This epoch is when ionizing UV radiation from early stars and galaxies converted the universe's neutral hydrogen gas into the ionized state seen today. Studying quasars and galaxies from this era can put a limit on the redshift at which it occurred.
Most quasars from this period are identified by their bright rest-frame ultraviolet light. This method may fail for quasars with even modest dust reddening—their UV emission may be heavily blocked by the surrounding dust envelope. Previous studies suggest that a large fraction of early active galactic nuclei (AGN) are obscured. Only a handful of reddened quasars are known at redshifts around and beyond 6, and they were found by different methods.
In this study, researchers led by Daming Yang of the Leiden Observatory present the details of a quasar at a redshift of 6.55, previously discovered in the Subaru High-z Exploration of Low-Luminosity Quasars (SHELLQs) survey. The team combined NIRSpec spectroscopy of the core from the James Webb Space Telescope (JWST) with observations from the Atacama Large Millimeter/submillimeter Array (ALMA) of the host galaxy's cold gas and dust.
Matching the modelsThe spectrum of J1440+0019 revealed a shape that matches that of reddening by dust. It revealed prominent emission lines, and together with prominent obscuration, it indicates the presence of a quasar that is moderately hidden by dust along the line of sight. "This combination identifies J1440+0019 as a red type-1 quasar: the nucleus is viewed directly, but through moderate dust extinction along the sightline," the team writes in the paper.
They found some features that are blueshifted—indicative of them moving toward us. Three high-ionization absorption systems appear blueshifted relative to the component that is moving away from us. The team estimated their speeds at up to 3,600 kilometers per second, a strong sign of fast nuclear outflows.
ALMA observations show that the host galaxy is exceptionally luminous in emission from ionized carbon, placing it among the brightest known sources of this kind at redshifts above 6.
Estimating how brightly the quasar is shining after appropriate correction revealed the rate at which it is accreting material. It turns out that it is radiating at about 80% of its Eddington luminosity.
The galaxy contains an estimated 400 million solar masses of dust and has a star-formation rate with an upper limit of approximately 1,330 sun-like stars per year.
Diverse propertiesThe core's reddening dust resembles that of "moderately reddened" quasars in the local universe. But the dust reservoir itself resembles those of heavily reddened systems. Compared with other early-universe reddened quasars, researchers found some similarities and dissimilarities. They conclude that red and obscured sources "span diverse accretion states and host properties."
Overall, the combined JWST and ALMA observations reveal a dust-reddened quasar whose supermassive black hole is accreting rapidly, while its host galaxy contains a massive dust reservoir and may be forming stars at an exceptional rate less than a billion years after the Big Bang.
The team notes that just 5.5 minutes of ALMA time was enough to extract primary tracers of gas and dust, showing promise for efficiently identifying dust-rich systems. "Such surveys can help flag promising reddened-quasar candidates for spectroscopic follow-up at a modest cost in ALMA observing time," they write. They also think Euclid and Roman will be able to build a more complete sample of reddened quasars and bridge the gap in observations.
Written for you by our author Shreejaya Karantha, edited by Gaby Clark, and fact-checked and reviewed by Robert Egan—this article is the result of careful human work. We rely on readers like you to keep independent science journalism alive. If this reporting matters to you, please consider a donation (especially monthly). You'll get an ad-free account as a thank-you.
Publication detailsDaming Yang et al., A dust-reddened quasar in a [C II]-luminous host at z=6.55, arXiv (2026). DOI: 10.48550/arxiv.2610.13758
Journal information: arXiv
Who's behind this story?
Shreejaya KaranthaShreejaya Karantha is a science writer and astronomy communicator based in India, with a focus on astrophysics and the early universe. Full profile →
Gaby ClarkMA in English, copy editor since 2021 with experience in higher education and health content. Dedicated to trustworthy science news. Full profile →
Robert EganBachelor's in mathematical biology, Master's in creative writing. Well-traveled with unique perspectives on science and language. Full profile →
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Citation: JWST and ALMA reveal a dusty, rapidly growing black hole in the early universe (2026, October 26) retrieved 26 October 2026 from https://phys.org/news/2026-10-jwst-alma-reveal-dusty-rapidly.html
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