Astronomers have described quasar J1440+0019, an object that existed when the Universe was less than a billion years old. A quasar is an active galactic nucleus in which a supermassive black hole absorbs matter and shines brighter than entire galaxies. The work was published as a preprint on the arXiv server; a preprint is a scientific paper that has not yet undergone full peer review in a journal.
The object is at a redshift of 6.55. Redshift shows how much radiation has been stretched by the expansion of the Universe: the larger the number, the farther away and more ancient the object. The mass of the black hole in J1440+0019 is estimated at about 1.1 billion solar masses.
The study was led by Daming Yang of Leiden Observatory. The team combined near-infrared spectroscopy from the James Webb Space Telescope (JWST) with observations from the ALMA array, which detects cold gas and dust in the host galaxy. Spectroscopy is a method in which light is split into wavelengths to determine the composition and motion of matter.
The spectrum of J1440+0019 showed a shape characteristic of reddening due to dust. Bright emission lines are visible, but part of the radiation is attenuated. According to the authors, this indicates a quasar moderately obscured by dust along the line of sight. They classify the object as a "red type 1 quasar": the nucleus is seen directly, but through a layer of dust.
Three systems of absorption by highly ionized gas were detected, shifted toward the blue, meaning their radiation is shifted because of motion toward us. Velocities reach 3600 km/s, which is considered a sign of fast outflows of matter from the nucleus.
ALMA showed that the host galaxy is exceptionally bright in ionized carbon emission and is among the brightest such sources at redshifts above 6. The dust mass was estimated at 400 million solar masses. The star formation rate is no higher than about 1330 stars similar to the Sun per year.
After correcting for dust, the scientists estimated the accretion rate, the rate at which matter falls onto the black hole. The quasar shines at about 80% of the Eddington limit, the maximum luminosity at which radiation pressure does not yet blow matter away.
The dust in the nucleus resembles that of "moderately reddened" quasars in the nearby Universe, but its supply is more similar to heavily dust-obscured systems. The authors conclude that red and obscured sources "span diverse accretion states and host properties."
Separately noted: only 5.5 minutes of ALMA observations were enough for the initial detections of gas and dust. According to the team, this makes such surveys a cheap way to select candidates for dusty quasars for subsequent spectroscopy. The researchers also expect that the Euclid and Roman telescopes will help assemble a more complete sample and close gaps in observations.