Quasar RACS J0320-35 and Its Unprecedented Growth

The black hole powers a quasar—a brilliant celestial object that outshines entire galaxies. Its extraordinary luminosity arises from immense amounts of material spiraling into the black hole.

Figure 1. Black Hole Defies Known Growth Limits, Astonishing Astronomers.

Discovered by the same team two years ago, RACS J0320-35 has revealed a surprising feature in new 2023 Chandra observations. The X-ray data indicate that its black hole is growing at a rate exceeding the typical limits expected for such objects. Figure 1 shows Black Hole Defies Known Growth Limits, Astonishing Astronomers.

Understanding the Eddington Limit

As matter falls toward a black hole, it heats up and emits intense radiation across a wide range of wavelengths, including X-rays and visible light. This radiation pushes back against the infalling material. When the inflow reaches a critical threshold, the outward pressure from radiation balances the black hole’s gravity, preventing matter from falling in faster. This upper threshold is known as the Eddington limit.

Researchers note that black holes growing more slowly than this limit must have started with masses of at least 10,000 Suns to reach a billion solar masses within the first billion years after the Big Bang, as seen with RACS J0320-35. One possible origin for such a massive “seed” black hole is the collapse of an enormous, metal-poor gas cloud—a rare cosmic event.

Possible Origins and Growth Scenarios

If RACS J0320-35 is indeed growing at a high rate—estimated at 2.4 times the Eddington limit—and has done so for an extended period, its black hole could have formed more conventionally, starting with a mass under 100 Suns from the collapse of a massive star.

“By knowing the mass of the black hole and calculating its growth rate, we can estimate how massive it was at birth,” said co-author Alberto Moretti of INAF-Osservatorio Astronomico di Brera in Italy. “This allows us to test different theories about black hole formation.”

To determine the growth rate—between 300 and 3,000 Suns per year—the team compared theoretical models with the X-ray spectrum observed by Chandra. The spectrum matched expectations for a black hole growing faster than the Eddington limit. Observations in optical and infrared light further support the conclusion that this black hole is gaining mass at an extraordinary pace.

Insights into Cosmic Mysteries

“How did the universe create the first generation of black holes?” said co-author Thomas Connor of the Center for Astrophysics. “This remains one of the biggest questions in astrophysics, and this object is helping us pursue the answer.”

Another mystery relates to the jets of particles observed streaming from RACS J0320-35 at nearly the speed of light. Such jets are rare in quasars, suggesting that the black hole’s extraordinary growth rate may play a role in producing them.

RACS J0320-35 was initially discovered through a radio survey using the Australian Square Kilometer Array Pathfinder, combined with optical observations from the Dark Energy Camera on the Victor M. Blanco 4-meter Telescope at Cerro Tololo Inter-American Observatory in Chile. The Gemini-South Telescope at Cerro Pachon, operated by the U.S. National Science Foundation’s National Optical-Infrared Astronomy Research Laboratory, provided precise measurements of the quasar’s distance.

Source: SciTECHDaily

Cite this article:

Priyadharshini S (2025), Astronomers Shocked as Black Hole Surpasses Known Growth Limits, AnaTechMaz, pp.568