Defying Expectations: NASA’s Chandra Uncovers a Quasar’s Surprising Galactic Impact

In the center of these images is the quasar H1821+643, a rapidly growing supermassive black hole that astronomers have found is underachieving, despite producing intense radiation and a jet of particles seen in radio data from the Very Large Array. Credit: X-ray: NASA/CXC/Univ. of Nottingham/H. Russell et al.; Radio: NSF/NRAO/VLA; Image Processing: NASA/CXC/SAO/N. Wolk

Research reveals the quasar H1821+643, despite its intense activity, has a minimal effect on its host galaxy, overturning expectations about the role of quasars.

• Astronomers have found a rapidly growing supermassive black hole (quasar) not achieving what they expect from it.
• Quasars are rapidly growing supermassive black holes that pull material in at a very high rate.
• H1821+643 is the closest quasar to Earth located in a galaxy cluster, at a distance of about 3.4 billion light-years.
• Using NASA’s Chandra X-ray Observatory and the VLA, researchers found H1821+643 was less influential than many giant black holes in other clusters.

This image shows a quasar, a rapidly growing supermassive black hole, which is not achieving what astronomers would expect from it. Data from NASA’s Chandra X-ray Observatory (blue) and radio data from the NSF’s Karl G. Jansky’s Very Large Array (red) reveal some of the evidence for this quasar’s disappointing impact on its host galaxy.

Known as H1821+643, this quasar is about 3.4 billion light-years from Earth. Quasars are a rare and extreme class of supermassive black holes that are furiously pulling material inwards, producing intense radiation and sometimes powerful jets. H1821+643 is the closest quasar to Earth in a cluster of galaxies.

The Impact of Quasars on Their Surroundings

Quasars are different than other supermassive black holes in the centers of galaxy clusters in that they pull in more material at a higher rate. Astronomers have found that non-quasar black holes growing at moderate rates influence their surroundings by preventing the intergalactic hot gas from cooling down too much. This regulates the growth of stars around the black hole.

The influence of quasars, however, is not as well known. This new study of H1821+643 that quasars — despite being so active — may be less important in driving the fate of their host galaxy and cluster than some scientists might expect.

Detailed Study Reveals Surprising Findings

To reach this conclusion the team used Chandra to study the hot gas that H1821+643 and its host galaxy are shrouded in. The bright X-rays from the quasar, however, made it difficult to study the weaker X-rays from the hot gas. The researchers carefully removed the X-ray glare to reveal what the black hole’s influence is, which is reflected in the new composite image showing X-rays from hot gas in the cluster surrounding the quasar. This allowed them to see that the quasar is actually having little effect on its surroundings.

Using Chandra, the team found that the density of gas near the black hole in the center of the galaxy is much higher, and the gas temperatures much lower, than in regions farther away. Scientists expect the hot gas to behave like this when there is little or no energy input (which would typically come from outbursts from a black hole) to prevent the hot gas from cooling down and flowing toward the center of the cluster.

A paper describing these results has been accepted into the Monthly Notices of the Royal Astronomical Society and is available online.

Reference: “A cooling flow around the low-redshift quasar H1821+643” by H R Russell, P E J Nulsen, A C Fabian, T E Braben, W N Brandt, L Clews, M McDonald, C S Reynolds, J S Sanders and S Veilleux, 27 January 2024, Monthly Notices of the Royal Astronomical Society.
DOI: 10.1093/mnras/stae026

The authors are Helen Russell (University of Nottingham, UK), Paul Nulsen (Center for Astrophysics | Harvard & Smithsonian), Andy Fabian (University of Cambridge, UK), Thomas Braben (University of Nottingham), Niel Brandt (Penn State University), Lucy Clews (University of Nottingham), Michael McDonald (Massachusetts Institute of Technology), Christopher Reynolds (University of Maryland), Jeremy Saunders (Max Planck Institute for Extraterrestrial Research), and Sylvain Veilleux (University of Maryland).

NASA’s Marshall Space Flight Center manages the Chandra program. The Smithsonian Astrophysical Observatory’s Chandra X-ray Center controls science from Cambridge Massachusetts and flight operations from Burlington, Massachusetts.