A team of astronomers has studied 16 supermassive black holes that are firing powerful beams into space, tracking where these beams, or jets, are pointing now and where they were aimed in the past, as reported in our latest press release. Using NASA’s Chandra X-ray Observatory and the U.S. National Science Foundation (NSF) National Radio Astronomical Observatory’s (NRAO) Very Large Baseline Array (VLBA), they found that some of the beams have changed directions by large amounts.
These two Chandra images show hot gas in the middle of the galaxy cluster Abell 478 (left) and the galaxy group NGC 5044 (right). The center of each image contains one of the sixteen black holes firing beams outwards. Each black hole is located in the center of a galaxy embedded in the hot gas.
In the images below, labels and the radio images appear. Ellipses show a pair of cavities in the hot gas for Abell 478 (left), while ellipses indicate two pairs of cavities for NGC 5044 (right). These cavities were carved out by the beams millions of years ago, illustrating the directions of the beams in the past. An X marks the location of each supermassive black hole.
The VLBA images, shown as insets, reveal the current direction of the beams as seen from Earth. These radio images are significantly smaller than the X-ray images, with the radio image of Abell 478 being about 3% of the width of its Chandra counterpart, and that of NGC 5044 about 4%. Comparing Chandra and VLBA images shows that Abell 478's beams have shifted by about 35 degrees, while NGC 5044's beams have shifted by about 70 degrees.
Researchers found that about a third of the 16 galaxies studied have beams pointing in completely different directions than before. In some cases, the beams have shifted nearly 90 degrees over timescales of one to several tens of millions of years. Considering the black holes are approximately 10 billion years old, these shifts represent a relatively rapid change.
Black holes generate beams when material falls onto them via a spinning disk of matter, with some of it being redirected outward. These beams, likely aligned with the black hole's rotation axis, point along a line connecting the poles and are perpendicular to the disk. If material falls towards the black hole at an angle different from that of the disk, it can alter the black hole’s rotation axis, changing the beam direction.
Scientists believe that these beams and the cavities they create are crucial in regulating star formation within galaxies. The beams inject energy into the surrounding hot gas, preventing it from cooling enough to form large numbers of new stars. Significant changes in beam direction can suppress star formation over larger areas of the galaxy.
The study detailing these findings was published in the January 20th, 2024 issue of The Astrophysical Journal. The authors include Francesco Ubertosi (University of Bologna), Gerritt Schellenberger, Ewan O’Sullivan, Jan Vrtilek, Laurence David, William Forman, and Christine Jones (Center for Astrophysics | Harvard & Smithsonian), Simona Giacintucci (Naval Research Laboratory), Myriam Gitti, and Fabrizio Brighenti (University of Bologna), and Tiziana Venturi (National Institute of Astrophysics—Institute of Radio Astronomy).
NASA’s Marshall Space Flight Center manages the Chandra program, with the Smithsonian Astrophysical Observatory’s Chandra X-ray Center overseeing scientific operations from Cambridge, Massachusetts, and flight operations from Burlington, Massachusetts.
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