- Four cavities in the hot gas of a single galaxy cluster have been found.
- Astronomers found this quartet of X-ray cavities in the cluster located about 3.9 billion light years from Earth using Chandra.
- This suggests there is a pair of supermassive black holes, both of which erupted and generated jets at about the same time.
- If confirmed, the two supermassive black holes would be among the closest pair ever discovered, with a separation of about 250 light years.
Four enormous cavities, or bubbles, have been found at the center of a galaxy cluster using NASAEstablished in 1958, the National Aeronautics and Space Administration (NASA) is an independent agency of the United States Federal Government that succeeded the National Advisory Committee for Aeronautics (NACA). It is responsible for the civilian space program, as well as aeronautics and aerospace research. It’s vision is “To discover and expand knowledge for the benefit of humanity.””>NASA’s Chandra X-ray Observatory. The left panel of this graphic shows an optical image of the galaxy cluster called RBS 797, from NASA’s Hubble Space TelescopeThe Hubble Space Telescope (often referred to as Hubble or HST) is one of NASA’s Great Observatories and was launched into low Earth orbit in 1990. It is one of the largest and most versatile space telescopes in use and features a 2.4-meter mirror and four main instruments that observe in the ultraviolet, visible, and near-infrared regions of the electromagnetic spectrum. It was named after astronomer Edwin Hubble.”>Hubble Space Telescope. Hot gas that envelopes the individual galaxies is invisible in optical light, but it is detected in X-rays by Chandra (below). One pair of cavities can be seen towards the left and right of center in the Chandra image as black oval-shaped regions. The other pair is less distinct, but can be found above and below the center of the image.
Scientists have seen these X-ray cavities before in other galaxy clusters. A pair of cavities is thought to be a byproduct of eruptions from a giant black holeA black hole is a place in space where the pull of gravity is so strong not even light can escape it. Astronomers classify black holes into three categories by size: miniature, stellar, and supermassive black holes. Miniature black holes could have a mass smaller than our Sun and supermassive black holes could have a mass equivalent to billions of our Sun.”>black hole in a large galaxy at the center of a cluster. The eruptions power jets in opposite directions, which push gas away to create a pair of cavities. However, to produce four cavities each roughly pointing 90 degrees away from one another, a more complex phenomenon must be at play.
A team of astronomers studying RBS 797 think the most likely answer is that the galaxy cluster contains a pair of supermassive black holes, each of which has launched jets in perpendicular directions at almost the same time. Another possible explanation for the four cavities seen in RBS 797 is that there is only one supermassive black hole — with jets that somehow manage to flip around in direction quite quickly. Analysis of the Chandra data shows that the age difference for the east-west and north-south cavities is less than 10 million years.
Previously, astronomers observed the pair of cavities in the east-west direction in RBS 797, but the pair in the north-south direction was only detected in a new, much longer Chandra observation. The deeper image uses almost five days of Chandra observing time, compared to about 14 hours for the original observation. The NSF’s Karl G. Jansky Very Large Array had already observed evidence for two pairs of jets as radio emission, which line up with the cavities.
Reference: “The deepest Chandra view of RBS 797: evidence for two pairs of equidistant X-ray cavities” by Francesco Ubertosi, Myriam Gitti, Fabrizio Brighenti, Gianfranco Brunetti, Michael McDonald, Paul Nulsen, Brian McNamara, Scott Randall, William Forman, Megan Donahue, Alessandro Ignesti, Massimo Gaspari, Stefano Ettori, Luigina Feretti, Elizabeth L. Blanton, Christine Jones, Michael S. Calzadilla, 16 December 2021, The Astrophysical Journal Letters.
A paper describing these results, led by Francesco Ubertosi (University of Bologna in Italy) appears in The Astrophysical Journal Letters. The other authors include Myriam Gitti (Univ. of Bologna), Fabrizio Brighenti (Univ. of Bologna), Gianfranco Brunetti (INAF), Michael McDonald (Massachusetts Insitute of Technology), Paul Nulsen (Center for Astrophysics | Harvard & Smithsonian), Brian McNamara (Perimeter Institute), Scott Randall (CfAThe Harvard-Smithsonian Center for Astrophysics (CfA) is a joint venture between the Smithsonian Astrophysical Observatory and the Harvard College Observatory. Founded in 1973, the Harvard-Smithsonian Center for Astrophysics is comprised of six research divisions: Atomic and Molecular Physics; Optical and Infrared Astronomy; High Energy Astrophysics; Radio and Geoastronomy; Stellar, Solar, and Planetary Sciences; and Theoretical Astrophysics.”>CfA), William Forman (CfA), Megan Donahue (Michigan State University), Alessandro Ignesti (INAF), Massimo Gaspari (INAF), Steffano Ettori (INAF), Luigina Feretti (INAF), Elizabeth L. Blanton (Boston University), Christine Jones (CfA), and Michael S. Calzadilla (MITMIT is an acronym for the Massachusetts Institute of Technology. It is a prestigious private research university in Cambridge, Massachusetts that was founded in 1861. It is organized into five Schools: architecture and planning; engineering; humanities, arts, and social sciences; management; and science. MIT’s impact includes many scientific breakthroughs and technological advances.”>MIT).
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.