Fastening black holes trapped in galactic spider webs

Black hole illustration. Credit: Aurore Simonnet and NASA’s Goddard Space Flight Center

  • To search for black holes around the “Spiderweb” galaxy, astronomers observed for over 8 days with[{” attribute=””>NASA’s Chandra X-ray Observatory.
  • Chandra revealed 14 actively growing supermassive black holes — a much higher rate than other similar samples.
  • The difference may be caused by collisions between galaxies in the forming cluster or by an excess of colder gas.
  • The “Spiderweb” gets its nickname from its appearance in some optical light images.
Spiderweb Galaxy Field Annotated

Credit: X-ray: NASA/CXC/INAF/P. Tozzi et al; Optical (Subaru): NAOJ/NINS; Optical (HST): NASA/STScI

Often, a spiderweb conjures the idea of captured prey soon to be consumed by a waiting predator. In the case of the “Spiderweb” protocluster, however, objects that lie within a giant cosmic web are feasting and growing, according to data from NASA’s Chandra X-ray Observatory.

The Spiderweb galaxy, officially known as J1140-2629, gets its nickname from its web-like appearance in some optical light images. This likeness can be seen in the inset box where data from NASA’s

To look for growing black holes in the Spiderweb protocol, a team of researchers observed it for over eight days with Chandra. In the main panel of this graphic, a composite image of the Spiderweb protocluster shows X-rays detected by Chandra (also in purple), which have been combined with optical data from the Subaru telescope at Mauna Kea in Hawaii (red, green, and white). The big picture is 11.3 million light-years across.

Spiderweb Galaxy Field

14 sources discovered by Chandra. Credit: X-ray: NASA / CXC / INAF / P. Tozzi et al; Optical (Subaru): NAOJ / NINS; Optical (HST): NASA / STScI

Most of the “blobs” in the optical image are galaxies in the protocol, including 14 that have been discovered in the new, deep Chandra image. These X-ray sources reveal the presence of material falling against supermassive black holes that contain hundreds of millions of times more mass than the Sun. Spiderweb protocluster exists in an era in the universe, which astronomers refer to as “cosmic dinner.” Scientists have found that during this time – about 3 billion years after the big bang – black holes and galaxies were experiencing extreme growth.

Spiderweb seems to exceed the high standards of even this active period in the universe. The 14 sources discovered by Chandra (circled in the image below) suggest that about 25% of the most massive galaxies contain actively growing black holes. This is between five and twenty times higher than the proportion found for other galaxies of the same age and with approximately the same mass fluctuations.

Spiderweb Sources

14 sources discovered by Chandra. Credit: X-ray: NASA / CXC / INAF / P. Tozzi et al; Optical (Subaru): NAOJ / NINS; Optical (HST): NASA / STScI

These results suggest that some environmental factors are responsible for the large number of fast-growing black holes in the Spiderweb protocluster. One reason may be that a high degree of collisions and interactions between galaxies sweep gas toward the black holes in the center of each galaxy, providing large amounts of material to consume. Another explanation is that the protocol still contains large amounts of cold gas that are more easily consumed by one[{” attribute=””>black hole than hot gas (this cold gas would be heated as the protocluster evolves into a galaxy cluster).

Feasting Black Holes Caught in Galactic Spiderweb

Close up. Credit: X-ray: NASA/CXC/INAF/P. Tozzi et al; Optical (Subaru): NAOJ/NINS; Optical (HST): NASA/STScI

A detailed study of Hubble data may provide important clues about the reasons for the large number of rapidly growing black holes in the Spiderweb protocluster. Extending this work to other protoclusters would also require the sharp X-ray vision of Chandra.

A paper describing these results has been accepted for publication in the journal Astronomy and astrophysics. The first author is Paolo Tozzi from the National Institute of Astrophysics in Arcetri, Italy.

Reference: “The 700 ks Chandra Spiderweb Field I: evidence for widespread nuclear activity in the Protocluster” by P. Tozzi, L. Pentericci, R. Gilli, M. Pannella, F. Fiore, G. Miley, M. Nonino, HJA Rottgering, V. Strazzullo, CS Anderson, S. Borgani, A. Calabro ‘, C. Carilli, H. Dannerbauer, L. Di Mascolo, C. Feruglio, R. Gobat, S. Jin, A. Liu, T. Mroczkowski , C. Norman, E. Rasia, P. Rosati and A. Saro, accepted, Astronomy and astrophysics.
arXiv: 2203.02208

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

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