The tumultuous evolution of a galaxy cluster captured close to its formation in the cosmic web
An international team of astronomers using the National Science Foundation’s Green Bank Telescope (GBT) in Green Bank, West Virginia, and the NASA’s Chandra X-ray Observatory have captured a snapshot of a massive galaxy cluster, very close to the epoch when it began to emerge from the cosmic web.
The light of the galaxy cluster IDCSJ1426+3508, located at z=1.75, has been captured after travelling almost 10 Gyr (75% of the Universe’s age.) This new measurement allows astronomers to record the properties of its tenuous hot gas, which fills the whole cluster – at the earliest epochs probed so far – and more precisely than for any other very distant cluster.
The incredible age recorded by this measurement – and the unprecedented precision – is made possible by the joint use of ACIS-I on Chandra, allowing the team to measure the gas density of the cluster, and the MUSTANG-2 camera on GBT, allowing them to measure the gas pressure at the various cluster locations. The red color of the outer cluster region indicates that the gas gets hotter with increasing distance from the center, from 50 to 150-million degrees Celsius.
MUSTANG-2 is a 223-feedhorn bolometer camera, with the current fastest mapping speed for continuum observations at 90 GHz with resolution of 10″ or less. ACIS-I is a wide field X-ray camera and delivers the sharpest resolution, 1″, among all X-ray missions.
By comparing the gas properties of IDCSJ1426+3508 to plausible present-day descendants, the team identified the cluster’s potential evolution. “It was quite tumultuous – everywhere but in the center – temperatures get hotter in spite of new cold gas incorporated from peripheral regions,” commented Stefano Andreon, lead author of the article, of the INAF-Osservatorio Astronomico di Brera. “Instead,” continued Charles Romero of the Green Bank Observatory and the University of Pennsylvania, “the cluster center has preserved its properties in spite of the many perturbations excerced by the tumultuous and hostile environment, indicating that a feedback mechanism is counter-balancing every disturbance.”
“One swallow doesn’t make a summer,” Stefano intervened, “The evolution of galaxy clusters is likely diverse, the reason why we are observing, and inviting colleagues to observe other clusters emerging from the cosmic web in the hope of identifying an overall common pattern and also individual differences.” Charles concludes, “Of course, we’re interested in how clusters evolve through time, not just from the perspective of astrophysics, for example ‘heat transport’, but cluster evolution is a foundational component of our ability to learn about cosmology from clusters of galaxies.”
Read the original paper Thermodynamic evolution of the z=1.75 galaxy cluster IDCS J1426.5+3508.
The Green Bank Observatory is a facility of the National Science Foundation and is operated by Associated Universities, Inc. MUSTANG-2 was developed by Simon Dicker and the University of Pennsylvania with funding provided by the University and the National Science Foundation.
Jill Malusky, Green Bank Observatory Public Relations, ude.o1702085005arn@y1702085005ksula1702085005mj1702085005