Astronomers using ESA's Planck space telescope have made the first conclusive detection of a bridge of hot gas connecting a pair of galaxy cluster. The hot gas bridge connects the Abell 399 and Abell 401 clusters across 10 million light-years of intergalactic space.
Jan Tauber, Planck project scientist at ESA, said in a release
, "This discovery highlights the ability of Planck to probe galaxy clusters out to their outskirts and even beyond, allowing us to investigate the connection between intra-cluster gas and gas that is part of the cosmic web."
Jose M. Diego, a Planck Collaboration scientist from the Instituto de Fisica de Cantabria (UC-CSIC) in Santander, Spain, says, "Planck can detect galaxy clusters across the sky because the hot gas that fills them imprints a characteristic signature on the Cosmic Microwave Background known as the Sunyaev-Zel'dovich effect. Based on the same principle, Planck could be sensitive to gas from the WHIM, too."
The WHIM stands for warm-hot intergalactic medium. The ESA scientists say the WHIM is the "baryonic component of the cosmic web, a filamentary network of both dark and baryonic matter that is believed to pervade the Universe."
Image: Sunyaev-Zel'dovich effect (orange): ESA & Planck Collaboration; optical image: STScI Digitized Sky Survey