On the largest scales, galaxies are pulled together by gravity to form clusters, which are connected by filaments making a web-like pattern. Radio emission is predicted from this cosmic web, which should originate from the strong accretion shocks around the cosmic structures. We present the first observational evidence that Fermi-type acceleration from strong shocks surrounding the filaments of the cosmic web, as well as in peripherals of low-mass clusters, is at work in the Universe. Using all-sky radio maps and stacking on clusters and filaments, we have detected the polarization signature of the synchrotron emission with polarization fractions ≥20%, which is best explained by the organization of local magnetic fields by strong shock waves both at the cluster peripheries and between clusters. Our interpretation is well supported by a detailed comparison with state-of-the-art cosmological simulations.
Polarized accretion shocks from the cosmic web / Vernstrom T.; West J.; Vazza F.; Wittor D.; Riseley C.J.; Heald G.. - In: SCIENCE ADVANCES. - ISSN 2375-2548. - ELETTRONICO. - 9:7(2023), pp. eade7233.1-eade7233.15. [10.1126/sciadv.ade7233]
Polarized accretion shocks from the cosmic web
Vazza F.;Wittor D.;
2023
Abstract
On the largest scales, galaxies are pulled together by gravity to form clusters, which are connected by filaments making a web-like pattern. Radio emission is predicted from this cosmic web, which should originate from the strong accretion shocks around the cosmic structures. We present the first observational evidence that Fermi-type acceleration from strong shocks surrounding the filaments of the cosmic web, as well as in peripherals of low-mass clusters, is at work in the Universe. Using all-sky radio maps and stacking on clusters and filaments, we have detected the polarization signature of the synchrotron emission with polarization fractions ≥20%, which is best explained by the organization of local magnetic fields by strong shock waves both at the cluster peripheries and between clusters. Our interpretation is well supported by a detailed comparison with state-of-the-art cosmological simulations.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
