Here below are listed the upcoming IFPU colloquia, usually taking place once a month on Fridays at 11:30am. Past colloquia from the current program can be found in the recent colloquia page, while older events can be found in the 2023-2024, 2022-2023, 2021-2022, 2020-2021 and 2019-2021 pages.
Francesco De Gasperin (INAF Bologna)
Exploring the largest structures of the universe at the lowest frequencies
Friday, 26 June, 11:30am – room TBD
Abstract. Within the cosmic web, the growth of the Universe’s largest structures release vast amounts of gravitational energy. This energy is dissipated via processes such as turbulence and shock waves. Such processes have a fundamental impact on the evolution of galaxy clusters, for instance altering local and global thermodynamical properties of the intra-cluster medium and contributing to the non-thermal energy budget of the clusters. These processes inefficiently accelerate cosmic rays emitting low-frequency radio waves, producing sources such as radio halos and cluster radio shocks (radio relics) that can be optimally studied at low frequencies. Recent low-frequency radio observations taken with LOFAR have shown that cosmic rays responsible for the radio brightness of these sources can flow between different regions and are re-accelerated multiple times over a cluster’s lifetime. This creates a complex cosmic ray life cycle driven by the environment. Moreover, their low-frequency emission can be observed over Gyr time scales, revealing the long-term actions and interactions of radio sources in cluster environments. To explore these phenomena, LOFAR conducted wide area surveys, covering a large sample of clusters. In this talk I will present these surveys and I will focus on the challenges and the main results of the LOFAR LBA Sky Survey (LoLSS), that covers the sky at declination >24 deg and it is the deepest and highest resolution large radio survey at <100 MHz to date. Among the main scientific results of the LOFAR surveys, I will discuss are the evidence of the re-acceleration of CR of AGN origin and the conclusive evidence of the origin of radio halos through turbulence acceleration. I will conclude giving an overview of the ongoing upgrade of LOFAR to LOFAR 2 and the plans to exploit this improved interferometer to further push the understanding of the large scale structure of the universe