Conveners
Galaxy clusters & LSS
- Chair: Rossella Cassano
Galaxy clusters & LSS: Galaxy Clusters & LSS
- Chair: Tiziana Venturi
Galaxy clusters & LSS
- Chair: Rossella Cassano
Synchrotron diffuse emission at the centre of merging galaxy clusters and along filaments connecting them demonstrates the presence of relativistic particles and magnetic fields in these environments. Their properties represent a unique tool to constrain large-scale magnetic fields and the physics of the acceleration and transport of the relativistic particles. However, radio observations of...
Magnetic fields play an important role in the Intra Cluster Medium (ICM) of galaxy clusters. Indeed, they mediate particle acceleration mechanisms, thermal conduction, and contribute to the ICM pressure and energy budget. Yet, magnetic fields are so far constrained only for a small sample of clusters, observed in different ways, which might introduce biases in the analysis.
In this talk, I...
The largely unexplored decameter radio band (10-30 MHz) provides a unique window for studying a range of astronomical topics, such as auroral emission from exoplanets, low-energy cosmic ray electrons, and the physics of free-free absorption. The scarcity of low-frequency studies is mainly due to the severe perturbing effects of the ionosphere. Correcting for the ionosphere is challenging as it...
Magnetic fields are everywhere in the Universe, but little is know about their origin and amplification, particularly on the largest scales. Proto-clusters, the distant progenitors of local galaxy clusters, offer a unique environment to study magnetic fields during the first phases of structure formation and especially to understand the magnetic field amplification during this process....
New generations of interferometers are revealing a wealth of spectacular filaments in the surrounding of radio galaxies, mostly residing in group/cluster environment, whose origin is still unknown. Filamentary structures present new opportunities for studying the physical processes in the intracluster medium, including their magnetic structures and the propagation of cosmic rays. Given the...
Diffuse radio emission in galaxy clusters has been established to be linked with the presence of (re-)accelerated particles (i.e. cosmic rays, CRs) and magnetic fields (B). In the last years, thanks to the advent of highly-sensitive radio telescopes such as LOFAR and MeerKAT, the detection of diffuse radio emission has become possible also in clusters at high redshift (z>0.6). This allowed a...
Radio halos are diffuse, large-scale radio sources with low surface brightness situated in the central region of galaxy clusters, extending over megaparsec scales. They are believed to originate from cosmic rays re-accelerated by merger-driven turbulence by second-order Fermi mechanism. The turbulent re-acceleration model anticipates a substantial population of radio halos with very-steep...
The Universe hierarchical formation process can be investigated through the fundamental relations of galaxy cluster observables. Since the matter accretion is gravity-dominated, the hot plasma within galaxy clusters displays a self-similar behaviour, following precise scaling relations that link spatially resolved quantities to global ones. Similarly, the diffuse, non-thermal cluster component...
The evolution of the Universe proceeds along the filaments of the cosmic web, where enormous amount of energy is dissipated through complex plasma processes that can be traced by radio emitting electrons. While the central regions of galaxy clusters, located at the knots of the cosmic web, have been studied in fair detail, their outskirts are still poorly explored, and cosmic filaments have...
Recent LOFAR observations of massive galaxy clusters revealed the presence of a new type of large scale diffuse radio emission, known as megahalo, extending up to clusters outskirts (Cuciti et al. 2022, Nature). Megahalos span scales of ~3-4 Mpc and, due to their extension, allow us to probe cluster volumes that are 30 times larger than the ones occupied by radio halos. This means that with...
The ViCTORIA (Virgo Cluster multi-Telescope Observations in Radio of Interacting galaxies and AGN) project is a unique multi-frequency radio survey of the Virgo cluster, combining LOFAR-LBA, LOFAR-HBA, and MeerKAT data to achieve unprecedented depth, resolution, and spectral coverage. The Virgo cluster, the closest rich cluster in the Universe, is a key target for understanding galaxy...
Satellite galaxies in clusters are significantly more likely to be red and passive than similar mass galaxies in the field. This fact is known as the environmental quenching of galaxy star formation, which is believed to be driven by the ram pressure stripping (RPS). The large velocity differences between the infalling galaxies and the intracluster medium (ICM) result in a strong ram pressure...
Over the past few decades, it has become clear that brightest cluster galaxies (BCG) of galaxy groups and clusters maintain the thermal balance of their surrounding halos through radio jet activity. Yet key questions remain: how frequently their black holes are triggered, how jet orientations evolve over time, and through which physical channels (bubbles, shocks, turbulence) feedback...
Magnetic fields have been detected so far through Faraday rotation in individual galaxy clusters and in stacked cosmic filaments; however, a direct measurement in individual filaments remains challenging. In this talk, I present the first attempt to constrain the magnetic field in the ∼13 Mpc inter-cluster filament connecting Abell 3667 and Abell 3651 (z ∼ 0.06), recently detected in X-rays by...
LOFAR surveys have enabled unprecedentedly detailed analysis of large-scale, diffuse, and steep-spectrum sources in galaxy clusters, such as radio relics and halos. These are thought to arise from particle re-acceleration operated in the intra-cluster medium (ICM) by shocks and turbulence triggered by a cluster merger. Similar processes are likely also responsible for the re-ignition of fossil...
In recent years, LOFAR conducted wide area surveys at low and ultra-low frequencies. These surveys were a fundamental exercise to learn what to do and what NOT to do when performing such large and complex observations. In this talk I will present 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...
Over the last two decades, significant progress has been made in understanding the physical processes observed in galaxy clusters. AGN feedback has emerged as the leading explanation for several longstanding astrophysical questions, including the origin of scaling relations between supermassive black holes and their host galaxies, as well as the discrepancy between the predicted and observed...
