A5045584734- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Cosmic Phenomena
- Radio Astronomy Observations and Technology
- Solar and Space Plasma Dynamics
- Astronomy and Astrophysical Research
- Geomagnetism and Paleomagnetism Studies
- Gamma-ray bursts and supernovae
- Cosmology and Gravitation Theories
- Astrophysics and Star Formation Studies
- Pulsars and Gravitational Waves Research
- Astrophysical Phenomena and Observations
- Stellar, planetary, and galactic studies
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Ionosphere and magnetosphere dynamics
- Insurance, Mortality, Demography, Risk Management
- Remote Sensing and LiDAR Applications
- Electromagnetic Compatibility and Measurements
- Economic Growth and Productivity
- Heat Transfer Mechanisms
- Advanced Data Storage Technologies
- Dark Matter and Cosmic Phenomena
- Adaptive optics and wavefront sensing
- Antenna Design and Analysis
- Advanced Antenna and Metasurface Technologies
Center for Astrophysics Harvard & Smithsonian
2024
Universität Hamburg
2018-2023
University of Bologna
2021-2023
Ulsan National Institute of Science and Technology
2021-2022
Hamburger Fern-Hochschule
2019-2022
University of Bonn
2017
During their lifetime, galaxy clusters grow through the accretion of matter from filaments large scale structure and mergers with other clusters. These release a amount energy into intracluster medium (ICM) merger shocks turbulence. phenomena are associated formation radio sources known as relics halos, respectively. Radio halos unique proxies to study complex properties these dynamically active regions in general micro physics ICM. Abell 3667 is spectacular examples merging system hosting...
We investigate the evolution of magnetic fields in galaxy clusters starting from constant primordial using highly resolved (|${\approx } \rm 4 ~kpc$|) cosmological (magnetohydrodynamic) MHD simulations. The our sample exhibit amplification via a small-scale dynamo and compression during structure formation. In particular, we study how spectral properties are affected by mergers, relate measured energy spectra to dynamical intracluster medium. grows factor ∼40–50 time span ∼9 Gyr...
We present the first deep low frequency radio observations of massive and highly disturbed galaxy cluster Abell 2744 using upgraded Giant Metrewave Radio Telescope (uGMRT). The is experiencing a very complex multiple merger hosts giant halo four relics. uGMRT observations, together with existing VLA Chandra allow us to study complexity physical mechanisms active in this system. Our new images reveal that central emission more extended toward frequencies. find integrated spectrum follows...
ABSTRACT Radio relics are the manifestation of electrons presumably being shock (re-)accelerated to high energies in outskirts galaxy clusters. However, estimates shocks’ strength yield different results when measured with radio or X-ray observations. In general, Mach numbers obtained from observations larger than corresponding measurements. this work, we investigate number discrepancy. For purpose, used cosmological code enzo simulate a sample clusters that host bright relics. each relic,...
Abstract We present deep XMM-Newton, Karl G. Jansky Very Large Array, and upgraded Giant Metrewave Radio Telescope observations of Abell 746, a cluster that hosts plethora diffuse emission sources provide evidence for the acceleration relativistic particles. Our new XMM-Newton images reveal complex morphology thermal gas with several substructures. observe an asymmetric temperature distribution across cluster: southern regions exhibit higher temperatures, reaching ∼9 keV, while northern have...
High-resolution radio observations of cluster relics often show complex spatial and spectral features. However, it is not clear what these features reveal about the underlying magnetic field properties. We performed three-dimensional magneto-hydrodynamical simulations merger shock waves propagating through a magnetised, turbulent intracluster medium. Our model includes diffusive acceleration cosmic-ray electrons, their advection energy losses at run-time. With this set-up we can investigate...
Primordial magnetic fields could explain the large-scale present in Universe. Inflation and phase transitions early Universe give rise to such with unique characteristics. We investigate magneto-hydrodynamic evolution of these magnetogenesis scenarios cosmological simulations. evolve inflation-generated either as (i) uniform (homogeneous) or (ii) scale-invariant stochastic fields, transition-generated ones (iii) helical (iv) non-helical from radiation-dominated epoch. find that final...
Abstract We present deep and high-fidelity images of the merging galaxy cluster A2256 at low frequencies using upgraded Giant Metrewave Radio Telescope (uGMRT) LOw-Frequency ARray (LOFAR). This hosts one most prominent known relics with a remarkably spectacular network filamentary substructures. The new uGMRT (300–850 MHz) LOFAR (120–169 observations, combined archival Karl G. Jansky Very Large Array (VLA; 1–4 GHz) data, allowed us to carry out first spatially resolved spectral analysis...
Radio emission in the form of giant radio relics is observed at periphery galaxy clusters. This non-thermal an important tracer for cosmic-ray electrons and intracluster magnetic fields. One striking observational feature these objects their high degree polarisation which provides information on fields relics' positions. In this contribution, we test if state-of-the-art resolution cosmological simulations are able to reproduce features relics. Therefore, present a new analysis...
ABSTRACT Magnetic fields are ubiquitous in galaxy clusters, yet their radial profile, power spectrum, and connection to host cluster properties poorly known. Merging clusters hosting diffuse polarized emission the form of radio relics offer a unique possibility study magnetic these complex systems. In this paper, we investigate intracluster field Abell 2345. This hosts two that detected polarization with 1–2 GHz Jansky Very Large Array observations. X-ray XMM–Newton images show very...
The detection of the radio signal from filaments in cosmic web is crucial to distinguish possible magnetogenesis scenarios. We review status different attempts detect at wavelengths. This put into context advanced simulations magnetism carried out last few years by our MAGCOW project. While first imaging with MWA and LOFAR have been encouraging could discard some models, complexity behind such observations makes a definitive answer still uncertain. A combination total intensity polarimetric...
Radio relics are diffuse, extended synchrotron sources that originate from shock fronts generated during cluster mergers. The massive merging galaxy MACS J0717.5+3745 hosts one of the more complex known to date. We present upgraded Giant Metrewave Telescope band 3 (300−500 MHz) and 4 (550−850 observations. These new observations, combined with published VLA LOFAR HBA data, allow us carry out a detailed, high spatial resolution spectral analysis relic over broad range frequencies. integrated...
Abstract The galaxy cluster A746 ( z = 0.214), featuring a double radio relic system, two isolated relics, possible halo, disturbed V-shaped X-ray emission, and intricate distributions, is unique complex merging system. We present weak-lensing analysis of based on wide-field imaging data from Subaru/Hyper Suprime-Cam observations. mass distribution characterized by main peak, which coincides with the center emission. At this we detect extensions toward north west tracing distributions....
We present wideband polarimetric observations, obtained with the Karl G. Jansky Very Large Array (VLA), of merging galaxy cluster MACS J0717.5+3745, which hosts one most complex known radio relic and halo systems. use both Rotation Measure Synthesis QU-fitting, find a reasonable agreement results these methods, in particular, when Faraday distribution is simple depolarization mild. The highly polarized over its entire length reaching fractional polarization ${>}30\%$ some regions. also...
Radio relics are diffuse radio sources in galaxy clusters that associated with merger shock waves. Detailed observations of total intensity and polarisation show complex structures on kiloparsec scales. The relation between the observed features underlying morphology magnetic field is not clear. Using three-dimensional magneto-hydrodynamical simulations, we study polarised emission produced by a wave propagates through turbulent medium resembles intracluster medium. We model synchrotron...
Primordial magnetic fields (PMFs) are possible candidates for explaining the observed in galaxy clusters. Two competing scenarios of primordial magnetogenesis have been discussed literature: inflationary and phase-transitional. We study amplification both large- small-scale correlated fields, corresponding to inflation- phase transition-generated PMFs, a massive cluster. employ high-resolution magnetohydrodynamic cosmological zoom-in simulations resolve turbulent motions intracluster medium....
The accretion of a spherically symmetric, collisionless kinetic gas cloud onto Schwarzschild black hole is analyzed. Whereas previous studies have treated this problem by specifying boundary conditions at infinity, here the properties are given sphere finite radius. corresponding steady-state solutions computed using four different models with an increasing level sophistication, starting purely radial infall Newtonian particles and culminating fully general relativistic calculation in which...
The detection of filaments in the cosmic web will be crucial to distinguish between possible magnetogenesis scenarios, and future large polarization surveys able shed light on their magnetization level. In this work, we use numerical simulations galaxy clusters investigate detection. We compute Faraday Rotation signal intracluster compare it its surrounding environment. find that expected big improvement sensitivity with SKA-MID principle allow a fraction clusters. However, contamination...
Recent observations have revealed detailed structures of radio relics across a wide range frequencies. In this work, we performed three-dimensional magnetohydrodynamical (3D MHD) simulations merger shocks propagating through turbulent magnetized intracluster medium. We then employed on-the-fly Lagrangian particles to explore the physical processes behind origination substructures and their appearance in high low-frequency observations. two cosmic-ray (CR) electron acceleration models, with...
Radio relics are extended radio emission features which trace shock waves in the periphery of galaxy clusters originating from cluster mergers. Some show a highly polarised emission, make an excellent probe for magnetisation intra-cluster medium. The origin relic polarisation is still debated. It could be result tangentially stretching magnetic field at surface. This scenario would naturally explain alignment (E-vectors) with normal. We have implemented toy model according to this scenario....
Recent observations have revealed detailed structures of radio relics in a wide range frequencies. In this work, we perform three-dimensional magnetohydrodynamical simulations merger shocks propagating through turbulent magnetized intracluster medium, and employ on-the-fly Lagrangian particles to explore the physical processes originating substructures their appearances high low-frequency observations. We two cosmic-ray (CR) electron acceleration models: fresh injection electrons from...
AGN bubbles in cool-core galaxy clusters are believed to significantly facilitate the transport of cosmic ray electrons (CRe) throughout cluster. Recent radio observations revealing complex morphologies cluster diffuse emission, potentially linked interactions between bursts and environment. We perform three-dimensional magneto-hydrodynamical simulations binary mergers inject a bi-directional jet at center main Kinetic, thermal, magnetic CRe energy included we use two-fluid formalism model...
Abstract The Faraday rotation effect, quantified by the measure (RM), is a powerful probe of large-scale magnetization Universe—tracing magnetic fields not only on galaxy and cluster scales but also in intergalactic medium (IGM; referred to as RM IGM ). redshift dependence latter has extensively been explored with observations. It shown that this relation can help distinguish between different scenarios. We study evolution for primordial magnetogenesis scenarios search imprints (PMFs;...