Osteochondritis Dissecans

Weeren, P. R. van

doi:10.1016/b978-0-323-48420-6.00089-2

Cited by 7 publications

(24 citation statements)

References 132 publications

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“…Some galaxy clusters show a central diffuse radio emission which is not associated with specific optical counterparts or discrete radio sources. The observed properties of these so-called radio haloes (see the reviews of van Weeren, et al 2019;Feretti et al 2012;Ferrari et al 2008) reveal their synchrotron nature, and prove the existence of a nonthermal component in the ICM, made of relativistic particles and large scale magnetic fields. Radio haloes are found at the centre of merging clusters, and are typically ∼ 1 Mpc in size.…”

Section: Introductionmentioning

confidence: 95%

Rotation measure synthesis applied to synthetic SKA images of galaxy clusters

Loi

Murgia

Govoni

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Future observations with next generation radio telescopes will help us to understand the presence and the evolution of magnetic fields in galaxy clusters through the determination of the so-called Rotation Measure (RM). In this work, we applied the RM-synthesis technique on synthetic SKA1-MID radio images of a pair of merging galaxy clusters, measured between 950 and 1750 MHz with a resolution of 10 and a thermal noise of 0.1µJy/beam. The results of our RM-synthesis analysis are compared to the simulations' input parameters. We study two cases: one with radio haloes at the cluster centres, and another without. We found that the information obtained with the RM-synthesis is in general agreement with the input information. Some discrepancies are however present. We characterise them in this work, with the final goal of determining the potential impact of SKA1-MID on the study of cluster magnetic fields.

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Section: Introductionmentioning

confidence: 95%

Rotation measure synthesis applied to synthetic SKA images of galaxy clusters

Loi

Murgia

Govoni

et al. 2019

Monthly Notices of the Royal Astronomical Society

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“…Another question which needs to be answered is what is the source of cosmic-ray electrons. As already pointed out in the Introduction, shock waves with weak Mach number cannot efficiently accelerate particles from the thermal pool (Brunetti & Jones 2014;van Weeren, et al 2019). Therefore, also for this particular case, we expect that a pre-existing relativistic particle population has been re-accelerated through the DSA mechanism at the shock passage.…”

Section: Discussionmentioning

confidence: 53%

“…All these findings motivates the search for complementary/alternative models with respect to the DSA to explain the observed emission. In particular, it has been proposed that nearby active galactic nuclei can inject cosmic-ray electrons (Enßlin & Gopal-Krishna 2001), a scenario confirmed in some cases (Bonafede, et al 2014;van Weeren, et al 2017;Botteon, et al 2019), or that the injection is caused by powerful galactic wind (Völk & Atoyan 1999). Sphericallyexpanding shocks with fossil particle populations re-accelerated through DSA can generated curved spectra, while a non-uniform magnetic field in the relic region (Donnert, et al 2016) could cause a steepening in the radio spectrum.…”

Section: Introductionmentioning

confidence: 96%

“…Several observations have challenged the DSA mechanism. These observations have revealed that for some relics the derived X-ray Mach numbers are low, namely weak shocks with M≤3 (Brunetti & Jones 2014;van Weeren, et al 2019). For such weak shocks, the DSA mechanism is not efficient enough to accelerate particles up to GeV energies from the thermal pool (see also Botteon, et al 2020).…”

Section: Introductionmentioning

confidence: 97%

“…Only recently, a new class of radio relics with low surface brightness, and emissivity compatible with the standard DSA scenario might have been discovered at low frequency using LOFAR (Locatelli, et al 2020). In some cases, the Mach number inferred from X-ray observations and the one obtained from radio spectra are not in agreement (see for example van Weeren, et al 2016). In addition, some authors have reported the presence of a break in the spectrum, based on interferomteric observations, which is inconsistent with DSA (Stroe, et al 2016;Trasatti, et al 2015).…”

Section: Introductionmentioning

confidence: 99%

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Spectro-polarimetric observations of the CIZA J2242.8+5301 northern radio relic: no evidence of high-frequency steepening

Loi,

Murgia,

Vacca

et al. 2020

Preprint

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Observations of radio relics at very high frequency (>10 GHz) can help to understand how particles age and are (re-)accelerated in galaxy cluster outskirts and how magnetic fields are amplified in these environments. In this work, we present new single-dish 18.6 GHz Sardinia Radio Telescope and 14.25 GHz Effelsberg observations of the well known northern radio relic of CIZA J2242.8+5301. We detected the relic which shows a length of ∼1.8 Mpc and a flux density equal to S 14.25 GHz = (9.5±3.9) mJy and S 18.6 GHz = (7.67±0.90) mJy at 14.25 GHz and 18.6 GHz respectively. The resulting best-fit model of the relic spectrum from 145 MHz to 18.6 GHz is a power-law spectrum with spectral index α = 1.12 ± 0.03: no evidence of steepening has been found in the new data presented in this work. For the first time, polarisation properties have been derived at 18.6 GHz, revealing an averaged polarisation fraction of ∼ 40% and a magnetic field aligned with the 'filaments' or 'sheets' of the relic.

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OLIMPO: A balloon-borne SZE imager to probe ICM dynamics and the WHIM

Sayers,

Avestruz,

Thakur

et al. 2024

EPJ Web Conf.

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OLIMPO is a proposed Antarctic balloon-borne Sunyaev-Zel’dovich effect (SZE) imager to study gas dynamics associated with structure formation along with the properties of the warm-hot intergalactic medium (WHIM) residing in the connective filaments. During a 25 day flight OLIMPO will image a total of 10 z∼0.05 galaxy clusters and 8 bridges at 145, 250, 365, and 460 GHz at an angular resolution of 1.0′–3.3′. The maps will be significantly deeper than those planned from CMB-S4 and CCAT-P, and will have excellent fidelity to the large angular scales of our low-z targets, which are difficult to probe from the ground. In combination with X-ray data from eROSITA and XRISM we will transform our current static view of galaxy clusters into a full dynamic picture by measuring the internal intra-cluster medium (ICM) velocity structure with the kinematic SZE, X-ray spectroscopy, and the power spectrum of ICM fluctuations. Radio observations from ASKAP and MeerKAT will be used to better understand the connection between ICM turbulence and shocks with the relativistic plasma. Beyond the cluster boundary, we will combine thermal SZE maps from OLIMPO with X-ray imaging from eROSITA to measure the thermodynamics of the WHIM residing in filaments, providing a better understanding of its properties and its contribution to the total baryon budget.

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Osteochondritis Dissecans

Cited by 7 publications

References 132 publications

Rotation measure synthesis applied to synthetic SKA images of galaxy clusters

Rotation measure synthesis applied to synthetic SKA images of galaxy clusters

Spectro-polarimetric observations of the CIZA J2242.8+5301 northern radio relic: no evidence of high-frequency steepening

OLIMPO: A balloon-borne SZE imager to probe ICM dynamics and the WHIM

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