Origin of Magnetic Field in the Intracluster Medium: Primordial or Astrophysical?

Cho, Jungyeon

doi:10.1088/0004-637x/797/2/133

Cited by 41 publications

(44 citation statements)

References 67 publications

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“…The contribution from un-resolved gas motions by the finite numerical resolution in our scheme may underestimate the level of smallscale dynamo amplification, which gets independent from the ampitude of seed fields for large enough Reynolds number (e.g. Cho 2014;Beresnyak & Miniati 2016). If this is the case, the ∼ 0.1 − 0.2 µG we measured for our intracluster bridge in Sec.3.3.4 may be underestimated, even if to our knowledge this run is the most resolved so far for objects of this kind.…”

Section: Discussion: Physical and Numerical Uncertaintiesmentioning

confidence: 99%

Detecting shocked intergalactic gas with X-ray and radio observations

Vazza

Ettori

Roncarelli

et al. 2019

A&A

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Detecting the thermal and non-thermal emission from the shocked cosmic gas surrounding large-scale structures represents a challenge for observations, as well as a unique window into the physics of the warm-hot intergalactic medium. In this work, we present synthetic radio and X-ray surveys of large cosmological simulations in order to assess the chances of jointly detecting the cosmic web in both frequency ranges. We then propose best observing strategies tailored for existing (LOFAR, MWA and XMM) or future instruments (SKA-LOW and SKA-MID, Athena and eROSITA). We find that the most promising targets are the extreme peripheries of galaxy clusters in an early merging stage, where the merger causes the fast compression of warm-hot gas onto the virial region. By taking advantage of a detection in the radio band, future deep X-ray observations will probe this gas in emission, and help us to study plasma conditions in the dynamic warm-hot intergalactic medium with unprecedented detail.

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Section: Discussion: Physical and Numerical Uncertaintiesmentioning

confidence: 99%

Detecting shocked intergalactic gas with X-ray and radio observations

Vazza

Ettori

Roncarelli

et al. 2019

A&A

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“…The Reynolds number achieved in simulations is also an important factor that directly affects the magnetic field growth. While the Reynolds number based on the full Spitzer viscosity in the ICM is believed to be of the order of Re ∼ 10 2 (e.g Cho 2014a), the reduced proton mean free path in the collisionless ICM can result in much larger Reynolds numbers (Beresnyak & Miniati 2016;Brunetti & Lazarian 2011b). This suggests that the fluid approximation provides a suited model for the properties of the ICM (e.g Santos-Lima et al 2017.…”

Section: Introductionmentioning

confidence: 99%

Dynamical evolution of magnetic fields in the intracluster medium

Domínguez-Fernández

Vazza

Brüggen

et al. 2019

Monthly Notices of the Royal Astronomical Society

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We investigate the evolution of magnetic fields in galaxy clusters starting from constant primordial fields using highly resolved (≈ 4 kpc) cosmological MHD simulations. The magnetic fields in our sample exhibit amplification via a small-scale dynamo and compression during structure formation. In particular, we study how the spectral properties of magnetic fields are affected by mergers, and we relate the measured magnetic energy spectra to the dynamical evolution of the intracluster medium. The magnetic energy grows by a factor of ∼ 40-50 in a time-span of ∼ 9 Gyr and equipartition between kinetic and magnetic energy occurs on a range of scales (< 160 kpc at all epochs) depending on the turbulence state of the system. We also find that, in general, the outer scale of the magnetic field and the MHD scale are not simply correlated in time. The effect of major mergers is to shift the peak magnetic spectra to smaller scales, whereas the magnetic amplification only starts after 1 Gyr. In contrast, continuous minor mergers promote the steady growth of the magnetic field. We discuss the implications of these findings in the interpretation of future radio observations of galaxy clusters.

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“…Unlike this, ICM turbulence is usually subsonic with M s 1/2 (see, e.g., Ryu et al 2008;Brunetti & Jones 2014). It also has crucial impacts on astrophysical phenomena in the ICM, including amplification of weak seed magnetic fields (e.g., Schekochihin et al 2004;Ryu et al 2008;Cho 2014). Magnetic fields permeated in turbulence appear in a variety of astrophysical objects and have huge impacts on them.…”

Section: Introductionmentioning

confidence: 99%

Generation of Solenoidal Modes and Magnetic Fields in Turbulence Driven by Compressive Driving

Lim

Cho

Yoon

2020

ApJ

Self Cite

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We perform numerical simulations of hydrodynamic (HD) and magnetohydrodynamic (MHD) turbulence driven by compressive driving to study generation of solenoidal velocity component and smallscale magnetic field. We mainly focus on the effects of mean magnetic field (B 0 ) and the sonic Mach number (M s ). We also consider two different driving schemes in terms of correlation timescale of forcing vectors: a finite-correlated driving and a delta-correlated driving. The former has a longer correlation timescale of forcing vectors, which is comparable to large-eddy turnover time, than the latter. Our findings are as follows. First, when we fix the value of B 0 , the level of solenoidal velocity component after saturation increases as M s increases. A similar trend is observed for generation of magnetic field when B 0 is small. Second, when we fix the value of M s , HD and MHD simulations result in similar level of the solenoidal component when B 0 0.2 (or Alfven Mach number of ∼ 5). However, the level increases when B 0 0.2. Roughly speaking, the magnetic energy density after saturation is a linearly increasing function of B 0 irrespective of M s . Third, generation of solenoidal velocity component is not sensitive to numerical resolution, but that of magnetic energy density is mildly sensitive. Lastly, when initial conditions are same, the finite-correlated driving always produces more solenoidal velocity and small-scale magnetic field components than the delta-correlated driving. We additionally analyze the vorticity equation to understand why higher M s and B 0 yield larger quantity of the solenoidal velocity component.

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Origin of Magnetic Field in the Intracluster Medium: Primordial or Astrophysical?

Cited by 41 publications

References 67 publications

Detecting shocked intergalactic gas with X-ray and radio observations

Detecting shocked intergalactic gas with X-ray and radio observations

Dynamical evolution of magnetic fields in the intracluster medium

Generation of Solenoidal Modes and Magnetic Fields in Turbulence Driven by Compressive Driving

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