Simulating Astro-H Observations of Sloshing Gas Motions in the Cores of Galaxy Clusters

ZuHone, John; Miller, Eric D.; Simionescu, A.; Bautz, Marshall W.

doi:10.3847/0004-637x/821/1/6

Cited by 31 publications

(21 citation statements)

References 74 publications

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“…The first such mission will be Astro-H (Takahashi et al 2014), to be launched in early 2016. A recent study carried out by ZuHone et al (2016) used synthetic observations to show that Astro-H will be able to measure the basic kinematic properties of sloshing cold fronts, namely the shift of the spectral lines produced by the bulk motion of the sloshing gas (provided that our line of sight is at least partially within the sloshing plane) and the line broadening produced by the variation in this bulk motion and sloshing-driven turbulence. Unfortunately, they also showed that due to Astro-H's poor spatial resolution of ∼1', it will be unable to place any meaningful constraints on the ICM viscosity from studies of cold fronts.…”

Section: Future Observationsmentioning

confidence: 99%

Cold fronts: probes of plasma astrophysics in galaxy clusters

ZuHone

Röediger

2016

J. Plasma Phys.

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The most massive baryonic component of galaxy clusters is the 'intracluster medium' (ICM), a diffuse, hot, weakly magnetized plasma that is most easily observed in the X-ray band. Despite being observed for decades, the macroscopic transport properties of the ICM are still not well constrained. A path to determine macroscopic ICM properties opened up with the discovery of 'cold fronts'. These were observed as sharp discontinuities in surface brightness and temperature in the ICM, with the property that the denser side of the discontinuity is the colder one. The high spatial resolution of the Chandra X-ray Observatory revealed two puzzles about cold fronts. First, they should be subject to Kelvin-Helmholtz instabilities, yet in many cases they appear relatively smooth and undisturbed. Second, the width of the interface between the two gas phases is typically narrower than the mean free path of the particles in the plasma, indicating negligible thermal conduction. It was thus realized that these special characteristics of cold fronts may be used to probe the properties of the cluster plasma. In this review, we will discuss the recent simulations of cold fronts in galaxy clusters, focusing on those which have attempted to use these features to constrain ICM physics. In particular, we will examine the effects of magnetic fields, viscosity, and thermal conductivity on the stability properties and long-term evolution of cold fronts. We conclude with a discussion on what important questions remain unanswered, and the future role of simulations and the next generation of X-ray observatories.

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Section: Future Observationsmentioning

confidence: 99%

Cold fronts: probes of plasma astrophysics in galaxy clusters

ZuHone

Röediger

2016

J. Plasma Phys.

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“…streaming motions. ZuHone et al (2016b), focusing on XRISM-like mock observations of bright central cluster regions in a relatively relaxed cluster with sloshing motions, also found that large number counts (10 3 or more) in the iron complex band are required to fully model the multi-component line shape. This is consistent with expectations obtained for observed systems in the preparatory studies for ASTRO-H (Kitayama et al 2014).…”

Section: Discussionmentioning

confidence: 99%

“…Predictions for Astro-H (Hitomi) indicate in fact that higher number of photons, of order 10 3 -10 4 , are required to accurately model the iron complex shape with multiple velocity components (e.g. Shang & Oh 2012;ZuHone et al 2016b). In Table 2 (three rightmost columns) we therefore only report the best-fit results for the z1 mock spectrum, which are consistent with the numerical simulation estimates within the uncertainties.…”

Section: Xrism Resolve Mock Observationsmentioning

confidence: 99%

“…The velocity diagnostics of the ICM provide, therefore, a complementary picture of cluster physics (Simionescu et al 2019) to the thermal and chemical pictures. Gas motions of non-thermal origin, driven for instance by accreting streams of gas from filaments, or in the form of motions caused by infalling substructures and mergers (Lau et al 2009;Fang et al 2009;Biffi et al 2011;ZuHone et al 2016b), are crucial to measure because they can provide substantial additional pressure support to the system. This, in turn, can bias X-ray and Sunyaev-Zeldovich (SZ) mass estimates based on the assumption of hydrostatic equilibrium (HE; e.g.…”

Section: Introductionmentioning

confidence: 99%

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The velocity structure of the intracluster medium during a major merger: simulated microcalorimeter observations

Biffi,

ZuHone,

Mroczkowski

et al. 2022

Preprint

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Major mergers between galaxy clusters can produce large turbulent and bulk flow velocities in the intra-cluster medium (ICM) and thus imprint useful diagnostic features in X-ray spectral emission lines from heavy ions. As successfully achieved by Hitomi in observations of the Perseus cluster, measurements of gas velocities in clusters from high-resolution X-ray spectra will be achievable with upcoming X-ray calorimeters like those on board XRISM, Athena, or a Lynx like mission. An interesting application to clusters involves detecting multiple velocity components or velocity gradients from diagnostic observations of specific interesting locations across the cluster. To explore this possibility in the case of a major head-on cluster merger, we perform velocity analyses of a clustercluster merger from a hydrodynamical simulation by means of X-ray synthetic spectra with spectral resolution of order of a few eV. We observed the system along two extreme line-of-sight directions: 1) perpendicular to the plane of the merger and 2) along the merger axis. In these geometrical configurations, we find that clear non-Gaussian shapes of the iron He-like K α line at 6.7 keV are expected. While the velocity dispersion predicted from the simulations can be retrieved for the brightest 100 ks pointings with XRISM Resolve, some discrepancy with respect to the expected value is noted and can be attributed to the complex non-Gaussian line shapes. Measurements in low surface brightness regions, especially when multiple velocity components are present along the line of sight, require high S/N and the larger collecting area of the Athena X-IFU calorimeter is therefore required. With the latter, we also investigate the ICM temperature and velocity gradient across the merger bow shock edge, from 20 -wide annuli extracted from a single 1 Ms X-IFU observation. For both temperature and velocity dispersion, we find best-fit values that are consistent with predictions from the simulations within 1-σ. The uncertainties on the inferred velocity dispersion are however too large to place any stringent constraints on the shallow gradient downstream of the shock. Additionally, we present simulated images of the thermal and kinetic Sunyaev-Zeldovich effects from this merging system, using the above viewing configurations, and compare the results at angular resolutions appropriate for future observatories such as CMB-S4 and the Atacama Large Aperture Submillimeter Telescope (AtLAST).

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“…The subcluster is DM-only (perhaps stripped of its gas on a previous cluster passage). The initial conditions in the simulation explored here are the same as in previous works ([ [24][25][26][27][28] and Z21), and produce spiral-shaped cold fronts in an otherwise relatively relaxed cluster very similar to those observed in X-ray observations. In Z21, this simulation also produced thin strips of bubble material which closely resembled radio relics more than the "Merger2" simulation from that work.…”

Section: Merger Simulationsmentioning

confidence: 91%

Turning AGN Bubbles into Radio Relics with Sloshing: Modeling CR Transport with Realistic Physics

et al. 2021

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Radio relics are arc-like synchrotron sources at the periphery of galaxy clusters, produced by cosmic-ray electrons in a μG magnetic field, which are believed to have been (re-)accelerated by merger shock fronts. However, not all relics appear at the same location as shocks as seen in the X-ray. In a previous work, we suggested that the shape of some relics may result from the pre-existing spatial distribution of cosmic-ray electrons, and tested this hypothesis using simulations by launching AGN jets into a cluster atmosphere with sloshing gas motions generated by a previous merger event. We showed that these motions could transport the cosmic ray-enriched material of the AGN bubbles to large radii and stretch it in a tangential direction, producing a filamentary shape resembling a radio relic. In this work, we improve our physical description for the cosmic rays by modeling them as a separate fluid which undergoes diffusion and Alfvén losses. We find that, including this additional cosmic ray physics significantly diminishes the appearance of these filamentary features, showing that our original hypothesis is sensitive to the modeling of cosmic ray physics in the intracluster medium.

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Simulating Astro-H Observations of Sloshing Gas Motions in the Cores of Galaxy Clusters

Cited by 31 publications

References 74 publications

Cold fronts: probes of plasma astrophysics in galaxy clusters

Cold fronts: probes of plasma astrophysics in galaxy clusters

The velocity structure of the intracluster medium during a major merger: simulated microcalorimeter observations

Turning AGN Bubbles into Radio Relics with Sloshing: Modeling CR Transport with Realistic Physics

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