High-frequency, high-resolution imaging of the Sunyaev-Zel'dovich (SZ) effect is an important technique to study the complex structures of the atmospheres of merging galaxy clusters. Such ...observations are sensitive to the details of the electron spectrum. We show that the morphology of the SZ intensity maps in simulated galaxy clusters observed at 345, 600 and 857 GHz are significantly different because of SZ relativistic corrections. These differences can be revealed by high-resolution imaging instruments.
We calculate relativistically corrected SZ intensity maps of a simulated, massive, merging galaxy cluster and of the massive, merging clusters 1E0657−558 (the Bullet cluster) and Abell 2219. The morphologies of the SZ intensity maps are remarkably different between 345 and 857 GHz for each merging cluster. We show that high-resolution imaging observations of the SZ intensity maps at these frequencies, obtainable with the LABOCA and HERSCHEL-SPIRE instruments, allow to fully exploit the astrophysical relevance of the predicted SZ morphological effect.
ABSTRACT
We perform relativistic hydrodynamic simulations of the formation and evolution of active galactic nucleus (AGN) cocoons produced by very light powerful jets. We calculate the intensity maps ...of the Sunyaev–Zel'dovich (SZ) effect at high frequencies for the simulated AGN cocoons using the relativistically correct Wright formalism. Our fully relativistic calculations demonstrate that the contribution from the high‐temperature gas (kbTe ≃ 100 keV) to the SZ signal from AGN cocoons at high frequencies is stronger than that from the shocked ambient intercluster medium owing to the fact that the relativistic spectral functions peak at these temperature values. We present simulations of the SZ effect from AGN cocoons at various frequencies, and demonstrate that SZ observations at 217 GHz and at higher frequencies, such as 857 GHz, will provide us with knowledge about the dynamically dominant component of AGN cocoons.
The Sunyaev-Zel'dovich (hereinafter SZ) effect is a promising tool to derive the gas temperature of galaxy clusters. Approximation of a spherically symmetric gas distribution is usually used to ...determine the temperature structure of galaxy clusters, but this approximation cannot properly describe merging galaxy clusters. The methods used so far, which do not assume the spherically symmetric distribution, permit us to derive 2D temperature maps of merging galaxy clusters. In this paper, we propose a method to derive the standard temperature deviation and temperature variance along the line of sight, which permits us to analyse the 3D temperature structure of galaxy clusters by means of the thermal SZ effect. We also propose a method to reveal merger shock waves in galaxy clusters by analysing the presence of temperature inhomogeneities along the line of sight.
Context. X-ray imaging observatories have revealed hydrodynamic structures with linear scales of ~10 kpc in clusters of galaxies, such as shock waves in the 1E0657-56 and A520 galaxy clusters and the ...hot plasma bubble in the MKW 3s cluster. The future X-ray observatory IXO will for the first time resolve the metal distribution in galaxy clusters at the these scales. Aims. Heating of plasmas by shocks and AGN activities can result in non-equilibrium ionization states of metal ions. We study the effect of the non-equilibrium ionization at linear scales of ≲50 kpc in galaxy clusters. Methods. A condition for non-equilibrium ionization is derived by comparing the ionization time-scale with the age of hydrodynamic structures. Modeling of non-equilibrium ionization is performed at a point in time when the plasma temperature suddenly changes. An analysis of the relaxation processes of the FeXXV and FeXXVI ions by means of eigenvectors of the transition matrix is given. Results. We conclude that the non-equilibrium ionization of iron can occur in galaxy clusters if the baryonic overdensity δ is smaller than $11.0/\tau$, where $\tau\ll1$ is the ratio of the hydrodynamic structure age to the Hubble time. Our modeling indicates that the emissivity in the helium-like emission lines of iron increases as a result of the deviation from the ionization equilibrium. A slow process of helium-like ionic fraction relaxation was analyzed. A new way to determine a shock velocity is proposed.
ABSTRACT
High‐resolution imaging of the Sunyaev–Zel'dovich (SZ) effect opens new possibilities for testing the presence of various high‐energy particle populations in clusters of galaxies. A detailed ...X‐ray analysis of the ‘Bullet cluster’ (1E 0657−56) with Chandra has revealed the presence of additional X‐ray spectral components beyond a simple, single‐temperature plasma in its X‐ray spectra. X‐ray methods alone are insufficient to elucidate the origins of these spectral components. We show that the morphology and magnitude of the SZ effect at high frequencies are critically dependent upon the mechanism by which the additional X‐ray spectra are created. We examine the differences between the predicted SZ effect emission maps at 600 GHz assuming the X‐ray spectra are composed of thermal gas with a steep power‐law index component and also thermal gas with a significant contribution of strongly heated gas. A two‐temperature model with a hot (kT ≃ 30–40 keV) second component is the most consistent with existing SZ data at high frequencies. However, significant morphological differences remain. High‐angular‐resolution SZ intensity maps at high frequencies in combination with deep X‐ray data provide a new window into understanding particle energization processes in the hottest, massive merging galaxy clusters.
Abstract
Single-crystalline lead substituted M-type barium hexaferrites doped with different concentrations of Al
3+
, synthesized by flux technique are investigated at terahertz and infrared ...frequencies (8-8000 cm
−1
). The spectra of reflection coefficient (R), transmission coefficient (T), complex dielectric permittivity (
ε
` and
ε
``) were obtained using terahertz time-domain, and infrared Fourier transform spectrometers over a broadband frequency range 0.24-240 THz and at temperatures 5 K-300 K. The observed absorption lines are assigned to the electronic transitions within the fine-structured ground state of Fe
2+
ions at terahertz frequencies and to optical phonon mode at far-infrared frequencies. To analyze the origin of terahertz excitations in the compounds, we provided a model that accounts for the second-order spin-orbit interactions, the triagonal distortion of the crystal field, and the selection rules of the (C
3v
) point group symmetry of tetrahedral site-position of Fe
2+
.
•Optical and magnetic properties of YGa3(BO3)4:Er crystals were studied.•The Debye temperature of YGa3(BO3)4:Er crystals was determined.•The spin Hamiltonian parameters of Er3+ ions were ...obtained.•The temperature behavior of the spin-lattice relaxation rate of Er3+ ions is described by the Orbach-Aminov process.•Er3+ ions reside yttrium ions in YGa3(BO3)4 crystal lattice.
The paper presents the results of a comprehensive study of yttrium gallium borate (YGa3(BO3)4) crystals low-doped (0.2 wt%) with erbium (Er3+) ions by in-situ X-ray diffraction (XRD), radioluminescence (RL), thermally stimulated luminescence (TSL) and electron paramagnetic resonance (EPR) techniques. Structural and elastic properties of YGa3(BO3)4: Er3+ crystals measured by the XRD method in the temperature range from 300 K to 1073 K have revealed the temperature variation of the volume thermal expansion coefficient. The analysis of RL spectra allowed us to assume the existence of the characteristic Er3+-related emission band located in the near-infrared region. The TSL spectra revealed strong peaks at low temperatures due to shallow traps and much less intense bands located above room temperature. Measurements of heat capacity in a wide temperature range allowed us to determine the Debye temperature θD ≈ 332 K. From the detailed analysis of the strongly anisotropic EPR spectra measured in YGa3(BO3)4:Er3+ crystals, the parameters of the spin Hamiltonian of Er3+ ions were determined: g⊥ = 9.34; g∥ = 1.269; A⊥ = 320.9 MHz; A∥ = 47.7 MHz. The temperature dependence of the spin-lattice relaxation rate of Er3+ ions was described well by the Orbach-Aminov process. It was proposed that Er3+ ions reside yttrium ions in YGa3(BO3)4 crystal lattice and are located in a slightly distorted prism made of six oxygen ions.
Abstract
In this article, we show the possibility for obtaining and deposition of gallium nitride nanoparticles under the action of femtosecond laser radiation. Using the developed setup for thermal ...vacuum deposition of copper on silicon plates, we obtained the thin-film substrates following by the deposition of gallium nitride on them. The gallium nitride was formed by applying the femtosecond laser radiation to the gallium targets in ammonia medium. The controlled collection of ablation products following by their removal from the processing area by means of electrostatic field was used in the setup in order to efficiently collect gallium nitride nanoparticles. The formation of gallium nitride nanoparticles is verified by the results of X-ray diffraction analysis.
Context. Measurements of the Sunyaev-Zel’dovich (hereafter SZ) effect distortion of the cosmic microwave background provide us with an independent method to derive the gas temperature of galaxy ...clusters. In merging galaxy clusters the gas distribution is inhomogeneous and, therefore, the method of temperature measuring based on the SZ effect should be more relevant than that based on an X-ray emission analysis. Aims. We study a method for measuring the gas temperature in merging clusters by means of the SZ effect. Methods. Our calculations of intensity maps of the SZ effect include relativistic corrections considered within the framework of the Wright formalism and utilize a cosmological numerical simulation of a merging galaxy cluster evolved with its baryon physics. Results. We found that the gas temperature in merging clusters can be inferred from the ratio of the SZ intensity at a low frequency (128 GHz) to that at a high frequency (369 GHz). This SZ intensity ratio permits us to reveal prominent features of the temperature structure caused by violent merger shock waves. Therefore, measurements of the ratio of the SZ intensities are a promising tool for measuring the gas temperature in merging galaxy clusters.
Aims. Spectral line emissivities have usually been calculated for a Maxwellian electron distribution. But many theoretical works on both galaxy groups and clusters and the solar corona consider ...modified Maxwellian electron distribution functions when fitting observed X-ray spectra. Here we examine the influence of high energy electron populations on measurements of metal abundances. Methods. A generalized approach proposed by ourselves is used to calculate the line emissivities for a modified Maxwellian distribution. We study metal abundances in galaxy groups and clusters in which hard X-ray excess emission was observed. Results. We found that for modified Maxwellian distributions the argon abundance decreases for the HCG 62 group, the iron abundance decreases for the Centaurus cluster, and the oxygen abundance decreases for the solar corona with respect to the case of a Maxwellian distribution. Therefore, metal abundance measurements are a promising tool for testing the presence of high energy electron populations.
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