Context. The evolution of the Universe during the dark ages (DA) and the epoch of reonization (EoR) marks an important transition in the history of the Universe but it is not yet fully understood. ...Aims. We study here an alternative technique to probe the DA and EoR that makes use of the Comptonization of the CMB spectrum modified by physical effects occurring during this epoch related to the emergence of the 21-cm radiation background. Inverse Compton scattering of 21-cm photon background by thermal and non-thermal electrons residing in the atmospheres of cosmic structures like galaxy clusters, radiogalaxy lobes and galaxy halos, produces a specific form of Sunyaev-Zel’dovich effect (SZE) that we refer to as SZE-21 cm. Methods. We derived the SZE-21 cm in a general relativistic approach, which is required to describe the correct spectral features of this astrophysical effect. We calculated the spectral features of the thermal and non-thermal SZE-21 cm in galaxy clusters and in radiogalaxy lobes, and their dependence on the history of physical mechanisms occurring during the DA and EoR. We studied how the spectral shape of the SZE-21 cm can be used to establish the global features in the mean 21-cm spectrum generated during and prior to the EoR, and how it depends on the properties of the (thermal and non-thermal) plasma in cosmic structures. Results. We found that the thermal and non-thermal SZE-21 cm have peculiar spectral shapes that allow to investigate the physics and history of the EoR and DA. Its spectrum depends on the gas temperature (for the thermal SZE-21 cm) and on the electrons minimum momentum (for the non-thermal SZE-21 cm). The global SZE-21 cm signal can be detected (in ~ 1000 h) by SKA1-low in the frequency range ν ≳ 75−90 MHz, for clusters in the temperature range 5 to 20 keV, and the difference between the SZE-21 cm and the standard SZE can be detected by SKA1 or SKA2 at frequencies depending on the background model and the cluster temperature. Conclusions. We have shown that the detection of the SZE-21 cm can provide unique information on the DA and EoR, and on the cosmic structures that produce the scattering; the frequencies at which the SZE-21 cm shows its main spectral features will indicate the epoch at which the physical processes related to the cosmological 21-cm signal occurred and shed light on the cosmic history during the DA and EoR by using local, well-known cosmic structures like galaxy clusters and radio galaxies.
Context. The origin of radio halos in galaxy clusters is still unknown and is the subject of a vibrant debate from both observational and theoretical points of view. In particular, the amount and the ...nature of nonthermal plasma and of the magnetic field energy density in clusters hosting radio halos is still unclear. Aims. The aim of this paper is to derive an estimate of the pressure ratio X = Pnon − th/Pth between the nonthermal and thermal plasma in radio halo clusters that have combined radio, X-ray and Sunyaev-Zel’dovich (SZ) effect observations. Methods. From the simultaneous P1.4 − LX and P1,4 − YSZ correlations for a sample of clusters observed with Planck, we derive a correlation between YSZ and LX that we use to derive a value for X. This is possible since the Compton parameter YSZ is proportional to the total plasma pressure in the cluster, which we characterize as the sum of the thermal and nonthermal pressure, while the X-ray luminosity LX is proportional only to the thermal pressure of the intracluster plasma. Results. Our results indicate that the average (best-fit) value of the pressure ratio in a self-similar cluster formation model is X = 0.55 ± 0.05 in the case of an isothermal β-model with β = 2/3 and a core radius rc = 0.3·R500, holding on average for the cluster sample. We also show that the theoretical prediction for the YSZ − LX correlation in this model has a slope that is steeper than the best-fit value for the available data. The agreement with the data can be recovered if the pressure ratio X decreases with increasing X-ray luminosity as LX-0.96. Conclusions. We conclude that the available data on radio halo clusters indicate a substantial amount of nonthermal pressure in cluster atmospheres whose value must decrease with increasing X-ray luminosity or increasing cluster mass (temperature). This is in agreement with the idea that nonthermal pressure is related to nonthermal sources of cosmic rays that live in cluster cores and inject nonthermal plasma in the cluster atmospheres, which is subsequently diluted by the intracluster medium acquired during cluster collapse, and has relevant impact for further studies of high-energy phenomena in galaxy clusters.
We study here an alternative technique to probe the Dark Ages (DA) and the Epoch of Reonization (EoR) that makes use of the Comptonization of the CMB spectrum modified by physical effects occurring ...during this epoch related to the emergence of the 21-cm radiation background. Inverse Compton scattering of 21-cm photon background by thermal and non-thermal electrons residing in the atmospheres of cosmic structures like galaxy clusters, radiogalaxy lobes and galaxy halos, produces a specific form of Sunyaev-Zel'dovich effect (SZE) that we refer to as SZE-21cm. We derive the SZE-21cm in a general relativistic approach which is required to describe the correct spectral features of this astrophysical effect. We calculate the spectral features of the thermal and non-thermal SZE-21cm in galaxy clusters and in radiogalaxy lobes, and their dependence on the history of physical mechanisms occurring during the DA and EoR. We study how the spectral shape of the SZE-21cm can be used to establish the global features in the mean 21-cm spectrum generated during and prior to the EoR, and how it depends on the properties of the (thermal and non-thermal) plasma in cosmic structures. We find that the thermal and non-thermal SZE-21cm have peculiar spectral shapes that allow to investigate the physics and history of the EoR and DA. Its spectrum depends on the gas temperature (for the thermal SZE-21cm) and on the electrons minimum momentum (for the non-thermal SZE-21cm). The global SZE-21cm signal can be detected (in \(\sim 1000\) hrs) by SKA1-low in the frequency range \(\nu \simgt 75-90\) MHz, for clusters in the temperature range 5 to 20 keV, and the difference between the SZE-21cm and the standard SZE can be detected by SKA1 or SKA2 at frequencies depending on the background model and the cluster temperature. abridged
Abridged Inverse Compton scattering of CMB fluctuations off cosmic electron plasma generates a polarization of the associated Sunyaev-Zel'dovich (SZ) effect. This signal has been studied so far ...mostly in the non-relativistic regime and for a thermal electron population and, as such, has limited astrophysical applications. Partial attempts to extend this calculation for a thermal electron plasma in the relativistic regime have been done but cannot be applied to a general relativistic electron distribution. Here we derive a general form of the SZ effect polarization valid in the full relativistic approach for both thermal and non-thermal electron plasmas, as well as for a generic combination of various electron population co-spatially distributed in the environments of galaxy clusters or radiogalaxy lobes. We derive the spectral shape of the Stokes parameters induced by the IC scattering of every CMB multipole, focusing on the CMB quadrupole and octupole that provide the largest detectable signals in galaxy clusters. We found that the CMB quadrupole induced Stoke parameter Q is always positive with a maximum amplitude at 216 GHz which increases slightly with increasing cluster temperature. The CMB octupole induced Q spectrum shows, instead, a cross-over frequency which depends on the cluster electron temperature, or on the minimum momentum p_1 as well as on the power-law spectral index of a non-thermal electron population. We discuss some possibilities to disentangle the quadrupole-induced Q spectrum from the octupole-induced one which allow to measure these quantities through the SZ effect polarization. We finally apply our model to the realistic case of the Bullet cluster and derive the visibility windows of the total, quandrupole-induced and octupole-induced Stoke parameter Q in the frequency ranges accessible to SKA, ALMA, MILLIMETRON and CORE++ experiments.
The origin of radio halos in galaxy clusters is still unknown and is the subject of a vibrant debate both from the observational and theoretical point of view. In particular the amount and the nature ...of non-thermal plasma and of the magnetic field energy density in clusters hosting radio halos is still unclear. The aim of this paper is to derive an estimate of the pressure ratio X between the non-thermal and thermal plasma in radio halo clusters that have combined radio, X-ray and SZ effect observations. From the simultaneous P_{1.4}-L_X and P_{1.4}-Y_{SZ} correlations for a sample of clusters observed with Planck, we derive a correlation between Y_{SZ} and L_X that we use to derive a value for X. This is possible since the Compton parameter Y_{SZ} is proportional to the total plasma pressure in the cluster (that we characterize as the sum of the thermal and non-thermal pressure) while the X-ray luminosity L_X is proportional only to the thermal pressure of the intracluster plasma. Our results indicate that the average (best fit) value of the pressure ratio in a self-similar cluster formation model is X =0.55 \pm 0.05 in the case of an isothermal beta-model with beta=2/3 and a core radius r_c = 0.3 R_{500} holding on average for the cluster sample. We also show that the theoretical prediction for the Y_{SZ}-L_X correlation in this model has a slope that is steeper than the best fit value for the available data. The agreement with the data can be recovered if the pressure ratio X decreases with increasing X-ray luminosity as L_X^{-0.96}. We conclude that the available data on radio halo clusters indicate a substantial amount of non-thermal pressure in cluster atmospheres whose value must decrease with increasing X-ray luminosity, or increasing cluster mass (temperature). (abridged)
The aim of this study was to compare the bioavailability of two atorvastatin formulations (Divator Drogsan Pharmaceuticals, Ankara, Turkey, as the test formulation, and Lipitor, Pfizer Ireland ...Pharmaceuticals, Dublin, Ireland, as the reference formulation) in 52 healthy volunteers. The study was conducted using a randomised, single-dose, two-way crossover study with a 2-week washout period between the doses. Since the 90% confidence intervals for Cmax, AUC0-72 and AUC0-proprtional to ratios for both, the parent atorvastatin and its main active metabolite ortho-hydroxy atorvastatin, were within the pre-defined Bioequivalance acceptance limits approved by EMEA, we concluded that the atorvastatin formulation elaborated by Drogsan Pharmaceuticals, was bioequivalent to the Lipitor in its rate and extent of absorption.
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