Aims. We explore the ability of spatially resolved spectroscopic measurements of the SZ effect (SZE) to determine the temperature profile of galaxy clusters. We derive a general formalism for the ...thermal SZE in galaxy clusters with a non-uniform temperature profile that can be applied to both cool-core clusters and non-cool-core clusters with an isothermal or non-isothermal temperature structure. Methods. We develop an inversion technique by means of which the electron distribution function can be extracted from spectroscopic SZE observations over a wide frequency range. We study the fitting procedure to extract the cluster temperature from a set of simulated spatially resolved spectroscopic SZE observations in different bands of the spectrum from 100 to 450 GHz. Results. We present our analysis results for three different cluster prototypes: A2199 with a low-temperature cool core, Perseus with a relatively high-temperature cool core, and Ophiuchus with an isothermal temperature distribution. These results indicate both the precision of the SZE observations and the optimal frequency bands required to determine the cluster temperature with similar or better accuracy than that obtainable from X-ray observations. The precision of SZE-derived temperature is also discussed for the outer regions of clusters. Using our method, we also study the possibility of extracting the parameters characterizing the non-thermal SZE spectrum of the relativistic plasma contained in the lobes of radio galaxies as well as the spectrum of relativistic electrons cospatially distributed with the thermal plasma in clusters that exhibit non-thermal phenomena. Conclusions. We find that the next generation SZE experiments, which will have both spectroscopic capabilities with moderate resolution of a few to tens GHz and imaging capabilities with spatial resolution of tens of arcsec up to arcmin, can provide precise temperature distribution measurements over a wide range of radial distances for galaxy clusters even out to high redshift.
Several galaxy clusters host X-ray cavities, often filled with relativistic electrons emitting in the radio band. In the cluster MS 0735.6+7421 the cavities have been detected through the Sunyaev ...Zel'dovich (SZ) effect, but it has not been possible to determine if this effect is thermal (produced by a very high temperature gas filling the cavity) or non-thermal (produced by the relativistic electrons that produce the diffuse radio emission detected in the cavity). In this paper we discuss the role of the density of the high temperature gas inside the cavities in determining whether the dominant SZ effect is the thermal or the non-thermal one, and how it can be possible to distinguish between the two possibilities, discussing the role of observations at higher energy bands.
The galaxy cluster MS 0735.6+7421 hosts two large X-ray cavities, filled with radio emission, where a decrease of the Sunyaev-Zel'dovich (SZ) effect has been detected, without establishing if its ...origin is thermal (from a gas with very high temperature) or non-thermal. In this paper we study how thermal and non-thermal contributions to the SZ effect in the cavities are related; in fact, Coulomb interactions with the thermal gas modify the spectrum of low energy non-thermal electrons, which dominate the non-thermal SZ effect; as a consequence, the intensity of the non-thermal SZ effect is stronger for lower density of the thermal gas inside the cavity. We calculate the non-thermal SZ effect in the cavities as a function of the thermal density, and compare the SZ effects produced by thermal and non-thermal components, and with the one from the external Intra Cluster Medium (ICM), searching for the best frequency range where it is possible to disentangle the different contributions. We find that for temperatures inside the cavities higher than \(\sim1500\) keV the non-thermal SZ effect is expected to dominate on the thermal one, particularly at high frequencies (\(\nu>500\) GHz), where it can also be a non-negligible fraction of the SZ effect from the external ICM. We also discuss the possible sources of astrophysical bias (as kinetic SZ effect and foreground emission from Galactic dust) and possible ways to address them, as well as necessary improvements in the modeling of the properties of cavities and the ICM.
Context. Young massive stellar clusters are extreme environments and potentially provide the means for efficient particle acceleration. Indeed, they are increasingly considered as being responsible ...for a significant fraction of cosmic rays (CRs) that are accelerated within the Milky Way. Westerlund 1, the most massive known young stellar cluster in our Galaxy, is a prime candidate for studying this hypothesis. While the very-high-energy gamma-ray source HESS J1646-458 has been detected in the vicinity of Westerlund 1 in the past, its association could not be firmly identified. Aims. We aim to identify the physical processes responsible for the gamma-ray emission around Westerlund 1 and thus to understand the role of massive stellar clusters in the acceleration of Galactic CRs better. Methods. Using 164 h of data recorded with the High Energy Stereoscopic System (H.E.S.S.), we carried out a deep spectromorphological study of the gamma-ray emission of HESS J1646-458. We furthermore employed H I and CO observations of the region to infer the presence of gas that could serve as target material for interactions of accelerated CRs. Results. We detected large-scale (similar to 2 degrees diameter) gamma-ray emission with a complex morphology, exhibiting a shell-like structure and showing no significant variation with gamma-ray energy. The combined energy spectrum of the emission extends to several tens of TeV, and it is uniform across the entire source region. We did not find a clear correlation of the gamma-ray emission with gas clouds as identified through H I and CO observations. Conclusions. We conclude that, of the known objects within the region, only Westerlund 1 can explain the majority of the gamma-ray emission. Several CR acceleration sites and mechanisms are conceivable and discussed in detail. While it seems clear that Westerlund 1 acts as a powerful particle accelerator, no firm conclusions on the contribution of massive stellar clusters to the flux of Galactic CRs in general can be drawn at this point.
In this paper we study the effect of reacceleration provided by turbulences on electrons produced by dark matter (DM) annihilation in the Coma cluster. We use a simplified phenomenological model to ...describe the effect of the turbulences, and explore a limited subset of three possible DM models for neutralino particles with different mass and annihilation channel. We find that, for values of the annihilation cross section of the order of the upper limits found with Fermi-LAT measurements in astrophysical objects, and for conservative values of the boosting factor due to DM substructures, the reacceleration due to turbulences can enhance the radio emission produced by DM-originated electrons up to the level of the observed flux of the radio halo in Coma, for moderate reacceleration intensity in relatively short times. Therefore we conclude that, even if it is not possible to distinguish between the fits obtained in this paper because of the scattering present in the radio flux data, the electrons produced by DM annihilation can be possible seed electrons for the reacceleration, as well as secondary electrons of hadronic origin. A possible discriminant between these two classes of models is the flux produced in the gamma ray band, that in the case of DM-originated electrons should be more than two orders of magnitude smaller than the present Fermi-LAT upper limits, whereas in the hadronic case the expected gamma ray flux should be close to the value of present upper limits.
In this paper we study the possibility of probing the low-energy part of the spectrum of non-thermal electrons in galaxy clusters by detecting their non-thermal bremsstrahlung (NTB) emission in the ...soft gamma ray band, using instruments like e-ASTROGAM. Using the Coma cluster as a reference case, we find that, for very low values of the minimum energy of the electrons, in principle the NTB is detectable, but this situation is possible only for conditions that can be maintained only for a short time compared to the cluster lifetime. The possibility of constraining the low energy spectrum of non-thermal electrons through NTB is therefore hard to achieve in next years.
Abstract
Issue
Chronic and acute diseases affects migrants and vulnerable people who often face barriers in accessing health care services. Here is the description of an innovative health center (HC) ...developed for identifying barriers and facilitating access to health care services of hard-to-reach (HTR) people in Rome.
Description of the Problem
The Community of Sant'Egidio together with the “Migrant Health Unit” of ASL Roma 1 has established an innovative HC program aimed to improve health outcomes in HTR urban population. One of the main Public Health challenge is to reduce inequalities among migrants and vulnerable people through improving access to health services. Data here analysed were collected during 2019.
Results
897 migrants and vulnerable people received heath care assistance. 52.4% were females, mean age 40.7±21.4 ds, 16.3% aged under 18 years and 69.6% were between 18-64 years. Countries of provenance: 56.8% Eastern Europe (Bosnia and Romania), 16.8% South America and 15.2% North Africa. 3.2% were refugees. Among 1986 health interventions 56.3% were general medical visits, 35.4% prescriptions and free drugs distribution, 4.1% children growth controls and baby milk supplies, 3.6% specialist visits and only 0.3% were sending to the Emergency Room.
Lessons
Improving the access to health care services of migrants is both a public health and an economic goal. The increase in chronic-degenerative diseases underlines the need to facilitate access to health services, also through collaboration networks between public and private social. This allows continuity in treatment, which has great meaning of secondary prevention, as well as rationalization of resources, reducing an improper use of the Emergency Room, which provides occasional intervention, but does not integrate into an efficient/effective therapeutic path.
Key messages
Promoting health care services like this can reduce barriers, improve health outcomes in migrants and increase sustainability of the NHS. Improving access to public and private social health services is important especially in presence of chronic-diseases which require continuous therapies and examinations.
The Sunyaev-Zel'dovich (SZ) effect is a powerful tool for studying clusters of galaxies and cosmology. Large mm-wave telescopes are now routinely detecting and mapping the SZ effect in a number of ...clusters, measure their comptonisation parameter and use them as probes of the large-scale structure and evolution of the universe. The authors used accurate simulations of observations with lines-of-sight through clusters of galaxies with different experimental configurations and different intracluster plasma stratifications. They find that measurements carried out with ground-based few-band photometers are biased towards high electron temperatures and low optical depths, and require coverage of high frequency and/or independent complementary observations to produce unbiased information; a differential spectrometer that covers 4 bands with a resolution of similar to 6 GHz eliminates most if not all bias; full-range differential spectrometers are the ultimate resource that allows a full recovery of all parameters.
A recent stacking analysis of Planck HFI data of galaxy clusters (Hurier 2016) allowed to derive the cluster temperatures by using the relativistic corrections to the Sunyaev-Zel'dovich effect (SZE). ...However, the temperatures of high-temperature clusters, as derived from this analysis, resulted to be basically higher than the temperatures derived from X-ray measurements, at a moderate statistical significance of \(1.5\sigma\). This discrepancy has been attributed by Hurier (2016) to calibration issues. In this paper we discuss an alternative explanation for this discrepancy in terms of a non-thermal SZE astrophysical component. We find that this explanation can work if non-thermal electrons in galaxy clusters have a low value of their minimum momentum (\(p_1\sim0.5-1\)), and if their pressure is of the order of \(20-30\%\) of the thermal gas pressure. Both these conditions are hard to obtain if the non-thermal electrons are mixed with the hot gas in the intra cluster medium, but can be possibly obtained if the non-thermal electrons are mainly confined in bubbles with high content of non-thermal plasma and low content of thermal plasma, or in giant radio lobes/relics located in the outskirts of clusters. In order to derive more precise results on the properties of non-thermal electrons in clusters, and in view of more solid detections of a discrepancy between X-rays and SZE derived clusters temperatures that cannot be explained in other ways, it would be necessary to reproduce the full analysis done by Hurier (2016) by adding systematically the non-thermal component of the SZE.
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