Subscribe to the gold package and get unlimited access to Shamra Academy
Register a new userChandra Observations of the Planck ESZ Sample: A Re-Examination of Masses and Mass Proxies
296
0
0.0
(
0
)
Added by
Felipe Andrade-Santos
Publication date
2021
fields
Physics
and research's language is
English
Ask ChatGPT about the research
No Arabic abstract
Using Chandra observations, we derive the $Y_{rm X}$ proxy and associated total mass measurement, $M_{500}^{rm Y_X}$, for 147 clusters with $z leq 0.35$ from the Planck Early Sunyaev-Zeldovich catalog, and for 80 clusters with $z leq 0.30$ from an X-ray flux-limited sample. We re-extract the Planck $Y_{rm SZ}$ measurements and obtain the corresponding mass proxy, $M_{500}^{rm SZ}$, from the full Planck mission maps, minimizing the Malmquist bias due to observational scatter. The masses re-extracted using the more precise X-ray position and characteristic size agree with the published PSZ2 values, but yield a significant reduction in the scatter (by a factor of two) in the $M_{500}^{rm SZ}$-$M_{500}^{rm X}$ relation. The slope is $0.93pm0.03$, and the median ratio, $M_{500}^{rm SZ}/M_{500}^{rm X}= 0.91pm0.01$, is within the expectations from known X-ray calibration systematics. The $Y_{rm SZ}/Y_{rm X}$ ratio is $0.88pm0.02$, in good agreement with predictions from cluster structure, and implying a low level of clumpiness. In agreement with the findings of the Planck Collaboration, the slope of the $Y_{rm SZ}$-$D_{rm A}^{-2} Y_{X}$ flux relation is significantly less than unity ($0.89pm0.01$). Using extensive simulations, we show that this result is not due to selection effects, intrinsic scatter, or covariance between quantities. We demonstrate analytically that changing the $Y_{rm SZ}$-$Y_{X}$ relation from apparent flux to intrinsic properties results in a best-fit slope that is closer to unity and increases the dispersion about the relation. The redistribution resulting from this transformation implies that the best fit parameters of the $M_{500}^{rm SZ}$-$M_{500}^{rm X}$ relation will be sample-dependent.
rate research
Read More
Total mass is arguably the most fundamental property for cosmological studies with galaxy clusters. We investigate the present differences in the mass estimates obtained through independent X-ray, weak-lensing, and dynamical studies. We quantify the differences as the mean ratio 1-$b$=M$_{rm HE}$/M$_{rm WL,dyn}$, where HE refers to hydrostatic masses obtained from X-ray observations, WL refers to the results of weak-lensing measurements, and dyn refers to the mass estimates either from velocity dispersion or from the caustic technique. Recent X-ray masses reported by independent groups show average differences smaller than $sim$10$%$, posing a strong limit on the systematics that can be ascribed to the differences in the X-ray analysis when studying the hydrostatic bias. The mean ratio between our X-ray masses and the weak-lensing masses in the LC$^2$-single catalog is 1-$b$=0.74$pm$0.06. However, the mean mass ratios inferred from the WL masses of different projects vary by a large amount, with APEX-SZ showing a bias consistent with zero (1-$b$=1.02$pm$0.12), LoCuSS and CCCP/MENeaCS showing a significant difference (1-$b$=0.76$pm$0.09 and 1-$b$=0.77$pm$0.10, respectively), and WtG pointing to the largest deviation (1-$b$=0.61$pm$0.12). At odds with the WL results, the dynamical mass measurements show better agreement with the X-ray hydrostatic masses, although there are significant differences when relaxed or disturbed clusters are used. The different ratios obtained using different mass estimators suggest that there are still systematics that are not accounted for in all the techniques used to recover cluster masses. This prevents the determination of firm constraints on the level of hydrostatic mass bias in galaxy clusters.
The on-going X-ray all-sky survey with the eROSITA instrument will yield large galaxy cluster samples, which will bring strong constraints on cosmological parameters. In particular, the survey holds great promise to investigate the tension between CMB and low-redshift measurements. The current bottleneck preventing the full exploitation of the survey data is the systematics associated with the relation between survey observable and halo mass. Numerous recent studies have shown that gas mass and core-excised X-ray luminosity exhibit very low scatter at fixed mass. We propose a new method to reconstruct these quantities from low photon count data and validate the method using extensive eROSITA-like simulations. We find that even near the detection threshold of ~50 counts the core-excised luminosity and the gas mass can be recovered with 20-30% precision, which is substantially less than the scatter of the full integrated X-ray luminosity at fixed mass. When combined with an accurate calibration of the absolute mass scale (e.g. through weak gravitational lensing), our technique reduces the systematics on cosmological parameters induced by the mass calibration.
The gas mass fraction in galaxy clusters has been widely used to determine cosmological parameters. This method assumes that the ratio of the cluster gas mass fraction to the cosmic baryon fraction ($gamma(z)$) is constant as a function of redshift. In this work, we look for a time evolution of $gamma(z)$ at $R_{500}$ by using both the SPT-SZ and Planck Early SZ (ESZ) cluster data, in a model-independent fashion without any explicit dependence on the underlying cosmology. For this calculation, we use a non-parametric functional form for the Hubble parameter obtained from Gaussian Process regression using cosmic chronometers. We parameterize $gamma(z)$ as: $gamma(z)= gamma_0(1+gamma_1 z)$ to constrain the redshift evolution. We find contradictory results between both the samples. For SPT-SZ, $gamma (z)$ decreases as a function of redshift (at more than 5$sigma$), whereas a positive trend with redshift is found for Planck ESZ data (at more than 4$sigma$). We however find that the $gamma_1$ values for a subset of SPT-SZ and Planck ESZ clusters between the same redshift interval agree to within $1sigma$. When we allow for a dependence on the halo mass in the evolution of the gas depletion factor, the $4-5sigma$ discrepancy reduces to $2sigma$.
Angular power spectra computed from Planck HFI 353 GHz intensity and polarization maps produce a TB correlation that can be approximated by a power law. Whether the observed TB correlation is an induced systematic feature or a physical property of Galactic dust emission is of interest both for cosmological and Galactic studies. We investigate the large angular scale E- and B-mode morphology of microwave polarized thermal dust emission, and relate it to physical quantities of polarization angle and polarization fraction. We use empirical models of polarized dust to show that dust polarization angle is a key factor in producing the TB correlation. A small sample of both simulated and observed polarization angle maps are combined with 353 GHz intensity and dust polarization fraction to produce a suite of maps from which we compute TB and EB. Model realizations that produce a positive TB correlation are common and can result from large-scale (>5 degree) structure in the polarization angle. The TB correlation appears robust to introduction of individual intensity, polarization angle and polarization fraction model components that are independent of the 353 GHz observations. We conclude that the observed TB correlation is likely the result of large-scale Galactic dust polarization properties.
A fraction of galaxy clusters host diffuse radio sources whose origins are investigated through multi-wavelength studies of cluster samples. We investigate the presence of diffuse radio emission in a sample of seven galaxy clusters in the largely unexplored intermediate redshift range (0.3 < z < 0.44). In search of diffuse emission, deep radio imaging of the clusters are presented from wide band (1.1-3.1 GHz), full resolution ($sim$ 5 arcsec) observations with the Australia Telescope Compact Array (ATCA). The visibilities were also imaged at lower resolution after point source modelling and subtraction and after a taper was applied to achieve better sensitivity to low surface brightness diffuse radio emission. In case of non-detection of diffuse sources, we set upper limits for the radio power of injected diffuse radio sources in the field of our observations. Furthermore, we discuss the dynamical state of the observed clusters based on an X-ray morphological analysis with XMM-Newton. We detect a giant radio halo in PSZ2 G284.97-23.69 (z=0.39) and a possible diffuse source in the nearly relaxed cluster PSZ2 G262.73-40.92 (z=0.421). Our sample contains three highly disturbed massive clusters without clear traces of diffuse emission at the observed frequencies. We were able to inject modelled radio halos with low values of total flux density to set upper detection limits; however, with our high-frequency observations we cannot exclude the presence of RH in these systems because of the sensitivity of our observations in combination with the high z of the observed clusters.
Log in to be able to interact and post comments
comments
Fetching comments
Sign in to be able to follow your search criteria
