Statistics of the fractional polarisation of compact radio sources in Planck maps

In this work we apply the stacking technique to estimate the average fractional polarisation from 30 to 353 GHz of a primary sample of 1560 compact sources - essentially all radio sources - detected in the 30 GHz Planck all-sky map and listed in the second version of the Planck Catalogue of Compact Sources (PCCS2). We divide our primary sample in two subsamples according to whether the sources lay (679 sources) or not (881 sources) inside the sky region defined by the Planck Galactic mask (fsky ~ 60 per cent) and the area around the Magellanic Clouds. We find that the average fractional polarisation of compact sources is approximately constant (with frequency) in both samples (with a weighted mean over all the channels of 3.08 per cent outside and 3.54 per cent inside the Planck mask). In the sky region outside the adopted mask, we also estimate the {\mu} and {\sigma} parameters for the log-normal distribution of the fractional polarisation, finding a weighted mean value over all the Planck frequency range of 1.0 for {\sigma} and 0.7 for {\mu} (that would imply a weighted mean value for the median fractional polarisation of 1.9 per cent).Comment: 12 pages, 7 figures, 2 tables, MNRAS in pres

Extragalactic Compact Sources in the Planck Sky and Their Cosmological Implications

The Planck satellite has proved to be a very successful mission, which has been operating flawlessly for more than 36 months. Its main purpose is to map the anisotropies of the CMB radiation at 9 frequencies, between 30 and 857 GHz, with unprecedented resolution and sensitivity. After a description of the properties and cosmological aims of Planck, we review the results obtained during the first 1.6 full sky surveys relative to compact extragalactic sources and their implications. The most recent and efficient methods and filters for compact source detection in the presence of Gaussian noise and CMB anisotropies are discussed. The first surveys of Planck have enabled the detection of about 200 galaxy clusters, by the SZ effect, and from several hundreds to many thousands of extragalactic point sources (EPS), presented in the Planck ERCSC. We review the results on the SZ effect in galaxy clusters. We discuss the possibilities of future Planck data to study clusters through the SZ effect and the interesting possibilities of combining these data with X ray observations. These EPS can be classified into two main source classes: radio sources, at intermediate to high z; far IR sources, typically at very z. Planck number counts of EPS at LFI frequencies are in agreement with WMAP counts. A clear steepening of the mean spectral index of bright radio sources is observed above 70 GHz, that can be interpreted in terms of a break frequency in their spectra. For nearby dusty galaxies, Planck observations find evidence of colder dust, with T < 20 K, than has previously been found. More recently, the number counts of bright local dusty galaxies and of synchrotron sources have been measured by Planck at submm wavelengths. Planck has provided interesting results on the angular distribution of CIB anisotropies, allowing us to put new constraints on clustering properties of dusty galaxies at high z.Comment: 30 pages, 12 figures. Abstract absent in the published version. See http://www.intechopen.com/articles/show/title/extragalactic-compact-sources-in-the-planck-sky-and-their-cosmological-implication

Estudio histórico y epistemológico de la óptica como base para la enseñanza en 2º de Bachillerato

[ES] En este trabajo analizamos los textos originales de los grandes científicos sobre la naturaleza de la luz destacando los avances principales que aportaron, y proponemos una relación entre dichas ideas clave y los estándares de aprendizaje que han de ser adquiridas por nuestros alumnos. A partir de estas ideas clave y teniendo en cuenta los posibles obstáculos asociados, desarrollaremos el estudio de la óptica de manera constructiva, para que tanto los alumnos, como el profesor, aprovechen en mayor medida el proceso de enseñanza-aprendizaje.Álvarez Jubete, E.; Hevia Artime, I.; Toffolatti Ballarin, L. (2020). Estudio histórico y epistemológico de la óptica como base para la enseñanza en 2º de Bachillerato. Editorial Universitat Politècnica de València. 451-459. https://doi.org/10.4995/INN2019.2019.10026OCS45145

Planck intermediate results XI. The gas content of dark matter halos: The sunyaev-zeldovich-stellar mass relation for locally brightest galaxies

We present the scaling relation between Sunyaev-Zeldovich (SZ) signal and stellar mass for almost 260,000 locally brightest galaxies (LBGs) selected from the Sloan Digital Sky Survey (SDSS). These are predominantly the central galaxies of their dark matter halos. We calibrate the stellar-to-halo mass conversion using realistic mock catalogues based on the Millennium Simulation. Applying a multi-frequency matched filter to the Planck data for each LBG, and averaging the results in bins of stellar mass, we measure the mean SZ signal down to M? ~ 2 × 1011 M?, with a clear indication of signal at even lower stellar mass. We derive the scaling relation between SZ signal and halo mass by assigning halo properties from our mock catalogues to the real LBGs and simulating the Planck observation process. This relation shows no evidence for deviation from a power law over a halo mass range extending from rich clusters down to M500 ~ 2 × 1013 M?, and there is a clear indication of signal down to M500 ~ 4 × 1012 M?. Planck?s SZdetections in such low-mass halos imply that about a quarter of all baryons have now been seen in the form of hot halo gas, and that this gas must be less concentrated than the dark matter in such halos in order to remain consistent with X-ray observations. At the high-mass end, the measured SZ signal is 20% lower than found from observations of X-ray clusters, a difference consistent with the magnitude of Malmquist bias effects that were previously estimated for the X-ray sample

Planck intermediate results VI. The dynamical structure of PLCKG214.6+37.0, a Planck discovered triple system of galaxy clusters

The survey of galaxy clusters performed by Planck through the Sunyaev-Zeldovich effect has already discovered many interesting objects, thanks to its full sky coverage. One of the SZcandidates detected in the early months of the mission near to the signal-to-noise threshold, PLCKG214.6+37.0, was later revealed by XMM-Newton to be a triple system of galaxy clusters. We present the results from a deep XMM-Newton re-observation of PLCKG214.6+37.0, part of a multi-wavelength programme to investigate Planck discovered superclusters. The characterisation of the physical properties of the three components has allowed us to build a template model to extract the total SZ signal of this system with Planck data. We have partly reconciled the discrepancy between the expected SZ signal derived from X-rays and the observed one, which are now consistent within 1.2?. We measured the redshift of the three components with the iron lines in the X-ray spectrum, and confirm that the three clumps are likely part of the same supercluster structure. The analysis of the dynamical state of the three components, as well as the absence of detectable excess X-ray emission, suggests that we are witnessing the formation of a massive cluster at an early phase of interaction

Planck intermediate results V. Pressure profiles of galaxy clusters from the Sunyaev-Zeldovich effect

Taking advantage of the all-sky coverage and broadfrequency range of the Planck satellite, we study the Sunyaev-Zeldovich (SZ) and pressure profiles of 62 nearby massive clusters detected at high significance in the 14-month nominal survey. Careful reconstruction of the SZ signal indicates that most clusters are individually detected at least out to R500. By stacking the radial profiles, we have statistically detected the radial SZ signal out to 3 × R500, i.e., at a density contrast of about 50?100, though the dispersion about the mean profile dominates the statistical errors across the whole radial range. Our measurement is fully consistent with previous Planck results on integrated SZ fluxes, further strengthening the agreement between SZ and X-ray measurements inside R500. Correcting for the effects of the Planck beam, we have calculated the corresponding pressure profiles. This new constraint from SZ measurements is consistent with the X-ray constraints from XMM-Newton in the region in which the profiles overlap (i.e., [0.1?1]?R500), and is in fairly good agreement with theoretical predictions within the expected dispersion. At larger radii the average pressure profile is slightly flatter than most predictions from numerical simulations. Combining the SZ and X-ray observed profiles into a joint fit to a generalised pressure profile gives best-fit parameters [P0,c500,?,?,? ] = [6.41,1.81,0.31,1.33,4.13 ] . Using a reasonable hypothesis for the gas temperature in the cluster outskirts we reconstruct from our stacked pressure profile the gas mass fraction profile out to 3?R500. Within the temperature driven uncertainties, our Planck constraints are compatible with the cosmic baryon fraction and expected gas fraction in halos

Planck intermediate results: II. Comparison of sunyaev-zeldovich measurements from planck and from the arcminute microkelvin imager for 11 galaxy clusters

A comparison is presented of Sunyaev-Zeldovich measurements for 11 galaxy clusters as obtained by Planck and by the ground-based interferometer, the Arcminute Microkelvin Imager. Assuming a universal spherically-symmetric Generalised Navarro, Frenk and White (GNFW) model for the cluster gas pressure profile, we jointly constrain the integrated Compton-Y parameter (Y500) and the scale radius (?500) of each cluster. Our resulting constraints in the Y500 ? ?500 2D parameter space derived from the two instruments overlap significantly for eight of the clusters, although, overall, there is a tendency for AMI to find the Sunyaev-Zeldovich signal to be smaller in angular size and fainter than Planck. Significant discrepancies exist for the three remaining clusters in the sample, namely A1413, A1914, and the newly-discovered Planck cluster PLCKESZ G139.59+24.18. The robustness of the analysis of both the Planck and AMI data is demonstrated through the use of detailed simulations, which also discount confusion from residual point (radio) sources and from diffuse astrophysical foregrounds as possible explanations for the discrepancies found. For a subset of our cluster sample, we have investigated the dependence of our results on the assumed pressure profile by repeating the analysis adopting the best-fitting GNFW profile shape which best matches X-ray observations. Adopting the best-fitting profile shape from the X-ray data does not, in general, resolve the discrepancies found in this subset of five clusters. Though based on a small sample, our results suggest that the adopted GNFW model may not be sufficiently flexible to describe clusters universally

Planck intermediate results: VIII. Filaments between interacting clusters

Context. About half of the baryons of the Universe are expected to be in the form of filaments of hot and low-density intergalactic medium. Most of these baryons remain undetected even by the most advanced X-ray observatories, which are limited in sensitivity to the diffuse low-density medium. Aims. The Planck satellite has provided hundreds of detections of the hot gas in clusters of galaxies via the thermal Sunyaev-Zel?dovich (tSZ) effect and is an ideal instrument for studying extended low-density media through the tSZ effect. In this paper we use the Planck data to search for signatures of a fraction of these missing baryons between pairs of galaxy clusters. Methods. Cluster pairs are good candidates for searching for the hotter and denser phase of the intergalactic medium (which is more easily observed through the SZ effect). Using an X-ray catalogue of clusters and the Planck data, we selected physical pairs of clusters as candidates. Using the Planck data, we constructed a local map of the tSZ effect centred on each pair of galaxy clusters. ROSAT data were used to construct X-ray maps of these pairs. After modelling and subtracting the tSZ effect and X-ray emission for each cluster in the pair, we studied the residuals on both the SZ and X-ray maps. Results. For the merging cluster pair A399-A401 we observe a significant tSZ effect signal in the intercluster region beyond the virial radii of the clusters. A joint X-ray SZ analysis allows us to constrain the temperature and density of this intercluster medium. We obtain a temperature of kT = 7.1 ± 0.9 ? keV (consistent with previous estimates) and a baryon density of (3.7 ± 0.2) × 10-4 ?cm-3. Conclusions. The Planck satellite mission has provided the first SZ detection of the hot and diffuse intercluster gas

SHALOS: Statistical Herschel-ATLAS lensed objects selection

Context. The statistical analysis of large sample of strong lensing events can be a powerful tool to extract astrophysical or cosmological valuable information. Their selection using submillimetre galaxies has been demonstrated to be very effective with more than ∼200 proposed candidates in the case of Herschel-ATLAS data and several tens in the case of the South Pole Telescope. However, the number of confirmed events is still relatively low, i.e. a few tens, mostly because of the lengthy observational validation process on individual events. Aims. In this work we propose a new methodology with a statistical selection approach to increase by a factor of ∼5 the number of such events within the Herschel-ATLAS data set. Although the methodology can be applied to address several selection problems, it has particular benefits in the case of the identification of strongly lensed galaxies: objectivity, minimal initial constrains in the main parameter space, and preservation of statistical properties. Methods. The proposed methodology is based on the Bhattacharyya distance as a measure of the similarity between probability distributions of properties of two different cross-matched galaxies. The particular implementation for the aim of this work is called SHALOS and it combines the information of four different properties of the pair of galaxies: angular separation, luminosity percentile, redshift, and the ratio of the optical to the submillimetre flux densities. Results. The SHALOS method provides a ranked list of strongly lensed galaxies. The number of candidates within ∼340 deg2 of the Herschel-ATLAS surveyed area for the final associated probability, Ptot > 0.7, is 447 and they have an estimated mean amplification factor of 3.12 for a halo with a typical cluster mass. Additional statistical properties of the SHALOS candidates, as the correlation function or the source number counts, are in agreement with previous results indicating the statistical lensing nature of the selected sampleJGN acknowledges financial from the Spanish MINECO for a “Ramon y Cajal” fellowship (RYC2013-13256). DH, FA, and LT acknowledge financial support from the I+D 2015 project AYA2015-64508-P (MINECO, FEDER)