Probing star formation in the dense environments of z ~ 1 lensing haloes aligned with dusty star-forming galaxies detected with the South Pole Telescope

We probe star formation in the environments of massive (∼10^(13) M_⊙) dark matter haloes at redshifts of z ∼ 1. This star formation is linked to a submillimetre clustering signal which we detect in maps of the Planck High Frequency Instrument that are stacked at the positions of a sample of high redshift (z > 2) strongly lensed dusty star-forming galaxies (DSFGs) selected from the South Pole Telescope (SPT) 2500 deg^2 survey. The clustering signal has submillimetre colours which are consistent with the mean redshift of the foreground lensing haloes (z ∼ 1). We report a mean excess of star formation rate (SFR) compared to the field, of (2700 ± 700) M_⊙ yr^(−1) from all galaxies contributing to this clustering signal within a radius of 3.5 arcmin from the SPT DSFGs. The magnitude of the Planck excess is in broad agreement with predictions of a current model of the cosmic infrared background. The model predicts that 80 per cent of the excess emission measured by Planck originates from galaxies lying in the neighbouring haloes of the lensing halo. Using Herschel maps of the same fields, we find a clear excess, relative to the field, of individual sources which contribute to the Planck excess. The mean excess SFR compared to the field is measured to be (370 ± 40) M_⊙ yr^(−1) per resolved, clustered source. Our findings suggest that the environments around these massive z ∼ 1 lensing haloes host intense star formation out to about 2 Mpc. The flux enhancement due to clustering should also be considered when measuring flux densities of galaxies in Planck data

Sous-produits de réaction formés lors de la filtration sur charbon actif de composés phénoliques en présence d'ions chlorite

L'étude des interactions entre les ions chlorite, un charbon actif en grains (CAG CECA 40) et des composés phénoliques (phénol et para-nitrophénol) a été réalisée à partir d'expériences de filtration sur mini-colonnes de CAG de solutions aqueuses de chlorite et du composé organique en mélange ([C102-] inf=50 mg.l-¹; [Composé Organique]jnf=200 µmol.l-¹ ; 3 g de CAG; Vitesse de filtration: 3,7 m.h-¹). Les résultats obtenus ont permis de montrer que la présence de chlorite conduit à une augmentation des capacités du CAG vis-à-vis de l'élimination du phénol et du para-nitrophénol. Cette augmentation résulte de réactions chimiques entre le composé organique et les sous-produits de décomposition des ions chlorite par le charbon actif. Les analyses par couplage CG/SM des extraits issus des charbons actifs à la fin des filtrations ont permis de mettre en évidence la présence de nombreux composés adsorbés sur le charbon actif. Les composés identifiés résultent de réactions d'oxydation, de deshydroxylation, de carboxylation, d'halogénation, d'hydroxylation et de dimérisation. L'action des ions chlorite sur le charbon actif peut conduire à la formation de radicaux à la surface du charbon actif ou en solution capables de réagir avec les composés organiques pour former les sous-produits observés.The use of chlorine dioxide for the chemical preoxidation of potable water with high oxidant demand requires that the major inorganic byproduct, chlorite, in the treatment system be removed, owing to the potential toxicity of this oxychlorine species. Granular Activated Carbon (GAC) filtration, in converting chlorite ions into chloride, appears to be an interesting approach, but very few data are available concerning possible interactions in the presence of organic matter. The present research was designed to examine the influence of phenolic compounds on the efficiency of activated carbon in removing chlorite and to study the reactions between chlorite, activated carbon and organic molecules. Laboratory experiments have been carried out with relatively high substrate concentrations in order to identify the resulting byproducts.Materials and Methods.Filtrations of solutions containing chlorite and a phenolic compound (phenol or para nitrophenol; [Organic Compound]inf=200 µmol.L-¹;[C102-] inf=50 mg L-¹; pH=7.2); were performed using 1- cm i.d. glass columns packed with 3.0 g of GAC CECA 40 (Flow rate: 3.7 m.h-¹). Inorganic species were analysed by HPLC, with an anion column and a conductimetric detector for chloride and chlorate, and with a C-18 column and a UV detector for chlorite. Phenol and para nitrophenol were also analysed by HPLC, in the reverse mode. At the conclusion of the filtrations, the Total Organic Halogen (TOX) adsorbed on the carbon was determined after combustion of the carbon and measurement of the liberated halides with a micro coulometer (Dohrmann DX20). In order to identify organic reaction byproducts, carbon samples were Soxhlet extracted with methylene chloride and half of the extracts were methylated with diazomethane. Identification of the organic products was then carried out by gas chromatography / mass spectrometry with a DB5 capillary column and a quadrupolar hyperbolic filter system CPV/MS.Results and Discussion.Effects of phenol and p nitrophenol on removal of chlorite by GAC. The effluent curves from columns that received solutions containing both chlorite and an organic solute (columns A and B; fig. 1) showed that the presence of phenol or p nitrophenol in the influent decreases the capacity of GAC to remove chlorite.Effect of chlorite on removal of phenol and p nitrophenol. An increase in the cumulative removal of the organic solute was observed for columns A and B compared with columns that received solutions of the phenolic compound only (fig. 2; table 11). p benzoquinone was found in the eff1uent of column A fed with a chlorite phenol solution (fig. 3).Formation of organic byproducts by reactions between chlorite and phenol or p nitrophenol in the presence of GAC. TOX analyses showed that interactions between chlorite, GAC, and phenol or p nitrophenol led to the production of organohalogenated compounds. These data clearly demonstrate that halogenation reactions take place in the GAC bed and that a fraction of the total amount of phenol or p nitrophenol removed can be due to chemical reactions. GC/MS analyses of GAC extracts of columns A and B (tables IV and V) indicated that the phenol chlorite GAC reactions yield a variety of organic byproducts that are produced by hydroxylation and carboxylation of the aromatic ring by oxidation to quinones, by chlorine substitution and by dehydroxylation and dimerization reactions. Fewer products could be identified in the reaction between p nitrophenol, chlorite, and GAC. Since chlorite is unreactive with phenol and p nitrophenol in neutral aqueous solution, the formation of these organic byproducts can be attributed to reactions between phenol or p nitrophenol present in the GAC pore solution or adsorbed on GAC and the chemical species (Cl· ClO·, ClO2, HOCl (ClO-), surface free radicals ...) generated from the reaction of chlorite and carbon. Thus, aromatic acids could come from radical processes between adsorbed molecules and carbon surface functional groups oxidized by chlorite. The formation of dimers can also be explained by a freeradical mechanism. The reactions between Cl·, ClO· radicals or radicals present on the GAC surface, with organic compounds produce organic radicals via H atom abstraction or one electron transfer. Organic radicals such as phenoxy radicals or other aromatic radicals can then undergo dimerization by carbon-oxygen or carbon-carbon coupling. The formation of organochlorinated compounds can be explained by the reaction of chlorine (HOCl, ClO-) and chlorine radicals with organic molecules present in the solution. However further investigation is needed in order to evaluate if such compounds can be formed on GAC filters and then desorbed in the effluent in thc case of drinking waters pretreated with chlorine dioxide

Planck intermediate results. L. Evidence of spatial variation of the polarized thermal dust spectral energy distribution and implications for CMB B-mode analysis

The characterization of the Galactic foregrounds has been shown to be the main obstacle in thechallenging quest to detect primordial B-modes in the polarized microwave sky. We make use of the Planck-HFI 2015 data release at high frequencies to place new constraints on the properties of the polarized thermal dust emission at high Galactic latitudes. Here, we specifically study the spatial variability of the dust polarized spectral energy distribution (SED), and its potential impact on the determination of the tensor-to-scalar ratio, r. We use the correlation ratio of the C^(BB)_ℓ angular power spectra between the 217 and 353 GHz channels as a tracer of these potential variations, computed on different high Galactic latitude regions, ranging from 80% to 20% of the sky. The new insight from Planck data is a departure of the correlation ratio from unity that cannot be attributed to a spurious decorrelation due to the cosmic microwave background, instrumental noise, or instrumental systematics. The effect is marginally detected on each region, but the statistical combination of all the regions gives more than 99% confidence for this variation in polarized dust properties. In addition, we show that the decorrelation increases when there is a decrease in the mean column density of the region of the sky being considered, and we propose a simple power-law empirical model for this dependence, which matches what is seen in the Planck data. We explore the effect that this measured decorrelation has on simulations of the BICEP2-Keck Array/Planck analysis and show that the 2015 constraints from these data still allow a decorrelation between the dust at 150 and 353 GHz that is compatible with our measured value. Finally, using simplified models, we show that either spatial variation of the dust SED or of the dust polarization angle are able to produce decorrelations between 217 and 353 GHz data similar to the values we observe in the data

Planck intermediate results. XLVIII. Disentangling Galactic dust emission and cosmic infrared background anisotropies

Using the Planck 2015 data release (PR2) temperature maps, we separate Galactic thermal dust emission from cosmic infrared background (CIB) anisotropies. For this purpose, we implement a specifically tailored component-separation method, the so-called generalized needlet internal linear combination (GNILC) method, which uses spatial information (the angular powerspectra) to disentangle the Galactic dust emission and CIB anisotropies. We produce significantly improved all-sky maps of Planck thermal dust emission, with reduced CIB contamination, at 353, 545, and 857 GHz. By reducing the CIB contamination of the thermal dust maps, we provide more accurate estimates of the local dust temperature and dust spectral index over the sky with reduced dispersion, especially at high Galactic latitudes above b = ±20°. We find that the dust temperature is T = (19.4 ± 1.3) K and the dust spectral index is β = 1.6 ± 0.1 averaged over the whole sky, while T = (19.4 ± 1.5) K and β = 1.6 ± 0.2 on 21% of the sky at high latitudes. Moreover, subtracting the new CIB-removed thermal dust maps from the CMB-removed Planck maps gives access to the CIB anisotropies over 60% of the sky at Galactic latitudes |b| > 20°. Because they are a significant improvement over previous Planck products, the GNILC maps are recommended for thermal dust science. The new CIB maps can be regarded as indirect tracers of the dark matter and they are recommended for exploring cross-correlations with lensing and large-scale structure optical surveys. The reconstructed GNILC thermal dust and CIB maps are delivered as Planck products