Compact source detection in multi-channel microwave surveys: from SZ clusters to polarized sources

In this paper we describe the state-of-the art status of multi-frequency detection techniques for compact sources in microwave astronomy. From the simplest cases where the spectral behaviour is well-known (i.e. thermal SZ clusters) to the more complex cases where there is little a priori information (i.e. polarized radio sources) we will review the main advances and the most recent results in the detection problem.Comment: 13 pages, 4 figures. Accepted for publication in the Special Issue "Astrophysical Foregrounds in Microwave Surveys" of the journal Advances in Astronom

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

A sparse approach to astronomical point source detection

In this work we introduce a method for the detection of point sources in images based on al l1-norm sparse approximation. The method is inspired on astronomical image analysis but is directly applicable to any kind of images. We introduce a "top-to-bottom" detection algorithm that can greatly reduce the computational burden of detection if the images are sufficiently well-behaved, in the sense that sources are truly sparse and the chances of source overlapping are small. We test our ideas with simulated faint sources embedded in white noise, comparing the results with the matched filter detector for a number of detection thresholds. We show that the sparse detection approach leads to better results in the ROC curve than the matched filter detector. Moreover, with the sparse approach it is possible to provide an objective stopping criterion for the detection algorithm.The authors acknowledge partial financial support from the Spanish Ministry of Education (MEC) under project ESP2004-07067-C03-01 and from the joint CNR-CSIC research project 2008IT0059. MLC acknowledges an EGEE-III postdoctoral contract at IFCA

Planck 2018 results: II. low frequency Instrument data processing

We present a final description of the data-processing pipeline for the Planck Low Frequency Instrument (LFI), implemented for the 2018 data release. Several improvements have been made with respect to the previous release, especially in the calibration process and in the correction of instrumental features such as the effects of nonlinearity in the response of the analogue-to-digital converters. We provide a brief pedagogical introduction to the complete pipeline, as well as a detailed description of the important changes implemented. Self-consistency of the pipeline is demonstrated using dedicated simulations and null tests. We present the final version of the LFI full sky maps at 30, 44, and 70 GHz, both in temperature and polarization, together with a refined estimate of the solar dipole and a final assessment of the main LFI instrumental parameter

Corneal densitometry after photorefractive keratectomy, laser- assisted in situ keratomileusis, and small-incision lenticule extraction

Purpose: The aim of this study was to gain greater insight into the corneal densitometry changes occurring as a result of refractive surgery and to compare these changes across three widely used surgical techniques, namely, photorefractive keratectomy (PRK), laser-assisted in situ keratomileusis with a femtosecond laser (LASIK-FS), or ReLEx small-incision lenticule extraction (ReLEx SMILE). Patients and methods: Three hundred and thirty-six patients (184 male and 152 female patients) participated in this study. They were split into three groups according to the refractive surgery technique they had undergone: LASIK-FS (74 patients), PRK (153 patients), and ReLEx SMILE (109 patients). All participants underwent an exhaustive eye examination both before and after surgery. Pre- and postoperative corneal densitometry was measured using an Oculus Pentacam system. Results: The mean postoperative total corneal densitometry values were 16.53 ± 1.94 for the LASIK- FS group, 15.53 ± 1.65 for PRK, and 16.10 ± 1.54 for ReLEx SMILE. When corneal densitometry was analyzed for specific corneal areas, the values corresponding to the 0–2, 2–6, and 6–10 mm annuli were similar across the three surgical techniques. The only region in which differences were found was the peripheral area (Po0.05), but these variations across techniques were not statistically significant. Conclusions: Corneal densitometry can be used as an objective metric to assess corneal response to refractive surgery, and to monitor patients over time. Corneal densitometry was not negatively affected by any of the refractive surgical procedures under evaluation

Lupinus mariae-josphi, a new lupin endemic of soils with active lime and high pH in South Eastern Spain, is nodulated by a new bacterial lineage within Bradyrhizobium genus

Lupinus mariae-josephi is a recently described species (Pascual, 2004) able to grow in soils with high pH and active lime content in the Valencia province (Spain). L. mariae-josephi endosymbionts are extremely slowgrowing bacteria with genetic and symbiotic characteristics that differentiate them from Bradyrhizobium strains nodulating Lupinus spp. native of the Iberian Peninsula and adapted to grow in acid soils. Cross-inoculation experiments revealed that all the endosymbiotic isolates from L. mariae-josephi tested are legume-host selective and are unable to nodulate species such as L. angustifolius, and L. luteus. In contrast, Bradyrhizobium strains from Lupinus spp. tested were able to nodulate L. mariae-josephi, although the nodules fixed nitrogen inefficiently. Phylogenetic analysis was performed with housekeeping genes (rrn, glnII, recA, atpD) and nodulation gene nodC. Housekeeping gene phylogeny revealed that L. mariae-josephi rhizobia form a strongly supported monophyletic group within Bradyrhizobium genus. This cluster also includes B. jicamae and certain strains of B. elkanii. Contrarily, isolates from other Lupinus spp. native of the Iberian Peninsula were grouped mainly within B. canariense and two B. japonicum lineages. Phylogenetic analysis of L. mariae-josephi isolates based on the nodC symbiotic gene defined a solid clade close to isolates from Algerian Retama spp. and to fast-growing rhizobia

Taxonomy of endosymbiotic bacteria from a novel Lupinus sp. (Lupinus mariae-josephi) endemic of a limed-alkaline soil habitat in Southeastern Spain

Lupinus mariae-josephi is a recently described Lupinus species (Pascual 2004) endemic of a Southeastern area of Spain with soils singularly of high pH and active lime content where it is endangered due to the reduced size of its habitat. Ten isolates of L. mariae-josephi endosymbiotic bacteria were obtained using trap-plants and soils from five sampling points within a native plant population area in Llombai (Valencia, Spain). The microsymbionts are extra-slow (ultrabradytrophic) growing bacteria with phenotypic and symbiotic characteristics singularly different from Bradyrhizobium strains nodulating other Lupinus spp. thriving in the Iberian Peninsula and adapted to growth in acidic soils. Cross-inoculation experiments revealed that these L. mariae-josephi endosymbiotic bacteria isolates are unable to nodulate or efficiently fix nitrogen with other Lupinus spp. Their phylogenetic status was examined by a multilocus sequence analysis of four housekeeping genes (16S rDNA, glnII, recA, atpD) and the symbiotic nodC gene. The 16S rDNA phylogenetic analysis showed that L. mariae-josephi isolates are related to strains nodulating Retama spp. in northeastern Algeria (Boulila et al., 2009), Phaseolus lunatus from Peru (Ormeño-Orrillo et al., 2006), as well as to B. elkanii, B. jicamae and B. pachyrhizi species, forming a new clade (Clade I) within the Bradyrhizobium genus. All the single and concatenated glnII+recA and glnII+recA+atpD analyses consistently support the existence of Clade I, and also revealed that, within this clade, the L. mariae-josephi endosymbiotic bacteria belong to a single evolutionary lineage that also includes strains nodulating Retama spp. from northeastern Algeria. Within this new Bradyrhizobium lineage, the phylogenetic analyses performed showed essentially convergent results indicating that the tested L. mariae-josephi isolates nested in three sub-groups that might correspond to novel sister Bradyrhizobium species. Bradyrhizobium Clade I is highly differentiated from the Bradyrhizobium clade (Clade II) that includes currently named Bradyrhizobium species and well-delineated unnamed genospecies. Singularly, all the endosymbiotic bacteria from Lupinus species adapted to acid soils in the Iberian Peninsula and tested in this study are included in Clade II. They are related either to strains of the B. canariense or B. japonicum lineages. The phylogenetic analysis based on the symbiotic nodC gene showed that L. mariae-josephi endosymbiotic bacteria define a novel branch in the nodC Bradyrhizobium tree. This branch groups together with a branch that gathers isolates from recently studied legume symbiosis such as isolates from Retama spp., which suggests the existence of a common unique ancestor for the symbiotic genes of these two groups of bradyrhizobia. In contrast, the symbiotic genes of isolates from other Lupinus spp. from the Iberian Peninsula are clearly related to the B. canariense lineage. The allopatric (geographic) speciation of the L. mariae-josephi bradyrhizobia may result from the colonization of a singular habitat, such as the basic and high calcium carbonate soils of the Valencia area, by its unique legume host

Endosymbiotic bacteria nodulating a new endemic lupine Lupinus mariae-josephi from alkaline soils in Eastern Spain represent a new lineage within the Bradyrhizobium genus

Lupinus mariae-josephi is a recently described endemic Lupinus species from a small area in Eastern Spain where it thrives in soils with active lime and high pH. The L. mariae-josephi root symbionts were shown to be very slow-growing bacteria with different phenotypic and symbiotic characteristics from those of Bradyrhizobium strains nodulating other Lupinus. Their phylogenetic status was examined by multilocus sequence analyses of four housekeeping genes (16S rRNA, glnII, recA, and atpD) and showed the existence of a distinct evolutionary lineage for L. mariae-josephi that also included Bradyrhizobium jicamae. Within this lineage, the tested isolates clustered in three different sub-groups that might correspond to novel sister Bradyrhizobium species. These core gene analyses consistently showed that all the endosymbiotic bacteria isolated from other Lupinus species of the Iberian Peninsula were related to strains of the B. canariense or B. japonicum lineages and were separate from the L. mariae-josephi isolates. Phylogenetic analysis based on nodC symbiotic gene sequences showed that L. mariae-josephi bacteria also constituted a new symbiotic lineage distant from those previously defined in the genus Bradyrhizobium. In contrast, the nodC genes of isolates from other Lupinus spp. from the Iberian Peninsula were again clearly related to the B. canariense and B. japonicum bv. genistearum lineages. Speciation of L. mariae-josephi bradyrhizobia may result from the colonization of a singular habitat by their unique legume host