Gravitational lensing analysis of the Kilo-Degree Survey

The Kilo-Degree Survey (KiDS) is a multi-band imaging survey designed for cosmological studies from weak lensing and photometric redshifts. It uses the European Southern Observatory VLT Survey Telescope with its wide-field camera OmegaCAM. KiDS images are taken in four filters similar to the Sloan Digital Sky Survey ugri bands. The best seeing time is reserved for deep r-band observations. The median 5σ limiting AB magnitude is 24.9 and the median seeing is below 0.7 arcsec. Initial KiDS observations have concentrated on the Galaxy and Mass Assembly (GAMA) regions near the celestial equator, where extensive, highly complete redshift catalogues are available. A total of 109 survey tiles, 1 square degree each, form the basis of the first set of lensing analyses of halo properties of GAMA galaxies. Nine galaxies per square arcminute enter the lensing analysis, for an effective inverse shear variance of 69 arcmin−2. Accounting for the shape measurement weight, the median redshift of the sources is 0.53. KiDS data processing follows two parallel tracks, one optimized for weak lensing measurement and one for accurate matched-aperture photometry (for photometric redshifts). This technical paper describes the lensing and photometric redshift measurements (including a detailed description of the Gaussian aperture and photometry pipeline), summarizes the data quality and presents extensive tests for systematic errors that might affect the lensing analyses. We also provide first demonstrations of the suitability of the data for cosmological measurements, and describe our blinding procedure for preventing confirmation bias in the scientific analyses. The KiDS catalogues presented in this paper are released to the community through http://kids.strw.leidenuniv.nl

Abstract P5-15-06: Evaluation of Treatment of Primary Early Breast Cancer in the Elderly

Abstract Background: National guidelines for treatment of breast cancer are not applicable for the frail elderly. Treatment should be individualized for these patients. Aim: Evaluation of treatment of the elderly (aged 70+) patient with primary early breast cancer: breast conservative surgery (BCS), guideline adherence and differences in (all cause and cancer specific) mortality risk and survival. Materials and Methods: female patients with stage cT1-2N0-1 primary breast cancer, diagnosed from January 2002 - December 2008 were included in this retrospective analysis. Treatment was compared with national guidelines. Age categories were made for 80-plus, 70 to 80 and 70-minus. Differences in tumor biology and treatment were evaluated using X2- tests, differences in Hazard ratio using Cox-regression analysis and differences in survival using Kaplan-Meier analysis. Results: 1569 patients were included. Divided by age: 80 and up (n=148), 70 to 80 (n=256), 70 and below (n=1165). Median time of follow-up was 48 (1-99) months. Tumor characteristics: there was no significant differences between patients aged 70 and up and below 70 for ER/PR status, Her2neu status, tumor grade and pathologic tumor size. There were significant differences for axillary lymph node involvement (pN0: 66,6% vs 56,6%, p=0,004) and tumor morphology (68,0% vs 77,8% ductal carcinoma, P&amp;lt;0,001). Comparison of treatment: 80+ vs 70-80 vs 70-, BCS: 29,6% vs 57,9% vs 55,7% (P&amp;lt;0,001 for 80+ vs 70-80), treatment according to guidelines: 38,9% vs 81,3% vs 93,3% (P&amp;lt;0,001 for 80+ vs 70-80 vs 70-), surgical treatment: 54,3% vs 96,1% vs 99,5% (P&amp;lt;0,001 for 80+ vs 70-80 vs 70-), radiotherapy following BCS: 56,5% vs 96,3% vs 98,4% (P&amp;lt;0,001 for 80+ vs 70-80), adjuvant systemic therapy when indicated: 73,2% vs 68,9% vs 90,1% (P&amp;lt;0,001 for 70-80 vs 70-). Hazard Ratio for mortality: ages 80 and up: individualized vs guideline-adhered all cause HR = 1,903 (P&amp;lt;0,001). Cancer specific HR = 0,601 (p = 0,431). Ages 70-80: individualized vs guideline-adhered HR = 3,184 (p &amp;lt;0,001). Cancer specific HR = 2,842 (p = 0,083). 5-year all-cause survival: ages 70 and up vs 70-: 64% vs 91%, log rank P&amp;lt;0,001 (fig.1). 5-year cancer specific survival: ages 70 and up vs 70-: 91% vs 94%, log rank p = 0,064 (fig.2). Conclusion: Individualized treatment was frequent in elderly breast cancer patients, especially in patients aged 80 and up. While overall survival was significantly lower for septuagenarians, there was no significant difference in cancer specific mortality and survival. Figures available in online version. Citation Information: Cancer Res 2010;70(24 Suppl):Abstract nr P5-15-06.</jats:p

KiDS-450: cosmological parameter constraints from tomographic weak gravitational lensing

We present cosmological parameter constraints from a tomographic weak gravitational lensing analysis of ∼450 deg2 of imaging data from the Kilo Degree Survey (KiDS). For a flat Λ cold dark matter (ΛCDM) cosmology with a prior on H0 that encompasses the most recent direct measurements, we find S8≡σ8Ωm/0.3−−−−−−√=0.745±0.039⁠. This result is in good agreement with other low-redshift probes of large-scale structure, including recent cosmic shear results, along with pre-Planck cosmic microwave background constraints. A 2.3σ tension in S8 and ‘substantial discordance’ in the full parameter space is found with respect to the Planck 2015 results. We use shear measurements for nearly 15 million galaxies, determined with a new improved ‘self-calibrating’ version of lensFIT validated using an extensive suite of image simulations. Four-band ugri photometric redshifts are calibrated directly with deep spectroscopic surveys. The redshift calibration is confirmed using two independent techniques based on angular cross-correlations and the properties of the photometric redshift probability distributions. Our covariance matrix is determined using an analytical approach, verified numerically with large mock galaxy catalogues. We account for uncertainties in the modelling of intrinsic galaxy alignments and the impact of baryon feedback on the shape of the non-linear matter power spectrum, in addition to the small residual uncertainties in the shear and redshift calibration. The cosmology analysis was performed blind. Our high-level data products, including shear correlation functions, covariance matrices, redshift distributions, and Monte Carlo Markov chains are available at http://kids.strw.leidenuniv.nl

The third data release of the Kilo-Degree Survey and associated data products

Context The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope. It aims to image 1500 square degrees in four filters (ugri). The core science driver is mapping the large-scale matter distribution in the Universe, using weak lensing shear and photometric redshift measurements. Further science cases include galaxy evolution, Milky Way structure, detection of high-redshift clusters, and finding rare sources such as strong lenses and quasars. Aims Here we present the third public data release and several associated data products, adding further area, homogenized photometric calibration, photometric redshifts and weak lensing shear measurements to the first two releases. Methods A dedicated pipeline embedded in the Astro-WISE information system is used for the production of the main release. Modifications with respect to earlier releases are described in detail. Photometric redshifts have been derived using both Bayesian template fitting, and machine-learning techniques. For the weak lensing measurements, optimized procedures based on the THELI data reduction and lensfit shear measurement packages are used. Results In this third data release an additional 292 new survey tiles (≈ 300 deg2) stacked ugri images are made available, accompanied by weight maps, masks, and source lists. The multi-band catalogue, including homogenized photometry and photometric redshifts, covers the combined DR1, DR2 and DR3 footprint of 440 survey tiles (447 deg2). Limiting magnitudes are typically 24.3, 25.1, 24.9, 23.8 (5σ in a 200aperture) in ugri, respectively, and the typical r-band PSF size is less than 0.700. The photometric homogenization scheme ensures accurate colors and an absolute calibration stable to ≈ 2% for gri and ≈ 3% in u. Separately released for the combined area of all KiDS releases to date are a weak lensing shear catalogue and photometric redshifts based on two different machine-learning techniques.</p