Measuring time delays between the multiple images of gravitationally lensed quasars is now recognized as a competitive way to constrain the cosmological parameters, and it is complementary with other ...cosmological probes. This requires long and well sampled optical light curves of numerous lensed quasars, such as those obtained by the COSMOGRAIL collaboration. High-quality data from our monitoring campaign call for novel numerical techniques to robustly measure the delays, as well as the associated random and systematic uncertainties, even in the presence of microlensing variations. We propose three different point estimators to measure time delays, which are explicitly designed to handle light curves with extrinsic variability. These methods share a common formalism, which enables them to process data from n-image lenses. Since the estimators rely on significantly contrasting ideas, we expect them to be sensitive to different bias sources. For each method and data set, we empirically estimate both the precision and accuracy (bias) of the time delay measurement using simulated light curves with known time delays that closely mimic the observations. Finally, we test the self-consistency of our approach, and we demonstrate that our bias estimation is serviceable. These new methods, including the empirical uncertainty estimator, will represent the standard benchmark for analyzing the COSMOGRAIL light curves.
We present a tomographic cosmic shear analysis of the Kilo-Degree Survey (KiDS) combined with the VISTA Kilo-Degree Infrared Galaxy Survey. This is the first time that a full optical to near-infrared ...data set has been used for a wide-field cosmological weak lensing experiment. This unprecedented data, spanning 450 deg
2
, allows us to significantly improve the estimation of photometric redshifts, such that we are able to include robustly higher-redshift sources for the lensing measurement, and – most importantly – to solidify our knowledge of the redshift distributions of the sources. Based on a flat ΛCDM model we find
S
8
≡ σ
8
Ω
m
/0.3 = 0.737
+0.040
−0.036
in a blind analysis from cosmic shear alone. The tension between KiDS cosmic shear and the Planck-Legacy CMB measurements remains in this systematically more robust analysis, with
S
8
differing by 2.3
σ
. This result is insensitive to changes in the priors on nuisance parameters for intrinsic alignment, baryon feedback, and neutrino mass. KiDS shear measurements are calibrated with a new, more realistic set of image simulations and no significant B-modes are detected in the survey, indicating that systematic errors are under control. When calibrating our redshift distributions by assuming the 30-band COSMOS-2015 photometric redshifts are correct (following the Dark Energy Survey and the Hyper Suprime-Cam Survey), we find the tension with
Planck
is alleviated. The robust determination of source redshift distributions remains one of the most challenging aspects for future cosmic shear surveys.
We present a new measurement of the Hubble Constant H sub( 0) and other cosmological parameters based on the joint analysis of three multiply imaged quasar systems with measured gravitational time ...delays. First, we measure the time delay of HE 0435-1223 from 13-yr light curves obtained as part of the COSMOGRAIL project. Companion papers detail the modelling of the main deflectors and line-of-sight effects, and how these data are combined to determine the time-delay distance of HE 0435-1223. Crucially, the measurements are carried out blindly with respect to cosmological parameters in order to avoid confirmation bias. We then combine the time-delay distance of HE 0435-1223 with previous measurements from systems B1608+656 and RXJ1131-1231 to create a Time Delay Strong Lensing probe (TDSL). In flat Lambda cold dark matter ( Lambda CDM) with free matter and energy density, we find H sub( 0) =71.9... km s super( -1) Mpc super( -1) and Omega sub( Lambda )=0.62... This measurement is completely independent of, and in agreement with, the local distance ladder measurements of H sub( 0). We explore more general cosmological models combining TDSL with other probes, illustrating its power to break degeneracies inherent to other methods. The joint constraints from TDSL and Planck are H sub( 0) = 69.2... km s super( -1) Mpc super( -1) , Omega sub( Lambda )=0.70... and Omega sub( k)=0.003+0.004-0.006 in open ...CDM and H sub( 0) =79.0... km s super( -1) Mpc super( -1), Omega sub( de)=0.77... and w=-1.38... in flat wCDM. In combination with Planck and baryon acoustic oscillation data, when relaxing the constraints on the numbers of relativistic species we find N sub( eff) = 3.34... in N sub( eff) Lambda CDM and when relaxing the total mass of neutrinos we find ...m sub( ...) less than or equal to ...0.182 eV in m sub( nu )...CDM. Finally, in an open wCDM in combination with Planck and cosmic microwave background lensing, we find H sub( 0) =77.9... km s super( -1) Mpc super( -1), Omega sub( de) = 0.77..., Omega sub( k) = -0.003... and w=-1.37... (ProQuest: ... denotes formulae/symbols omitted.)
Context. The Kilo-Degree Survey (KiDS) is an ongoing optical wide-field imaging survey with the OmegaCAM camera at the VLT Survey Telescope, specifically designed for measuring weak gravitational ...lensing by galaxies and large-scale structure. When completed it will consist of 1350 square degrees imaged in four filters (ugri). Aims. Here we present the fourth public data release which more than doubles the area of sky covered by data release 3. We also include aperture-matched ZYJHKs photometry from our partner VIKING survey on the VISTA telescope in the photometry catalogue. We illustrate the data quality and describe the catalogue content. Methods. Two dedicated pipelines are used for the production of the optical data. The ASTRO-WISE information system is used for the production of co-added images in the four survey bands, while a separate reduction of the r-band images using the THELI pipeline is used to provide a source catalogue suitable for the core weak lensing science case. All data have been re-reduced for this data release using the latest versions of the pipelines. The VIKING photometry is obtained as forced photometry on the THELI sources, using a re-reduction of the VIKING data that starts from the VISTA pawprints. Modifications to the pipelines with respect to earlier releases are described in detail. The photometry is calibrated to the Gaia DR2 G band using stellar locus regression. Results. In this data release a total of 1006 square-degree survey tiles with stacked ugri images are made available, accompanied by weight maps, masks, and single-band source lists. We also provide a multi-band catalogue based on r-band detections, including homogenized photometry and photometric redshifts, for the whole dataset. Mean limiting magnitudes (5σ in a 2″ aperture) and the tile-to-tile rms scatter are 24.23 ± 0.12, 25.12 ± 0.14, 25.02 ± 0.13, 23.68 ± 0.27 in ugri, respectively, and the mean r-band seeing is 0.″70.
COSMOGRAIL is a long-term photometric monitoring of gravitationally lensed quasars aimed at implementing Refsdal's time-delay method to measure cosmological parameters, in particular H sub(0). Given ...the long and well sampled light curves of strongly lensed quasars, time-delay measurements require numerical techniques whose quality must be assessed. To this end, and also in view of future monitoring programs or surveys such as the LSST, a blind signal processing competition named Time Delay Challenge 1 (TDC1) was held in 2014. The aim of the present paper, which is based on the simulated light curves from the TDC1, is double. First, we test the performance of the time-delay measurement techniques currently used in COSMOGRAIL. Second, we analyse the quantity and quality of the harvest of time delays obtained from the TDC1 simulations. To achieve these goals, we first discover time delays through a careful inspection of the light curves via a dedicated visual interface. Our measurement algorithms can then be applied to the data in an automated way. We show that our techniques have no significant biases, and yield adequate uncertainty estimates resulting in reduced chi super(2) values between 0.5 and 1.0. We provide estimates for the number and precision of time-delay measurements that can be expected from future time-delay monitoring campaigns as a function of the photometric signal-to-noise ratio and of the true time delay. We make our blind measurements on the TDC1 data publicly available.
In order to counteract fatigue, physical activity (PA) is recommended for all stages of cancer. However, only few advanced cancer patients (ACP) are physically active. Quantitative data with high ...numbers of ACP reporting barriers to PA are missing. This study aimed to identify barriers to PA in ACP with tiredness/weakness and investigate their motivation towards it.
Outpatients with metastatic cancer receiving cancer care at a German Cancer Center reporting moderate/severe tiredness/weakness during self-assessment (MIDOS II) were enrolled. We assessed Fatigue-(FACF-F) and Depression (PHQ8) Scores, demographics, cancer-specific parameters, motivation for PA, physical, psychological and social barriers.
141 of 440 eligible patients (32.0%) with different diagnoses agreed to participate. Patients frequently reported "I feel weakened due to my tumor therapy" (n = 108; 76.6%), physical symptoms (tiredness, weakness, dyspnea, joint-problems, pain, nausea n = 107; 75.9%) and fatigue (n = 99; 70.2%) as barriers to PA. However, no significant group differences regarding these barriers were found between physically active and inactive patients. Social barriers were rarely chosen. Motivated patients were 5.6 times more likely to be physically active (p < 0.001), also motivation turned out to be the strongest predictor for a physically active behavior (β = 1.044; p = 0.005). Motivated attitude towards PA was predicted by fatigue (β = - 2.301; p = 0.008), clinically relevant depression (β = - 1.390, p = 0.039), knowledge about PA and quality of life (QoL) (β = 0.929; p = 0.002), PA before diagnosis (β = 0.688; p = 0.005 and Interest in exercise program (β = 0.635; p = 0.008).
"I feel weakened due to my tumor therapy" is the most reported barrier to PA among both, physically and inactive patients. Motivation for PA is the strongest predictor of performing PA. Interest in PA, knowledge about PA/QoL and PA before diagnosis are main predictors of a motivated attitude. Absence/presence of social barriers did not associate with motivation, fatigue and depression proved to be a negative predictor. Programs including information, motivational counseling and individualized training should be offered for ACP to overcome barriers and reduce fatigue.
German Register of Clinical Trials DRKS00012514, registration date: 30.5.2017.
Strong gravitational lenses with measured time delays between the multiple images and models of the lens mass distribution allow a one-step determination of the time-delay distance, and thus a ...measure of cosmological parameters. We present a blind analysis of the gravitational lens RXJ1131-1231 incorporating (1) the newly measured time delays from COSMOGRAIL, the COSmological MOnitoring of GRAvItational Lenses, (2) archival Hubble Space Telescope imaging of the lens system, (3) a new velocity-dispersion measurement of the lens galaxy of 323 + or- 20 km ssup -1 based on Keck spectroscopy, and (4) a characterization of the line-of-sight structures via observations of the lens' environment and ray tracing through the Millennium Simulation. The joint analysis of the data sets allows a time-delay distance measurement to 6% precision that takes into account all known systematic uncertainties. Our measurement of the Hubble constant is completely independent of those based on the local distance ladder method, providing an important consistency check of the standard cosmological model and of general relativity.
Abstract
Galaxies located in the environment or along the line of sight towards gravitational lenses can significantly affect lensing observables, and can lead to systematic errors on the measurement ...of H
0 from the time-delay technique. We present the results of a systematic spectroscopic identification of the galaxies in the field of view of the lensed quasar HE 0435−1223 using the W. M. Keck, Gemini and ESO-Very Large telescopes. Our new catalogue triples the number of known galaxy redshifts in the direct vicinity of the lens, expanding to 102 the number of measured redshifts for galaxies separated by less than 3 arcmin from the lens. We complement our catalogue with literature data to gather redshifts up to 15 arcmin from the lens, and search for galaxy groups or clusters projected towards HE 0435−1223. We confirm that the lens is a member of a small group that includes at least 12 galaxies, and find 8 other group candidates near the line of sight of the lens. The flexion shift, namely the shift of lensed images produced by high-order perturbation of the lens potential, is calculated for each galaxy/group and used to identify which objects produce the largest perturbation of the lens potential. This analysis demonstrates that (i) at most three of the five brightest galaxies projected within 12 arcsec of the lens need to be explicitly used in the lens models, and (ii) the groups can be treated in the lens model as an external tidal field (shear) contribution.
Information on the spectral types of stars is of great interest in view of the exploitation of space-based imaging surveys. In this article, we investigate the classification of stars into spectral ...types using only the shape of their diffraction pattern in a single broad-band image. We propose a supervised machine learning approach to this endeavour, based on principal component analysis (PCA) for dimensionality reduction, followed by artificial neural networks (ANNs) estimating the spectral type. Our analysis is performed with image simulations mimicking the Hubble Space Telescope (HST) Advanced Camera for Surveys (ACS) in the F606W and F814W bands, as well as the Euclid VIS imager. We first demonstrate this classification in a simple context, assuming perfect knowledge of the point spread function (PSF) model and the possibility of accurately generating mock training data for the machine learning. We then analyse its performance in a fully data-driven situation, in which the training would be performed with a limited subset of bright stars from a survey, and an unknown PSF with spatial variations across the detector. We use simulations of main-sequence stars with flat distributions in spectral type and in signal-to-noise ratio, and classify these stars into 13 spectral subclasses, from O5 to M5. Under these conditions, the algorithm achieves a high success rate both for Euclid and HST images, with typical errors of half a spectral class. Although more detailed simulations would be needed to assess the performance of the algorithm on a specific survey, this shows that stellar classification from single-band images is well possible.
PDF
