Publications (132)518.2 Total impact
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ABSTRACT: Applying a transformation to a nonGaussian field can enhance the information content of the resulting power spectrum, by reducing the correlations between Fourier modes. In the context of weak gravitational lensing, it has been shown that this gain in information content is significantly compromised by the presence of shape noise. We apply clipping to mock convergence fields, a technique which is known to be robust in the presence of noise and has been successfully applied to galaxy number density fields. When analysed in isolation the resulting convergence power spectrum returns degraded constraints on cosmological parameters. However substantial gains can be achieved by performing a combined analysis of the power spectra derived from both the original and transformed fields. Even in the presence of realistic levels of shape noise, we demonstrate that this approach is capable of reducing the area of likelihood contours within the $\Omega_m  \sigma_8$ plane by more than a factor of three.  [Show abstract] [Hide abstract]
ABSTRACT: We present weak lensing constraints on the ellipticity of galaxyscale matter haloes and the galaxyhalo misalignment. Using data from the CanadaFranceHawaii Telescope Lensing Survey (CFHTLenS), we measure the weightedaverage ratio of the aligned projected ellipticity components of galaxy matter haloes and their embedded galaxies, $f_\mathrm{h}$, split by galaxy type. We then compare our observations to measurements taken from the Millennium Simulation, assuming different models of galaxyhalo misalignment. Using the Millennium Simulation we verify that the statistical estimator used removes contamination from cosmic shear. We also detect an additional signal in the simulation, which we interpret as the impact of intrinsic shapeshear alignments between the lenses and their largescale structure environment. These alignments are likely to have caused some of the previous observational constraints on $f_\mathrm{h}$ to be biased high. From CFHTLenS we find $f_\mathrm{h}=0.04 \pm 0.25$ for earlytype galaxies, which is consistent with current models for the galaxyhalo misalignment predicting $f_\mathrm{h}\simeq 0.20$. For latetype galaxies we measure $f_\mathrm{h}=0.69_{0.36}^{+0.37}$ from CFHTLenS. This can be compared to the simulated results which yield $f_\mathrm{h}\simeq 0.02$ for misaligned latetype models.Monthly Notices of the Royal Astronomical Society 07/2015; 454(2). DOI:10.1093/mnras/stv2053 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The unknown nature of dark energy motivates continued cosmological tests of largescale gravitational physics. We present a new consistency check based on the relative amplitude of nonrelativistic galaxy peculiar motions, measured via redshiftspace distortion, and the relativistic deflection of light by those same galaxies traced by galaxygalaxy lensing. We take advantage of the latest generation of deep, overlapping imaging and spectroscopic datasets, combining the Red Cluster Sequence Lensing Survey (RCSLenS), the CanadaFranceHawaii Telescope Lensing Survey (CFHTLenS), the WiggleZ Dark Energy Survey and the Baryon Oscillation Spectroscopic Survey (BOSS). We quantify the results using the "gravitational slip" statistic E_G, which we estimate as 0.48 +/ 0.10 at z=0.32 and 0.30 +/ 0.07 at z=0.57, the latter constituting the highest redshift at which this quantity has been determined. These measurements are consistent with the predictions of General Relativity, for a perturbed FriedmannRobertsonWalker metric in a Universe dominated by a cosmological constant, which are E_G = 0.41 and 0.36 at these respective redshifts. The combination of redshiftspace distortion and gravitational lensing data from current and future galaxy surveys will offer increasingly stringent tests of fundamental cosmology. 
Article: The masses of satellites in GAMA galaxy groups from 100 square degrees of KiDS weak lensing data
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ABSTRACT: We use the first 100 sq. deg. of overlap between the KiloDegree Survey (KiDS) and the Galaxy And Mass Assembly (GAMA) survey to determine the galaxy halo mass of ~10,000 spectroscopicallyconfirmed satellite galaxies in massive ($M > 10^{13}h^{1}{\rm M}_\odot$) galaxy groups. Separating the sample as a function of projected distance to the group centre, we jointly model the satellites and their host groups with NavarroFrenkWhite (NFW) density profiles, fully accounting for the data covariance. The probed satellite galaxies in these groups have total masses $\log M_{\rm sub} /(h^{1}{\rm M}_\odot) \approx 11.7  12.2$ consistent across groupcentric distance within the errorbars. Given their typical stellar masses, $\log M_{\rm \star,sat}/(h^{2}{\rm M}_\odot) \sim 10.5$, such total masses imply stellar mass fractions of $M_{\rm \star,sat} /M_{\rm sub} \approx 0.04 h^{1}$ . The average subhalo hosting these satellite galaxies has a mass $M_{\rm sub} \sim 0.015M_{\rm host}$ independent of host halo mass, in broad agreement with the expectations of structure formation in a $\Lambda$CDM universe.Monthly Notices of the Royal Astronomical Society 07/2015; 454(4). DOI:10.1093/mnras/stv2051 · 5.11 Impact Factor 
Article: Dark matter halo properties of GAMA galaxy groups from 100 square degrees of KiDS weak lensing data
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ABSTRACT: The KiloDegree Survey is an optical widefield survey designed to map the matter distribution in the Universe using weak gravitational lensing. In this paper, we use these data to measure the density profiles and masses of a sample of ∼1400 spectroscopically identified galaxy groups and clusters from the Galaxy And Mass Assembly survey. We detect a highly significant signal (signaltonoiseratio ∼120), allowing us to study the properties of dark matter haloes over one and a half order of magnitude in mass, from M ∼ 1013–1014.5 h−1 M⊙. We interpret the results for various subsamples of groups using a halo model framework which accounts for the miscentring of the brightest cluster galaxy (used as the tracer of the group centre) with respect to the centre of the group's dark matter halo. We find that the density profiles of the haloes are well described by an NFW profile with concentrations that agree with predictions from numerical simulations. In addition, we constrain scaling relations between the mass and a number of observable group properties. We find that the mass scales with the total rband luminosity as a power law with slope 1.16 ± 0.13 (1σ) and with the group velocity dispersion as a power law with slope 1.89 ± 0.27 (1σ). Finally, we demonstrate the potential of weak lensing studies of groups to discriminate between models of baryonic feedback at group scales by comparing our results with the predictions from the CosmoOverWhelmingly Large Simulations project, ruling out models without AGN feedback.Monthly Notices of the Royal Astronomical Society 07/2015; 452(4). DOI:10.1093/mnras/stv1447 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The KiloDegree Survey (KiDS) is a multiband imaging survey designed for cosmological studies from weak lensing and photometric redshifts. It uses the ESO VLT Survey Telescope with its widefield camera OmegaCAM. KiDS images are taken in four filters similar to the SDSS ugri bands. The bestseeing time is reserved for deep rband observations that reach a median 5sigma limiting AB magnitude of 24.9 with a median seeing that is better than 0.7arcsec. Initial KiDS observations have concentrated on the GAMA regions near the celestial equator, where extensive, highly complete redshift catalogues are available. A total of 101 survey tiles, one square degree each, form the basis of the first set of lensing analyses, which focus on measurements of halo properties of GAMA galaxies. 9 galaxies per square arcminute enter the lensing analysis, for an effective inverse shear variance of 69 per square arcminute. 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 galaxy shape measurement (for weak lensing), and one for accurate matchedaperture photometry in four bands (for photometric redshifts). This technical paper describes how the lensing and photometric redshift catalogues have been produced (including an extensive 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 explain how the shear catalogues were blinded to prevent confirmation bias in the scientific analyses. The KiDS shear and photometric redshift catalogues, presented in this paper, are released to the community through http://kids.strw.leidenuniv.nl .Monthly Notices of the Royal Astronomical Society 07/2015; 454(4). DOI:10.1093/mnras/stv2140 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: The KiloDegree Survey (KiDS) is an optical widefield imaging survey carried out with the VLT Survey Telescope and the OmegaCAM camera. KiDS will image 1500 square degrees in four filters (ugri), and together with its nearinfrared counterpart VIKING will produce deep photometry in nine bands. Designed for weak lensing shape and photometric redshift measurements, the core science driver of the survey is mapping the largescale matter distribution in the Universe back to a redshift of ~0.5. Secondary science cases are manifold, covering topics such as galaxy evolution, Milky Way structure, and the detection of highredshift clusters and quasars. KiDS is an ESO Public Survey and dedicated to serving the astronomical community with highquality data products derived from the survey data, as well as with calibration data. Public data releases will be made on a yearly basis, the first two of which are presented here. For a total of 148 survey tiles (~160 sq.deg.) astrometrically and photometrically calibrated, coadded ugri images have been released, accompanied by weight maps, masks, source lists, and a multiband source catalog. A dedicated pipeline and data management system based on the AstroWISE software system, combined with newly developed masking and source classification software, is used for the data production of the data products described here. The achieved data quality and early science projects based on the data products in the first two data releases are reviewed in order to validate the survey data. Early scientific results include the detection of nine highz QSOs, fifteen candidate strong gravitational lenses, highquality photometric redshifts and galaxy structural parameters for hundreds of thousands of galaxies. (Abridged)Astronomy and Astrophysics 07/2015; · 4.38 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present an optimised variant of the halo model, designed to produce accurate matter power spectra well into the nonlinear regime for a wide range of cosmological models. To do this, we introduce physicallymotivated free parameters into the halomodel formalism and fit these to data from highresolution Nbody simulations. For a variety of $\Lambda$CDM and $w$CDM models the halomodel power is accurate to $\simeq 5$ per cent for $k\leq 10h\,\mathrm{Mpc}^{1}$ and $z\leq 2$. We compare our results with recent revisions of the popular HALOFIT model and show that our predictions are more accurate. An advantage of our new halo model is that it can be adapted to account for the effects of baryonic feedback on the power spectrum. We demonstrate this by fitting the halo model to power spectra from the OWLS hydrodynamical simulation suite via parameters that govern halo internal structure. We are able to fit all feedback models investigated at the 5 per cent level using only two free parameters, and we place limits on the range of these halo parameters for feedback models investigated by the OWLS simulations. Accurate predictions to high$k$ are vital for weak lensing surveys, and these halo parameters could be considered nuisance parameters to marginalise over in future analyses to mitigate uncertainty regarding the details of feedback, the limits we find on these parameters provide a prior. Finally we investigate how lensing observables predicted by our model compare to those from simulations and from HALOFIT for a range of $k$cuts and feedback models and quantify the angular scales at which these effects become important. Code to calculate power spectra from the model presented in this paper can be found at https://github.com/alexandermead/hmcode.Monthly Notices of the Royal Astronomical Society 05/2015; 454(2). DOI:10.1093/mnras/stv2036 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present the first cosmological measurement derived from a galaxy density field subject to a `clipping' transformation. By enforcing an upper bound on the galaxy number density field in the Galaxy and Mass Assembly survey (GAMA), contributions from the nonlinear processes of virialisation and galaxy bias are greatly reduced. This leads to a galaxy power spectrum which is easier to model, without calibration from numerical simulations. We develop a theoretical model for the power spectrum of a clipped field in redshift space, which is exact for the case of anisotropic Gaussian fields. Clipping is found to extend the applicability of the conventional Kaiser prescription by more than a factor of three in wavenumber, or a factor of thirty in terms of the number of Fourier modes. By modelling the galaxy power spectrum on scales k < 0.3 h/Mpc and density fluctuations $\delta_g < 4$ we measure the normalised growth rate $f\sigma_8(z = 0.18) = 0.29 \pm 0.10$.  [Show abstract] [Hide abstract]
ABSTRACT: Aims. We present the detection, identification and calibration of extended sources in the deepest Xray dataset to date, the Extended Chandra Deep Field South (ECDFS). Methods. Ultradeep observations of ECDFS with Chandra and XMMNewton enable a search for extended Xray emission down to an unprecedented flux of 2 × 1016 ergs? s1 cm2. By using simulations and comparing them with the Chandra and XMM data, we show that it is feasible to probe extended sources of this flux level, which is 10? 000 times fainter than the first Xray group catalogs of the ROSAT all sky survey. Extensive spectroscopic surveys at the VLT and Magellan have been completed, providing spectroscopic identification of galaxy groups to high redshifts. Furthermore, available HST imaging enables a weaklensing calibration of the group masses. Results. We present the search for the extended emission on spatial scales of 32″ in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDFS, such as log? N  log? S and Xray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/dΩ test reveals that a redshift range of 0.2 < z < 0.5 in ECDFS is sparsely populated. The lack of nearby structure, however, makes studies of highredshift groups particularly easier both in Xrays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weaklensing analysis to show that the detected lowluminosity systems are indeed lowmass systems. We verify the applicability of the scaling relations between the Xray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDFS by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30% in mass. Conclusions. Ultradeep Xray surveys uniquely probe the lowmass galaxy groups across a broad range of redshifts. These groups constitute the most common environment for galaxy evolution. Together with the exquisite data set available in the best studied part of the Universe, the ECDFS group catalog presented here has an exceptional legacy value.Astronomy and Astrophysics 04/2015; 576:A130. DOI:10.1051/00046361/201323053 · 4.38 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We measure the crosscorrelation of cosmic microwave background lensing convergence maps derived from Atacama Cosmology Telescope data with galaxy lensing convergence maps as measured by the CanadaFranceHawaii Telescope Stripe 82 Survey. The CMBgalaxy lensing cross power spectrum is measured for the first time with a significance of 3.2{\sigma}, which corresponds to a 16% constraint on the amplitude of density fluctuations at redshifts ~ 0.9. With upcoming improved lensing data, this novel type of measurement will become a powerful cosmological probe, providing a precise measurement of the mass distribution at intermediate redshifts and serving as a calibrator for systematic biases in weak lensing measurements.Physical Review D 03/2015; 91:062001. DOI:10.1103/PhysRevD.91.062001 · 4.86 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We study the correlations of the shear signal between triplets of sources in the CanadaFranceHawaii Lensing Survey (CFHTLenS) to probe cosmological parameters via the matter bispectrum. In contrast to previous studies, we adopted a nonGaussian model of the data likelihood which is supported by our simulations of the survey. We find that for stateoftheart surveys, similar to CFHTLenS, a Gaussian likelihood analysis is a reasonable approximation, albeit small differences in the parameter constraints are already visible. For future surveys we expect that a Gaussian model becomes inaccurate. Our algorithm for a refined nonGaussian analysis and data compression is then of great utility especially because it is not much more elaborate if simulated data are available. Applying this algorithm to the thirdorder correlations of shear alone in a blind analysis, we find a good agreement with the standard cosmological model: $\Sigma_8$=$\sigma_8$ $(\Omega_{\rm m}/0.27)^{0.64}$=$0.79^{+0.08}_{0.11}$ for a flat $\Lambda\rm CDM$ cosmology with $h=0.7\pm0.04$ ($68\%$ credible interval). Nevertheless our models provide only moderately good fits as indicated by $\chi^2/{\rm dof}=2.9$, including a $20\%$ r.m.s. uncertainty in the predicted signal amplitude. The models cannot explain a signal drop on scales around 15 arcmin, which may be caused by systematics. It is unclear whether the discrepancy can be fully explained by residual PSF systematics of which we find evidence at least on scales of a few arcmin. Therefore we need a better understanding of higherorder correlations of cosmic shear and their systematics to confidently apply them as cosmological probes.Monthly Notices of the Royal Astronomical Society 02/2015; 449(2). DOI:10.1093/mnras/stv339 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present new constraints on the relationship between galaxies and their host dark matter halos, measured from the location of the peak of the stellartohalo mass ratio (SHMR), up to the most massive galaxy clusters at redshift $z\sim0.8$ and over a volume of nearly 0.1~Gpc$^3$. We use a unique combination of deep observations in the CFHTLenS/VIPERS field from the nearUV to the nearIR, supplemented by $\sim60\,000$ secure spectroscopic redshifts, analysing galaxy clustering, galaxygalaxy lensing and the stellar mass function. We interpret our measurements within the halo occupation distribution (HOD) framework, separating the contributions from central and satellite galaxies. We find that the SHMR for the central galaxies peaks at $M_{\rm h, peak} = 1.9^{+0.2}_{0.1}\times10^{12} M_{\odot}$ with an amplitude of $0.025$, which decreases to $\sim0.001$ for massive halos ($M_{\rm h} > 10^{14} M_{\odot}$). Compared to central galaxies only, the total SHMR (including satellites) is boosted by a factor 10 in the highmass regime (clustersize halos), a result consistent with cluster analyses from the literature based on fully independent methods. After properly accounting for differences in modelling, we have compared our results with a large number of results from the literature up to $z=1$: we find good general agreement, independently of the method used, within the typical stellarmass systematic errors at low to intermediate mass (${M}_{\star} < 10^{11} M_{\odot}$) and the statistical errors above. We have also compared our SHMR results to semianalytic simulations and found that the SHMR is tilted compared to our measurements in such a way that they over (under) predict star formation efficiency in central (satellite) galaxies.Monthly Notices of the Royal Astronomical Society 02/2015; 449(2). DOI:10.1093/mnras/stv276 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Ultradeep observations of ECDFS with Chandra and XMMNewton enable a search for extended Xray emission down to an unprecedented flux of $2\times10^{16}$ ergs s$^{1}$ cm$^{2}$. We present the search for the extended emission on spatial scales of 32$^{\prime\prime}$ in both Chandra and XMM data, covering 0.3 square degrees and model the extended emission on scales of arcminutes. We present a catalog of 46 spectroscopically identified groups, reaching a redshift of 1.6. We show that the statistical properties of ECDFS, such as logNlogS and Xray luminosity function are broadly consistent with LCDM, with the exception that dn/dz/d$\Omega$ test reveals that a redshift range of $0.2<z<0.5$ in ECDFS is sparsely populated. The lack of nearby structure, however, makes studies of highredshift groups particularly easier both in Xrays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weaklensing analysis to show that the detected lowluminosity systems are indeed lowmass systems. We verify the applicability of the scaling relations between the Xray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDFS by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30\% in mass. Abridged.  [Show abstract] [Hide abstract]
ABSTRACT: We investigate the dependence of the galaxy luminosity function on geometric environment within the Galaxy And Mass Assembly (GAMA) survey. The tidal tensor prescription, based on the Hessian of the pseudogravitational potential, is used to classify the cosmic web and define the geometric environments: for a given smoothing scale, we classify every position of the surveyed region, 0.04 < z < 0.26, as either a void, a sheet, a filament or a knot. We consider how to choose appropriate thresholds in the eigenvalues of the Hessian in order to partition the galaxies approximately evenly between environments. We find a significant variation in the luminosity function of galaxies between different geometric environments; the normalization, characterized by ϕ* in a Schechter function fit, increases by an order of magnitude from voids to knots. The turnover magnitude, characterized by M*, brightens by approximately 0.5 mag from voids to knots. However, we show that the observed modulation can be entirely attributed to the indirect localdensity dependence. We therefore find no evidence of a direct influence of the cosmic web on the galaxy luminosity function.Monthly Notices of the Royal Astronomical Society 12/2014; 448(4). DOI:10.1093/mnras/stv237 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present weak lensing and Xray analysis of 12 lowmass clusters from the Canada–France–Hawaii Telescope Lensing Survey and XMMCFHTLS surveys. We combine these systems with highmass systems from Canadian Cluster Comparison Project and lowmass systems from Cosmic Evolution Survey to obtain a sample of 70 systems, spanning over two orders of magnitude in mass. We measure coreexcised LX–TX, M–LX and M–TX scaling relations and include corrections for observational biases. By providing fully biascorrected relations, we give the current limitations for LX and TX as cluster mass proxies. We demonstrate that TX benefits from a significantly lower intrinsic scatter at fixed mass than LX. By studying the residuals of the biascorrected relations, we show for the first time using weak lensing masses that galaxy groups seem more luminous and warmer for their mass than clusters. This implies a steepening of the M–LX and M–TX relations at low masses. We verify the inferred steepening using a different highmass sample from the literature and show that variance between samples is the dominant effect leading to discrepant scaling relations. We divide our sample into subsamples of merging and relaxed systems, and find that mergers may have enhanced scatter in lensing measurements, most likely due to stronger triaxiality and more substructure. For the LX–TX relation, which is unaffected by lensing measurements, we find the opposite trend in scatter. We also explore the effects of Xray crosscalibration and find that Chandra calibration leads to flatter LX–TX and M–TX relations than XMM–Newton.Monthly Notices of the Royal Astronomical Society 10/2014; 451(2). DOI:10.1093/mnras/stv923 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: We present the cluster massrichness scaling relation calibrated by a weak lensing analysis of ≳ 18 000 galaxy cluster candidates in the Canada–France–Hawaii Telescope Lensing Survey (CFHTLenS). Detected using the 3DMatchedFilter (MF) clusterfinder of Milkeraitis et al., these cluster candidates span a wide range of masses, from the small group scale up to ∼1015 M⊙, and redshifts 0.2 ≲ z ≲ 0.9. The total significance of the stacked shear measurement amounts to 54σ. We compare cluster masses determined using weak lensing shear and magnification, finding the measurements in individual richness bins to yield 1σ compatibility, but with magnification estimates biased low. This first direct mass comparison yields important insights for improving the systematics handling of future lensing magnification work. In addition, we confirm analyses that suggest cluster miscentring has an important effect on the observed 3DMF halo profiles, and we quantify this by fitting for projected cluster centroid offsets, which are typically ∼0.4 arcmin. We bin the cluster candidates as a function of redshift, finding similar cluster masses and richness across the full range up to z ∼ 0.9. We measure the 3DMF massrichness scaling relation M200 = M0(N200/20)β. We find a normalization $M_0 \sim (2.7^{+0.5}_{0.4}) \times 10^{13} \,\mathrm{M}_{{\odot }}$, and a logarithmic slope of β ∼ 1.4 ± 0.1, both of which are in 1σ agreement with results from the magnification analysis. We find no evidence for a redshift dependence of the normalization. The CFHTLenS 3DMF cluster catalogue is now available at cfhtlens.org.Monthly Notices of the Royal Astronomical Society 09/2014; 447(2). DOI:10.1093/mnras/stu2545 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: (Abridged) The effect of baryonic feedback on the dark matter mass distribution is generally considered to be a nuisance to weak gravitational lensing. Measurements of cosmological parameters are affected as feedback alters the cosmic shear signal on angular scales smaller than a few arcminutes. Recent progress on the numerical modelling of baryon physics has shown that this effect could be so large that, rather than being a nuisance, the effect can be constrained with current weak lensing surveys, hence providing an alternative astrophysical insight on one of the most challenging questions of galaxy formation. In order to perform our analysis, we construct an analytic fitting formula that describes the effect of the baryons on the mass power spectrum. This fitting formula is based on three scenarios of the OWL hydrodynamical simulations. It is specifically calibrated for $z<1.5$, where it models the simulations to an accuracy that is better than $2\%$ for scales $k<10 h\mbox{Mpc}^{1}$ and better than $5\%$ for $10 < k < 100 h\mbox{Mpc}^{1}$. Equipped with this precise tool, this paper presents the first constraint on baryonic feedback models using gravitational lensing data, from the Canada France Hawaii Telescope Lensing Survey (CFHTLenS). In this analysis, we show that the effect of neutrino mass on the mass power spectrum is degenerate with the baryonic feedback at small angular scales and cannot be ignored. Assuming a cosmology precision fixed by WMAP9, we find that a universe with no baryon feedback and massless neutrinos is rejected by the CFHTLenS lensing data with 96\% confidence. Our study shows that ongoing weak gravitational lensing surveys (KiDS, HSC and DES) will offer a unique opportunity to probe the physics of baryons at galactic scales, in addition to the expected constraints on the total neutrino mass.Monthly Notices of the Royal Astronomical Society 07/2014; 450(2). DOI:10.1093/mnras/stv646 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: Higherorder, nonGaussian aspects of the largescale structure carry valuable information on structure formation and cosmology, which is complementary to secondorder statistics. In this work we measure second and thirdorder weaklensing aperturemass moments from CFHTLenS and combine those with CMB anisotropy probes. The third moment is measured with a significance of $2\sigma$. The combined constraint on $\Sigma_8 = \sigma_8 (\Omega_{\rm m}/0.27)^\alpha$ is improved by 10%, in comparison to the secondorder only, and the allowed ranges for $\Omega_{\rm m}$ and $\sigma_8$ are substantially reduced. Including general triangles of the lensing bispectrum yields tighter constraints compared to probing mainly equilateral triangles. Second and thirdorder CFHTLenS lensing measurements improve Planck CMB constraints on $\Omega_{\rm m}$ and $\sigma_8$ by 26% for flat $\Lambda$CDM. For a model with free curvature, the joint CFHTLenSPlanck result is $\Omega_{\rm m} = 0.28 \pm 0.02$ (68% confidence), which is an improvement of 43% compared to Planck alone. We test how our results are potentially subject to three astrophysical sources of contamination: sourcelens clustering, the intrinsic alignment of galaxy shapes, and baryonic effects. We explore future limitations of the cosmological use of thirdorder weak lensing, such as the nonlinear model and the Gaussianity of the likelihood function.Monthly Notices of the Royal Astronomical Society 04/2014; 441(3). DOI:10.1093/mnras/stu754 · 5.11 Impact Factor  [Show abstract] [Hide abstract]
ABSTRACT: This paper presents the first application of 3D cosmic shear to a widefield weak lensing survey. 3D cosmic shear is a technique that analyses weak lensing in three dimensions using a spherical harmonic approach, and does not bin data in the redshift direction. This is applied to CFHTLenS, a 154 square degree imaging survey with a median redshift of 0.7 and an effective number density of 11 galaxies per square arcminute usable for weak lensing. To account for survey masks we apply a 3D pseudoCl approach on weak lensing data, and to avoid uncertainties in the highly nonlinear regime, we separately analyse radial wavenumbers k<=1.5h/Mpc and k<=5.0h/Mpc, and angular wavenumbers l~4005000. We show how one can recover 2D and tomographic power spectra from the full 3D cosmic shear power spectra and present a measurement of the 2D cosmic shear power spectrum, and measurements of a set of 2bin and 6bin cosmic shear tomographic power spectra; in doing so we find that using the 3D power in the calculation of such 2D and tomographic power spectra from data naturally accounts for a minimum scale in the matter power spectrum. We use 3D cosmic shear to constrain cosmologies with parameters OmegaM, OmegaB, sigma8, h, ns, w0, wa. For a nonevolving dark energy equation of state, and assuming a flat cosmology, lensing combined with WMAP7 results in h=0.78+/0.12, OmegaM=0.252+/0.079, sigma8=0.88+/0.23 and w=1.16+/0.38 using only scales k<=1.5h/Mpc. We also present results of lensing combined with first year Planck results, where we find no tension with the results from this analysis, but we also find no significant improvement over the Planck results alone. We find evidence of a suppression of power compared to LCDM on small scales 1.5<k<=5.0h/Mpc in the lensing data, which is consistent with predictions of the effect of baryonic feedback on the matter power spectrum. [abridged]Monthly Notices of the Royal Astronomical Society 01/2014; 442(2). DOI:10.1093/mnras/stu934 · 5.11 Impact Factor
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Institutions

20102015

Scottish Universities Physics Alliance
Glasgow, Scotland, United Kingdom


20002015

The University of Edinburgh
 Institute for Astronomy (IfA)
Edinburgh, Scotland, United Kingdom


2012

The Ohio State University
 Department of Physics
Columbus, Ohio, United States


2009

University of Nottingham
 School of Physics and Astronomy
Nottigham, England, United Kingdom


20062009

University of British Columbia  Vancouver
 Department of Physics and Astronomy
Vancouver, British Columbia, Canada


20072008

Pierre and Marie Curie University  Paris 6
 Institut d'astrophysique de Paris
Paris, IledeFrance, France 
Institut d'astrophysique de Paris
Lutetia Parisorum, ÎledeFrance, France


20042008

Max Planck Institute for Astronomy
Heidelburg, BadenWürttemberg, Germany


20022005

University of Oxford
 Department of Physics
Oxford, England, United Kingdom
