[Show abstract][Hide abstract] ABSTRACT: Applying a transformation to a non-Gaussian 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 galaxy-scale matter
haloes and the galaxy-halo misalignment. Using data from the
Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), we measure the
weighted-average 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 galaxy-halo 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 shape-shear
alignments between the lenses and their large-scale 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 early-type galaxies, which is consistent with
current models for the galaxy-halo misalignment predicting $f_\mathrm{h}\simeq
0.20$. For late-type 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 late-type 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
large-scale gravitational physics. We present a new consistency check based on
the relative amplitude of non-relativistic galaxy peculiar motions, measured
via redshift-space distortion, and the relativistic deflection of light by
those same galaxies traced by galaxy-galaxy lensing. We take advantage of the
latest generation of deep, overlapping imaging and spectroscopic datasets,
combining the Red Cluster Sequence Lensing Survey (RCSLenS), the
Canada-France-Hawaii 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 Friedmann-Robertson-Walker 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 redshift-space distortion and gravitational
lensing data from current and future galaxy surveys will offer increasingly
stringent tests of fundamental cosmology.
[Show abstract][Hide abstract] ABSTRACT: We use the first 100 sq. deg. of overlap between the Kilo-Degree Survey
(KiDS) and the Galaxy And Mass Assembly (GAMA) survey to determine the galaxy
halo mass of ~10,000 spectroscopically-confirmed 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 Navarro-Frenk-White (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 group-centric 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.
[Show abstract][Hide abstract] ABSTRACT: The Kilo-Degree Survey (KiDS) is an optical wide-field 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 $\sim \mathrm{1400}$ spectroscopically identified galaxy groups and
clusters from the Galaxy And Mass Assembly (GAMA) survey. We detect a highly
significant signal (signal-to-noise-ratio $\sim$ 120), allowing us to study the
properties of dark matter haloes over one and a half order of magnitude in
mass, from $M \sim 10^{13}-10^{14.5} h^{-1}\mathrm{M_{\odot}}$. We interpret
the results for various subsamples of groups using a halo model framework which
accounts for the mis-centring 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 r-band luminosity as a power-law with slope $1.16 \pm 0.13$
(1-sigma) and with the group velocity dispersion as a power-law with slope
$1.89 \pm 0.27$ (1-sigma). 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
Cosmo-OverWhelmingly Large Simulations (Cosmo-OWLS) 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 Kilo-Degree Survey (KiDS) is a multi-band imaging survey designed for
cosmological studies from weak lensing and photometric redshifts. It uses the
ESO VLT Survey Telescope with its wide-field camera OmegaCAM. KiDS images are
taken in four filters similar to the SDSS ugri bands. The best-seeing time is
reserved for deep r-band observations that reach a median 5-sigma 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 matched-aperture
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 .
[Show abstract][Hide abstract] ABSTRACT: The Kilo-Degree Survey (KiDS) is an optical wide-field 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 near-infrared
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 large-scale 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 high-redshift clusters and quasars.
KiDS is an ESO Public Survey and dedicated to serving the astronomical
community with high-quality 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 multi-band source catalog.
A dedicated pipeline and data management system based on the Astro-WISE
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 high-z QSOs, fifteen candidate strong gravitational lenses, high-quality
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 non-linear regime for a wide range
of cosmological models. To do this, we introduce physically-motivated free
parameters into the halo-model formalism and fit these to data from
high-resolution N-body simulations. For a variety of $\Lambda$CDM and $w$CDM
models the halo-model 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/alexander-mead/hmcode.
[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 X-ray dataset to date, the Extended Chandra Deep Field South (ECDF-S). Methods. Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search for extended X-ray emission down to an unprecedented flux of 2 × 10-16 ergs? s-1 cm-2. 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 X-ray 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 weak-lensing 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 ECDF-S, such as log? N - log? S and X-ray 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 ECDF-S is sparsely populated. The lack of nearby structure, however, makes studies of high-redshift groups particularly easier both in X-rays and lensing, due to a lower level of clustered foreground. We present one and two point statistics of the galaxy groups as well as weak-lensing analysis to show that the detected low-luminosity systems are indeed low-mass systems. We verify the applicability of the scaling relations between the X-ray luminosity and the total mass of the group, derived for the COSMOS survey to lower masses and higher redshifts probed by ECDF-S by means of stacked weak lensing and clustering analysis, constraining any possible departures to be within 30% in mass. Conclusions. Ultra-deep X-ray surveys uniquely probe the low-mass 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 ECDF-S group catalog presented here has an exceptional legacy value.
Astronomy and Astrophysics 04/2015; 576:A130. DOI:10.1051/0004-6361/201323053 · 4.38 Impact Factor
[Show abstract][Hide abstract] ABSTRACT: We measure the cross-correlation of cosmic microwave background lensing
convergence maps derived from Atacama Cosmology Telescope data with galaxy
lensing convergence maps as measured by the Canada-France-Hawaii Telescope
Stripe 82 Survey. The CMB-galaxy 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 Canada-France-Hawaii Lensing Survey (CFHTLenS) to probe cosmological
parameters via the matter bispectrum. In contrast to previous studies, we
adopted a non-Gaussian model of the data likelihood which is supported by our
simulations of the survey. We find that for state-of-the-art 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 non-Gaussian 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 third-order 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 higher-order 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
stellar-to-halo 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 near-UV
to the near-IR, supplemented by $\sim60\,000$ secure spectroscopic redshifts,
analysing galaxy clustering, galaxy-galaxy 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 high-mass regime (cluster-size
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 stellar-mass 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 semi-analytic
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: Ultra-deep observations of ECDF-S with Chandra and XMM-Newton enable a search
for extended X-ray 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 ECDF-S, such as
logN-logS and X-ray 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 ECDF-S is sparsely populated. The lack of nearby structure,
however, makes studies of high-redshift groups particularly easier both in
X-rays and lensing, due to a lower level of clustered foreground. We present
one and two point statistics of the galaxy groups as well as weak-lensing
analysis to show that the detected low-luminosity systems are indeed low-mass
systems. We verify the applicability of the scaling relations between the X-ray
luminosity and the total mass of the group, derived for the COSMOS survey to
lower masses and higher redshifts probed by ECDF-S 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 pseudo-gravitational 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 local-density 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 X-ray analysis of 12 low-mass clusters from the Canada–France–Hawaii Telescope Lensing Survey
and XMM-CFHTLS surveys. We combine these systems with high-mass systems from Canadian Cluster Comparison Project and low-mass systems
from Cosmic Evolution Survey to obtain a sample of 70 systems, spanning over two orders of magnitude in mass. We measure core-excised
LX–TX, M–LX and M–TX scaling relations and include corrections for observational biases. By providing fully bias-corrected 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 bias-corrected 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 high-mass 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 X-ray cross-calibration 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 mass-richness 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 3D-Matched-Filter (MF) cluster-finder
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 3D-MF 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 3D-MF mass-richness 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 3D-MF 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: Higher-order, non-Gaussian aspects of the large-scale structure carry
valuable information on structure formation and cosmology, which is
complementary to second-order statistics. In this work we measure second- and
third-order weak-lensing aperture-mass 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 second-order 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
third-order 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 CFHTLenS-Planck 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: source-lens clustering, the intrinsic alignment of
galaxy shapes, and baryonic effects. We explore future limitations of the
cosmological use of third-order 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 wide-field
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 pseudo-Cl approach on weak lensing data, and to avoid
uncertainties in the highly non-linear regime, we separately analyse radial
wavenumbers k<=1.5h/Mpc and k<=5.0h/Mpc, and angular wavenumbers l~400-5000. 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 2-bin and 6-bin 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 non-evolving 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