-
[show abstract]
[hide abstract]
ABSTRACT: Well-calibrated scaling relations between the observable properties and the
total masses of clusters of galaxies are important for understanding the
physical processes that give rise to these relations. They are also a critical
ingredient for studies that aim to constrain cosmological parameters using
galaxy clusters. For this reason much effort has been spent during the last
decade to better understand and interpret relations of the properties of the
intra-cluster medium. Improved X-ray data have expanded the mass range down to
galaxy groups, whereas SZ surveys have openened a new observational window on
the intracluster medium. In addition,continued progress in the performance of
cosmological simulations has allowed a better understanding of the physical
processes and selection effects affecting the observed scaling relations. Here
we review the recent literature on various scaling relations, focussing on the
latest observational measurements and the progress in our understanding of the
deviations from self similarity.
05/2013;
-
R. Laureijs,
J. Amiaux,
S. Arduini,
J. L. Auguères,
J. Brinchmann,
R. Cole,
M. Cropper,
C. Dabin,
L. Duvet,
A Ealet, [......],
S. Serrano,
N. Shane,
J. -L. Starck,
C. Surace,
A Taylor,
G. Verdoes Kleijn,
C. Vuerli,
O. R. Williams,
A. Zacchei,
B. Altieri
-
P. Simon,
T. Erben,
P. Schneider,
C. Heymans,
H. Hildebrandt, H. Hoekstra,
T. D. Kitching,
Y. Mellier,
L. Miller,
L. Van Waerbeke,
C. Bonnett,
J. Coupon,
L. Fu,
M. J. Hudson,
K. Kuijken,
B. T. P. Rowe,
T. Schrabback,
E. Semboloni,
M. Velander
[show abstract]
[hide abstract]
ABSTRACT: We present the first direct measurement of the galaxy-matter bispectrum as a
function of galaxy luminosity, stellar mass, and SED type. Our analysis uses a
galaxy-galaxy-galaxy lensing technique (G3L), on angular scales between 9
arcsec to 50 arcmin, to quantify (i) the excess surface mass density around
galaxy pairs (excess mass hereafter) and (ii) the excess shear-shear
correlations around single galaxies, both of which yield a measure of two types
of galaxy-matter bispectra. We apply our method to the state-of-the-art
Canada-France-Hawaii Telescope Lensing Survey (CFHTLenS), spanning 154 square
degrees. This survey allows us to detect a significant change of the bispectra
with lens properties. Measurements for lens populations with distinct redshift
distributions become comparable by a newly devised normalisation technique.
That will also aid future comparisons to other surveys or simulations. A
significant dependence of the normalised G3L statistics on luminosity within
-23<M_r<-18 and stellar mass within 5x10^9 M_sol<M_star<2x10^11 M_sol is found
(h=0.73). Both bispectra exhibit a stronger signal for more luminous lenses or
those with higher stellar mass (up to a factor 2-3). This is accompanied by a
steeper equilateral bispectrum for more luminous or higher stellar mass lenses
for the excess mass. Importantly, we find the excess mass to be very sensitive
to galaxy type as recently predicted with semi-analytic galaxy models: luminous
(M_r<-21) late-type galaxies show no detectable signal, while all excess mass
detected for luminous galaxies seems to be associated with early-type galaxies.
We also present the first observational constraints on third-order stochastic
galaxy biasing parameters.
01/2013;
-
J. W. den Herder,
L. Piro,
T. Ohashi,
C. Kouveliotou,
D. H. Hartmann,
J. S. Kaastra,
L. Amati,
M. I. Andersen,
M. Arnaud,
J-L. Attéia, [......],
O. Ruchayskiy,
R. Salvaterra,
S. Sasaki,
K. Sato,
S. Savaglio,
J. Schaye,
S. Sciortino,
M. Shaposhnikov,
R. Sharples,
K. Shinozaki
-
T. Erben,
H. Hildebrandt,
L. Miller,
L. van Waerbeke,
C. Heymans, H. Hoekstra,
T. D. Kitching,
Y. Mellier,
J. Benjamin,
C. Blake, [......],
M. Milkeraitis,
B. T. P. Rowe,
T. Schrabback,
E. Semboloni,
P. Simon,
M. Smit,
O. Toader,
S. Vafaei,
E. van Uitert,
M. Velander
[show abstract]
[hide abstract]
ABSTRACT: We present data products from the Canada-France-Hawaii Telescope Lensing
Survey (CFHTLenS). CFHTLenS is based on the Wide component of the
Canada-France-Hawaii Telescope Legacy Survey (CFHTLS). It encompasses 154 deg^2
of deep, optical, high-quality, sub-arcsecond imaging data in the five optical
filters u^*g'r'i'z'. The article presents our data processing of the complete
CFHTLenS data set. We were able to obtain a data set with very good image
quality and high-quality astrometric and photometric calibration. Our external
astrometric accuracy is between 60-70 mas with respect to SDSS data and the
internal alignment in all filters is around 30 mas. Our average photometric
calibration shows a dispersion on the order of 0.01 to 0.03 mag for g'r'i'z'
and about 0.04 mag for u^* with respect to SDSS sources down to i <= 21.
In the spirit of the CFHTLS all our data products are released to the
astronomical community via the Canadian Astronomy Data Centre. We give a
description and how-to manuals of the public products which include image pixel
data, source catalogues with photometric redshift estimates and all relevant
quantities to perform weak lensing studies.
10/2012;
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L. Miller,
C. Heymans,
T. D. Kitching,
L. Van Waerbeke,
T. Erben,
H. Hildebrandt, H. Hoekstra,
Y. Mellier,
B. T. P. Rowe,
J. Coupon,
J. P. Dietrich,
L. Fu,
J. Harnois-Deraps,
M. J. Hudson,
M. Kilbinger,
K. Kuijken,
T. Schrabback,
E. Semboloni,
S. Vafaei,
M. Velander
[show abstract]
[hide abstract]
ABSTRACT: A likelihood-based method for measuring weak gravitational lensing shear in
deep galaxy surveys is described and applied to the Canada-France-Hawaii
Telescope (CFHT) Lensing Survey (CFHTLenS). CFHTLenS comprises 154 sq deg of
multicolour optical data from the CFHT Legacy Survey, with lensing measurements
being made in the i' band to a depth i'(AB)<24.7, for galaxies with
signal-to-noise ratio greater than about 10. The method is based on the lensfit
algorithm described in earlier papers, but here we describe a full analysis
pipeline that takes into account the properties of real surveys. The method
creates pixel-based models of the varying point spread function (PSF) in
individual image exposures. It fits PSF-convolved two-component (disk plus
bulge) models, to measure the ellipticity of each galaxy, with bayesian
marginalisation over model nuisance parameters of galaxy position, size,
brightness and bulge fraction. The method allows optimal joint measurement of
multiple, dithered image exposures, taking into account imaging distortion and
the alignment of the multiple measurements. We discuss the effects of noise
bias on the likelihood distribution of galaxy ellipticity. Two sets of image
simulations that mirror the observed properties of CFHTLenS have been created,
to establish the method's accuracy and to derive an empirical correction for
the effects of noise bias.
10/2012;
-
C. Lidman,
J. Suherli,
A. Muzzin,
G. Wilson,
R. Demarco,
S. Brough,
A. Rettura,
J. Cox,
A. DeGroot,
H. K. C. Yee,
D. Gilbank, H. Hoekstra,
M. Balogh,
E. Ellingson,
A. Hicks,
J. Nantais,
A. Noble,
M. Lacy,
J. Surace,
T. Webb
[show abstract]
[hide abstract]
ABSTRACT: Using new and published data, we construct a sample of 160 brightest cluster
galaxies (BCGs) spanning the redshift interval 0.03 < z < 1.63. We use this
sample, which covers 70% of the history of the universe, to measure the growth
in the stellar mass of BCGs after correcting for the correlation between the
stellar mass of the BCG and the mass of the cluster in which it lives. We find
that the stellar mass of BCGs increase by a factor of 1.8 between z=0.9 and
z=0.2. Compared to earlier works, our result is closer to the predictions of
semi-analytic models. However, BCGs at z=0.9, relative to BCGs at z=0.2, are
still a factor of 1.5 more massive than the predictions of these models. Star
formation rates in BCGs at z~1 are generally to low to result in significant
amounts of mass. Instead, it is likely that most of the mass build up occurs
through mainly dry mergers in which perhaps half of the mass is lost to the
intra-cluster medium of the cluster.
08/2012;
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Mark Cropper,
R. Cole,
A. James,
Y. Mellier,
J. Martignac,
A. -M. di Giorgio,
S. Paltani,
L. Genolet,
J. -J. Fourmond,
C. Cara, [......],
J. Gow,
N. Murray,
L. Duvet,
J. -L. Augueres,
R. Laureijs,
P. Gondoin,
T. Kitching,
R. Massey, H. Hoekstra,
the Euclid collaboration
[show abstract]
[hide abstract]
ABSTRACT: Euclid-VIS is a large format visible imager for the ESA Euclid space mission
in their Cosmic Vision program, scheduled for launch in 2019. Together with the
near infrared imaging within the NISP instrument it forms the basis of the weak
lensing measurements of Euclid. VIS will image in a single r+i+z band from
550-900 nm over a field of view of ~0.5 deg2. By combining 4 exposures with a
total of 2240 sec, VIS will reach to V=24.5 (10{\sigma}) for sources with
extent ~0.3 arcsec. The image sampling is 0.1 arcsec. VIS will provide deep
imaging with a tightly controlled and stable point spread function (PSF) over a
wide survey area of 15000 deg2 to measure the cosmic shear from nearly 1.5
billion galaxies to high levels of accuracy, from which the cosmological
parameters will be measured. In addition, VIS will also provide a legacy
imaging dataset with an unprecedented combination of spatial resolution, depth
and area covering most of the extra-Galactic sky. Here we will present the
results of the study carried out by the Euclid Consortium during the Euclid
Definition phase.
08/2012;
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F. W. High, H. Hoekstra,
N. Leethochawalit,
T. de Haan,
L. Abramson,
K. A. Aird,
R. Armstrong,
M. L. N. Ashby,
M. Bautz,
M. Bayliss, [......],
C. W. Stubbs,
R. Suhada,
S. Tokarz,
A. van Engelen,
K. Vanderlinde,
J. D. Vieira,
A. Vikhlinin,
R. Williamson,
O. Zahn,
A. Zenteno
[show abstract]
[hide abstract]
ABSTRACT: We use weak gravitational lensing to measure the masses of five galaxy
clusters selected from the South Pole Telescope (SPT) survey, with the primary
goal of comparing these with the SPT Sunyaev--Zel'dovich (SZ) and X-ray based
mass estimates. The clusters span redshifts 0.28 < z < 0.43 and have masses
M_500 > 2 x 10^14 h^-1 M_sun, and three of the five clusters were discovered by
the SPT survey. We observed the clusters in the g'r'i' passbands with the
Megacam imager on the Magellan Clay 6.5m telescope. We measure a mean ratio of
weak lensing (WL) aperture masses to inferred aperture masses from the SZ data,
both within an aperture of R_500,SZ derived from the SZ mass, of 1.04 +/- 0.18.
We measure a mean ratio of spherical WL masses evaluated at R_500,SZ to
spherical SZ masses of 1.07 +/- 0.18, and a mean ratio of spherical WL masses
evaluated at R_500,WL to spherical SZ masses of 1.10 +/- 0.24. We explore
potential sources of systematic error in the mass comparisons and conclude that
all are subdominant to the statistical uncertainty, with dominant terms being
cluster concentration uncertainty and N-body simulation calibration bias.
Expanding the sample of SPT clusters with WL observations has the potential to
significantly improve the SPT cluster mass calibration and the resulting
cosmological constraints from the SPT cluster survey. These are the first WL
detections using Megacam on the Magellan Clay telescope.
05/2012;
-
Jan-Willem den Herder,
Luigi Piro,
Takaya Ohashi,
Chryssa Kouveliotou,
Dieter H. Hartmann,
Jelle S. Kaastra,
L. Amati,
M. I. Andersen,
M. Arnaud,
J. -L. Attéia, [......],
S. Wachter,
D. Watson,
M. Weisskopf,
N. Werner,
N. White,
R. Willingale,
R. Wijers,
N. Yamasaki,
K. Yoshikawa,
S. Zane
[show abstract]
[hide abstract]
ABSTRACT: ORIGIN is a proposal for the M3 mission call of ESA aimed at the study of metal creation from the epoch of cosmic dawn. Using
high-spectral resolution in the soft X-ray band, ORIGIN will be able to identify the physical conditions of all abundant elements
between C and Ni to red-shifts of z = 10, and beyond. The mission will answer questions such as: When were the first metals created? How does the cosmic metal
content evolve? Where do most of the metals reside in the Universe? What is the role of metals in structure formation and
evolution? To reach out to the early Universe ORIGIN will use Gamma-Ray Bursts (GRBs) to study their local environments in
their host galaxies. This requires the capability to slew the satellite in less than a minute to the GRB location. By studying
the chemical composition and properties of clusters of galaxies we can extend the range of exploration to lower redshifts
(z ∼0.2). For this task we need a high-resolution spectral imaging instrument with a large field of view. Using the same instrument,
we can also study the so far only partially detected baryons in the Warm-Hot Intergalactic Medium (WHIM). The less dense part
of the WHIM will be studied using absorption lines at low redshift in the spectra for GRBs. The ORIGIN mission includes a
Transient Event Detector (coded mask with a sensitivity of 0.4 photon/cm2/s in 10s in the 5–150keV band) to identify and localize 2000GRBs over a five year mission, of which ∼65GRBs have a redshift
>7. The Cryogenic Imaging Spectrometer, with a spectral resolution of 2.5eV, a field of view of 30arcmin and large effective
area below 1keV has the sensitivity to study clusters up to a significant fraction of the virial radius and to map the denser
parts of the WHIM (factor 30 higher than achievable with current instruments). The payload is complemented by a Burst InfraRed
Telescope to enable onboard red-shift determination of GRBs (hence securing proper follow up of high-z bursts) and also probes
the mildly ionized state of the gas. Fast repointing is achieved by a dedicated Controlled Momentum Gyro and a low background
is achieved by the selected low Earth orbit.
KeywordsX-ray–Mission–Gamma-ray bursts–Clusters of galaxies–Warm-hot intergalactic medium–Chemical evolution
Experimental Astronomy 04/2012; · 1.82 Impact Factor
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[show abstract]
[hide abstract]
ABSTRACT: The statistical properties of the ellipticities of galaxy images test the
paradigm of structure formation and galaxy evolution, and constrain models of
galaxy morphology, which are key to the removal of the intrinsic alignment
contamination of cosmological weak lensing surveys. We construct such models
based on the halo properties of the Millennium Simulation and confront them
with a sample of 150,000 galaxies from the COSMOS Survey, covering 4 decades in
luminosity and redshifts out to z=2. The ellipticity measurements are corrected
for effects of PSF smearing, spurious image distortions, and measurement noise.
We find that early-type galaxies have a 25% lower intrinsic ellipticity
dispersion than late-type galaxies, which is quantitatively reproduced by our
best models. None of the samples shows evidence for redshift evolution, while
the ellipticity dispersion for late-type galaxies scales strongly with absolute
magnitude at the bright end. The low ellipticity dispersions predicted by
models based on reduced inertia tensors of simulated haloes are generally
disfavoured by the observations. The fraction of close to circular late-type
galaxy images in COSMOS is much lower than expected for a sample of circular
inclined thick disks, indicating a substantial fraction of galaxies with
irregular morphology.
03/2012;
-
A. G. Noble,
T. M. A. Webb,
E. Ellingson,
A. J. Faloon,
R. R. Gal,
M. D. Gladders,
A. K. Hicks, H. Hoekstra,
B. C. Hsieh,
R. J. Ivison,
B. C. Lemaux,
L. M. Lubin,
D. V. O’Donnell,
H. K. C. Yee
[show abstract]
[hide abstract]
ABSTRACT: We present a submillimetre survey of seven high-redshift galaxy clusters (0.64 < z < 1.0) using the Submillimetre Common-User Bolometer Array (SCUBA) at 850 and 450 m. The targets, of similar richness and redshift, are selected from the Red-sequence Cluster Survey (RCS). We use this sample to investigate the apparent excess of submillimetre source counts in the direction of cluster fields compared to blank fields, as seen in the literature. The sample consists of three galaxy clusters that exhibit multiple optical arcs due to strong gravitational lensing, and a control group of four clusters with no apparent strong lensing. A tentative excess of 2.7σ is seen in the number density of submillimetre sources within the lensing cluster fields compared to that in the control group. Ancillary observations at radio, mid-infrared, optical and X-ray wavelengths allow for the identification of counterparts to many of the submillimetre luminous galaxies (SMGs), and provide improved astrometry and redshift constraints. Utilizing photometric redshifts, we conclude that at least three of the galaxies within the lensing fields have redshifts consistent with the clusters and implied infrared luminosities of ∼1012 L⊙. The existence of submillimetre cluster members may therefore be boosting source counts in the lensing cluster fields, which might be an effect of the dynamical state of those clusters. However, we find that the removal of potential cluster members from the counts analysis does not entirely eliminate the difference between the cluster samples. We also investigate possible occurrences of lensing between background submillimetre sources and lower redshift optical galaxies, though further observations are required to make any conclusive claims. Although the excess counts between the two cluster samples have not been unambiguously accounted for, these results warrant caution for interpreting submillimetre source counts in cluster fields and point source contamination for Sunyaev–Zel’dovich surveys.
Monthly Notices of the Royal Astronomical Society 01/2012; 419(3):1983 - 2013. · 4.90 Impact Factor
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H. Hildebrandt,
T. Erben,
K. Kuijken,
L. van Waerbeke,
C. Heymans,
J. Coupon,
J. Benjamin,
C. Bonnett,
L. Fu, H. Hoekstra,
T. D. Kitching,
Y. Mellier,
L Miller,
M. Velander,
M. J. Hudson,
B. T. P. Rowe,
T. Schrabback,
E. Semboloni,
N. Benitez
[show abstract]
[hide abstract]
ABSTRACT: Here we present the results of various approaches to measure accurate colours
and photometric redshifts (photo-z's) from wide-field imaging data. We use data
from the Canada-France-Hawaii-Telescope Legacy Survey (CFHTLS) which have been
re- processed by the CFHT Lensing Survey (CFHTLenS) team in order to carry out
a number of weak gravitational lensing studies. An emphasis is put on the
correction of systematic effects in the photo-z's arising from the different
Point Spread Functions (PSF) in the five optical bands. Different ways of
correcting these effects are discussed and the resulting photo-z accuracies are
quantified by comparing the photo-z's to large spectroscopic redshift (spec-z)
data sets. Careful homogenisation of the PSF between bands leads to increased
overall accuracy of photo-z's. The gain is particularly pronounced at fainter
magnitudes where galaxies are smaller and flux measurements are affected more
by PSF-effects. We also study possible re- calibrations of the photometric
zeropoints (ZPs) with the help of galaxies with known spec-z's. We find that if
PSF-effects are properly taken into account, a re-calibration of the ZPs
becomes much less important suggesting that previous such re-calibrations
described in the literature could in fact be mostly corrections for PSF-effects
rather than corrections for real inaccuracies in the ZPs. The implications of
this finding for future surveys like KiDS, DES, LSST, or Euclid are mixed. On
the one hand, ZP re-calibrations with spec-z's might not be as accurate as
previously thought. On the other hand, careful PSF homogenisation might provide
a way out and yield accurate, homogeneous photometry without the need for full
spectroscopic coverage. This is the first paper in a series describing the
technical aspects of CFHTLenS. (abridged)
11/2011;
-
R. Laureijs,
J. Amiaux,
S. Arduini,
J. L. Auguères,
J. Brinchmann,
R. Cole,
M. Cropper,
C. Dabin,
L. Duvet,
A Ealet, [......],
S. Spiro,
M Sullivan,
A Tilquin,
R. Trotta,
L. Verde,
Y Wang,
G. Williger,
G Zhao,
J. Zoubian,
E. Zucca
[show abstract]
[hide abstract]
ABSTRACT: Euclid is a space-based survey mission from the European Space Agency
designed to understand the origin of the Universe's accelerating expansion. It
will use cosmological probes to investigate the nature of dark energy, dark
matter and gravity by tracking their observational signatures on the geometry
of the universe and on the cosmic history of structure formation. The mission
is optimised for two independent primary cosmological probes: Weak
gravitational Lensing (WL) and Baryonic Acoustic Oscillations (BAO). The Euclid
payload consists of a 1.2 m Korsch telescope designed to provide a large field
of view. It carries two instruments with a common field-of-view of ~0.54 deg2:
the visual imager (VIS) and the near infrared instrument (NISP) which contains
a slitless spectrometer and a three bands photometer. The Euclid wide survey
will cover 15,000 deg2 of the extragalactic sky and is complemented by two 20
deg2 deep fields. For WL, Euclid measures the shapes of 30-40 resolved galaxies
per arcmin2 in one broad visible R+I+Z band (550-920 nm). The photometric
redshifts for these galaxies reach a precision of dz/(1+z) < 0.05. They are
derived from three additional Euclid NIR bands (Y, J, H in the range 0.92-2.0
micron), complemented by ground based photometry in visible bands derived from
public data or through engaged collaborations. The BAO are determined from a
spectroscopic survey with a redshift accuracy dz/(1+z) =0.001. The slitless
spectrometer, with spectral resolution ~250, predominantly detects Ha emission
line galaxies. Euclid is a Medium Class mission of the ESA Cosmic Vision
2015-2025 programme, with a foreseen launch date in 2019. This report (also
known as the Euclid Red Book) describes the outcome of the Phase A study.
10/2011;
-
A. G. Noble,
T. M. A. Webb,
E. Ellingson,
A. J. Faloon,
R. R. Gal,
M. D. Gladders,
A. K. Hicks, H. Hoekstra,
B. C. Hsieh,
R. J. Ivison,
B. C. Lemaux,
L. M. Lubin,
D. V. O'Donnell,
H. K. C. Yee
[show abstract]
[hide abstract]
ABSTRACT: We present a submillimetre survey of seven high-z galaxy clusters
(0.64<z<1.0) using the Submillimetre Common-User Bolometer Array (SCUBA) at 850
and 450 um. The targets, of similar richness and redshift, are selected from
the Red-sequence Cluster Survey (RCS). We use this sample to investigate the
apparent excess of submillimetre source counts in the direction of cluster
fields compared to blank fields. The sample consists of three galaxy clusters
that exhibit multiple optical arcs due to strong gravitational lensing, and a
control group of four clusters with no apparent strong lensing. A tentative
excess of 2.7-sigma is seen in the number density of submillimetre luminous
galaxies (SMGs) within the lensing cluster fields compared to that in the
control group. Ancillary observations at radio, mid-infrared, optical, and
X-ray wavelengths allow for the identification of counterparts to many of the
SMGs. Utilizing photometric redshifts, we conclude that at least three of the
galaxies within the lensing fields have redshifts consistent with the clusters
and implied infrared luminosities of ~10^12 Lsol. The existence of SMG cluster
members may therefore be boosting source counts in the lensing cluster fields,
which might be an effect of the dynamical state of those clusters. However, we
find that the removal of potential cluster members from the counts analysis
does not entirely eliminate the difference between the cluster samples. We also
investigate possible occurrences of lensing between background SMGs and lower-z
optical galaxies, though further observations are required to make any
conclusive claims. Although the excess counts between the two cluster samples
have not been unambiguously accounted for, these results warrant caution for
interpreting submillimetre source counts in cluster fields and point source
contamination for Sunyaev-Zel'dovich surveys. [Abridged]
09/2011;
-
M. J. Jee,
K. S. Dawson, H. Hoekstra,
S. Perlmutter,
P. Rosati,
M. Brodwin,
N. Suzuki,
B. Koester,
M. Postman,
L. Lubin, [......],
H. C. Ford,
D. G. Gilbank,
M. D. Gladders,
A. Gonzalez,
D. W. Harris,
X. Huang,
C. Lidman,
E. S. Rykoff,
D. Rubin,
and A. L. Spadafora
[show abstract]
[hide abstract]
ABSTRACT: We present weak gravitational lensing analysis of 22 high-redshift (z 1) clusters based on Hubble Space Telescope images. Most clusters in our sample provide significant lensing signals and are well detected in their reconstructed two-dimensional mass maps. Combining the current results and our previous weak-lensing studies of five other high-z clusters, we compare gravitational lensing masses of these clusters with other observables. We revisit the question whether the presence of the most massive clusters in our sample is in tension with the current ΛCDM structure formation paradigm. We find that the lensing masses are tightly correlated with the gas temperatures and establish, for the first time, the lensing mass-temperature relation at z 1. For the power-law slope of the M-TX relation (MT α), we obtain α = 1.54 ± 0.23. This is consistent with the theoretical self-similar prediction α = 3/2 and with the results previously reported in the literature for much lower redshift samples. However, our normalization is lower than the previous results by 20%-30%, indicating that the normalization in the M-TX relation might evolve. After correcting for Eddington bias and updating the discovery area with a more conservative choice, we find that the existence of the most massive clusters in our sample still provides a tension with the current ΛCDM model. The combined probability of finding the four most massive clusters in this sample after the marginalization over cosmological parameters is less than 1%.
The Astrophysical Journal 08/2011; 737(2):59. · 6.02 Impact Factor
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N. Suzuki,
D. Rubin,
C. Lidman,
G. Aldering,
R. Amanullah,
K. Barbary,
L. F. Barrientos,
J. Botyanszki,
M. Brodwin,
N. Connolly, [......],
S. A. Stanford,
V. Stanishev,
D. Stern,
M. Strovink,
N. Takanashi,
K. Tokita,
M. Wagner,
L. Wang,
N. Yasuda,
H. K. C. Yee
[show abstract]
[hide abstract]
ABSTRACT: We present ACS, NICMOS, and Keck AO-assisted photometry of 20 Type Ia
supernovae SNe Ia from the HST Cluster Supernova Survey. The SNe Ia were
discovered over the redshift interval 0.623 < z < 1.415. Fourteen of these SNe
Ia pass our strict selection cuts and are used in combination with the world's
sample of SNe Ia to derive the best current constraints on dark energy. Ten of
our new SNe Ia are beyond redshift $z=1$, thereby nearly doubling the
statistical weight of HST-discovered SNe Ia beyond this redshift. Our detailed
analysis corrects for the recently identified correlation between SN Ia
luminosity and host galaxy mass and corrects the NICMOS zeropoint at the count
rates appropriate for very distant SNe Ia. Adding these supernovae improves the
best combined constraint on the dark energy density \rho_{DE}(z) at redshifts
1.0 < z < 1.6 by 18% (including systematic errors). For a LambdaCDM universe,
we find \Omega_\Lambda = 0.724 +0.015/-0.016 (68% CL including systematic
errors). For a flat wCDM model, we measure a constant dark energy
equation-of-state parameter w = -0.985 +0.071/-0.077 (68% CL). Curvature is
constrained to ~0.7% in the owCDM model and to ~2% in a model in which dark
energy is allowed to vary with parameters w_0 and w_a. Tightening further the
constraints on the time evolution of dark energy will require several
improvements, including high-quality multi-passband photometry of a sample of
several dozen z>1 SNe Ia. We describe how such a sample could be efficiently
obtained by targeting cluster fields with WFC3 on HST.
The Astrophysical Journal 05/2011; 746(1). · 6.02 Impact Factor
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M. J. Jee,
K. S. Dawson, H. Hoekstra,
S. Perlmutter,
P. Rosati,
M. Brodwin,
N Suzuki,
B. Koester,
M. Postman,
L. Lubin, [......],
H. C. Ford,
D. G. Gilbank,
M. D. Gladders,
A. Gonzalez,
D. W. Harris,
X Huang,
C. Lidman,
E. S. Rykoff,
D. Rubin,
A. L. Spadafora
[show abstract]
[hide abstract]
ABSTRACT: We present weak gravitational lensing analysis of 22 high-redshift (z >~1)
clusters based on Hubble Space Telescope images. Most clusters in our sample
provide significant lensing signals and are well detected in their
reconstructed two-dimensional mass maps. Combining the current results and our
previous weak-lensing studies of five other high-z clusters, we compare
gravitational lensing masses of these clusters with other observables. We
revisit the question whether the presence of the most massive clusters in our
sample is in tension with the current LambdaCDM structure formation paradigm.
We find that the lensing masses are tightly correlated with the gas
temperatures and establish, for the first time, the lensing mass-temperature
relation at z >~ 1. For the power law slope of the M-TX relation (M propto
T^{\alpha}), we obtain \alpha=1.54 +/- 0.23. This is consistent with the
theoretical self-similar prediction \alpha=3/2 and with the results previously
reported in the literature for much lower redshift samples. However, our
normalization is lower than the previous results by 20-30%, indicating that the
normalization in the M-TX relation might evolve. After correcting for Eddington
bias and updating the discovery area with a more conservative choice, we find
that the existence of the most massive clusters in our sample still provides a
tension with the current Lambda CDM model. The combined probability of finding
the four most massive clusters in this sample after marginalization over
current cosmological parameters is less than 1%.
05/2011;
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[show abstract]
[hide abstract]
ABSTRACT: We introduce a novel method to measure the masses of galaxy clusters at high redshift selected from optical and IR Spitzer data via the red-sequence technique. Lyman-break galaxies are used as a well-understood, high-redshift background sample allowing mass measurements of lenses at unprecedented high redshifts using weak lensing magnification. By stacking a significant number of clusters at different redshifts with average masses of ~(1-3) × 1014 M ☉, as estimated from their richness, we can calibrate the normalization of the mass-richness relation. With the current data set (area: 6 deg2) we detect a magnification signal at the >3σ level. There is good agreement between the masses estimated from the richness of the clusters and the average masses estimated from magnification, albeit with large uncertainties. We perform tests that suggest the absence of strong systematic effects and support the robustness of the measurement. This method—when applied to larger data sets in the future—will yield an accurate calibration of the mass-observable relations at z 1 which will represent an invaluable input for cosmological studies using the galaxy cluster mass function and astrophysical studies of cluster formation. Furthermore, this method will probably be the least expensive way to measure masses of large numbers of z > 1 clusters detected in future IR-imaging surveys.
The Astrophysical Journal Letters 05/2011; 733(2):L30. · 5.53 Impact Factor
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N Suzuki,
D Rubin,
C Lidman,
G Aldering,
R Amanullah,
K Barbary,
L F Barrientos,
J Botyanszki,
M Brodwin,
N Connolly, [......],
S Perlmutter,
M Postman,
T Pritchard,
J Rhodes,
P Ripoche,
P Rosati,
D J Schlegel,
A Spadafora,
S A Stanford,
W M Keck
[show abstract]
[hide abstract]
ABSTRACT: We present ACS, NICMOS, and Keck AO-assisted photometry of 20 Type Ia supernovae (SNe Ia) from the HST Cluster Supernova Survey. The SNe Ia were discovered over the redshift interval 0.623 < z < 1.415. Fourteen of these SNe Ia pass our strict selection cuts and are used in combination with the world's sample of SNe Ia to derive the best current constraints on dark energy. Ten of our new SNe Ia are beyond redshift z = 1, thereby nearly doubling the statistical weight of HST-discovered SNe Ia beyond this redshift. Our detailed analysis corrects for the recently identified correlation between SN Ia luminosity and host galaxy mass and corrects the NICMOS zeropoint at the count rates appropriate for very distant SNe Ia. Adding these supernovae improves the best combined constraint on dark energy density, ρ DE (z), at redshifts 1.0 < z < 1.6 by 18% (including systematic errors). For a flat ΛCDM universe, we find Ω Λ = 0.729 +0.014 −0.014 (68% CL including systematic errors). For a flat wCDM model, we measure a constant dark energy equation-of-state parameter w = −1.013 +0.068 −0.073 (68% CL). Curvature is constrained to ∼ 0.7% in the owCDM model and to ∼ 2% in a model in which dark energy is allowed to vary with parameters w 0 and w a . Tightening further the constraints on the time evolution of dark energy will require several improvements, including high-quality multi-passband photometry of a sample of several dozen z > 1 SNe Ia. We describe how such a sample could be efficiently obtained by targeting cluster fields with WFC3 on HST.
N. PANAGIA. 04/2011; 27292528323839(43).
