46 research outputs found
XMMU J100750.5+125818: A strong lensing cluster at z=1.082
We report on the discovery of the X-ray luminous cluster XMMU
J100750.5+125818 at redshift 1.082 based on 19 spectroscopic members, which
displays several strong lensing features. SED modeling of the lensed arc
features from multicolor imaging with the VLT and the LBT reveals likely
redshifts ~2.7 for the most prominent of the lensed background galaxies. Mass
estimates are derived for different radii from the velocity dispersion of the
cluster members, M_200 ~ 1.8 10^{14} Msun, from the X-ray spectral parameters,
M_500 ~ 1.0 10^{14} Msun, and the largest lensing arc, M_SL ~ 2.3 10^{13} Msun.
The projected spatial distribution of cluster galaxies appears to be elongated,
and the brightest galaxy lies off center with respect to the X-ray emission
indicating a not yet relaxed structure. XMMU J100750.5+125818 offers excellent
diagnostics of the inner mass distribution of a distant cluster with a
combination of strong and weak lensing, optical and X-ray spectroscopy.Comment: A&A, accepted for publicatio
The x-ray luminous galaxy cluster population at 0.9 < z ≲ 1.6 as revealed by the XMM-Newton Distant Cluster Project*
We present the largest sample to date of spectroscopically confirmed x-ray luminous high-redshift galaxy clusters comprising 22 systems in the range 0.9 1.3. The median system mass of the sample is M 200 ≃ 2×10 14 M ⊙, while the probed mass range for the distant clusters spans approximately (0.7-7)×10 14 M ⊙. The majority (>70%) of the x-ray selected clusters show rather regular x-ray morphologies, albeit in most cases with a discernible elongation along one axis. In contrast to local clusters, the z > 0.9 systems mostly do not harbor central dominant galaxies coincident with the x-ray centroid position, but rather exhibit significant brightest cluster galaxy (BCG) offsets from the x-ray center with a median value of about 50 kpc in projection and a smaller median luminosity gap to the second-ranked galaxy of Δm 12 ≃ 0.3 mag. We estimate a fraction of cluster-associated NVSS 1.4 GHz radio sources of about 30%, preferentially located within 1' from the x-ray center. This value suggests an increase of the fraction of very luminous cluster-associated radio sources by about a factor of 2.5-5 relative to lowz systems. The galaxy populations in z ≳ 1.5 cluster environments show first evidence for drastic changes on the high-mass end of galaxies and signs of a gradual disappearance of a well-defined cluster red-sequence as strong star formation activity is observed in an increasing fraction of massive galaxies down to the densest core regions. The presented XDCP high-z sample will allow first detailed studies of the cluster population during the critical cosmic epoch at lookback times of 7.3-9.5Gyr on the aggregation and evolution of baryons in the cold and hot phases as a function of redshift and system mass
Exploring the galaxy cluster-group transition regime at high redshifts: Physical properties of two newly detected z > 1 systems
Context: Multi-wavelength surveys for clusters of galaxies are opening a
window on the elusive high-redshift (z>1) cluster population. Well controlled
statistical samples of distant clusters will enable us to answer questions
about their cosmological context, early assembly phases and the thermodynamical
evolution of the intracluster medium. Aims: We report on the detection of two
z>1 systems, XMMU J0302.2-0001 and XMMU J1532.2-0836, as part of the XMM-Newton
Distant Cluster Project (XDCP) sample. We investigate the nature of the
sources, measure their spectroscopic redshift and determine their basic
physical parameters. Methods: The results of the present paper are based on the
analysis of XMM-Newton archival data, optical/near-infrared imaging and deep
optical follow-up spectroscopy of the clusters. Results: We confirm the X-ray
source XMMU J0302.2-0001 as a gravitationally bound, bona fide cluster of
galaxies at spectroscopic redshift z=1.185. We estimate its M500 mass to
(1.6+/-0.3) times 10^{14} Msun from its measured X-ray luminosity. This ranks
the cluster among intermediate mass system. In the case of XMMU J1532.2-0836 we
find the X-ray detection to be coincident with a dynamically bound system of
galaxies at z=1.358. Optical spectroscopy reveals the presence of a central
active galactic nucleus, which can be a dominant source of the detected X-ray
emission from this system. We provide upper limits of X-ray parameters for the
system and discuss cluster identification challenges in the high-redshift
low-mass cluster regime. A third, intermediate redshift (z=0.647) cluster, XMMU
J0302.1-0000, is serendipitously detected in the same field as XMMU
J0302.2-0001. We provide its analysis as well.Comment: Accepted to A&A, 13/04/2011. 15 pages, 18 figures, 5 tables, 2
appendice
A pan-chromatic view of the galaxy cluster XMMU J1230.3+1339 at z=0.975 - Observing the assembly of a massive system
We present a comprehensive galaxy cluster study of XMMU J1230.3+1339 based on
a joint analysis of X-ray data, optical imaging and spectroscopy observations,
weak lensing results, and radio properties for achieving a detailed
multi-component view of this newly discovered system at z=0.975. We find an
optically very rich and massive system with
M200(4.20.8)10^14 M\sun, Tx5.3(+0.7--0.6)keV,
and Lx(6.50.7)10^44 erg/s, for which various widely used
mass proxies are measured and compared. We have identified multiple
cluster-related components including a central fly-through group close to core
passage with associated marginally extended 1.4GHz radio emission possibly
originating from the turbulent wake region of the merging event. On the cluster
outskirts we see evidence for an on-axis infalling group with a second
Brightest Cluster Galaxy (BCG) and indications for an additional off-axis group
accretion event. We trace two galaxy filaments beyond the nominal cluster
radius and provide a tentative reconstruction of the 3D-accretion geometry of
the system. In terms of total mass, ICM structure, optical richness, and the
presence of two dominant BCG-type galaxies, the newly confirmed cluster XMMU
J1230.3+1339 is likely the progenitor of a system very similar to the local
Coma cluster, differing by 7.6 Gyr of structure evolution.Comment: 26 pages, 14 color figures, accepted for publication in A&
First simultaneous optical/near-infrared imaging of an X-ray selected, high-redshift cluster of galaxies with GROND: the galaxy population of XMMU J0338.7+0030 at z=1.1
The XMM-Newton Distant Cluster Project is a serendipitous survey for clusters
of galaxies at redshifts z>=0.8 based on deep archival XMM-Newton observations.
... Low-significance candidate high-z clusters are followed up with the
seven-channel imager GROND (Gamma-Ray Burst Optical and Near-Infrared Detector)
that is mounted at a 2m-class telescope. ... The test case is XMMU
J0338.7+0030, suggested to be at z~1.45+/-0.15 from the analysis of the z-H vs
H colour-magnitude diagram obtained from the follow-up imaging. Later VLT-FORS2
spectroscopy enabled us to identify four members, which set this cluster at
z=1.097+/-0.002. To reach a better knowledge of its galaxy population, we
observed XMMU J0338.7+0030 with GROND for about 6 hr. The publicly available
photo-z code le Phare was used. The Ks-band number counts of the non-stellar
sources out of the 832 detected down to z'~26 AB-mag in the 3.9x4.3 square
arcmin region of XMMU J0338.7+0030 imaged at all GROND bands clearly exceed
those computed in deep fields/survey areas at ~20.5 - 22.5 AB-mag. The
photo-z's of the three imaged spectroscopic members yield z=1.12+/-0.09. The
spatial distribution and the properties of the GROND sources with a photo-z in
the range 1.01 - 1.23 confirm the correspondence of the X-ray source with a
galaxy over-density at a significance of at least 4.3 sigma. Candidate members
that are spectro-photometrically classified as elliptical galaxies define a red
locus in the i'-z' vs z' colour-magnitude diagram that is consistent with the
red sequence of the cluster RDCS J0910+5422 at z=1.106. XMMU J0338.7+0030 hosts
also a population of bluer late-type spirals and irregulars. The starbursts
among the photometric members populate both loci, consistently with previous
results. The analysis of the available data set indicates that XMMU
J0338.7+0030 is a low-mass cluster (M_200 ~ 1E14 M_sun) at z=1.1. (Abridged)Comment: accepted for publication in Astronomy & Astrophysics Main Journal, 27
pages, 24 figures, 1 tabl
Discovery of the X-ray selected galaxy cluster XMMU J0338.8+0021 at z = 1.49 - Indications for a young system with a forming brightest galaxy
We report on the discovery of a galaxy cluster at z = 1.490 originally
selected as an extended X-ray source in the XMM-Newton Distant Cluster Project.
Further observations carried out with the VLT-FORS2 spectrograph allowed the
spectroscopic confirmation of seven secure cluster members, providing a median
system redshift of z = 1.490 +/- 0.009. The color magnitude diagram of XMMU
J0338.8+0021 reveals the presence of a well populated red sequence with z-H ~
3, albeit with an apparent significant scatter in color. Since we do not detect
indications for strong star formation activity in any of the objects, the color
spread could indicate different stellar ages of the member galaxies. In
addition, we found the brightest cluster galaxy in a very active dynamical
state, with an interacting, merging companion located at a physical projected
distance of d ~ 20kpc. From the X-ray luminosity we estimate a cluster mass of
M200 ~ 1.2 x 10^(14) Msun. The data seem to suggest a scenario in which XMMU
J0338.8+0021 is a young system, possibly caught in a moment of active ongoing
mass assembly.Comment: 6 pages, 4 figures, 2 Table
Observational constraints on the redshift evolution of X-ray scaling relations of galaxy clusters out to z ~ 1.5
A precise understanding of the relations between observable X-ray properties
of galaxy clusters and cluster mass is a vital part of the application of X-ray
galaxy cluster surveys to test cosmological models. An understanding of how
these relations evolve with redshift is just emerging from a number of
observational data sets.
The current literature provides a diverse and inhomogeneous picture of
scaling relation evolution. We attempt to transform these results and the data
on recently discovered distant clusters into an updated and consistent
framework, and provide an overall view of scaling relation evolution.
We study in particular the M-T, L_X-T, and M-L_X relation combining 14
published data sets supplemented with recently published data of distant
clusters and new results from follow-up observations of the XMM-Newton Distant
Cluster Project (XDCP).
We find that the evolution of the M-T relation is consistent with the
self-similar prediction, while the evolution of X-ray luminosity for a given
temperature and mass for a given X-ray luminosity is slower than predicted. Our
best fit results for the evolution factor E(z)^alpha are alpha = -1.04+-0.07
for the M-T relation, alpha = -0.23+0.12-0.62 for the L-T relation, and alpha =
-0.93+0.62-0.12 for the M-L_X relation. We find that selection biases are the
most likely reason for apparent inconsistencies between different published
data sets.
The new results provide the currently most robust calibration of
high-redshift cluster mass estimates based on X-ray luminosity and temperature
and help us to improve the prediction of the number of clusters to be found in
future galaxy cluster X-ray surveys, such as eROSITA. The comparison of
evolution results with hydrodynamical cosmological simulations suggests that
early preheating of the intracluster medium provides the most suitable scenario
to explain the observed evolution.Comment: 24 pages, 18 figures, accepted for publication in A&
The XMM-BCS galaxy cluster survey: I. The X-ray selected cluster catalog from the initial 6 deg
The XMM-Newton - Blanco Cosmology Survey project (XMM-BCS) is a coordinated
X-ray, optical and mid-infrared cluster survey in a field also covered by
Sunyaev-Zel'dovich effect surveys by the South Pole Telescope and the Atacama
Cosmology Telescope. The aim of the project is to study the cluster population
in a 14 deg field.
In this work, we present a catalog of 46 X-ray selected clusters from the
initial 6 deg survey core. We describe the XMM-BCS source detection
pipeline and derive physical properties of the clusters. We provide photometric
redshift estimates derived from the BCS imaging data and spectroscopic redshift
measurements for a low redshift subset of the clusters. We derive the cluster
log N - log S relation using an approximation to the survey selection function
and find it in good agreement with previous studies. We carry out an initial
comparison between X-ray luminosity derived masses and masses from optical
estimators from the Southern Cosmology Survey for a subset of the cluster
sample. Optical masses based on cluster richness and total optical luminosity
are found to be significantly higher than the X-ray values.
(abridged)Comment: Accepted to A&A. Version with full resolution images and better
layout is available at the author or at A&A. 34 pages, 35 figures, 18 table
HE-LHC: The High-Energy Large Hadron Collider – Future Circular Collider Conceptual Design Report Volume 4
In response to the 2013 Update of the European Strategy for Particle Physics (EPPSU), the Future Circular Collider (FCC) study was launched as a world-wide international collaboration hosted by CERN. The FCC study covered an energy-frontier hadron collider (FCC-hh), a highest-luminosity high-energy lepton collider (FCC-ee), the corresponding 100 km tunnel infrastructure, as well as the physics opportunities of these two colliders, and a high-energy LHC, based on FCC-hh technology. This document constitutes the third volume of the FCC Conceptual Design Report, devoted to the hadron collider FCC-hh. It summarizes the FCC-hh physics discovery opportunities, presents the FCC-hh accelerator design, performance reach, and staged operation plan, discusses the underlying technologies, the civil engineering and technical infrastructure, and also sketches a possible implementation. Combining ingredients from the Large Hadron Collider (LHC), the high-luminosity LHC upgrade and adding novel technologies and approaches, the FCC-hh design aims at significantly extending the energy frontier to 100 TeV. Its unprecedented centre-of-mass collision energy will make the FCC-hh a unique instrument to explore physics beyond the Standard Model, offering great direct sensitivity to new physics and discoveries