Abstract
The variation of galaxy stellar masses and colour types with the distance to projected cosmic filaments are quantified using the precise photometric redshifts of the COSMOS2015 catalogue ...extracted from Cosmological Evolution Survey (COSMOS) field (2 deg2). Realistic mock catalogues are also extracted from the lightcone of the cosmological hydrodynamical simulation Horizon-AGN. They show that the photometric redshift accuracy of the observed catalogue (σz < 0.015 at M* > 1010M⊙ and z < 0.9) is sufficient to provide two-dimensional (2D) filaments that closely match their projected three-dimensional (3D) counterparts. Transverse stellar mass gradients are measured in projected slices of thickness 75 Mpc between 0.5 < z < 0.9, showing that the most massive galaxies are statistically closer to their neighbouring filament. At fixed stellar mass, passive galaxies are also found closer to their filament, while active star-forming galaxies statistically lie further away. The contributions of nodes and local density are removed from these gradients to highlight the specific role played by the geometry of the filaments. We find that the measured signal does persist after this removal, clearly demonstrating that proximity to a filament is not equivalent to proximity to an overdensity. These findings are in agreement with gradients measured in both 2D and 3D in the Horizon-AGN simulation and those observed in the spectroscopic surveys VIPERS and GAMA (which both rely on the identification of 3D filaments). They are consistent with a picture in which the influence of the geometry of the large-scale environment drives anisotropic tides that impact the assembly history of galaxies, and hence their observed properties.
The ΛCDM standard model, although an excellent parametrization of the present cosmological data, contains two as yet unobserved components, dark matter and dark energy, that constitute more than 95% ...of the Universe. Faced with this unsatisfactory situation, we study an unconventional cosmology, the Dirac-Milne universe, a matter-antimatter symmetric cosmology, in which antimatter is supposed to present a negative active gravitational mass. The main feature of this cosmology is the linear evolution of the scale factor with time, which directly solves the age and horizon problems of a matter-dominated universe. We study the concordance of this model to the cosmological test of type Ia supernovae distance measurements and calculate the theoretical primordial abundances of light elements for this cosmology. We also show that the acoustic scale of the cosmic microwave background naturally emerges at the degree scale despite an open geometry.
The COVID-19 pandemic was characterized by an abundance of information, some of it reliable and some of it misinformation. Evidence-based data on the impact of misinformation on attitudes and ...behaviours remains limited. Studies indicate that older adults are more likely to embrace and disseminate misinformation than other population groups, making them vulnerable to misinformation. The purpose of this article is to explore the effects of misinformation and information overload on older adults, and to present the management strategies put in place to deal with such effects, in the context of COVID-19.
A qualitative exploratory approach was adopted to conduct this research. A total of 36 semi-structured interviews were conducted with older adults living in Quebec, Canada. The interviews were fully transcribed and subjected to a thematic content analysis.
Participants said they could easily spot misinformation online. Despite this, misinformation and its treatment by the media could generate fear, stress and anxiety. Moreover, the polarization induced by misinformation resulted in tensions and even friendship breakdowns. Participants also denounced the information overload produced largely by the media. To this end, the participants set up information routines targeting the sources of information and the times at which they consulted the information.
This article questions the concept of vulnerability to misinformation by highlighting older adults' agency in managing misinformation and information overload. Furthermore, this study invites us to rethink communication strategies by distinguishing between information overload and misinformation.
•There is a paradox when using outsourcing as a mean to develop IT innovations.•A paradox means that conflicting sets of constraints are managed at the same time.•Managers can use roles, sequences, ...actors, or structures to manage the paradox.•Recognizing the paradox is key to understand how outsourcing can generate innovation.
This paper identifies the conditions that create a paradox when firms try to obtain innovation using outsourcing contracts. While outsourcing can be a way to obtain new ideas from business partners, most of the guidelines related to good contract management seem to deter innovative behavior. Managers trying to innovate using outsourcing are therefore facing two opposing sets of constraints, and have to manage both at the same time. In this paper, the nature of the “innovation through outsourcing” paradox is discussed in terms of the tensions between a contractual view of outsourcing and an innovation view of outsourcing, along with their associated reinforcing cycles. The paper outlines four mechanisms that are essentially self-correcting cycles. They include: 1) dual formal reviews; 2) matching governance with level of innovation focus; 3) dynamic decision-making/“extreme contracting”; and 4) ambidextrous organization. These can enable managers to deal with this paradox and obtain innovation from outsourcing arrangements in a successful manner. Complexities involved in implementing these mechanisms are discussed and some avenues for future research are offered.
Context.
Characterising the large-scale structure in the Universe from present times to the high redshift epoch of reionisation is essential to constraining the cosmology, the history of star ...formation, and reionisation, to measuring the gas content of the Universe, and to obtaining a better understanding of the physical processes that drive galaxy formation and evolution. Using the integrated emission from unresolved galaxies or gas clouds, line intensity mapping (LIM) provides a new observational window to measure the larger properties of structures. This very promising technique motivates the community to plan for LIM experiments.
Aims.
We describe the development of a large field-of-view instrument, named CONCERTO (for CarbON CII line in post-rEionisation and ReionisaTiOn epoch), operating in the range 130–310 GHz from the APEX 12-m telescope (5100 m above sea level). CONCERTO is a low-resolution spectrometer based on the lumped element kinetic inductance detectors (LEKID) technology. Spectra are obtained using a fast Fourier transform spectrometer (FTS), coupled to a dilution cryostat with a base temperature of 0.1 K. Two two kilo-pixel arrays of LEKID are mounted inside the cryostat that also contains the cold optics and the front-end electronics.
Methods.
We present, in detail, the technological choices leading to the instrumental concept, together with the design and fabrication of the instrument and preliminary laboratory tests on the detectors. We also give our best estimates for CONCERTO sensitivity and give predictions for two of the main scientific goals of CONCERTO, that is, a CII-intensity mapping survey and observations of galaxy clusters.
Results.
We provide a detailed description of the instrument design. Based on realistic comparisons with existing instruments developed by our group (NIKA, NIKA2, and KISS), and on the laboratory characterisation of our detectors, we provide an estimate for CONCERTO sensitivity on the sky. Finally, we describe, in detail, two of the main scientific goals offered by CONCERTO at APEX.
The prototype of the NIKA2 camera, NIKA, is a dual-band instrument operating at the IRAM 30-m telescope, which can observe the sky simultaneously at 150 and 260 GHz. One of the main goals of NIKA ...(and NIKA2) is to measure the pressure distribution in galaxy clusters at high angular resolution using the thermal Sunyaev-Zel’dovich (tSZ) effect. Such observations have already proved to be an excellent probe of cluster pressure distributions even at intermediate and high redshifts. However, an important fraction of clusters host sub-millimeter and/or radio point sources, which can significantly affect the reconstructed signal. Here we report on <20 arcsec angular resolution observations at 150 and 260 GHz of the cluster MACS J1423.8+2404, which hosts both radio and sub-millimeter point sources. We examine the morphological distribution of the tSZ signal and compare it to other datasets. The NIKA data are combined with Herschel satellite data to study the spectral energy distribution (SED) of the sub-millimeter point source contaminants. We then perform a joint reconstruction of the intracluster medium (ICM) electronic pressure and density by combining NIKA, Planck, XMM-Newton, and Chandra data, focusing on the impact of the radio and sub-millimeter sources on the reconstructed pressureprofile. We find that large-scale pressure distribution is unaffected by the point sources because of the resolved nature of the NIKA observations. The reconstructed pressure in the inner region is slightly higher when the contribution of point sources are removed. We show that it is not possible to set strong constraints on the central pressure distribution without accurately removing these contaminants. The comparison with X-ray only data shows good agreement for the pressure, temperature, and entropy profiles, which all indicate that MACS J1423.8+2404 is a dynamically relaxed cool core system. The present observations illustrate the possibility of measuring these quantities with a relatively small integration time, even at high redshift and without X-ray spectroscopy. This work is part of a pilot study aiming at optimizing tSZ observations with the future NIKA2 camera.
Context.
Large field-of-view imaging and polarimetry instruments operating at millimetre and sub-millimetre wavelengths are fundamental tools to understand the role of magnetic fields in channelling ...filament material into prestellar cores, providing unique insight in the physics of galactic star-forming regions. Among other topics, at extra-galactic scales, polarisation observations of Active Galactic Nuclei (AGNs) will allow us to constrain the possible physical conditions of the emitting plasma from the jets and/or explore the physics of dust inside supernova remnants. The kilo-pixel New IRAM KIDs Array 2 (NIKA2) camera, installed today at the Institut de Radioastronomie Millimétrique (IRAM) 30-m telescope, represents one of the best tools available to astronomers to produce simultaneous intensity and polarimetry maps over large fields at 260 GHz (1.15 mm).
Aims.
The polarisation measurement, in NIKA and NIKA2, is achieved by rapidly modulating the total incoming polarisation. In the end, this allows one to safely isolate the small science signal from the large, un-polarised, and strongly variable, atmospheric background.
Methods.
The polarisation modulation is achieved by inserting a fast rotating half-wave plate (HWP) in the optical beam. In order to allow wide field-of-view observations, the plate has to be large, with a diameter of 250 mm. The modulation of the polarised signal at 12 Hz also requires the waveplate to be sufficiently light. In addition, this key optical element has to exhibit optimal electromagnetic characteristics in terms of transmission and differential phase-shift. For this purpose, three metamaterial HWPs have been developed using the mesh-filter technology. The knowledge acquired in developing the first two single-band HWPs was used to achieve the more challenging performance requirements of the last dual-band HWP. The first and the third waveplates met the requirements for both the NIKA and NIKA2 instruments.
Results.
We first illustrate the design, the technical developments, the fabrication, and laboratory characterisation of the three mesh-HWPs. The deployment of two such elements in the NIKA and NIKA2 instruments at the 30-metre telescope is then described. We conclude with representative examples of astrophysical maps integrating polarimetry.
Background & Aims: Bone morphogenetic proteins (Bmps) are morphogens known to play key roles in gastrointestinal development and pathology. Most Bmps are produced primarily by the mesenchymal ...compartment and activate their signaling pathways following a paracrine or autocrine route. The aim of this study was to investigate the role of epithelial Bmp signaling in intestinal morphogenesis and maintenance of adult epithelial cell functions. Methods: With the use of tissue-specific gene ablation, we generated mice lacking the Bmp receptor type IA (Bmpr1a) exclusively in the intestinal epithelium. Bmpr1a mutant and control mice were sacrificed for histology, immunofluorescence, Western blot analysis, electron microscopy, and quantitative polymerase chain reaction. Results: As well as showing increased proliferation and altered intestinal epithelial morphology, Bmpr1a mutant mice revealed that epithelial Bmp signaling is associated with impaired terminal differentiation of cells from the secretory lineage but not with the determination of cell fate. Loss of Bmp signaling exclusively in the epithelial compartment is not sufficient for the initiation of the de novo crypt phenomenon associated with juvenile polyposis syndrome. Conclusions: Epithelial Bmp signaling plays an important role in the terminal differentiation of the intestinal secretory cell lineage but not in de novo crypt formation. These findings emphasize the importance of delineating the contribution of the stroma vs the epithelium in gastrointestinal physiology and pathology.
We detect the kinematic Sunyaev-Zel'dovich (kSZ) effect with a statistical significance of 4.2σ by combining a cluster catalogue derived from the first year data of the Dark Energy Survey with cosmic ...microwave background temperature maps from the South Pole Telescope Sunyaev-Zel'dovich Survey. This measurement is performed with a differential statistic that isolates the pairwise kSZ signal, providing the first detection of the large-scale, pairwise motion of clusters using redshifts derived from photometric data. By fitting the pairwise kSZ signal to a theoretical template, we measure the average central optical depth of the cluster sample,
$\bar{\tau }_e = (3.75 \pm 0.89)\times 10^{-3}$
. We compare the extracted signal to realistic simulations and find good agreement with respect to the signal to noise, the constraint on
$\bar{\tau }_e$
, and the corresponding gas fraction. High-precision measurements of the pairwise kSZ signal with future data will be able to place constraints on the baryonic physics of galaxy clusters, and could be used to probe gravity on scales ≳100 Mpc.
PDF
