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Weak-lensing Mass Bias in Merging Galaxy Clusters
No full textAlthough weak lensing (WL) is a powerful method to estimate a galaxy cluster mass without any dynamical assumptions, a model bias can arise when the cluster density profile departs from the assumed model profile. In a merging system, the bias is expected to become most severe because the constituent halos undergo significant structural changes. In this study, we investigate WL mass bias in binary cluster mergers using a suite of idealized hydrodynamical simulations. Realistic WL shear catalogs are generated by matching the source galaxy properties, such as intrinsic shape dispersion, measurement noise, source densities, etc., to those from Subaru and Hubble Space Telescope observations. We find that, with the typical mass–concentration (M–c) relation and the Navarro–Frenk–White profile, the halo mass bias depends on the time since the first pericenter passage and increases with the mass of the companion cluster. The time evolution of the mass bias is similar to that of the concentration, indicating that, to first order, the mass bias is modulated by the concentration change. For a collision between two ∼10¹⁵ M_⊙ clusters, the maximum bias amounts to ∼60%. This suggests that previous WL studies may have significantly overestimated the mass of the clusters in some of the most massive mergers. Finally, we apply our results to three merger cases: A2034, MACS J1752.0 + 4440, and ZwCl 1856.8 + 6616, and report their mass biases at the observed epoch, as well as their pre-merger masses, utilizing their merger shock locations as tracers of the merger phases
BICEP/Keck. XVI. Characterizing Dust Polarization through Correlations with Neutral Hydrogen
No full textWe characterize Galactic dust filaments by correlating BICEP/Keck and Planck data with polarization templates based on neutral hydrogen (H i) observations. Dust polarization is important for both our understanding of astrophysical processes in the interstellar medium (ISM) and the search for primordial gravitational waves in the cosmic microwave background (CMB). In the diffuse ISM, H i is strongly correlated with the dust and partly organized into filaments that are aligned with the local magnetic field. We analyze the deep BICEP/Keck data at 95, 150, and 220 GHz, over the low-column-density region of sky where BICEP/Keck has set the best limits on primordial gravitational waves. We separate the H i emission into distinct velocity components and detect dust polarization correlated with the local Galactic H i but not with the H i associated with Magellanic Stream i. We present a robust, multifrequency detection of polarized dust emission correlated with the filamentary H i morphology template down to 95 GHz. For assessing its utility for foreground cleaning, we report that the Hi morphology template correlates in B modes at a ∼10%–65% level over the multipole range 20 ℓ < 200 with the BICEP/Keck maps, which contain contributions from dust, CMB, and noise components. We measure the spectral index of the filamentary dust component spectral energy distribution to be β = 1.54 ± 0.13. We find no evidence for decorrelation in this region between the filaments and the rest of the dust field or from the inclusion of dust associated with the intermediate velocity H i. Finally, we explore the morphological parameter space in the H i-based filamentary model
Shaking table tests for seismic stability of stacked concrete blocks used for radiation shielding
No full textThis paper describes the shaking table tests carried out at the European Centre for Training and Research in Earthquake Engineering (EUCENTRE) to investigate the seismic behaviour of four configurations of stacked concrete blocks, commonly used at the European Organisation for Nuclear Research (CERN) as a shielding barrier against different types of radiation. The blocks used for these configurations have been designed to guarantee an adequate level of protection to radiation and, at the same time, to be easily transported and managed for different installations. The block configuration specimens have been tested using the acceleration time-histories of two different earthquakes occurred in the Mediterranean region. Each configuration has been tested several times with acceleration amplitude increments until rigid kinematisms are triggered. This paper presents the test setup and inputs, the related experimental readings and the main results obtained by these tests. The two main mechanisms observed at the interfaces between the blocks during the tests were sliding and rocking. The data collected at the end of the experimental campaign constitute an important source to calibrate different discrete-system-models, in order to study the seismic response of block configurations used for radiation protection in particle physics research institutions
Total Synthesis of Strempeliopidine and Non-Natural Stereoisomers through a Convergent Petasis Borono-Mannich Reaction
No full textStrempeliopidine is a member of the monoterpenoid bisindole alkaloid family, a class of natural products that have been shown to elicit an array of biological responses including modulating protein–protein interactions in human cancer cells. Our synthesis of strempeliopidine leverages palladium-catalyzed decarboxylative asymmetric allylic alkylations to install the requisite all-carbon quaternary centers found in each of the two monomeric natural products, aspidospermidine and eburnamine. Initial studies employing Suzuki–Miyaura cross-coupling followed by diastereoselective hydrogenation provided evidence for a structural reassignment of the natural product. Our final synthetic sequence employs a diastereoselective Petasis borono–Mannich reaction to couple eburnamine to a trifluoroborate aspidospermidine derivative. These convergent approaches enabled the synthesis of eight diastereomers of this heterodimer and offer support for the reassignment of the absolute configuration of strempeliopidine
Lobbyists as Gatekeepers: Theory and Evidence
No full textLobbyists are omnipresent in the policy-making process, but the value that they bring to both clients and politicians remains poorly understood. We develop a model in which a lobbyist’s value derives from his ability to selectively screen which clients he brings to a politician, thereby earning the politician’s trust and preferential treatment for his clients. Lobbyists face a dilemma, as their ability to screen also increases their value to special interests and the prices they can charge. A lobbyist’s profit motive undermines his ability to solve this dilemma, but an interest in policy outcomes—due to either a political ideology or a personal connection—enhances it, which paradoxically increases his profits. Using a unique data set from reports mandated by the Foreign Agents Registration Act, we find that lobbyists become more selective when they are more ideologically aligned with politicians, consistent with our prediction
Probing neutron-star matter in the lab: Similarities and differences between binary mergers and heavy-ion collisions
No full textBinary neutron-star mergers and heavy-ion collisions are related through the properties of the hot and dense nuclear matter formed during these extreme events. In particular, low-energy heavy-ion collisions offer exciting prospects to recreate such extreme conditions in the laboratory. However, it remains unexplored to what degree those collisions can actually reproduce hot and dense matter formed in binary neutron star mergers. As a way to understand similarities and differences between these systems, we discuss their geometry and perform a direct numerical comparison of the thermodynamic conditions probed in both collisions. To enable a direct comparison, we employ a finite-temperature equation of state able to describe the entire high-energy phase diagram of quantum chromodynamics. Putting side by side the evolution of both systems, we find that laboratory heavy-ion collisions at the energy range of E_(lab) = 0.4–0.6 A MeV probe (thermodynamic) states of matter that are very similar to those created in binary neutron-star mergers. These results can inform future low-energy heavy-ion collisions probing this regime
Theoretical and Experimental Constraints for the Equation of State of Dense and Hot Matter
No full textThis review aims at providing an extensive discussion of modern constraints relevant for dense and hot strongly interacting matter. It includes theoretical first-principle results from lattice and perturbative QCD, as well as chiral effective field theory results. From the experimental side, it includes heavy-ion collision and low-energy nuclear physics results, as well as observations from neutron stars and their mergers. The validity of different constraints, concerning specific conditions and ranges of applicability, is also provided
Existence of infinitely many minimal hypersurfaces in closed manifolds
No full textUsing min-max theory, we show that in any closed Riemannian manifold of dimension at least 3 and at most 7, there exist infinitely many smoothly embedded closed minimal hypersurfaces. It proves a conjecture of S.-T. Yau. This paper builds on the methods developed by F. C. Marques and A. Neves
Broad Emission Lines in Optical Spectra of Hot, Dust-obscured Galaxies Can Contribute Significantly to JWST/NIRCam Photometry
No full textSelecting the first galaxies at z > 7 − 10 from JWST surveys is complicated by z z 7–10 Lyman-break galaxies (LBGs). Dust-obscured 3 z z − 1.5 and z > 4. While there are some redshifts (z ∼ 3.75) where our stack is more degenerate with the photometry of z > 10 LBGs at λ_(rest) ∼ 0.3–0.8 μm , redder filter coverage beyond λ_(obs) > 3.5 μm and far-IR/submillimeter follow-up may be useful for breaking the degeneracy and making a crucial separation between two fairly unconstrained populations, dust-obscured galaxies at z ∼ 3–6 and LBGs at z > 10
Cryptic Chemical Variation in a Marine Red Alga as Revealed by Nontargeted Metabolomics
No full textMany marine algae occupy habitats that are dark, deep, or encrusted on other organisms and hence are frequently overlooked by natural product chemists. However, exploration of less-studied organisms can lead to new opportunities for drug discovery. Genetic variation at the individual, species, genus, and population levels as well as environmental influences on gene expression enable expansion of the chemical repertoire associated with a taxonomic group, enabling natural product exploration using innovative analytical methods. A nontargeted LC-MS and ¹H NMR spectroscopy-based metabolomic study of 32 collections of representatives of the calcareous red algal genus Peyssonnelia from coral reef habitats in Fiji and the Solomon Islands revealed significant correlations between natural products’ chemistry, phylogeny, and biomedically relevant biological activity. Hierarchical cluster analysis (HCA) of LC-MS data in conjunction with NMR profiling and MS/MS-based molecular networking revealed the presence of at least four distinct algal chemotypes within the genus Peyssonnelia. Two Fijian collections were prioritized for further analysis, leading to the isolation of three novel sulfated triterpene glycosides with a rearranged isomalabaricane carbon skeleton, guided by the metabolomic data. The discovery of peyssobaricanosides A–C (15–17) from two Fijian Peyssonnelia collections, but not from closely related specimens collected in the Solomon Islands that were otherwise chemically and phylogenetically very similar, alludes to population-level variation in secondary metabolite production. Our study reinforces the significance of exploring unusual ecological niches and showcases marine red algae as a chemically rich treasure trove