We use data from the ESA Gaia mission Early Data Release 3 (EDR3) to measure the trigonometric parallax of ω Cen, the first high-precision parallax measurement for the most massive globular cluster in the Milky Way. We use a combination of positional and high-quality proper motion data from EDR3 to identify over 100,000 cluster members, of which 67,000 are in the magnitude and color range where EDR3 parallaxes are best calibrated. We find the estimated parallax to be robust, demonstrating good control of systematics within the color–magnitude diagram of the cluster. We find a parallax for the cluster of 0.191 ± 0.001 (statistical) ±0.004 (systematic) mas (2.2% total uncertainty) corresponding to a distance of 5.24 ± 0.11 kpc. The parallax of ω Cen provides a unique opportunity to directly and geometrically calibrate the luminosity of the tip of the red giant branch (TRGB) because it is the only cluster with sufficient mass to provide enough red giant stars, more than 100 one magnitude below the tip, for a precise, model-free measurement of the tip. Combined with the preexisting and most widely used measurements of the tip and foreground Milky Way extinction, we find M I,TRGB =−3.97 ± 0.06 mag for the I-band luminosity of the blue edge. Using the TRGB luminosity calibrated from the Gaia EDR3 parallax of ω Cen to calibrate the luminosity of Type Ia supernovae results in a value for the Hubble constant of H 0 = 72.1 ± 2.0 km s−1 Mpc−1. We make the data for the stars in ω Cen available electronically and encourage independent analyses of the results presented here.
We propose and implement a novel, robust, and non-parametric test of statistical isotropy of the expansion of the universe, and apply it to around one thousand type Ia supernovae from the Pantheon sample. We calculate the angular clustering of supernova magnitude residuals and compare it to the noise expected under the isotropic assumption. We also test for systematic effects and demonstrate that their effects are negligible or are already accounted for in our procedure. We express our constraints as an upper limit on the rms spatial variation in the Hubble parameter at late times. For the sky smoothed with a Gaussian with FWHM = 60 • , less than 1% rms spatial variation in the Hubble parameter is allowed at 99.7% confidence.
We evaluate the effectiveness of deep learning (DL) models for reconstructing the masses of galaxy clusters using X-ray photometry data from next-generation surveys. We establish these constraints using a catalogue of realistic mock eROSITA X-ray observations which use hydrodynamical simulations to model realistic cluster morphology, background emission, telescope response, and AGN sources. Using bolometric X-ray photon maps as input, DL models achieve a predictive mass scatter of $\sigma _{\ln M_\mathrm{500c}} = 17.8~{{\%}}$, a factor of two improvements on scalar observables such as richness Ngal, 1D velocity dispersion σv, 1D, and photon count Nphot as well as a 32% improvement upon idealised, volume-integrated measurements of the bolometric X-ray luminosity LX. We then show that extending this model to handle multichannel X-ray photon maps, separated in low, medium, and high energy bands, further reduces the mass scatter to 16.2%. We also tested a multimodal DL model incorporating both dynamical and X-ray cluster probes and achieved marginal gains at a mass scatter of 15.9%. Finally, we conduct a quantitative interpretability study of our DL models and find that they greatly down-weight the importance of pixels in the centres of clusters and at the location of AGN sources, validating previous claims of DL modelling improvements and suggesting practical and theoretical benefits for using DL in X-ray mass inference.
This chapter discusses special construction in the following areas: building modules, manufactured—fabricated rooms, special structures, manufactured engineered structures, special function construction, special facilities components and athletic and recreation special construction. Steel mobile buildings are much stronger than fiberglass units because of the construction—most frequently they are continuously welded 6 by 6 in., 4 by 4 in., or 2 by 4 in. Speed of construction and low initial cost are the main advantages of mobile modules; moreover, on‐site labor requirements are minimal. Isolated rooms incorporate special construction to reduce intrusive noise and vibration from outside a room or to contain the sound and impact energy generated within a room. The most effective floor construction is a floating concrete slab, which is separated from the building structure by steel springs, neoprene, or glass‐fiber isolation mounts. Designating responsibility for engineering, fabrication, and construction may allow better cost control.
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