Multi-probe analysis of the galaxy cluster CL J1226.9+3332: Hydrostatic mass and hydrostatic-to-lensing bias

We present a multi-probe analysis of the well-known galaxy cluster CL J1226.9+3332 as a proof of concept for multi-wavelength studies within the framework of the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ). CL J1226.9+3332 is a massive and high redshift (z = 0.888) cluster that has already been observed at several wavelengths. A joint analysis of the thermal SZ (tSZ) effect at millimeter wavelength with the NIKA2 camera and in X-ray with the XMM-Newton satellite permits the reconstruction of the cluster’s thermodynamical properties and mass assuming hydrostatic equilibrium. We test the robustness of our mass estimates against different definitions of the data analysis transfer function. Using convergence maps reconstructed from the data of the CLASH program we obtain estimates of the lensing mass, which we compare to the estimated hydrostatic mass. This allows us to measure the hydrostatic-to-lensing mass bias and the associated systematic effects related to the NIKA2 measurement. We obtain M500HSE = (7:65 ± 1:03) × 1014M⊙ and M500lens = (7:35 ± 0:65) × 1014M⊙, which implies a HSE-to-lensing bias consistent with 0 within 20%.

PSZ2 G091: A massive double cluster at z ~ 0.822 observed by the NIKA2 camera

PSZ2 G091.83+26.11 is a massive galaxy cluster with M500 = 7:43 × 1014M⊙ at z = 0:822. This object exhibits a complex morphology with a clear bimodality observed in X-rays. However, it was detected and analysed in the Planck sample as a single, spherical cluster following a universal profile [1]. This model can lead to miscalculations of thermodynamical quantities, like the pressure profile. As future multiwavelength cluster experiments will detect more and more objects at higher redshifts (where we expect the fraction of merging objects to be higher), it is crucial to quantify this systematic effect. In this work, we use high-resolution observations of PSZ2 G091.83+26.11 by the NIKA2 camera to integrate the morphological characteristics of the cluster in our modelling. This is achieved by fitting a two-halo model to the SZ image and then by reconstruction of the resulting projected pressure profile. We then compare these results with the spherical assumption.

The LPSZ-CLASH galaxy cluster sample: Combining lensing and hydrostatic mass estimates

Starting from the clusters included in the NIKA sample and in the NIKA2 Sunyaev-Zel’dovich Large Program (LPSZ) we have selected a sample of six common objects with the Cluster Lensing And Supernova survey with Hubble (CLASH) lensing data. For the LPSZ clusters we have at our disposal both high-angular resolution observations of the thermal SZ with NIKA and NIKA2 and X-ray observations with XMM-Newton from which hydrostatic mass estimates can be derived. In addition, the CLASH dataset includes lensing convergence maps that can be converted into lensing estimates of the total mass of the cluster. One-dimensional mass profiles are used to derive integrated mass estimates accounting for systematic effects (data processing, modeling, etc.). Two-dimensional analysis of the maps can reveal substructures in the cluster and, therefore, inform us about the dynamical state of each system. Moreover, we are able to study the hydrostatic mass to lensing mass bias, across different morphology and a range of redshift clusters to give more insight on the hydrostatic mass bias. The analysis presented in this proceeding follows the study discussed in [20].

Mapping the gas thermodynamic properties of the massive cluster merger MOO J1142+1527 at z = 1.2

We present the results of the analysis of the very massive cluster MOO J1142+1527 at a redshift z = 1.2 based on high angular resolution NIKA2 Sunyaev-Zel’dovich (SZ) andChandraX-ray data. This multi-wavelength analysis enables us to estimate the shape of the temperature profile with unprecedented precision at this redshift and to obtain a map of the gas entropy distribution averaged along the line of sight. The comparison between the cluster morphological properties observed in the NIKA2 andChandramaps together with the analysis of the entropy map allows us to conclude that MOOJ1142+1527 is an on-going merger hosting a cool-core at the position of the X-ray peak. This work demonstrates how the addition of spatially-resolved SZ observations to low signal-to-noise X-ray data can bring valuable insights on the intracluster medium thermodynamic properties atz>1.

Joint analysis of BICEP2/keck array and Planck Data

We report the results of a joint analysis of data from BICEP2/Keck Array and Planck. BICEP2 and Keck Array have observed the same approximately 400  deg^{2} patch of sky centered on RA 0 h, Dec. -57.5°. The combined maps reach a depth of 57 nK deg in Stokes Q and U in a band centered at 150 GHz. Planck has observed the full sky in polarization at seven frequencies from 30 to 353 GHz, but much less deeply in any given region (1.2  μK deg in Q and U at 143 GHz). We detect 150×353 cross-correlation in B modes at high significance. We fit the single- and cross-frequency power spectra at frequencies ≥150  GHz to a lensed-ΛCDM model that includes dust and a possible contribution from inflationary gravitational waves (as parametrized by the tensor-to-scalar ratio r), using a prior on the frequency spectral behavior of polarized dust emission from previous Planck analysis of other regions of the sky. We find strong evidence for dust and no statistically significant evidence for tensor modes. We probe various model variations and extensions, including adding a synchrotron component in combination with lower frequency data, and find that these make little difference to the r constraint. Finally, we present an alternative analysis which is similar to a map-based cleaning of the dust contribution, and show that this gives similar constraints. The final result is expressed as a likelihood curve for r, and yields an upper limit r_{0.05}<0.12 at 95% confidence. Marginalizing over dust and r, lensing B modes are detected at 7.0σ significance.

Model for injury to the foreleg of the Thoroughbred racehorse

A discussion is presented of contributing factors to the injury to the foreleg of the Thoroughbred racehorse. The critical part of the step is taken to be the first 10-20 ms after ground contact as the hoof slides forward and stops. Large nonaxial loads associated with the deceleration of the hoof are shown to arise. Results of accelerometer measurements on the hoof of a horse running at racing speed are presented as well as mechanical properties of the racing surface. The mechanical properties of the track surface, the type of shoe, and the degree of fatigue of the horse all work together to determine the level of risk.

Ultrasonic measurement of immobilization-induced osteopenia: an experimental study in sheep

An animal model was used to examine the use of noninvasive transmission ultrasound to measure changes in bone mass which occur following disuse. Unilateral achilles tenectomy was performed on the left leg of eight adult sheep. Following a 12-week period of nonweight bearing, presacrifice transmission ultrasound measurements were taken across the calcanei of the intact and the experimental limbs and compared with those values taken postoperatively. Following specimen harvest, cross-sectional areas of the bones were quantified by microradiography and stereology, and compared with the in vivo ultrasound measurements. There was an average of 8.6% less total bone area, and 18.0% less trabecular volume fraction in the experimental nonweight-bearing limbs as compared with control intact calcanei. The difference in bone mass was associated with a 9.0% decrease in the velocity of sound from the postoperative to the presacrifice ultrasound measurements taken from the experimental calcanei, and a 2.3% increase in the control calcanei. The velocity of sound was found by the Student's t test to be a highly reliable discriminator between the experimental and control limbs.

The use of ultrasound in vivo to determine acute change in the mechanical properties of bone following intense physical activity

The velocity of ultrasound was measured transcutaneously across the patella and tibia in 98 volunteers both before and after running the 26 mile Boston Marathon. Absolute sound velocities were 2.9% higher in those runners finishing before 3 h when compared to runners finishing after 3 h. Tibial velocities in males were 8.8% higher than in female runners. The mean velocity across the patella of three wheelchair racers was 28% lower than the mean combined patella velocity measured in all runners. These data suggest that 'faster' velocities are associated with bone that is better suited for high functional demands. Surprisingly, when pre- and post-race velocities were compared in each runner, there was a 1.6% increase in ultrasonic velocity across the tibia, and a 3.5% increase across the patella. An increase in ultrasonic velocity following extreme physical activity suggests that adaptive mechanisms exist in healthy bone to withstand, or possibly avoid, the microdamage which might be caused by repetitive cyclic loading.

An Evaluation of Total Hip Replacement Cementing Technique Using Sonic Resonance

The feasibility of assessing the quality of the bond achieved by cement fixation of implants by their sonic characteristics was examined by theoretical and experimental models. Mechanical excitation of implants in the audio sonic range in vitro produced experimental results that were in close agreement with computer predicted values. The sonic technique was utilized to evaluate certain aspects of current surgical technique using in vitro models. By sonic criteria, steady state polymerization of surgical simplex cement occurs approximately eleven minutes after hand held cement has cured. The value of meticulous preparation of bone surfaces prior to cement introduction is confirmed. Differences in the quality of bond obtained by variations in cement technique, or recementing to old cement, can be distinguished by this method. These results suggest that sonic assessment may provide a more sensitive measure of the quality of bond achieved than does roentgen examination. In clinical use, both intra-operatively and post-operatively, application of this technique may yield an immediate assessment of the quality of cement fixation.

A relationship between gait and breakdown in the horse

A biomechanical model of running has been presented. A basic premise has been that the swing time is nearly independent of speed. In fact, both the racehorse and the trotter have nearly equal swing times. Consequently, as speed increases and the stance phase becomes shorter, the horse must compensate by increasing his extension or the length of the airborne phase (or both). The safe speed which allows the horse adequate preparation time for contact of a leg with the ground is calculated, using a stride-by-stride analysis of the motion of the horse. This is seen to be a very sensitive function of the overlap time in the gait. The overlap between the legs appears to affect both the ultimate performance potential of the horse and also his prospects for soundness.

Force plate studies of equine biomechanics

The force plate can measure a wide range of effects in the horse. The same instrument can record forces from more than a ton in the galloping animal to 25 g associated with the action of the heart. In all probability, the force plate will develop into a valuable clinical instrument.

Colles' fractures. Functional bracing in supination

The classic position of immobilization of Colles' fractures with the elbow in flexion, the forearm in pronation, and the wrist in volar flexion and ulnar deviation is probably the main reason for the common and rapid recurrence of the original deformity. Such a position places the brachioradialis muscle, a strong flexor of the elbow and the only muscle attached to the distal fracture fragment, in an ideal physiological position to exert a deforming force on the fracture fragments. Based on this assumption, further supported by electromyographic studies, a method of treatment was developed which calls for the initial immobilization of the arm in an above-the-elbow cast with the elbow in flexion, the forearm in supination, and the wrist inmoderate ulnar and volar flexion. This cast is changed a few days after application for an Orthoplast brace that permits motion of the elbow and volar flexion of the wrist while preventing pronation and supination of the forearm and dorsiflexion of the wrist. The proposed method did not prevent collapse of the fragments in all instances. However, the degree of collapse was minimum. The position of supination of the forearm and the freedom of motion of all joints seemed to reduce the swelling, stiffness, and incapacitation frequently found during active treatment of these fractures.