Clash-VLT: Insights on the mass substructures in the frontier fields cluster MACS J0416.1-2403 through accurate strong lens modeling

We present a detailed mass reconstruction and a novel study on the substructure properties in the core of the Cluster Lensing And Supernova survey with Hubble (CLASH) and Frontier Fields galaxy cluster MACS J0416.1\u20132403. We show and employ our extensive spectroscopic data set taken with the VIsible Multi-Object Spectrograph instrument as part of our CLASH-VLT program, to confirm spectroscopically 10 strong lensing systems and to select a sample of 175 plausible cluster members to a limiting stellar mass of log (M */M &09) ~= 8.6. We reproduce the measured positions of a set of 30 multiple images with a remarkable median offset of only 0.''3 by means of a comprehensive strong lensing model comprised of two cluster dark-matter halos, represented by cored elliptical pseudo-isothermal mass distributions, and the cluster member components, parameterized with dual pseudo-isothermal total mass profiles. The latter have total mass-to-light ratios increasing with the galaxy HST/WFC3 near-IR (F160W) luminosities. The measurement of the total enclosed mass within the Einstein radius is accurate to ~5%, including the systematic uncertainties estimated from six distinct mass models. We emphasize that the use of multiple-image systems with spectroscopic redshifts and knowledge of cluster membership based on extensive spectroscopic information is key to constructing robust high-resolution mass maps. We also produce magnification maps over the central area that is covered with HST observations. We investigate the galaxy contribution, both in terms of total and stellar mass, to the total mass budget of the cluster. When compared with the outcomes of cosmological N-body simulations, our results point to a lack of massive subhalos in the inner regions of simulated clusters with total masses similar to that of MACS J0416.1\u20132403. Our findings of the location and shape of the cluster dark-matter halo density profiles and on the cluster substructures provide intriguing tests of the assumed collisionless, cold nature of dark matter and of the role played by baryons in the process of structure formation. This work is based in large part on data collected at ESO VLT (prog. ID 186.A-0798) and NASA HST

Mass and environment as drivers of galaxy evolution in SDSS and zCOSMOS and the origin of the Schechter function

We explore the inter-relationships between mass, star-formation rate and environment in the SDSS, zCOSMOS and other surveys. The differential effects of mass and environment are completely separable to z ~ 1, indicating that two distinct processes are operating, "mass-quenching" and "environment-quenching". Environment-quenching, at fixed over-density, evidently does not change with epoch to z ~ 1, suggesting that it occurs as large-scale structure develops in the Universe. The observed constancy of the mass-function shape for star-forming galaxies, demands that the mass-quenching of galaxies around and above M*, must be proportional to their star-formation rates at all z < 2. We postulate that this simple mass-quenching law also holds over a much broader range of stellar mass and epoch. These two simple quenching processes, plus some additional quenching due to merging, then naturally produce (a) a quasi-static Schechter mass function for star-forming galaxies with a value of M* that is set by the proportionality between the star-formation and mass-quenching rates, (b) a double Schechter function for passive galaxies with two components: the dominant one is produced by mass-quenching and has exactly the same M* as the star-forming galaxies but an alpha shallower by +1, while the other is produced by environment effects and has the same M* and alpha as the star-forming galaxies, and is larger in high density environments. Subsequent merging of quenched galaxies modifies these predictions somewhat in the denser environments, slightly increasing M* and making alpha more negative. All of these detailed quantitative relationships between the Schechter parameters are indeed seen in the SDSS, lending strong support to our simple empirically-based model. The model naturally produces for passive galaxies the "anti-hierarchical" run of mean ages and alpha-element abundances with mass.Comment: 66 pages, 19 figures, 1 movie, accepted for publication in ApJ. The movie is also available at http://www.exp-astro.phys.ethz.ch/zCOSMOS/MF_simulation_d1_d4.mo

zCOSMOS survey galaxy groups: exploring the effect of group environment on galaxy properties

The evolution of galaxies in groups may have important implications for the global evolution of the galaxy population as a whole. The fraction of galaxies bound in groups at z ∼ 0 is as high as 60% and many processes operating in groups may concur in shaping galaxy evolution. The rich zCOSMOS spectroscopic data (about 20000 galaxies with IAB ≤ 22.5 up to z ∼ 1) and its excellent group catalog (∼ 200 groups with more that 5 members up to z ∼ 1) coupled with the wide photometric coverage of the COSMOS survey, can shed new light on this topic, enabling us to study in a continuous way, up to z ∼ 1, the complex interplay between environment and galaxy evolution. In this thesis I present the new results I have obtained on this topic by exploring the group-centric dependence of galaxy colors, masses, morphologies and star formation. In brief, by building two composite groups at intermediate (0.2 ≤ z ≤ 0.45) and high (0.45 < z ≤ 0.8) redshifts, I was able to study in detail how galaxy stellar masses, colors, morphologies, and spectral features vary as a function of the distance from the group center. My analysis was performed in narrow bin of stellar masses/colors, in order to disentangle the obvious galaxy stellar mass/color dependencies. To build the composite group I developed an algorithm to incorporate the galaxies brighter than IAB = 22.5 and missing a secure spectroscopic redshift, thus improving the statistics of the sample. To confidently determine all galaxy projected distance and rescale them into the composite group, I defined a new centering technique. From the color/mass analysis I found that the evolution of most massive galaxies (log(Mgal/M⊙) > 10.6) is mainly driven by internal processes, as no strong group-centric environment dependence is visible. For galaxies of lower masses (9.8 ≤ log(Mgal/M⊙) ≤ 10.6) there is a radial depen- dence in the changing mix of red and blue galaxies, red galaxies residing preferentially in the group center. Such dependence is most evident in poor groups, whereas richer groups do not display any obvious color trend. Interestingly mass segregation shows the opposite behavior: it is visible only in rich groups, while poorer groups have a a constant mix of galaxy stellar masses as a function of radius. The morpho-spectral analysis showed the presence of a mild morphological segregation at fixed galaxy stellar mass, with massive early-type galaxies preferentially located in the core of groups. Galaxies with 9.8 ≤ log(Mgal/M⊙) ≤ 10.6 exhibit the strongest morphological differences between group and field environment. These galaxies also have an excess of red-passive spirals in the group with respect to the field. Despite the presence of a significant segregation of the spectral properties of group galaxies, such that the typical core galaxy have less intense emission lines, the star forming galaxies share the same level of activity at fixed stellar mass irrespective of the environment they reside in. This findings can be explained in a simple scenario where color/SFR and mass segregation originates from different physical processes. Mass segregation is driven by dynamical phenomena within groups, and therefore its presence/absence in rich/poor groups is a possible indication that poorer groups start to assemble later in cosmic time than richer structures. The parallel absence/presence of color segregation in rich/poor groups hints to the fact that nurture effects are still in action in poorer structures, whereas in richer systems are already largely over, so that all galaxies are red irrespective of their position within the group (at least down to the galaxy stellar masses we explored). Poorer groups hold the smoking gun of environmental effects in action superimposed to secular galaxy evolution: galaxies display gradually redder colors as a consequence of the still recent accretion history of these groups. The physical processes causing these environmental effects should act on rather short timescales, 1.5-2 Gyrs, because they are not able to erase the strinking bi-modality of galaxy color distribution and, moreover, we are not able to observed blue active galaxies showing less intense star formation activity in groups than in the field

zCOSMOS survey galaxy groups: exploring the effect of group environment on galaxy properties

The evolution of galaxies in groups may have important implications for the global evolution of the galaxy population as a whole. The fraction of galaxies bound in groups at z ∼ 0 is as high as 60% and many processes operating in groups may concur in shaping galaxy evolution. The rich zCOSMOS spectroscopic data (about 20000 galaxies with IAB ≤ 22.5 up to z ∼ 1) and its excellent group catalog (∼ 200 groups with more that 5 members up to z ∼ 1) coupled with the wide photometric coverage of the COSMOS survey, can shed new light on this topic, enabling us to study in a continuous way, up to z ∼ 1, the complex interplay between environment and galaxy evolution. In this thesis I present the new results I have obtained on this topic by exploring the group-centric dependence of galaxy colors, masses, morphologies and star formation. In brief, by building two composite groups at intermediate (0.2 ≤ z ≤ 0.45) and high (0.45 < z ≤ 0.8) redshifts, I was able to study in detail how galaxy stellar masses, colors, morphologies, and spectral features vary as a function of the distance from the group center. My analysis was performed in narrow bin of stellar masses/colors, in order to disentangle the obvious galaxy stellar mass/color dependencies. To build the composite group I developed an algorithm to incorporate the galaxies brighter than IAB = 22.5 and missing a secure spectroscopic redshift, thus improving the statistics of the sample. To confidently determine all galaxy projected distance and rescale them into the composite group, I defined a new centering technique. From the color/mass analysis I found that the evolution of most massive galaxies (log(Mgal/M⊙) > 10.6) is mainly driven by internal processes, as no strong group-centric environment dependence is visible. For galaxies of lower masses (9.8 ≤ log(Mgal/M⊙) ≤ 10.6) there is a radial depen- dence in the changing mix of red and blue galaxies, red galaxies residing preferentially in the group center. Such dependence is most evident in poor groups, whereas richer groups do not display any obvious color trend. Interestingly mass segregation shows the opposite behavior: it is visible only in rich groups, while poorer groups have a a constant mix of galaxy stellar masses as a function of radius. The morpho-spectral analysis showed the presence of a mild morphological segregation at fixed galaxy stellar mass, with massive early-type galaxies preferentially located in the core of groups. Galaxies with 9.8 ≤ log(Mgal/M⊙) ≤ 10.6 exhibit the strongest morphological differences between group and field environment. These galaxies also have an excess of red-passive spirals in the group with respect to the field. Despite the presence of a significant segregation of the spectral properties of group galaxies, such that the typical core galaxy have less intense emission lines, the star forming galaxies share the same level of activity at fixed stellar mass irrespective of the environment they reside in. This findings can be explained in a simple scenario where color/SFR and mass segregation originates from different physical processes. Mass segregation is driven by dynamical phenomena within groups, and therefore its presence/absence in rich/poor groups is a possible indication that poorer groups start to assemble later in cosmic time than richer structures. The parallel absence/presence of color segregation in rich/poor groups hints to the fact that nurture effects are still in action in poorer structures, whereas in richer systems are already largely over, so that all galaxies are red irrespective of their position within the group (at least down to the galaxy stellar masses we explored). Poorer groups hold the smoking gun of environmental effects in action superimposed to secular galaxy evolution: galaxies display gradually redder colors as a consequence of the still recent accretion history of these groups. The physical processes causing these environmental effects should act on rather short timescales, 1.5-2 Gyrs, because they are not able to erase the strinking bi-modality of galaxy color distribution and, moreover, we are not able to observed blue active galaxies showing less intense star formation activity in groups than in the field

Gender differences in healthy aging and Alzheimer's Dementia: A18F-FDG-PET study of brain and cognitive reserve

Cognitive reserve (CR) and brain reserve (BR) are protective factors against age-associated cognitive decline and neurodegenerative disorders. Very limited evidence exists about gender effects on brain aging and on the effect of CR on brain modulation in healthy aging and Alzheimer's Dementia (AD). We investigated gender differences in brain metabolic activity and resting-state network connectivity, as measured by18F-FDG-PET, in healthy aging and AD, also considering the effects of education and occupation. The clinical and imaging data were retrieved from large datasets of healthy elderly subjects (HE) (225) and AD patients (282). In HE, males showed more extended age-related reduction of brain metabolism than females in frontal medial cortex. We also found differences in brain modulation as metabolic increases induced by education and occupation, namely in posterior associative cortices in HE males and in the anterior limbic-affective and executive networks in HE females. In AD patients, the correlations between education and occupation levels and brain hypometabolism showed gender differences, namely a posterior temporo-parietal association in males and a frontal and limbic association in females, indicating the involvement of different networks. Finally, the metabolic connectivity in both HE and AD aligned with these results, suggesting greater efficiency in the posterior default mode network for males, and in the anterior frontal executive network for females. The basis of these brain gender differences in both aging and AD, obtained exploring cerebral metabolism, metabolic connectivity and the effects of education and occupation, is likely at the intersection between biological and sociodemographic factors. Hum Brain Mapp 38:4212-4227, 2017. © 2017 Wiley Periodicals, Inc

Axonal damage and loss of connectivity in nigrostriatal and mesolimbic dopamine pathways in early Parkinson's disease

A progressive loss of dopamine neurons in the substantia nigra (SN) is considered the main feature of idiopathic Parkinson's disease (PD). Recent neuropathological evidence however suggests that the axons of the nigrostriatal dopaminergic system are the earliest target of α-synuclein accumulation in PD, thus the principal site for vulnerability. Whether this applies toin vivoPD, and also to the mesolimbic system has not been investigated yet. We used [11C]FeCIT PET to measure presynaptic dopamine transporter (DAT) activity in both nigrostriatal and mesolimbic systems, in 36 early PD patients (mean disease duration in months ± SD 21.8 ± 10.7) and 14 healthy controls similar for age. We also performed anatomically-driven partial correlation analysis to evaluate possible changes in the connectivity within both the dopamine networks at an early clinical phase. In the nigrostriatal system, we found a severe DAT reduction in the afferents to the dorsal putamen (DPU) (η2 = 0.84), whereas the SN was the less affected region (η2 = 0.31). DAT activity in the ventral tegmental area (VTA) and the ventral striatum (VST) were also reduced in the patient group, but to a lesser degree (VST η2 = 0.71 and VTA η2 = 0.31). In the PD patients compared to the controls, there was a marked decrease in dopamine network connectivity between SN and DPU nodes, supporting the significant derangement in the nigrostriatal pathway. These results suggest that neurodegeneration in the dopamine pathways is initially more prominent in the afferent axons and more severe in the nigrostriatal system. Considering PD as a disconnection syndrome starting from the axons, it would justify neuroprotective interventions even if patients have already manifested clinical symptoms

Data for publication "Determination of Void Fraction in Wet-Gas Vertical Flows via Differential Pressure Measurement"

This data set is for publication "Determination of Void Fraction in Wet-Gas Vertical Flows via Differential Pressure Measurement". The measurement of void fraction in multiphase flow is important for a wide range of industrial processes. Existing methods for void fraction measurement require intrusive, expensive and potentially hazardous equipments which constrict the flow, adding both capital and operational costs. Two phase flow experiments were carried out at the National Engineering Laboratory (NEL) to measure void fraction via pressure drop in a vertical pipe. Additional experiments are carried out at Spirax Sarco Inc. to validate the efficacy of the method on steam/water flow mixtures at high temperature and pressure, in gas mass fraction range between 0.17 and 0.95 and void fraction range between 0.75 and 1.0. The void fraction calculated by the presented differential pressure (dP) method is confirmed via established correlations. The work demonstrates the efficacy of a low cost, non-intrusive method to determine void fraction in two phase flow over a wide range of flow conditions.Tait, Paul; Jia, Jiabin; Chen, Yuan; Wataru, Senjyu; Toru, Watanabe; Yasuo, Inamura; Valentina, Presotto; Radek, Mojsak; Gabriele, Chinello. (2021). Data for publication "Determination of Void Fraction in Wet-Gas Vertical Flows via Differential Pressure Measurement", 2019-2021 [dataset]. University of Edinburgh. School of Engineering. Institute of Digital Communication. https://doi.org/10.7488/ds/3168

Neural correlates of naming errors across different neurodegenerative diseases: A FDG-PET study.

OBJECTIVE: To investigate the type of errors produced in a picture naming task by patients affected by neurodegenerative dementia due to different etiologies and their neural correlates. METHODS: The same standardized picture naming test was administered to a consecutive sample of patients (n = 148) who had been studied with [18F] FDG-PET. The errors were analyzed in 3 categories (visual, semantic, and phonological). The PET data were analyzed using an optimized single-subject procedure, and the Statistical Parametric Mapping multiple regression design was used to explore the correlation between each type of error and brain hypometabolism in the whole group. Metabolic connectivity analyses were run at the group-level on 7 left hemisphere cortical areas corresponding to an a priori defined naming network. RESULTS: Semantic errors were predominant in most patients, independent of clinical diagnosis. In the whole group analysis, visual errors correlated with hypometabolism in the right inferior occipital lobe and in the left middle occipital lobe. Semantic errors correlated with hypometabolism in the left fusiform gyrus, the inferior and middle temporal gyri, and the temporal pole. Phonological errors were associated with hypometabolism in the left superior and middle temporal gyri. Both positive (occipital -posterior fusiform) and negative (anterior fusiform gyrus and the superior anterior temporal lobe) connectivity changes were associated with semantic errors. CONCLUSIONS: Naming errors reflect the dysfunction of separate stages of the naming process and are specific markers for different patterns of brain involvement. These correlations are not limited to PPA but extend to other neurodegenerative dementias