The parallelism between galaxy clusters and early-type galaxies: I. The light and mass profiles

We have analyzed the parallelism between the properties of galaxy clusters and early-type galaxies (ETGs) by looking at the similarity between their light profiles. We find that the equivalent luminosity profiles of all these systems in the \vfilt\ band, once normalized to the effective radius \re\ and shifted in surface brightness, can be fitted by the S\'ersic's law \Sers\ and superposed with a small scatter ($\le0.3$ mag). By grouping objects in different classes of luminosity, the average profile of each class slightly deviates from the other only in the inner and outer regions (outside $0.1\leq r/R_e\leq 3$), but the range of values of $n$ remains ample for the members of each class, indicating that objects with similar luminosity have quite different shapes. The "Illustris" simulation reproduces quite well the luminosity profiles of ETGs, with the exception of in the inner and outer regions where feedback from supernovae and active galactic nuclei, wet and dry mergers, are at work. The total mass and luminosity of galaxy clusters as well as their light profiles are not well reproduced. By exploiting simulations we have followed the variation of the effective half-light and half-mass radius of ETGs up to $z=0.8$, noting that progenitors are not necessarily smaller in size than current objects. We have also analyzed the projected dark+baryonic and dark-only mass profiles discovering that after a normalization to the half-mass radius, they can be well superposed and fitted by the S\'ersic's law.Comment: 25 pages, 19 figure

Cosmological interpretation of the color-magnitude diagrams of galaxy clusters

We investigate the color-magnitude diagram (CMD) of cluster galaxies in the hierarchical $\Lambda$-CDM cosmological scenario using both single stellar populations and simple galaxy models. First, we analyze the effect of bursts and mergers and companion chemical pollution and rejuvenation of the stellar content on the integrated light emitted by galaxies. The dispersion of the galaxy magnitudes and colors on the $M_V-(B-V)$ plane is mainly due to mixing of ages and metallicities of the stellar populations, with mergers weighting more than bursts of similar mass fractions. The analysis is made using the Monte-Carlo technique applied to ideal model galaxies reduced to single stellar populations with galaxy-size mass to evaluate mass, age and metallicity of each object. We show that separately determining the contributions by bursts and mergers leads to a better understanding of observed properties of CMD of cluster galaxies. Then we repeat the analysis using suitable chemo-photometric models of galaxies whose mass is derived from the cosmological predictions of the galaxy content of typical clusters. Using the halo mass function and the Monte-Carlo technique, we derive the formation redshift of each galaxy and its photometric history. These are used to simulate the CMD of the cluster galaxies. The main conclusion is that most massive galaxies have acquired the red color they show today in very early epochs and remained the same ever since. The simulations nicely reproduce the Red Sequence, the Green Valley and the Blue Cloud, the three main regions of the CMD in which galaxies crowd.Comment: Accepted for publication in Ap

Cosmic Star Formation: a simple model of the SFRD(z)

We investigate the evolution of the cosmic star formation rate density (SFRD) from redshift z=20 to z=0 and compare it with the observational one by Madau and Dickinson derived from recent compilations of UV and IR data. The theoretical SFRD(z) and its evolution are obtained using a simple model which folds together the star formation histories of prototype galaxies designed to represent real objects of different morphological type along the Hubble sequence and the hierarchical growing of structures under the action of gravity from small perturbations to large scale objects in \Lambda-CDM cosmogony, i.e. the number density of dark matter halos N(M,z). Although the overall model is very simple and easy to set up, it provides results that well mimic those obtained from large scale N-body simulations of great complexity. The simplicity of our approach allows us to test different assumptions for the star formation law in galaxies, the effects of energy feedback from stars to interstellar gas and the efficiency of galactic winds, and also the effect of N(M,z). The result of our analysis is that in the framework of the hierarchical assembly of galaxies the so-called time-delayed star formation under plain assumptions mainly for the energy feedback and galactic winds can reproduce the observational SFRD(z).Comment: ApJ (accepted for publication

The parallelism between galaxy clusters and early-type galaxies: II. Clues on the origin of the scaling relations

Context. This is the second work dedicated to the observed parallelism between galaxy clusters and early-type galaxies. The focus is on the distribution of these systems in the scaling relations (SRs) observed when effective radii, effective surface brightness, total luminosities and velocity dispersions are mutually correlated. Aims. Using the data of the Illustris simulation we try to speculate on the origin of the observed SRs. Methods. We compare the observational SRs extracted from the database of the WIde-field Nearby Galaxy-cluster Survey (WINGS) with the relevant parameters coming from the Illustris simulations. Then we use the simulated data at different redshift to infer the evolution of the SRs. Results. The comparison demonstrate that galaxy clusters (GCs) at z~0 follow the same log(L)-log(sigma) relation of early-type galaxies (ETGs) and that both in the log(Ie)-log(Re) and log(Re)-log(M*) planes the distribution of GCs is along the sequence defined by the brightest and massive early-type galaxies (BCGs). The Illustris simulation reproduces the tails of the massive galaxies visible both in the log(Ie)-log(Re) and log(Re)-log(M*) planes, but fail to give the correct estimate of the effective radii of the dwarf galaxies that appear too large and those of GCs that are too small. The evolution of the SRs up to z=4 permits to reveal the complex evolutionary paths of galaxies in the SRs and indicate that the line marking the Zone of Exclusion (ZoE), visible both in the log(Ie)-log(Re) and log(Re)-log(M*) planes, is the trend followed by virialized and passively evolving systems. Conclusions. We speculate that the observed SRs originate from the intersection of the virial theorem and a relation L=L_0 x sigma^beta where the luminosities depend on the star formation history.Comment: 22 pages, 14 figures, 4 table

CDC's COVID-19 International Vaccine Implementation and Evaluation Program and Lessons from Earlier Vaccine Introductions.

The US Centers for Disease Control and Prevention (CDC) supports international partners in introducing vaccines, including those against SARS-CoV-2 virus. CDC contributes to the development of global technical tools, guidance, and policy for COVID-19 vaccination and has established its COVID-19 International Vaccine Implementation and Evaluation (CIVIE) program. CIVIE supports ministries of health and their partner organizations in developing or strengthening their national capacities for the planning, implementation, and evaluation of COVID-19 vaccination programs. CIVIE's 7 priority areas for country-specific technical assistance are vaccine policy development, program planning, vaccine confidence and demand, data management and use, workforce development, vaccine safety, and evaluation. We discuss CDC's work on global COVID-19 vaccine implementation, including priorities, challenges, opportunities, and applicable lessons learned from prior experiences with Ebola, influenza, and meningococcal serogroup A conjugate vaccine introductions

16-SCIARRATTA, Carmiña (Instituto de Enseñanza Superior N° 28 “Olga Cossettini”- Rosario) - LURIE, Alison, El lenguaje de la moda. Una interpretación de las formas de vestir, Barcelona, Ed. Paidós, cuarta edición 2011, 302 pág, ISBN 978-84–493–0004-2, pp. 70-72.

Reseñas.Net. Revista de reseñas bibliográficas de Historia y Ciencias Sociales en la red es una publicación del Centro de Estudios “Espacio, Memoria e Identidad” (CEEMI), perteneciente a la Facultad de Humanidades y Artes y a la Facultad de Ciencia Política y Relaciones Internacionales (RRII) de la Universidad Nacional de Rosario-Argentina En: Reseñas Net, Año 7, Nº 12, Rosario- Argentina, abril de 2014Instituto de Enseñanza Superior N° 28 “Olga Cossettini”- Rosari

L'assorbimento della radiazione solare su scala planetaria

In the present paper the AA. search an eventual phenomenonwith the universal diurnal variation, which may influence thenatural terrestrial phenomena. Considering that the first cause of thediurnal variations is the solar radiation arriving 011 the Earth, such a phenomenonmay be founded in the diurnal rotation of the Earth, therefore1 lie regions illuminated by the sun are different according to the universaltime. Since the regions of the Earth have different albedo, the solar radiationabsorbed by the entire Earth will have an universal diurnal variation.The A A. have calculated the apparent surface (with the sun as a pointof view) of the lands and of the seas at different hours (U.T.) and in thedifferent period of the year.In order of include in computation the absorption of the solar radiationby the atmosphere, the AA. have calculated these surfaces with acorrection due to this absorption. In these computations the eventualcloudiness not appears, because in this first approximation the cloudinessis supposed equal 011 the entire Earth. These surfaces with the correctionof the atmospheric absorption are proportional to the solar energy reallyabsorbed by the entire Earth.By the comparison of the universal diurnal variation of those surfaceswith that of a natural phenomenon (the atmospheric electric field), theAA. show that it is possible, with some reductions, to make these variationscoincide. These reductions are an advance of the maximum (4 hours) anda coefficient which reckons the albedo's difference.The AA. recognize that it is no possible with this preliminary studyto explain the influence of the solar energy absorbed by the entire Earth011 the atmospheric electric field; but according to the AA. this correlationwill take an important contribution also to the researches for the generalatmospheric circulation