170,294 research outputs found
SuperModel Analysis of A1246 and J255: On the Evolution of Galaxy Clusters from High to Low Entropy States
No full textWe present an analysis of high-quality X-ray data out to the virial radius for the two galaxy clusters A1246 and GMBCG J255.34805+64.23661 (J255) by means of our entropy-based SuperModel. For A1246 we find that the spherically averaged entropy profile of the intracluster medium (ICM) progressively flattens outward, and that a nonthermal pressure component amounting to ≈20% of the total is required to support hydrostatic equilibrium in the outskirts; there we also estimate a modest value C ≈ 1.6 of the ICM clumping factor. These findings agree with previous analyses on other cool-core, relaxed clusters, and lend further support to the picture by Lapi et al. that relates the entropy flattening, the development of the nonthermal pressure component, and the azimuthal variation of ICM properties to weakening boundary shocks. In this scenario clusters are born in a high-entropy state throughout, and are expected to develop on similar timescales a low-entropy state both at the center due to cooling, and in the outskirts due to weakening shocks. However, the analysis of J255 testifies how such a typical evolutionary course can be interrupted or even reversed by merging especially at intermediate redshift, as predicted by Cavaliere et al. In fact, a merger has rejuvenated the ICM of this cluster at z ≈ 0.45 by reestablishing a high-entropy state in the outskirts, while leaving intact or erasing only partially the low-entropy, cool core at the center
Il 5 per mille dopo la riforma. Tra scelte (e non scelte) dei contribuenti
No full textIl contributo si prefigge l'obiettivo di esaminare le seguenti questioni. In quale misura il cittadino italiano partecipa alle decisioni dello Stato in termini di allocazione delle risorse pubbliche, derivanti dal prelievo fiscale? Il cittadino ha contezza di quanto sia importante la sua scelta? È consapevole che tale scelta ha una dimensione etica? Lo Stato è in grado di tutelare l’eticità della scelta del contribuente? Quanto pesano le scelte non espresse? L'analisi muove dall'istituto del 5 per mille, oggetto della riforma del Terzo settore (Legge 106/2016; D.Lgs. 111/2017), per poi spostarsi sull'istituto dell'8 per mille e del 2 per mille
Angular momentum transfer in dark matter halos: Erasing the cusp
No full textWe propose that angular momentum transfer from the baryons to the dark matter (DM) during the early stages of galaxy formation can flatten the halo inner density profile and modify the halo dynamics. We compute the phase-space distribution function of DM halos that corresponds to the density and anisotropy profiles obtained from N-body simulations in the concordance cosmology. We then describe an injection of angular momentum into the halo by modifying the distribution function and show that the system evolves into a new equilibrium configuration; the latter features a constant central density and a tangentially dominated anisotropy profile in the inner regions, while the structure is nearly unchanged beyond 10% of the virial radius. Then we propose a toy model to account for such a halo evolution, based on the angular momentum exchange due to dynamical friction; at the epoch of galaxy formation this is efficiently exerted by the DM onto the gas clouds spiralling down the potential well. The comparison between the angular momentum profile gained by the halo through dynamical friction and that provided by the perturbed distribution function reveals a surprising similarity, hinting at the reliability of the process
La Gara : componimento drammatico in occasione del faustissimo arrivo in Livorno delle loro Altezze Reali Ferdinando III. arciduca d'Austria, granduca di Toscana &c. &c. &c. e Luisa Maria Amalia infanta di Spagna, granduchessa di Toscana &c. &c. &c. : in segno di sincero giubbilo consacrato alle LL. AA. RR. dal pubblico di Livorno e dalle nazioni olandese-alemanna, inglese, greca orientale ed ebrea, commercianti in detta città.
No full textIllustrations engraved by Angelo Emilio Lapi: armorial frontispiece (unsigned), allegorical title vignette, head-piece after Giovanni Lapi (del), and a triumphal float, by Angelo Emilio Lapi.Last page blank.Mode of access: Internet.Library's copy lacks engraving depicting the float
The H I Content of Local Late-type Galaxies
No full textWe present a solid relationship between the neutral hydrogen (H I) disk mass and the stellar disk mass of late-type galaxies in the local universe. This relationship is derived by comparing the stellar disk mass function from the Sloan Digital Sky Survey and the H I mass function from the H I Parkes All Sky Survey (HIPASS). We find that the H I mass in late-type galaxies tightly correlates with the stellar mass over three orders of magnitude in stellar disk mass. We cross-check our result with that obtained from a sample of HIPASS objects for which the stellar mass has been obtained by inner kinematics. In addition, we derive the H I versus halo mass relationship and the dependence of all the baryonic components in spirals on the host halo mass. These relationships bear the imprint of the processes ruling galaxy formation, and highlight the inefficiency of galaxies both in forming stars and in retaining their pristine H I gas
Measuring the spin of spiral galaxies
No full textWe compute the angular momentum, the spin parameter, and the related distribution function for dark matter halos hosting a spiral galaxy. We rely on scaling laws, inferred from observations, that link the properties of the galaxy to those of the host halo; we further assume that the dark matter has the same total specific angular momentum of the baryons. Our main results are as follows: (1) We find that the gas component of the disk significantly contributes to the total angular momentum of the system. (2) By adopting for the dark matter the observationally supported Burkert profile, we compute the total angular momentum of the disk and its correlation with the rotation velocity. (3) We find that the distribution function of the spin parameter λ peaks at a value of about 0.03, consistent with a no-major-merger scenario for the late evolution of spiral galaxies
Toward a tomographic analysis of the cross-correlation between planck cmb lensing and h-atlas galaxies
No full textINAF PRIN; ASI/INAF [2014-024-R.0]; INFN-INDARK initiative; Spanish MINECOBianchini, F., Lapi, A., Calabrese, M., Bielewicz, P., Gonzalez-Nuevo, J., Baccigalupi, C., Danese, L., Zotti, G.D., Bourne, N., Cooray, A., Dunne, L., Eales, S., Valiante, E
Quenching of singlet oxygen by tertiary aliphatic amines. Structural effects on rates and products
No full textA kinetic and product study of the reaction of a series of alpha-methyl-substituted N-methylpiperidines with thermally generated O-1(2) in MeCN was carried out. It was found that as the number of alpha-methyl groups (Me in alpha-position relative to the N-atom) increases, the rate of O-1(2) quenching (physical plus chemical) slightly decreases. This finding shows that, with respect to the reaction rate, steric effects are much more important than electronic effects as the latter should have produced the opposite result. The opposite outcome was instead found for the chemical quenching that leads to the N-demethylation products and N-formyl derivatives. The same trend was observed for the ratio between N-demethylation and formation of the N-formyl derivatives (NH/NCHO ratio). All these results are consistent with the mechanism reported in Scheme I where an exciplex is first formed that by a H-atom transfer process produces an alpha-amino-substituted C-radical. The latter forms the product of N-demethylation by one electron oxidation, or affords the N-formyl derivative by radical coupling (Scheme 1). Similar results were obtained with N,N-dimethylcyclohexanamine. However, this 'acyclic' amine exhibited behaviors quite distinct from those of the N-methylpiperidines series, with respect to reaction rate, extent of chemical quenching, and NH/NCHO ratio
IL RUOLO DELLA DONNA NEL DIRITTO INDÙ.
No full textThe goal of this thesis is to understand the legal position of women in Hindu personal law through the examination of the rules governing succession. Hindu law is a religious law on the formation of which has played a very strong influence induism. The decision to deal with one aspect of the Hindu law is born by the wish to understand the reason for the existence of a religious law in the present age
Measuring the spin of spiral galaxies
No full textA Birthday Celebration of the Contributions of Bernard Jones to our unserstanding of the Universe. On June 3rd, 2006, Bernard Jones will celebrate his 60th birthday. To celebrate this occasion and pay tribute to his substantial contributions to science and the scientific world we organize a dedicated conference on cosmology, galaxy and cosmic structure formation and star formation
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