arXiv subjects

G. Mantovani

Publications and source records attributed to G. Mantovani.

6 recordsLinked to original sources

arXiv2024

XMM-Newton --NuSTAR monitoring campaign of the Seyfert 1 galaxy IC 4329A

We present the results of a joint {\it XMM-Newton} and {\it NuSTAR} campaign on the active galactic nucleus (AGN) IC 4329A, consisting of 9 $\times$ 20 ks {\it XMM-Newton} observations, and 5 $\times$ 20 ks {\it NuSTAR} observations within nine days, performed in August 2021. Within each observation, the AGN is not very variable, with the fractional variability never exceeding 5%. Flux variations are observed between the different observations, on timescales of days, with a 30% ratio between the minimum and the maximum 2-10 keV flux. These variations follow the softer-when-brighter behavior typically observed in AGN. In all observations, a soft excess is clearly present. Consistently with previous observations, the X-ray spectra of the source exhibit a cut-off energy between 140 and 250 keV, constant within the error in the different observations. We detected a prominent component of the $6.4$\,keV Fe~K$α$ line consistent with being constant during the monitoring, consisting of an unresolved narrow core and a broader component likely originating in the inner accredion disc. We find that the reflection component is weak ($R_{\rm max}=0.009\pm0.002$) and most likely originating in distant neutral medium. We also found the presence of a warm absorber component together with an ultra-fast outflow. Looking at their energetic, these outflows have enough mechanical power to exercise a significant feedback impact on the AGN surrounding environment.

astro-ph.HE↗

arXiv2020

Dynamical fission of the quasiprojectile and isospin equilibration for the system 80Kr+ 48 Ca at 35 MeV/nucleon

Experimental results concerning the dynamical fission of quasiprojectiles in semiperipheral collisions for the system 80 Kr+ 48 Ca at 35 MeV/nucleon are presented. Data have been collected with four blocks of the FAZIA setup in the first physics experiment of the FAZIA Collaboration. The degree of isospin equilibration between the two fission fragments and its dependence on their charge asymmetry is investigated. The data are compared with the results of the AMD model coupled to GEMINI as an afterburner, in order to get hints about the timescale of the process.

nucl-ex↗

arXiv2020

Influence of fast emissions and statistical de-excitation on the isospin transport ratio

Isospin transport ratio is a powerful method to estimate the neutron-proton (n-p) equilibration in heavy-ion collisions, and extensively used to obtain information on the asy-stiffness of the nuclear Equation of State. In fact such a ratio is expected to bypass any perturbations introducing a linear transformation of the chosen observable. In particular, it is supposed to overcome contributions due to emission, either of dynamical or statistical nature, from the primary fragments formed during the collisions. In this paper we explore the validity of this assumption, looking at the quasi-projectile n-p ratio ($N/Z$) in peripheral and semi-peripheral events for Ca+Ca reactions at 35\amev{}, simulated via the Antisymmetrized Molecular Dynamics transport model, coupled to different statistical decay codes. The statistical de-excitation of the primary fragments introduces a linear transformation at relatively high excitation energies (above 2\amev{}) when the residue approaches the Evaporation Attractor Line, while some effect is produced at lower excitation energies due to the occurrence of some non-linearities. As for fast emissions after the end of the projectile-target interaction it is shown that they introduce a non-linear transformation too.

nucl-th↗

arXiv2020

Experimental study of precisely selected evaporation chains in the decay of excited $^{25}$Mg

The reaction $^{12}$C + $^{13}$C at 95 MeV bombarding energy is studied using the GARFIELD + Ring Counter apparatus located at the INFN Laboratori Nazionali di Legnaro. In this paper we want to investigate the de-excitation of $^{25}$Mg aiming both at a new stringent test of the statistical description of nuclear decay and a direct comparison with the decay of the system $^{24}$Mg formed through $^{12}$C+$^{12}$C reactions previously studied. Thanks to the large acceptance of the detector and to its good fragment identification capabilities, we could apply stringent selections on fusion-evaporation events, requiring their completeness in charge. The main decay features of the evaporation residues and of the emitted light particles are overall well described by a pure statistical model; however, as for the case of the previously studied 24Mg, we observed some deviations in the branching ratios, in particular for those chains involving only the evaporation of $α$ particles. From this point of view the behavior of the $^{24}$Mg and $^{25}$Mg decay cases appear to be rather similar. An attempt to obtain a full mass balance even without neutron detection is also discussed.

nucl-ex↗

arXiv2019

The FAZIA setup: a review on the electronics and the mechanical mounting

In this paper the technological aspects of the FAZIA array will be explored. After a productive commissioning phase, FAZIA blocks started to measure and give very useful data to explore the physics of Fermi energy heavy-ion reactions. This was possible thanks to many technical measures and innovations developed in the commissioning phase and tuned during the first experimental campaigns. This paper gives a detailed description of the present status of the FAZIA setup from the electronic and mechanical point of view, trying also to trace a path for new improvements and refinements of the apparatus.

physics.ins-det↗

arXiv2019

The KMS Condition for the homoclinic equivalence relation and Gibbs probabilities

D. Ruelle considered a general setting where he is able to characterize equilibrium states for Hölder potentials based on properties of conjugating homeomorphism in the so called Smale spaces. On this setting he also shows a relation of KMS states of $C^*$-algebras and equilibrium probabilities of Thermodynamic Formalism. A later paper by N. Haydn and D. Ruelle presents a shorter proof of this equivalence. Here we consider similar problems but now on the symbolic space $Ω= \{1,2,...,d\}^{\mathbb{Z} - \{ 0 \} }$ and the dynamics will be given by the shift $τ$. In the case of potentials depending on a finite coordinates we will present a simplified proof of the equivalence mentioned above which is the main issue of the papers by D. Ruelle and N. Haydn. The class of conjugating homeomorphism is explicit and reduced to a minimal set of conditions. We also present with details (following D. Ruelle) the relation of these probabilities with the KMS dynamical $C^*$-state on the $C^*$-Algebra associated to the groupoid defined by the homoclinic equivalence relation. The topics presented here are not new but we believe the main ideas of the proof of the results by Ruelle and Haydn will be quite transparent in our exposition.

math.DS↗