Istituto Universitario Di Studi Superiori Di Pavia

About: Istituto Universitario Di Studi Superiori Di Pavia is a education organization based out in Pavia, Italy. It is known for research contribution in the topics: Pulsar & Neutron star. The organization has 162 authors who have published 566 publications receiving 22605 citations.

Time domain astronomy with the THESEUS satellite

Abstract: THESEUS is a medium size space mission of the European Space Agency, currently under evaluation for a possible launch in 2032. Its main objectives are to investigate the early Universe through the observation of gamma-ray bursts and to study the gravitational waves electromagnetic counterparts and neutrino events. On the other hand, its instruments, which include a wide field of view X-ray (0.3-5 keV) telescope based on lobster-eye focussing optics and a gamma-ray spectrometer with imaging capabilities in the 2-150 keV range, are also ideal for carrying out unprecedented studies in time domain astrophysics. In addition, the presence onboard of a 70 cm near infrared telescope will allow simultaneous multiwavelegth studies. Here we present the THESEUS capabilities for studying the time variability of different classes of sources in parallel to, and without affecting, the gamma-ray bursts hunt.

The method of mothers for non-overlapping non-matching DDM

Abstract: In this paper we introduce a variant of the three-field formulation where we use only two sets of variables. Considering, to fix the ideas, the homogeneous Dirichlet problem for $$-\Delta\,u = g$$ in $$\Omega$$, our variables are i) the approximations $$u_h^{s}$$ of u in each sub-domain $$\Omega^s$$ (each on its own grid), and ii) an approximation $$\Psi_h$$ of u on the skeleton (the union of the interfaces of the sub-domains) on an independent grid (that could often be uniform). The novelty is in the way to derive, from $$\Psi_h$$, the values of each trace of $$u_h^{s}$$ on the boundary of each $$\Omega$$. We do it by solving an auxiliary problem on each $$\partial\Omega^s$$ that resembles the mortar method but is more flexible. Under suitable assumptions, quasi-optimal error estimates are proved, uniformly with respect to the number and size of the subdomains. A preliminary version of the method and of its theoretical analysis has been presented in Bertoluzza et al. (15th international conference on domain decomposition methods, 2002).

A Deep XMM-Newton Serendipitous Survey of a middle-latitude area. II. New deeper X-ray and optical observations

Abstract: The radio-quiet neutron star 1E1207.4-5209 has been the target of several XMM-Newton observations, with a total exposure of ~350 ks. The source is located at intermediate galactic latitude (b~10 degrees), i.e. in a sky region with an extremely interesting mix of both galactic and extra-galactic X-ray sources. The aim of our work is to investigate the properties of both the intermediate-latitude galactic and extra-galactic X-ray source populations in the 1E1207.4-5209 field. We performed a coherent analysis of the whole XMM-Newton observation data set to build a catalogue of serendipitous X-ray sources detected with high confidence and to derive information on the source flux, spectra, and time variability. In addition, we performed a complete multi-band (UBVRI) optical coverage of the field with the Wide Field Imager (WFI) of the ESO/MPG 2.2m telescope (La Silla) to search for candidate optical counterparts to the X-ray sources, down to a V-band limiting magnitude of ~24.5. We detected a total of 144 serendipitous X-ray sources. Thanks to the refined X-ray positions and to the WFI observations, we found candidate optical counterparts for most of the X-ray sources in our compilation. For most of the brightest ones we proposed a likely classification based on both the X-ray spectra and the optical colours. Our results indicate that at intermediate galactic latitude the X-ray source population is dominated by the extra-galactic component, but with a significant contribution from the galactic component in the soft energy band, below 2 keV.

Predicting approximate seismic responses in multistory buildings from real-time earthquake source information, for earthquake early warning applications

Abstract: Regional earthquake early warning (EEW) alerts and related risk-mitigation actions are often triggered when the expected value of a ground-motion intensity measure (IM), computed from real-time magnitude and source location estimates, exceeds a predefined critical IM threshold. However, the shaking experienced in mid- to high-rise buildings may be significantly different from that on the ground, which could lead to sub-optimal decision-making (i.e., increased occurrences of false and missed EEW alarms) with the aforementioned strategy. This study facilitates an important advancement in EEW decision-support, by developing empirical models that directly relate earthquake source parameters to resulting approximate responses in multistory buildings. The proposed models can leverage real-time earthquake information provided by a regional EEW system, to provide rapid predictions of structure-specific engineering demand parameters that can be used to more accurately determine whether or not an alert is triggered. We use a simplified continuum building model consisting of a flexural/shear beam combination and vary its parameters to capture a wide range of deformation modes in different building types. We analyse the approximate responses for the building model variations, using Italian accelerometric data and corresponding source parameter information from 54 earthquakes. The resulting empirical prediction equations are incorporated in a real-time Bayesian framework that can be used for building-specific EEW applications, such as (1) early warning of floor-shaking sensed by occupants; and (2) elevator control. Finally, we demonstrate the improvement in EEW alert accuracy that can be achieved using the proposed models.

The X-ray evolution and geometry of the 2018 outburst of XTE J1810−197

Abstract: AB and FCZ are supported by Juan de la Cierva Fellowship. AB, NR, FCZ, DV, AI, and RS are supported by the ERC Consolidator Grant ‘MAGNESIA’ (nr. 817661), and acknowledge funding from grants SGR2017-1383 and PGC2018-095512-BI00. RT, MR, and SM acknowledge financial support from the Italian MIUR through grant ‘UNIAM’ (PRIN 2017LJ39LM). EVG and JAJA acknowledge support for this project from NASA grants 80NSSC20K0717, 80NSSC19K1462, 80NSSC20K0046, and 80NSSC21K0129. AP and MB gratefully acknowledge financial support by the research grant iPeska (P.I. Andrea Possenti) funded under the INAF national call Prin-SKA/CTA approved with the Presidential Decree 70/2016.