Fitoussi - Boudon : le défi du libéralisme ; à quelles conditions la France est-elle réformable ?.

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Observation of gravitational waves from the coalescence of a 2.5–4.5 M ⊙ compact object and a neutron star

We report the observation of a coalescing compact binary with component masses 2.5–4.5 M ⊙ and 1.2–2.0 M ⊙ (all measurements quoted at the 90% credible level). The gravitational-wave signal GW230529_181500 was observed during the fourth observing run of the LIGO–Virgo–KAGRA detector network on 2023 May 29 by the LIGO Livingston observatory. The primary component of the source has a mass less than 5 M ⊙ at 99% credibility. We cannot definitively determine from gravitational-wave data alone whether either component of the source is a neutron star or a black hole. However, given existing estimates of the maximum neutron star mass, we find the most probable interpretation of the source to be the coalescence of a neutron star with a black hole that has a mass between the most massive neutron stars and the least massive black holes observed in the Galaxy. We provisionally estimate a merger rate density of 55−47+127Gpc−3yr−1 for compact binary coalescences with properties similar to the source of GW230529_181500; assuming that the source is a neutron star–black hole merger, GW230529_181500-like sources may make up the majority of neutron star–black hole coalescences. The discovery of this system implies an increase in the expected rate of neutron star–black hole mergers with electromagnetic counterparts and provides further evidence for compact objects existing within the purported lower mass gap

The partition sum of methane at high temperature

11 pages, 4 Tables, 3 Figures Computer code on line at http://icb.u-bourgogne.fr/JSP/TIPS.jspInternational audienceThe total internal partition function of methane is revisited to provide reliable values at high temperature. A multi-resolution approach is used to perform a direct summation over all the rovibrational energy levels up to the dissociation limit. A computer code is executable on line at the URL : http://icb.u-bourgogne.fr/JSP/TIPS.jsp to allow the calculation of the partition sum of methane at temperatures up to 3000 K. It also provides detailed information on the density of states in the relevant spectral ranges. The recommended values include uncertainty estimates. It is shown that at the upper limit of 3000 K, the systematic error (underestimation) of previous calculations (HITRAN 2004) reaches -50 % equivalent to a temperature error of the order of +200 K

The STDS Dijon system : Present status and prospects.

The Dijon spectroscopy group has developed powerful techniques based on group theory and tensorial formalism in order to analyze and simulate absorption and Raman spectra of molecules with various symmetries. Software packages and databases implementing these tools have been created [1]. Compared to the widely used spectroscopic databases (HITRAN, GEISA), these packages, with their XTDS common interface [2], are primarily devoted to the calculation of line parameters and spectra from a database of model parameters. Future developments include improved fitting algorithms, inclusion of C3v symmetric tops, rovibronic couplings, uncertainty estimates. Moreover, calculated line lists will be accessible from the VAMDC system. References 1. http://www.icb.cnrs.fr/OMR/SMA/SHTDS/ 2. Ch. Wenger, V. Boudon, M. Rotger, M. Sanzharov, J.-P. Champion, Journal of Molecular Spectroscopy 251, 102–113 (2008

The present status of methane spectroscopy for planetary applications

International audienc

XTDS and SPVIEW: Graphical tools for the analysis and simulation of high-resolution molecular spectra

International audienceXTDS is a Java front-end to the different programs implementing the tensorial formalism developed in the Dijon group [see for instance: V. Boudon, J.-P. Champion, T. Gabard, M. Loëte, F. Michelot, G. Pierre, M. Rotger, Ch. Wenger, M. Rey, J. Mol. Spectrosc. 228 (2004) 620–634 ]. It allows the simulation and analysis of polyad systems for molecules of various symmetries (Td and Oh spherical tops like CH4 and SF6, C2v and C4v quasi-spherical tops like SO2F2 and SF5Cl, D2h molecules like C2H4). SPVIEW is a multiplatform Java application that allows graphical assignment of high-resolution molecular spectra. It is possible to load, display and manipulate experimental and simulated spectra (XY ASCII format) as well as stick spectra in various formats (including HITRAN format). Lines can be assigned graphically using the mouse. Assignments can also be modified or removed. Local simulations can be performed in order, for instance, to help assignment in partly resolved line clusters. SPVIEW is also able to produce peak lists from an experimental spectrum. Both software can be freely downloaded at the URL http://icb.u-bourgogne.fr/OMR/SMA/SHTDS