Physical Properties of Galactic Planck Cold Cores revealed by the Hi-GAL survey

Previous studies of the initial conditions of massive star formation have mainly targeted Infrared-Dark Clouds (IRDCs) toward the inner Galaxy. This is due to the fact that IRDCs were first detected in absorption against the bright mid-IR background, requiring a favourable location to be observed. By selection, IRDCs represent only a fraction of the Galactic clouds capable of forming massive stars and star clusters. Due to their low dust temperatures, IRDCs are bright in the far-IR and millimeter and thus, observations at these wavelengths have the potential to provide a complete sample of star-forming massive clouds across the Galaxy. Our aim is to identify the clouds at the initial conditions of massive star formation across the Galaxy and compare their physical properties as a function of their Galactic location. We have examined the physical properties of a homogeneous galactic cold core sample obtained with the Planck satellite across the Galactic Plane. With the use of Herschel Hi-GAL observations, we have characterized the internal structure of them. By using background-subtracted Herschel images, we have derived the H2 column density and dust temperature maps for 48 Planck clumps. Their basic physical parameters have been calculated and analyzed as a function of location within the Galaxy. These properties have also been compared with the empirical relation for massive star formation derived by Kauffmann & Pillai (2010). Most of the Planck clumps contain signs of star formation. About 25% of them are massive enough to form high mass stars. Planck clumps toward the Galactic center region show higher peak column densities and higher average dust temperatures than those of the clumps in the outer Galaxy. Although we only have seven clumps without associated YSOs, the Hi-GAL data show no apparent differences in the properties of Planck cold clumps with and without star formation.Comment: 22 pages, 11 figures, accepted for publication in A&

A new intermediate mass protostar in the Cepheus A HW2 region

We present the discovery of the first molecular hot core associated with an intermediate mass protostar in the CepA HW2 region. The hot condensation was detected from single dish and interferometric observations of several high excitation rotational lines (from 100 to 880K above the ground state) of SO2 in the ground vibrational state and of HC3N in the vibrationally excited states v7=1 and v7=2. The kinetic temperature derived from both molecules is 160K. The high-angular resolution observations (1.25'' x 0.99'') of the SO2 J=28(7,21)-29(6,24) line (488K above the ground state) show that the hot gas is concentrated in a compact condensation with a size of 0.6''(430AU), located 0.4'' (300AU) east from the radio-jet HW2. The total SO2 column density in the hot condensation is 10E18cm-2, with a H2 column density ranging from 10E23 to 6 x 10E24cm-2. The H2 density and the SO2 fractional abundance must be larger than 10E7cm-3 and 2 x 10E-7 respectively. The most likely alternatives for the nature of the hot and very dense condensation are discussed. From the large column densities of hot gas, the detection of the HC3N vibrationally excited lines and the large SO2 abundance, we favor the interpretation of a hot core heated by an intermediate mass protostar of 10E3 Lo. This indicates that the CepA HW2 region contains a cluster of very young stars

Collisional excitation of interstellar PO(X-2 Pi) by He: new ab initio potential energy surfaces and scattering calculations

We acknowledge the financial support from the COST Action CM1401 “Our Astrochemical History”. This research utilized Queen Mary's Mid-Plus computational facilities, supported by QMUL Research-IT and funded by EPSRC grant EP/K000128/1. S. M. acknowledges Indigo Dean for very useful discussions. I. J.-S. acknowledges the financial support received from the STFC through an Ernest Rutherford Fellowship (proposal number ST/L004801)

Old high-redshift galaxies and primordial density fluctuation spectra

We have discovered a population of extremely red galaxies at $z\simeq 1.5$ which have apparent stellar ages of \gs 3 Gyr, based on detailed spectroscopy in the rest-frame ultraviolet. In order for galaxies to have existed at the high collapse redshifts indicated by these ages, there must be a minimum level of power in the density fluctuation spectrum on galaxy scales. This paper compares the required power with that inferred from other high-redshift populations. If the collapse redshifts for the old red galaxies are in the range $z_c\simeq 6$ -- 8, there is general agreement between the various tracers on the required inhomogeneity on 1-Mpc scales. This level of small-scale power requires the Lyman-limit galaxies to be approximately $\nu\simeq 3.0$ fluctuations, implying a very large bias parameter $b\simeq 6$. The high collapse redshifts of the red galaxies as deduced from gravitational collapse provides independent support for the ages estimated from their stellar populations. Such early-forming galaxies are rare, and their contribution to the cosmological stellar density is consistent with an extrapolation to higher redshifts of the star-formation rate measured at $z<5$; there is no evidence for a general era of spheroid formation at extreme redshifts.Comment: 9 Pages MNRAS in press. Uses MNRAS Plain TeX macro

Relation entre notation sociale et structure financière des entreprises : une étude empirique.

Relation entre notation sociale et structure financière des entreprises : une étude empirique Cet article étudie le lien entre la structure du capital des entreprises et leur notation sociale. Notre modèle théorique montre que les entreprises les moins éthiques, pour échapper à la sanction du marché financier, recourent plus massivement à l'endettement, notamment à l'emprunt bancaire. En effet, l'intérêt croissant des investisseurs pour la responsabilité sociale fait que les entreprises non éthiques supportent un coût des capitaux propres plus élevé que leurs concurrentes éthiques. Inversement, le coût de la dette n'est pas lié à la qualité éthique de l'entreprise, les banques ne prenant pas en compte le critère éthique dans la fixation des taux d'intérêt. Nous proposons de vérifier que le niveau d'endettement des entreprises est en relation décroissante avec la note RSE (responsabilité sociale de l'entreprise). Nous tenons compte dans notre analyse de l'influence de plusieurs déterminants de la structure du capital, comme les coûts de faillite, le niveau de taxation, les variables d'agence et d'asymétrie d'information. L'étude porte sur un échantillon de 562 entreprises européennes pour lesquelles nous disposons de la note RSE fournie par l'agence de notation Vigéo. La période d'étude s'étend sur les années 1999 à 2007. Nos résultats montrent que la structure financière actuelle des entreprises est encore peu influencée par la note éthique. En revanche, lorsque l'on cherche à comprendre comment cette structure évolue, on identifie clairement la note éthique comme un facteur de changement : plus une entreprise a une bonne note éthique, plus elle se détourne de l'endettement.investissement socialement responsable ; notation éthique ; coût du capital ; endettement ; structure du capital ; optimum.

On the physics of the Gravitational Wave Background

It is a matter of fact that the universe lives on a Gravitational Wave Background (GWB). This GWB is extra energy that is not contained in Einstein's equations. In \cite{Matos:2021jef}, a new model was developed to explain the accelerating expansion of the universe where a GWB was incorporated into Einstein's equations by extending them as $R_{\mu\nu}-\frac{1}{2}Rg_{\mu\nu}+\frac{2\pi^2}{{\lambda}^2}g_{\mu\nu}=\kappa ^2 T_{\mu\nu}$, where ${\lambda}$ is the Compton wavelength of the graviton. In this paper, we continue to study this new paradigm. Due to GWB, quantum particles cannot follow geodesics, but rather stochastic trajectories. In the present work, we start by adding a stochastic term to the trajectories of quantum particles and derive the corresponding field equations of a quantum particle. We arrive at the Klein-Gordon equation in curved spacetime and from it we obtain a generalized Schr\"odinger equation. This leads to the following relevant result: the Schr\"odinger equation can be a direct consequence of the fact that the universe lives on a GWB