Data report: early Pleistocene calcareous nannofossils, IODP Expedition 339, Site U1387

We present a revision and refinement of semiquantitative analyses of calcareous nannofossil assemblages in early Pleistocene samples from Holes U1387A and U1387C recovered toward the eastern end of the Faro Drift (36°48.3210N, 7°43.1321W) during Integrated Ocean Drilling Program Expedition 339, Mediterranean Outflow (November 2011–January 2012). The record is characterized by intervals very rich in calcareous nannofossils that are in general moderately to well preserved. On the other hand, the record contains an interval directly above the youngest dolomite layer in Section 339-U1387C-19R-4 (~0.7 m) where no coccoliths were preserved. The new stratigraphic constraints of events such as the lowest occurrence (LO) of large Gephyrocapsa, the highest occurrence (HO) of Calcidiscus macintyrei (1.66 Ma), the LO of medium-sized Gephyrocapsa group, and the HO of Discoaster brouweri (1.95 Ma) allow better interpretation of the isotope stratigraphy applied to this interval.FCT Portugal projects CCMAR:UID/Multi/04326/2019info:eu-repo/semantics/publishedVersio

CLASH-VLT: Strangulation of cluster galaxies in MACSJ0416.1-2403 as seen from their chemical enrichment

(abridged) We explore the Frontier Fields cluster MACS J0416.1-2403 at z=0.3972 with VIMOS/VLT spectroscopy from the CLASH-VLT survey covering a region which corresponds to almost three virial radii. We measure fluxes of 5 emission lines of 76 cluster members enabling us to unambiguously derive O/H gas metallicities, and also SFRs from Halpha. For intermediate massses we find a similar distribution of cluster and field galaxies in the MZR and mass vs. sSFR diagrams. Bulge-dominated cluster galaxies have on average lower sSFRs and higher O/Hs compared to their disk-dominated counterparts. We use the location of galaxies in the projected velocity vs. position phase-space to separate our cluster sample into a region of objects accreted longer time ago and a region of recently accreted and infalling galaxies. We find a higher fraction of accreted metal-rich galaxies (63%) compared to the fraction of 28% of metal-rich galaxies in the infalling regions. Intermediate mass galaxies falling into the cluster for the first time are found to be in agreement with predictions of the fundamental metallicity relation. In contrast, for already accreted star-forming galaxies of similar masses, we find on average metallicities higher than predicted by the models. This trend is intensified for accreted cluster galaxies of the lowest mass bin, that display metallicities 2-3 times higher than predicted by models with primordial gas inflow. Environmental effects therefore strongly influence gas regulations and control gas metallicities of log(M/Msun)<10.2 (Salpeter IMF) cluster galaxies. We also investigate chemical evolutionary paths of model galaxies with and without inflow of gas showing that strangulation is needed to explain the higher metallicities of accreted cluster galaxies. Our results favor a strangulation scenario in which gas inflow stops for log(M/Msun)<10.2 galaxies when accreted by the cluster.Comment: Version better matched to the published version, including table with observed and derived quantities for the 76 cluster galaxie

Combined Analysis of Near-Threshold Production of omega and phi Mesons in Nucleon-Nucleon Collisions within an Effective Meson-Nucleon Model

Vector meson ($V = \omega, \phi$) production in near-threshold elementary nucleon-nucleon collisions $pp\to ppV$, $pn\to pnV$ and $pn\to dV$ is studied within an effective meson-nucleon theory. It is shown that a set of effective parameters can be established to describe fairly well the available experimental data of angular distributions and the energy dependence of the total cross sections without explicit implementation of the Okubo-Zweig-Iisuka rule violation. Isospin effects are considered in detail and compared with experimental data whenever available

Discovery of a faint, star-forming, multiply lensed, Lyman-alpha blob

We report the discovery of a multiply lensed Lyman-$\alpha$ blob (LAB) behind the galaxy cluster AS1063 using the Multi Unit Spectroscopic Explorer (MUSE) on the Very Large Telescope (VLT). The background source is at $z=$ 3.117 and is intrinsically faint compared to almost all previously reported LABs. We used our highly precise strong lensing model to reconstruct the source properties, and we find an intrinsic luminosity of $L_{\rm Ly\alpha}$=$1.9\times10^{42}$ erg s$^{-1}$, extending to 33 kpc. We find that the LAB is associated with a group of galaxies, and possibly a protocluster, in agreement with previous studies that find LABs in overdensities. In addition to Lyman-$\alpha$ (Ly$\alpha$) emission, we find \ion{C}{IV}, \ion{He}{II}, and \ion{O}{III}] ultraviolet (UV) emission lines arising from the centre of the nebula. We used the compactness of these lines in combination with the line ratios to conclude that the \Lya nebula is likely powered by embedded star formation. Resonant scattering of the \Lya photons then produces the extended shape of the emission. Thanks to the combined power of MUSE and strong gravitational lensing, we are now able to probe the circumgalatic medium of sub-$L_{*}$ galaxies at $z\approx 3$.Comment: 7 pages, 7 figures; moderate changes to match the accepted A&A versoi

CLASH-VLT: Testing the Nature of Gravity with Galaxy Cluster Mass Profiles

We use high-precision kinematic and lensing measurements of the total mass profile of the dynamically relaxed galaxy cluster MACS J1206.2-0847 at $z=0.44$ to estimate the value of the ratio $\eta=\Psi/\Phi$ between the two scalar potentials in the linear perturbed Friedmann-Lemaitre-Robertson-Walker metric.[...] Complementary kinematic and lensing mass profiles were derived from exhaustive analyses using the data from the Cluster Lensing And Supernova survey with Hubble (CLASH) and the spectroscopic follow-up with the Very Large Telescope (CLASH-VLT). Whereas the kinematic mass profile tracks only the time-time part of the perturbed metric (i.e. only $\Phi$), the lensing mass profile reflects the contribution of both time-time and space-space components (i.e. the sum $\Phi+\Psi$). We thus express $\eta$ as a function of the mass profiles and perform our analysis over the radial range $0.5\,Mpc\le r\le r_{200}=1.96\,Mpc$. Using a spherical Navarro-Frenk-White mass profile, which well fits the data, we obtain \eta(r_{200})=1.01\,_{-0.28}^{+0.31} at the 68\% C.L. We discuss the effect of assuming different functional forms for mass profiles and of the orbit anisotropy in the kinematic reconstruction. Interpreting this result within the well-studied $f(R)$ modified gravity model, the constraint on $\eta$ translates into an upper bound to the interaction length (inverse of the scalaron mass) smaller than 2 Mpc. This tight constraint on the $f(R)$ interaction range is however substantially relaxed when systematic uncertainties in the analysis are considered. Our analysis highlights the potential of this method to detect deviations from general relativity, while calling for the need of further high-quality data on the total mass distribution of clusters and improved control on systematic effects.Comment: 18 pages, 3 figures, submitted to JCA

High efficiency thermionic converter studies

Research in thermionic energy conversion technology is reported. The objectives were to produce converters suitable for use in out of core space reactors, radioisotope generators, and solar satellites. The development of emitter electrodes that operate at low cesium pressure, stable low work function collector electrodes, and more efficient means of space charge neutralization were investigated to improve thermionic converter performance. Potential improvements in collector properties were noted with evaporated thin film barium oxide coatings. Experiments with cesium carbonate suggest this substance may provide optimum combinations of cesium and oxygen for thermionic conversion

Constraining Antimatter Domains in the Early Universe with Big Bang Nucleosynthesis

We consider the effect of a small-scale matter-antimatter domain structure on big bang nucleosynthesis and place upper limits on the amount of antimatter in the early universe. For small domains, which annihilate before nucleosynthesis, this limit comes from underproduction of He-4. For larger domains, the limit comes from He-3 overproduction. Most of the He-3 from antiproton-helium annihilation is annihilated also. The main source of He-3 is photodisintegration of He-4 by the electromagnetic cascades initiated by the annihilation.Comment: 4 pages, 2 figures, revtex, (slightly shortened

New XMM-Newton observation of the Phoenix cluster: properties of the cool core

(Abridged) We present a spectral analysis of a deep (220 ks) XMM-Newton observation of the Phoenix cluster (SPT-CL J2344-4243), which we also combine with Chandra archival ACIS-I data. We extract CCD and RGS X-ray spectra from the core region to search for the signature of cold gas, and constrain the mass deposition rate in the cooling flow which is thought to be responsible of the massive star formation episode observed in the BCG. We find an average mass deposition rate of $\dot M = 620 (-190 +200)_{stat} (-50 +150)_{syst} M_\odot$/yr in the temperature range 0.3-3.0 keV from MOS data. A temperature-resolved analysis shows that a significant amount of gas is deposited only above 1.8 keV, while upper limits of the order of hundreds of $M_\odot$/yr can be put in the 0.3-1.8 keV temperature range. From pn data we obtain $\dot M = 210 (-80 +85)_{stat} ( -35 +60)_{syst} M_\odot$/yr, and the upper limits from the temperature-resolved analysis are typically a factor of 3 lower than MOS data. In the RGS spectrum, no line emission from ionization states below Fe XXIII is seen above $12 \AA$, and the amount of gas cooling below $\sim 3$ keV has a best-fit value $\dot M = 122_{-122}^{+343}$ $M_{\odot}$/yr. In addition, our analysis of the FIR SED of the BCG based on Herschel data provides $SFR = (530 \pm 50) M_\odot$/yr, significantly lower than previous estimates by a factor 1.5. Current data are able to firmly identify substantial amount of cooling gas only above 1.8 keV in the core of the Phoenix cluster. While MOS data analysis is consistent with values as high as $\dot M \sim 1000$ within $1 \sigma$, pn data provide $\dot M < 500 M_\odot$ yr$^{-1}$ at $3\sigma$ c.l. at temperature below 1.8 keV. At present, this discrepancy cannot be explained on the basis of known calibration uncertainties or other sources of statistical noise.Comment: A&A in press, typos corrected, revised text according to published versio

The reaction Δ+N→N+N+ϕ\Delta+N\to N+N+\phi in ion-ion collisions

We study the threshold $\phi$-meson production in the process $\Delta+N\to N+N+\phi$, which appears as a possible important mechanism in high energy nuclei-nuclei collisions. The isotopic invariance of the strong interaction and the selection rules due to P-parity and total angular momentum result in a general and model independent parametrization of the spin structure of the matrix element in terms of three partial amplitudes. In the framework of one-pion exchange model these amplitudes can be derived in terms of the two threshold partial amplitudes for the process $\pi+N\to N+\phi$. We predict the ratio of cross sections for $\phi-$meson production in $pp$- and $\Delta N$-collisions and the polarization properties of the $\phi$-meson, in $\Delta+N\to N+N+\phi$, as a function of a single parameter, which characterizes the relative role of transversal and longitudinal $\phi$-meson polarizations in the process $\pi+N\to N+\phi$.Comment: 10 pages 3 figure