Future CMB tests of dark matter: ultra-light axions and massive neutrinos

Measurements of cosmic microwave background (CMB) anisotropies provide strong evidence for the existence of dark matter and dark energy. They can also test its composition, probing the energy density and particle mass of different dark-matter and dark-energy components. CMB data have already shown that ultra-light axions (ULAs) with mass in the range $10^{-32}~{\rm eV} \to 10^{-26}~{\rm eV}$ compose a fraction $< 0.01$ of the cosmological critical density. Here, the sensitivity of a proposed CMB-Stage IV (CMB-S4) experiment (assuming a 1 arcmin beam and $< 1~\mu K{\rm-arcmin}$ noise levels over a sky fraction of 0.4) to the density of ULAs and other dark-sector components is assessed. CMB-S4 data should be $\sim 10$ times more sensitive to the ULA energy-density than Planck data alone, across a wide range of ULA masses $10^{-32}< m_{a}< 10^{-23}~{\rm eV}$, and will probe axion decay constants of $f_{a}\approx 10^{16}~{\rm GeV}$, at the grand unified scale. CMB-S4 could improve the CMB lower bound on the ULA mass from $\sim 10^{-25}~{\rm eV}$ to $10^{-23}~{\rm eV}$, nearing the mass range probed by dwarf galaxy abundances and dark-matter halo density profiles. These improvements will allow for a multi-$\sigma$ detection of percent-level departures from CDM over a wide range of masses. Much of this improvement is driven by the effects of weak gravitational lensing on the CMB, which breaks degeneracies between ULAs and neutrinos. We also find that the addition of ULA parameters does not significantly degrade the sensitivity of the CMB to neutrino masses. These results were obtained using the axionCAMB code (a modification to the CAMB Boltzmann code), presented here for public use.Comment: 16 pages, 12 figures. The axionCAMB code will be available online at http://github.com/dgrin1/axionCAMB from 1 August 201

Climate model and proxy data constraints on ocean warming across the Paleocene-Eocene Thermal Maximum

Constraining the greenhouse gas forcing, climatic warming and estimates of climate sensitivity across ancient large transient warming events is a major challenge to the palaeoclimate research community. Here we provide a new compilation and synthesis of the available marine proxy temperature data across the largest of these hyperthermals, the Paleocene-Eocene Thermal Maximum (PETM). This includes the application of consistent temperature calibrations to all data, including the most recent set of calibrations for archaeal lipid-derived palaeothermometry. This compilation provides the basis for an informed discussion of the likely range of PETM warming, the biases present in the existing record and an initial assessment of the geographical pattern of PETM ocean warming. To aid interpretation of the geographic variability of the proxy-derived estimates of PETM warming, we present a comparison of this data with the patterns of warming produced by high pCO2 simulations of Eocene climates using the Hadley Centre atmosphere-ocean general circulation model (AOGCM) HadCM3L. On the basis of this comparison and taking into account the patterns of intermediate-water warming we estimate that the global mean surface temperature anomaly for the PETM is within the range of 4 to 5°C

Metamorphism of felsic to mafic orthogneisses from Kasumi Rocks, Lützow-Holm Complex, East Antarctica

第6回極域科学シンポジウム[OG] 地圏11月16日（月）　国立極地研究所１階交流アトリウ

Geological fieldwork of the Lützow-Holm Complex by JARE-52 geology party

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議

Mineral ages for multi isotope system in phlogopite-bearing pyroxene granulite and felsic gneiss, the Howard Hills, Enderby Land, East Antarctica: Possible Proterozoic tectonothermal events in the Napier Complex

Large mafic to ultramafic blocks in felsic gneisses on the northern part of the Howard Hills, Napier Complex, East Antarctica are accompanied by phlogopite-bearing pyroxene granulite occurring in the margins of the block. In order to understand the crustal evolution of the Napier Complex, especially regarding the thermal history after peak metamorphism, Rb-Sr, Sm-Nd and U-Pb isotopic analyses have been carried out on different minerals from the phlogopite-bearing pyroxene granulite and adjacent orthopyroxene felsic gneiss. Zircon grains from the orthopyroxene felsic gneiss yielded near concordant U-Pb isotopic ages of about 2.5Ga by conventional isotope dilution methods and defined a discordia with 2.44±0.02Ga lower intercept age. This age shows the waning stage of UHT granulite facies metamorphism in the Howard Hills. Rutile fractions from pyroxene granulite yielded a near concordant U-Pb isotopic age of about 1.5Ga. This age is interpreted as the final thermal episode, excepting local igneous intrusions, in the Howard Hills region. Fluorophlogopite fractions from pyroxene granulite yielded Rb-Sr model ages of about 1.85Ga, although evidence of retrograde metamorphism with fluid activity or deformation were poor in the pyroxene granulite. An internal Sm-Nd isochron of whole rock and orthopyroxene and feldspar separated from the same sample shows 1.85±0.15Ga. The Rb-Sr phlogopite model age, along with the Sm-Nd internal isochron age, records the time when the rocks of the Howard Hills underwent medium to high grade metamorphism at temperatures well above the currently accepted closure temperature of biotite (about 300-350°C )

Occurrences of metamorphosed ultramafic rock and associating rocks in Howard Hills, Enderby Land, East Antarctica: Evidence of partial melting from geochemical and isotopic characteristics

Large blocks of metamorphic rocks with mafic to ultramafic compositions were discovered in felsic gneiss at the central part of northern Howard Hills in Enderby Land. The ultramafic core is separated from the felsic gneiss by a mantle of pyroxene granulite. We can recognize from mineral assemblages and chemical compositions that the metamorphic rocks experienced ultrahigh temperature (UHT) metamorphism. Rubidium-strontium and samarium neodymium analytical data from the metamorphic rocks yield apparent ages of about 2.65 Ga within analytical error on isochron diagrams. Metamorphic rocks with mafic to ultramafic compositions are enriched in incompatible elements and have high Sr isotope ratios, resulting in some samples in improbable Nd model ages. This is attributed to enrichment of compatible elements and/or depletion of incompatible elements during metamorphism. We conclude that these metamorphic rocks experienced partial melting during UHT metamorphism. Pyroxene granulite was produced as a residual material after partial melting of LILE-enriched protoliths with high Sr isotope ratios

Resolving orogenic events in construction of the Lutzow-Holm Complex, east Antarctica

第2回極域科学シンポジウム/第31回極域地学シンポジウム 11月17日（木） 国立極地研究所　2階大会議

High-grade metamorphic rocks from Skallevikshalsen in the Lutzow-Holm Complex, East Antarctica: metamorphic conditions and possibility of partial melting

The high-grade metamorphic rocks of Skallevikshalsen, Lutzow-Holm Complex, East Antarctica predominantly comprise garnet-sillimanite gneiss, garnet-spinel-sillimanite gneiss, garnet-biotite gneiss and garnet-two pyroxene-mafic granulite. The metamorphic conditions were estimated using various geothermometers and geobarometers for garnet-biotite gneiss and mafic gneiss. The results were 770-940℃and 0.65-1.2 GPa for garnet-biotite gneiss and 780-960℃ and 0.6-1.1 GPa for mafic gneiss. Garnet-biotite gneiss is widespread in this area and displays a well-developed migmatitic structure. Garnet porphyroblasts in the leucosome and the boundaries between leucosome and melanosome in garnet-biotite gneiss commonly have a poikiloblastic texture with euhedral feldspar and quartz inclusions. High Y concentrations in garnet cores, high An values for plagioclase inclusions, and high Ba contents in K-feldspar from garnet-biotite gneiss are inferred to reflect growth in the presence of partial melt. Garnet in garnet-sillimanite gneiss also has high Y and P contents and chemical zoning that implies changes in trace element distribution coefficients. It is suggested that hydrous melt in garnet-sillimanite gneiss was generated during prograde metamorphism while anhydrous restite underwent continuous high-temperature metamorphism. Garnet-sillimanite gneiss is likely to be the restitic product of partial melting and shows evidence for melt segregation and movement

Timing of UHT metamorphism at Mather Peninsula in Rauer Islands: Zircon and monazite U-Th-Pb and rare earth elements chemistry constraints

第6回極域科学シンポジウム[OG] 地圏11月16日（月）　国立極地研究所３階セミナー

‘Okunen’ in a long, hot orogen: a timeline of tectonometamorphic activity in southern LützowHolm Bay

第3回極域科学シンポジウム/第32回極域地学シンポジウム 11月30日（金） 統計数理研究所 ３階セミナー