Supersonic Gas Streams Enhance the Formation of Massive Black Holes in the Early Universe

The origin of super-massive black holes in the early universe remains poorly understood.Gravitational collapse of a massive primordial gas cloud is a promising initial process,but theoretical studies have difficulty growing the black hole fast enough.We report numerical simulations of early black hole formation starting from realistic cosmological conditions.Supersonic gas motions left over from the Big Bang prevent early gas cloud formation until rapid gas condensation is triggered in a proto-galactic halo. A protostar is formed in the dense, turbulent gas cloud, and it grows by sporadic mass accretion until it acquires 34,000 solar masses.The massive star ends its life with a catastrophic collapse to leave a black hole -- a promising seed for the formation of a monstrous black hole.Comment: Published in Science, combined with updated SOM, additional images and movies are available at http://www-utap.phys.s.u-tokyo.ac.jp/naoki.yoshida/Blackhole/0929e.htm

耐乾・耐湿性に関するヤマブドウ（Vitis colignetiae Pilliat）と生食用ブドウ品種の比較

Excess-water and drought tolerance of Vitis coignetiae grapevines were compared against 2 V. vinifera cultivars, Muscat of Alexandria and Rizamat; and 2 hydrids (V. vinifera × V. labrusca), Delaware and Kyoho. Three-year-old cutting vines of each, planted in root zone restricted beds in a plastic house, were tested under water logged and irrigation-withheld conditions starting from early and mid July, respectively. Control vines were irrigated at pF 2.2 of soil water tension. Effects of water logging were firstly observed in V. coignetiae vines where the basal leaves turned dark red after 12 days, and then abscised after 3 weeks. Under 2 weeks of water logged conditions, net assimilation rate (NAR) of the primary leaves decreased signficantly in V. coignetiae and the hybrid cultivars, Kyoho leaves turned yellow 3 weeks after the onset of the treatment and then dried out 4 weeks later. Leaves of Rizamat, Delaware, and Muscut of Alexandria vines exhibited a slight color fading or leaf curling after 4 weeks of irrigation withholding, but these symptoms did not extend thereafter. Leaf NAR and transpiration rate decreased significantly in all tested vines after 10 days of irrigation withholding, though the decrease was rapid in Kyoho vines. These results indicate that V. coignetiae vines have a lower tolerance for water logging than other ciltivars, whereas they have moderate drought tolerance

Soil CO2 emissions and net primary production of an oil palm plantation established on tropical peat

The C dynamics of a young (7 years old) smallholder oil palm plantation on peat soil in South Kalimantan (Indonesia) was investigated by directly assessing soil carbon dioxide (CO2) emissions and C sequestration as net primary production (NPP) over a period of 19 months, from September 2018 to March 2020. Soil CO2 efflux was measured monthly using a closed chamber system in ‘near (1m)’ and ‘far (3m)’ positions relative to tree bases, in order to measure total soil respiration (SR) and peat decomposition (PD), respectively. Simultaneously, litter (frond) decomposition (LD) was measured using a litter bag method. NPP was calculated as the sum of above-ground and below-ground biomass production. The C fluxes via SR, PD and LD were estimated to be 23.1 ± 6.13, 15.4 ± 4.37 (mean ± SD) and 0.38 Mg ha-1 yr-1, respectively. NPP (as C) was estimated to be 1090 g m-2 yr-1. NPP was low, mostly due to immaturity of the plantation. Heterotrophic respiration (HR) (= PD + LD) was 15.8 Mg ha-1 yr 1, resulting in the plantation acting as a net C source of 4.9 Mg ha−1 yr-1 (= NPP - HR)