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Spectroscopic confirmation of a mature galaxy cluster at a redshift of 2 期刊论文
NATURE, 2020, 577 (7788) : 39-+
作者:  Willis, J. P.;  Canning, R. E. A.;  Noordeh, E. S.;  Allen, S. W.;  King, A. L.;  Mantz, A.;  Morris, R. G.;  Stanford, S. A.;  Brammer, G.
收藏  |  浏览/下载:12/0  |  提交时间:2020/07/03

Galaxy clusters are the most massive virialized structures in the Universe and are formed through the gravitational accretion of matter over cosmic time(1). The discovery(2) of an evolved galaxy cluster at redshift z = 2, corresponding to a look-back time of 10.4 billion years, provides an opportunity to study its properties. The galaxy cluster XLSSC 122 was originally detected as a faint, extended X-ray source in the XMM Large Scale Structure survey and was revealed to be coincident with a compact over-density of galaxies(2) with photometric redshifts of 1.9 +/- 0.2. Subsequent observations3 at millimetre wavelengths detected a Sunyaev-Zel'  dovich decrement along the line of sight to XLSSC 122, thus confirming the existence of hot intracluster gas, while deep imaging spectroscopy from the European Space Agency'  s X-ray Multi-Mirror Mission (XMM-Newton) revealed(4) an extended, X-ray-bright gaseous atmosphere with a virial temperature of 60 million Kelvin, enriched with metals to the same extent as are local clusters. Here we report optical spectroscopic observations of XLSSC 122 and identify 37 member galaxies at a mean redshift of 1.98, corresponding to a look-back time of 10.4 billion years. We use photometry to determine a mean, dust-free stellar age of 2.98 billion years, indicating that star formation commenced in these galaxies at a mean redshift of 12, when the Universe was only 370 million years old. The full range of inferred formation redshifts, including the effects of dust, covers the interval from 7 to 13. These observations confirm that XLSSC 122 is a remarkably mature galaxy cluster with both evolved stellar populations in the member galaxies and a hot, metal-rich gas composing the intracluster medium.


  
Dating the skull from Broken Hill, Zambia, and its position in human evolution 期刊论文
NATURE, 2020, 580 (7803) : 372-+
作者:  Mergner, Julia;  Frejno, Martin;  List, Markus;  Papacek, Michael;  Chen, Xia;  Chaudhary, Ajeet;  Samaras, Patroklos;  Richter, Sandra;  Shikata, Hiromasa;  Messerer, Maxim;  Lang, Daniel;  Altmann, Stefan;  Cyprys, Philipp;  Zolg, Daniel P.;  Mathieson, Toby;  Bantscheff, Marcus
收藏  |  浏览/下载:5/0  |  提交时间:2020/07/03

The cranium from Broken Hill (Kabwe) was recovered from cave deposits in 1921, during metal ore mining in what is now Zambia(1). It is one of the best-preserved skulls of a fossil hominin, and was initially designated as the type specimen of Homo rhodesiensis, but recently it has often been included in the taxon Homo heidelbergensis(2-4). However, the original site has since been completely quarried away, and-although the cranium is often estimated to be around 500 thousand years old(5-7)-its unsystematic recovery impedes its accurate dating and placement in human evolution. Here we carried out analyses directly on the skull and found a best age estimate of 299 +/- 25 thousand years (mean +/- 2s). The result suggests that later Middle Pleistocene Africa contained multiple contemporaneous hominin lineages (that is, Homo sapiens(8,9), H. heidelbergensis/H. rhodesiensis and Homo naledi(10,11)), similar to Eurasia, where Homo neanderthalensis, the Denisovans, Homo floresiensis, Homo luzonensis and perhaps also Homo heidelbergensis and Homo erectus(12) were found contemporaneously. The age estimate also raises further questions about the mode of evolution of H. sapiens in Africa and whether H. heidelbergensis/H. rhodesiensis was a direct ancestor of our species(13,14).


  
Stand carbon density drivers and changes under future climate scenarios across global forests 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2019, 449
作者:  Guo, Yanrong;  Peng, Changhui;  Trancoso, Ralph;  Zhu, Qiuan;  Zhou, Xiaolu
收藏  |  浏览/下载:9/0  |  提交时间:2019/11/27
Aboveground and belowground carbon densities  Stand age  Mean annual precipitation  Mean annual temperature  Dryness index  Clay content  
Impacts of Subsurface Tile Drainage on AgeConcentration Dynamics of Inorganic Nitrogen in Soil 期刊论文
WATER RESOURCES RESEARCH, 2019, 55 (2) : 1470-1489
作者:  Woo, Dong K.;  Kumar, Praveen
收藏  |  浏览/下载:6/0  |  提交时间:2019/11/26
nitrogen age  mean age  inorganic nitrogen  nitrate  reactive  tile drainage  
Annual global mean temperature explains reproductive success in a marine vertebrate from 1955 to 2010 期刊论文
GLOBAL CHANGE BIOLOGY, 2018, 24 (4) : 1599-1613
作者:  Mauck, Robert A.;  Dearborn, Donald C.;  Huntington, Charles E.
收藏  |  浏览/下载:5/0  |  提交时间:2019/04/09
age effects  air temperature  climate change  global mean temperature  longitudinal study  long-term dataset  seabirds  sea surface temperature  storm-petrels  
Decadal changes in Southern Ocean ventilation inferred from deconvolutions of repeat hydrographies 期刊论文
GEOPHYSICAL RESEARCH LETTERS, 2017, 44 (11)
作者:  Ting, Yu-Heng;  Holzer, Mark
收藏  |  浏览/下载:3/0  |  提交时间:2019/04/09
ocean ventilation  tracer deconvolution  transport  climate change  mean age  water-mass fraction  
Improving biomass estimation in a Populus short rotation coppice plantation 期刊论文
FOREST ECOLOGY AND MANAGEMENT, 2017, 391
作者:  Oliveira, Nerea;  Rodriguez-Soalleiro, Roque;  Jose Hernandez, Maria;  Canellas, Isabel;  Sixto, Hortensia;  Perez-Cruzado, Cesar
收藏  |  浏览/下载:5/0  |  提交时间:2019/04/09
Poplar  Allometric models  Age-influence  Mean deviation