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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： K.B. Mao Y. Ma Z. Y. Zuo Y. Q. Jiao F. Wang Q. Liu Z. W. Sun National Hulunber Grassland Ecosystem Observation and Research Station Chinese Academy of Agricultural Sciences Beijing China Chinese Academy of Agricultural Big Data and Nutrition Hong Kong China State Key Laboratory of Remote Sensing Science Beijing Normal University Beijing China College of Science China University of Petroleum Beijing China National-Local Joint Engineering Laboratory of Geo-spatial Information Technology Hunan University of Science and Technology Xiangtan China Space Star Technology Co. Ltd. Beijing China

Water vapor in the Earth's upper atmosphere plays a crucial in the radiative balance, hydrological process, and climate change. Based on the latest MODIS data, this study probes the spatio-temporal variations of global water vapor content in the past decade. It is found that overall the global water vapor concentrations declined over 2003-2012 (b=- 0.0149, R 2 =0.797, p=0.0005). The decreasing trend over the ocean surface (b= -0.017, R 2 =0.824, p=0.0003) is more explicit than over terrestrial surface (b= -0.010, R 2 =0.612, p=0.007), more significant over the Northern Hemisphere (b= -0.0175, R 2 =0.852, p=0.0001) than over the Southern Hemisphere (b= -0.0123, R 2 =0.682, p=0.003). Vegetation cover change is critical for an understanding of the impacts and responses of vegetation to climate change. The global vegetation growth has been analysised from 2001 to 2012. After thorough analysis based on satellite data, we find evidence that the global vegetation change little, and it is increasing slightly in Northern hemisphere while it is deceasing slightly in Southern Hemisphere. For different latitudes, the vegetation is increasing 0.17% every year from 60°N to 70 °N (R 2 =0.47, P>0.013), while the vegetation is decreasing 0.11% every year from 10°N to 10°S (R 2 =0.54, P>0.004). For different continents, the vegetation in South America is decreasing 0.16% every year (R 2 =0.78, P>0.0001) and it is increasing 0.05% every year in Asia (R 2 =0.28, P>0.072) and 0.25% every year in Oceania (R 2 =0.24, P>0.1).

关键词： Vegetation mapping Vegetation MODIS Remote sensing Meteorology Market research Ocean temperature

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First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole

arXiv

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arXiv 2019年

作者： Akiyama, Kazunori Alberdi, Antxon Alef, Walter Asada, Keiichi Azulay, Rebecca Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bintley, Dan Blackburn, Lindy Boland, Wilfred Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Byun, Do-Young Carlstrom, John E. Chael, Andrew Chan, Chi-kwan Chatterjee, Shami Chatterjee, Koushik Chen, Ming-Tang Chen, Yongjun Cho, Ilje Christian, Pierre Conway, John E. Cordes, James M. Crew, Geoffrey B. Cui, Yuzhu Davelaar, Jordy de Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Doeleman, Sheperd S. Eatough, Ralph P. Falcke, Heino Fish, Vincent L. Fomalont, Ed Fraga-Encinas, Raquel Friberg, Per Fromm, Christian M. Gómez, José L. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Hesper, Ronald Ho, Luis C. Hecht, Michael H. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Johnson, Michael D. Jorstad, Svetlana Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Jae-Young Kim, Junhan Kim, Jongsoo Kino, Motoki Koay, Jun Yi Koch, Patrick M. Koyama, Shoko Kramer, Michael Kramer, Carsten Krichbaum, Thomas P. Kuo, Cheng-Yu Lauer, Tod R. Lee, Sang-Sung Li, Yan-Rong Li, Zhiyuan Lindqvist, Michael Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin Lu, Ru-Sen MacDonald, Nicholas R. Jirong Markoff, Sera Marrone, Daniel P. Marscher, Alan P. Martí-Vidal, Iván Matsushita, Satoki Matthews, Lynn D. Medeiros, Lia Menten, Karl M. Mizuno, Yosuke Mizuno, Izumi Moran, James M. Moriyama, Kotaro Moscibrodzka, Monika Müller, Cornelia Nagai, Hiroshi Nagar, Neil M. Nakamura, Masanori Narayan, Ramesh Narayana National Radio Astronomy Observatory 520 Edgemont Rd CharlottesvilleVA22903 United States Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Black Hole Initiative at Harvard University 20 Garden Street CambridgeMA02138 United States Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Section 4 Roosevelt Rd Taipei10617 Taiwan Departament d’Astronomia i Astrofísica Universitat de València C. Dr. Moliner 50 Burjassot ValènciaE-46100 Spain Observatori Astronòmic Universitat de València C. Catedrático José Beltrán 2 PaternaValènciaE-46980 Spain Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Center for Astrophysics ∣ Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States East Asian Observatory 660 N. A’ohoku Pl. HiloHI96720 United States P.O. Box 9513 Leiden2300 RA Netherlands California Institute of Technology 1200 East California Boulevard PasadenaCA91125 United States Institute of Astronomy and Astrophysics Academia Sinica 645 N. A’ohoku Place HiloHI96720 United States Institut de Radioastronomie Millimétrique 300 rue de la Piscine Saint Martin d’HèresF-38406 France Radboud University P.O. Box 9010 Nijmegen6500 GL Netherlands Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Waterloo Centre for Astrophysics University of Waterloo WaterlooONN2L 3G1 Canada Korea Astronomy and Space Science Institute Daedeok-daero 776

We present measurements of the properties of the central radio source in M87 using Event Horizon Telescope data obtained during the 2017 campaign. We develop and fit geometric crescent models (asymmetric rings with interior brightness depressions) using two independent sampling algorithms that consider distinct representations of the visibility data. We show that the crescent family of models is statistically preferred over other comparably complex geometric models that we explore. We calibrate the geometric model parameters using general relativistic magnetohydrodynamic (GRMHD) models of the emission region and estimate physical properties of the source. We further fit images generated from GRMHD models directly to the data. We compare the derived emission region and black hole parameters from these analyses with those recovered from reconstructed images. There is a remarkable consistency among all methods and data sets. We find that >50% of the total flux at arcsecond scales comes from near the horizon, and that the emission is dramatically suppressed interior to this region by a factor >10, providing direct evidence of the predicted shadow of a black hole. Across all methods, we measure a crescent diameter of 42 ± 3 μas and constrain its fractional width to be 2 = 3.8 ± 0.4 μas. Folding in a distance measurement of 16.8-+0.70.8 Mpc gives a black hole mass of M = 6.5 + 0.2∣stat +0.7∣sys ´ 109 M☉. This measurement from lensed emission near the event horizon is consistent with the presence of a central Kerr black hole, as predicted by the general theory of relativity. Copyright © 2019, The Authors. All rights reserved.

关键词： Gravitation

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First M87 Event Horizon Telescope Results. VI. The Shadow and Mass of the Central Black Hole

arXiv

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arXiv 2019年

关键词： Gravitation

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First M87 event horizon telescope results. III. data processing and calibration

arXiv

引用

arXiv 2019年

作者： Akiyama, Kazunori Alberdi, Antxon Alef, Walter Asada, Keiichi Azulay, Rebecca Baczko, Anne-Kathrin Ball, David Baloković, Mislav Barrett, John Bintley, Dan Blackburn, Lindy Boland, Wilfred Bouman, Katherine L. Bower, Geoffrey C. Bremer, Michael Brinkerink, Christiaan D. Brissenden, Roger Britzen, Silke Broderick, Avery E. Broguiere, Dominique Bronzwaer, Thomas Byun, Do-Young Carlstrom, John E. Chael, Andrew Chan, Chikwan Chatterjee, Shami Chatterjee, Koushik Chen, Ming-Tang Chen, Yongjun Cho, Ilje Christian, Pierre Conway, John E. Cordes, James M. Crew, Geoffrey B. Cui, Yuzhu Davelaar, Jordy de Laurentis, Mariafelicia Deane, Roger Dempsey, Jessica Desvignes, Gregory Dexter, Jason Doeleman, Sheperd S. Eatough, Ralph P. Falcke, Heino Fish, Vincent L. Fomalont, Ed Fraga-Encinas, Raquel Friberg, Per Fromm, Christian M. Gómez, José L. Galison, Peter Gammie, Charles F. García, Roberto Gentaz, Olivier Georgiev, Boris Goddi, Ciriaco Gold, Roman Gu, Minfeng Gurwell, Mark Hada, Kazuhiro Hesper, Ronald Ho, Luis C. Hecht, Michael H. Ho, Paul Honma, Mareki Huang, Chih-Wei L. Huang, Lei Hughes, David H. Ikeda, Shiro Inoue, Makoto Issaoun, Sara James, David J. Jannuzi, Buell T. Janssen, Michael Jeter, Britton Jiang, Wu Johnson, Michael D. Jorstad, Svetlana Jung, Taehyun Karami, Mansour Karuppusamy, Ramesh Kawashima, Tomohisa Keating, Garrett K. Kettenis, Mark Kim, Jae-Young Kim, Junhan Kim, Jongsoo Kino, Motoki Koay, Jun Yi Koch, Patrick M. Koyama, Shoko Kramer, Michael Kramer, Carsten Krichbaum, Thomas P. Kuo, Cheng-Yu Lauer, Tod R. Lee, Sang-Sung Yan-Rong, Li Li, Zhiyuan Lindqvist, Michael Liu, Kuo Liuzzo, Elisabetta Lo, Wen-Ping Lobanov, Andrei P. Loinard, Laurent Lonsdale, Colin Ru-Sen, Lu MacDonald, Nicholas R. Mao, Jirong Markoff, Sera Marrone, Daniel P. Marscher, Alan P. Martí-Vidal, Iván Matsushita, Satoki Matthews, Lynn D. Medeiros, Lia Menten, Karl M. Mizuno, Yosuke Mizuno, Izumi Moran, James M. Moriyama, Kotaro Moscibrodzka, Monika Müller, Cornelia Nagai, Hiroshi Nagar, Neil M. Nakamura, Masanori Narayan, Ramesh Nara National Radio Astronomy Observatory 520 Edgemont Rd CharlottesvilleVA22903 United States Massachusetts Institute of Technology Haystack Observatory 99 Millstone Road WestfordMA01886 United States National Astronomical Observatory of Japan 2-21-1 Osawa Mitaka Tokyo181-8588 Japan Black Hole Initiative at Harvard University 20 Garden Street CambridgeMA02138 United States Instituto de Astrofísica de Andalucía-CSIC Glorieta de la Astronomía s/n GranadaE-18008 Spain Max-Planck-Institut für Radioastronomie Auf dem Hügel 69 BonnD-53121 Germany Institute of Astronomy and Astrophysics Academia Sinica 11F of Astronomy-Mathematics Building AS/NTU No. 1 Sec. 4 Roosevelt Rd Taipei10617 Taiwan Departament d’Astronomia i Astrofísica Universitat de València C. Dr. Moliner 50 Burjassot ValènciaE-46100 Spain Observatori Astronòmic Universitat de València C. Catedrático José Beltrán 2 PaternaValènciaE-46980 Spain Steward Observatory and Department of Astronomy University of Arizona 933 N. Cherry Avenue TucsonAZ85721 United States Center for Astrophysics Harvard & Smithsonian 60 Garden Street CambridgeMA02138 United States East Asian Observatory 660 N. A’ohoku Pl. HiloHI96720 United States PO Box 9513 Leiden2300 RA Netherlands California Institute of Technology 1200 East California Boulevard PasadenaCA91125 United States Institute of Astronomy and Astrophysics Academia Sinica 645 N. A’ohoku Place HiloHI96720 United States Institut de Radioastronomie Millimétrique 300 rue de la Piscine Saint Martin d’HèresF-38406 France Radboud University P.O. Box 9010 Nijmegen6500 GL Netherlands Perimeter Institute for Theoretical Physics 31 Caroline Street North WaterlooONN2L 2Y5 Canada Department of Physics and Astronomy University of Waterloo 200 University Avenue West WaterlooONN2L 3G1 Canada Waterloo Centre for Astrophysics University of Waterloo WaterlooONN2L 3G1 Canada Korea Astronomy and Space Science Institute Daedeok-daero 776 Yuse

We present the calibration and reduction of Event Horizon Telescope (EHT) 1.3 mm radio wavelength observations of the supermassive black hole candidate at the center of the radio galaxy M87 and the quasar 3C 279, taken during the 2017 April 5–11 observing campaign. These global very long baseline interferometric observations include for the first time the highly sensitive Atacama Large Millimeter/submillimeter Array (ALMA);reaching an angular resolution of 25 μas, with characteristic sensitivity limits of ∼1 mJy on baselines to ALMA and ∼10 mJy on other baselines. The observations present challenges for existing data processing tools, arising from the rapid atmospheric phase fluctuations, wide recording bandwidth, and highly heterogeneous array. In response, we developed three independent pipelines for phase calibration and fringe detection, each tailored to the specific needs of the EHT. The final data products include calibrated total intensity amplitude and phase information. They are validated through a series of quality assurance tests that show consistency across pipelines and set limits on baseline systematic errors of 2% in amplitude and 1° in phase. The M87 data reveal the presence of two nulls in correlated flux density at ∼3.4 and ∼8.3 Gλ and temporal evolution in closure quantities, indicating intrinsic variability of compact structure on a timescale of days, or several light-crossing times for a few billion solar-mass black hole. These measurements provide the first opportunity to image horizon-scale structure in M87. Copyright © 2019, The Authors. All rights reserved.

关键词： Telescopes

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The fraction of ionizing radiation from massive stars that escapes to the intergalactic medium

arXiv

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arXiv 2018年

作者： Tanvir, N.R. Fynbo, J.P.U. de Ugarte Postigo, A. Japelj, J. Wiersema, K. Malesani, D. Perley, D.A. Levan, A.J. Selsing, J. Cenko, S.B. Kann, D.A. Milvang-Jensen, B. Berger, E. Cano, Z. Chornock, R. Covino, S. Cucchiara, A. D'Elia, V. Goldoni, P. Gomboc, A. Heintz, K.E. Hjorth, J. Izzo, L. Jakobsson, P. Kaper, L. Krühler, T. Laskar, T. Myers, M. Piranomonte, S. Pugliese, G. Sánchez-Ramírez, R. Schulze, S. Sparre, M. Stanway, E.R. Tagliaferri, G. Thöne, C.C. Vergani, S. Vreeswijk, P.M. Wijers, R.A.M.J. Watson, D. Xu, D. University of Leicester Department of Physics & Astronomy Leicester Institute of Space & Earth Observation University Road LeicesterLE1 7RH United Kingdom Dark Cosmology Centre Niels Bohr Institute University of Copenhagen Juliane Maries Vej 30 Copenhagen Ø2100 Denmark Glorieta de la Astronomía s/n GranadaE-18008 Spain Astronomical Institute Anton Pannekoek University of Amsterdam PO Box 94249 Amsterdam1090 GE Netherlands Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom Department of Physics University of Warwick CoventryCV4 7AL United Kingdom Harvard-Smithsonian Center for Astrophysics 60 Garden Street CambridgeMA02138 United States NASA's Goddard Space Flight Center GreenbeltMD20771 United States Joint Space-Science Institute University of Maryland College ParkMD20742 United States Astrophysical Institute Department of Physics and Astronomy Ohio University AthensOH45701 United States INAF Osservatorio Astronomico di Brera Via Bianchi 46 Merate23807 Italy University of the Virgin Islands College of Science and Mathematics USVI #2 Brewers Bay Road Charlotte Amalie00802 I-00040 00078 Italy ASI-Science Data Centre Via del Politecnico snc RomeI-00133 Italy APC Astroparticule et Cosmologie Université Paris Diderot CNRS IN2P3 CEA Irfu Observatoire de Paris Sorbonne Paris Cité 10 Rue Alice Domon et Léonie Duquet Paris Cedex 1375205 France Centre for Astrophysics and Cosmology University of Nova Gorica Vipavska 11c Ajdovščina5270 Slovenia Centre for Astrophysics and Cosmology Science Institute University of Iceland Dunhagi 5 Reykjavík107 Iceland Max-Planck-Institut für Extraterrestrische Physik Giessenbachstrasse Garching85748 Germany National Radio Astronomy Observatory 520 Edgemont Road CharlottesvilleVA22903 United States Department of Astronomy University of California 501 Campbell Hall BerkeleyCA94720-3411 United Stat

The part played by stars in the ionization of the intergalactic medium (IGM) remains an open question. A key issue is the proportion of the stellar ionizing radiation that escapes the galaxies in which it is produced. Spectroscopy of gamma-ray burst (GRB) afterglows can be used to determine the neutral hydrogen column-density, NH i, in their host galaxies and hence the opacity to extreme ultra-violet (EUV) radiation along the lines-of-sight to the bursts. Thus, making the reasonable assumption that long-duration GRB locations are representative of the sites of massive stars that dominate EUV production, one can calculate an average escape fraction of ionizing radiation in a way that is independent of galaxy size, luminosity or underlying spectrum. Here we present a sample of NH i measures for 138 GRBs in the range 1.6 esci ≈ 0.005, with a 98% confidence upper limit of h fesci ≈ 0.015. This analysis suggests that stars provide a small contribution to the ionizing radiation budget of the IGM at z 5, firm conclusions are limited by the small size of the GRB sample (7/138), but any decline in average H i column-density seems to be modest. We also find no indication of a significant correlation of NH i with galaxy UV luminosity or host stellar mass, for the subset of events for which these are available. We discuss in some detail a number of selection effects and potential biases. Drawing on a range of evidence we argue that such effects, while not negligible, are unlikely to produce systematic errors (in either direction) of more than a factor ∼ 2 in fesc, and so would not affect the primary conclusions. Given that many GRB hosts are low metallicity, high specific star-formation rate, dwarf galaxies, these results present a particular problem for the hypothesis that such galaxies dominated the reionization of the universe. Copyright © 2018, The Authors. All rights reserved.

关键词： Stars

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Light-absorbing Particles in Snow and Ice: Measurement and Modeling of Climatic and Hydrological impact

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Advances in Atmospheric Sciences 2015年第1期32卷 64-91页

作者： Yun QIAN Teppei J.YASUNARI Sarah J.DOHERTY Mark G.FLANNER William K.M.LAU MING Jing Hailong WANG Mo WANG Stephen G.WARREN Rudong ZHANG Atmospheric Sciences and Global Change Division Pacific Northwest National Laboratory Goddard Earth Sciences Technology and Research Universities Space Research Association NASA Goddard Space Flight Center Department of Atmospheric Sciences University of Washington Department of Atmospheric Sciences University of Michigan Earth System Science Interdisciplinary Center University of Maryland College Park 20740MD USA Earth Science Division NASA Goddard Space Flight Center National Climate Center China Meteorological Administration Key Laboratory of Tibetan Environment Changes and Land Surface Processes Institute of Tibetan Plateau ResearchChinese Academy of Sciences College of Atmospheric Sciences Lanzhou University

Light absorbing particles（LAP, e.g., black carbon, brown carbon, and dust） influence water and energy budgets of the atmosphere and snowpack in multiple ways. In addition to their effects associated with atmospheric heating by absorption of solar radiation and interactions with clouds, LAP in snow on land and ice can reduce the surface reflectance（a.k.a., surface darkening）, which is likely to accelerate the snow aging process and further reduces snow albedo and increases the speed of snowpack melt. LAP in snow and ice（LAPSI） has been identified as one of major forcings affecting climate change, *** the fourth and fifth assessment reports of IPCC. However, the uncertainty level in quantifying this effect remains very high. In this review paper, we document various technical methods of measuring LAPSI and review the progress made in measuring the LAPSI in Arctic, Tibetan Plateau and other mid-latitude regions. We also report the progress in modeling the mass concentrations, albedo reduction, radiative forcing, and climatic and hydrological impact of LAPSI at global and regional scales. Finally we identify some research needs for reducing the uncertainties in the impact of LAPSI on global and regional climate and the hydrological cycle.

关键词： light-absorbing aerosol snow ice albedo measurement climate modeling hydrological cycle

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The monitoring of land use and land cover change of Sichuan province and Chengdu district, China

The monitoring of land use and land cover change of Sichuan ...

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IEEE International Symposium on Geoscience and Remote Sensing (IGARSS)

作者： Shijie Yu Zezhong Zheng Wunian Yang Mingcang Zhu Yong He Zhenlu Yu Shengli Wang Fu Wang Jiang Li School of Resources and Environment Univ. of Electronic Science and Technology of China Chengdu Sichuan PRC State Key Laboratory of Water Resources and Hydropower Engineering Science Wuhan Univ. Wuhan Hubei PRC Ministry of Land and Resources of the China Chengdu Univ. of Technology Chengdu Sichuan PRC Guangxi Key Laboratory for Spatial Information and Geomatics Guilin Guangxi PRC Land and Resources Department of Sichuan Province Chengdu Sichuan PRC Sichuan Institute of Geo-Environment Monitoring Chengdu Sichuan PRC China National Space Administration Earth Observation System and Data Center Beijing PRC CMA National Satellite Meteorological Center Beijing PRC Dep. of Electrical and Computer Engineering Old Dominion Univ. Norfolk VA USA

Land use and land cover change (LUCC) is necessary to explore the factors leading to heavy drought and rainy-flood disaster in some districts of Sichuan province. A method based RS, GIS, GPS and Google earth (GE) is presented to establish LUCC database in Sichuan province and Chengdu district. At first, LUCC is interpreted based on the new temporal images and the land use and land cover database from TM in ***, some ground objects, which could not be identified in the new temporal images, were interpreted utilizing GE with some higher spatial resolution images. Thirdly, the new interpreted LUCC was validated in the field with GPS handheld receiver. Then, LUCC of Sichuan province was updated. A comparative analysis of LUCC between in Sichuan province and in Chengdu district was conducted and the result showed: (1) a large amount of farmland in Sichuan Province was occupied from 2000 to 2005 and the area is 84 573 ha. While construction land gained obviously and the area was 35 828 ha. The dynamic degree of construction land was 111.10 0 / 00 from 2000 to 2005. The LUCC demonstrated that the economy of Sichuan province continued to develop, the cities were overspreading and the urban heat island effect was deteriorated from 2000 to 2005. (2) A large amount of farmland was also occupied in Chengdu district from 2000 to 2005, the area amounted to 12 989 ha. The farmland lost was mainly changed to construction land, amounting to 93%. And the dynamic degree was 117.41 0 / 00 from 2000 to 2005, which was bigger than that in Sichuan province.

关键词： Spatial resolution Global Positioning system Urban areas Thermal pollution Remote sensing Google databases

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Dense matter with eXTP

arXiv

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arXiv 2018年

作者： Watts, Anna L. Yu, Wenfei Poutanen, Juri Zhang, Shu Bhattacharyya, Sudip Bogdanov, Slavko Ji, Long Patruno, Alessandro Riley, Thomas E. Bakala, Pavel Baykal, Altan Bernardini, Federico Bombaci, Ignazio Brown, Edward Cavecchi, Yuri Chakrabarty, Deepto Chenevez, Jérôme Degenaar, Nathalie Santo, Melania Del Salvo, Tiziana Di Doroshenko, Victor Falanga, Maurizio Ferdman, Robert D. Feroci, Marco Gambino, Angelo F. Ge, MingYu Greif, Svenja K. Guillot, Sebastien Gungor, Can Hartmann, Dieter H. Hebeler, Kai Heger, Alexander Homan, Jeroen Iaria, Rosario in’t Zand, Jean Kargaltsev, Oleg Kurkela, Aleksi Lai, Xiaoyu Li, Ang Li, XiangDong Li, Zhaosheng Linares, Manuel Lu, FangJun Mahmoodifar, Simin Méndez, Mariano Miller, M. Coleman Morsink, Sharon Nättilä, Joonas Possenti, Andrea Prescod-Weinstein, Chanda Qu, JinLu Riggio, Alessandro Salmi, Tuomo Sanna, Andrea Santangelo, Andrea Schatz, Hendrik Schwenk, Achim Song, LiMing Šrámková, Eva Stappers, Benjamin Stiele, Holger Strohmayer, Tod Tews, Ingo Tolos, Laura Török, Gabriel Tsang, David Urbanec, Martin Vacchi, Andrea Xu, RenXin Xu, Ypeng Zane, Silvia Zhang, Guobao Zhang, ShuangNan Zhang, Wenda Zheng, ShiJie Zhou, Xia Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Shanghai Astronomical Observatory Shanghai200030 China Tuorla Observatory Department of Physics and Astronomy University of Turku Väisäläntie 20 PiikkiöFIN-21500 Finland Nordita KTH Royal Institute of Technology Stockholm University Roslagstullsbacken 23 StockholmSE-10691 Sweden Institute of High Energy Physics CAS Beijing100049 China Tata Institute of Fundamental Research Mumbai400005 India Columbia Astrophysics Laboratory Columbia University 550 West 120th Street New YorkNY10027 United States Institut für Astronomie und Astrophysik Tübingen Universität Tübingen Sand 1 TübingenD-72076 Germany Leiden Observatory Leiden University PO Box 9513 Leiden2300 RA Netherlands Research Center for Computational Physics and Data Processing Silesian University in Opava Bezrucovo nam. 13 OpavaCZ-74601 Czech Republic Physics Department Middle East Technical University Ankara06531 Turkey INAF Osservatorio Astronomico di Roma Via Frascati 33 Monteporzio CatoneI-00078 Italy New York University Abu Dhabi PO Box 129188 Abu Dhabi United Arab Emirates Dipartimento di Fisica Enrico Fermi University of Pisa PisaI-56127 Italy INFN Italian National Institute for Nuclear Physics Pisa Section Pisa56127 Italy Department of Physics and Astronomy Michigan State University East LansingMI48824 United States Department of Astrophysical Sciences Princeton University Peyton Hall PrincetonNJ08544 United States Mathematical Sciences and STAG Research Centre University of Southampton SouthamptonSO17 1BJ United Kingdom MIT Kavli Institute for Astrophysics and Space Research CambridgeMA02139 United States DTU Space Technical University of Denmark Elektrovej 327-328 Kgs Lyngby2800 Denmark INAF/IASF Palermo via Ugo La Malfa 153 PalermoI-90146 Italy Universita degli Studi di Palermo Dipartimento di Fisica e Chimica via Archira 36 Palermo90123 Italy

In this White Paper we present the potential of the Enhanced X-ray Timing and Polarimetry (eXTP) mission for determining the nature of dense matter;neutron star cores host an extreme density regime which cannot be replicated in a terrestrial laboratory. The tightest statistical constraints on the dense matter equation of state will come from pulse profile modelling of accretion-powered pulsars, burst oscillation sources, and rotation-powered pulsars. Additional constraints will derive from spin measurements, burst spectra, and properties of the accretion flows in the vicinity of the neutron star. Under development by an international Consortium led by the Institute of High Energy Physics of the Chinese Academy of Science, the eXTP mission is expected to be launched in the mid 2020s. Copyright © 2018, The Authors. All rights reserved.

关键词： Pulsars

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The X-shooter GRB afterglow legacy sample (XS-GRB)?

arXiv

引用

arXiv 2018年

作者： Selsing, J. Malesani, D. Goldoni, P. Fynbo, J.P.U. Krühler, T. Antonelli, L.A. Arabsalmani, M. Bolmer, J. Cano, Z. Christensen, L. Covino, S. D’Avanzo, P. D’Elia, V. de Cia, A. de Ugarte, A. Postigo Flores, H. Friis, M. Gomboc, A. Greiner, J. Groot, P. Hammer, F. Hartoog, O.E. Heintz, K.E. Hjorth, J. Jakobsson, P. Japelj, J. Kann, D.A. Kaper, L. Ledoux, C. Leloudas, G. Levan, A.J. Maiorano, E. Melandri, A. Milvang-Jensen, B. Palazzi, E. Palmerio, J.T. Perley, D.A. Pian, E. Piranomonte, S. Pugliese, G. Sánchez-Ramírez, R. Savaglio, S. Schady, P. Schulze, S. Sollerman, J. Sparre, M. Tagliaferri, G. Tanvir, N.R. Thöne, C.C. Vergani, S.D. Vreeswijk, P. Watson, D. Wiersema, K. Wijers, R. Xu, D. Zafar, T. Dark Cosmology Centre Niels Bohr Institute University of Copenhagen Juliane Maries Vej 30 København Ø2100 Denmark Cosmic Dawn Center Niels Bohr Institute University of Copenhagen Juliane Maries Vej 30 København Ø2100 Denmark DTU Space National Space Institute Technical University of Denmark Elektrovej 327 Lyngby2800 Denmark APC Astroparticule et Cosmologie Université Paris Diderot CNRS/IN2P3 CEA/Irfu Observatoire de Paris Sorbonne Paris Cité 10 Rue Alice Domon et Léonie Duquet Paris Cedex 1375205 France Max-Planck-Institut für extraterrestrische Physik Giessenbachstraße Garching85748 Germany 00078 Italy IRFU CEA Université Paris-Saclay Gif-sur-YvetteF-91191 France Université Paris Diderot AIM Sorbonne Paris Cité CEA CNRS Gif-sur-YvetteF-91191 France European Southern Observatory Alonso de Córdova 3107 Vitacura Casilla Santiago 1919001 Chile Glorieta de la Astronomía s/n GranadaE-18008 Spain 23807 Italy Space Science Data Center - Agenzia Spaziale Italiana via del Politecnico s.n.c. RomaI-00133 Italy European Southern Observatory Karl-Schwarzschild Str. 2 Garching bei München85748 Germany GEPI Observatoire de Paris PSL University CNRS 5 place Jules Janssen 92195 Meudon France KTH Royal Institute of Technology Department of Physics Stockholm106 91 Sweden The Oskar Klein Centre for Cosmoparticle Physics AlbaNova University Centre Stockholm106 91 Sweden Center for Astrophysics and Cosmology University of Nova Gorica Vipavska 11c Ajdovščina5270 Slovenia Department of Astrophysics IMAPP Radboud University Nijmegen PO Box 9010 Nijmegen6500 GL Netherlands Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Centre for Astrophysics and Cosmology Science Institute University of Iceland Dunhagi 5 Reykjavik107 Iceland Department of Physics University of Warwick CoventryCV4 7AL United Kingdom IASF/INAF Bologna via Piero Gobetti 101 Bologna40129 Italy Sorbonne

In this work we present spectra of all γ-ray burst (GRB) afterglows that have been promptly observed with the X-shooter spectrograph until 31/03/2017. In total, we obtained spectroscopic observations of 103 individual GRBs observed within 48 hours of the GRB trigger. Redshifts have been measured for 97 per cent of these, covering a redshift range from 0.059 to 7.84. Based on a set of observational selection criteria that minimize biases with regards to intrinsic properties of the GRBs, the follow-up effort has been focused on producing a homogeneous sample of 93 afterglow spectra for GRBs discovered by the Swift satellite. We here provide a public release of all the reduced spectra, including continuum estimates and telluric absorption corrections. For completeness, we also provide reductions for the 18 late-time observations of the underlying host galaxies. We provide an assessment of the degree of completeness with respect to the parent GRB population, in terms of the X-ray properties of the bursts in the sample and find that the sample presented here is representative of the full Swift sample. We constrain the fraction of dark bursts to be Copyright © 2018, The Authors. All rights reserved.

关键词： X ray absorption

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Models of Rosetta/OSIRIS 67P dust coma phase function

arXiv

引用

arXiv 2018年

作者： Moreno, F. Guirado, D. Muñoz, O. Bertini, I. Tubiana, C. Güttler, C. Fulle, M. Rotundi, A. della Corte, V. Ivanovski, S.L. Rinaldi, G. Bockelée-Morvan, D. Zakharov, V.V. Agarwal, J. Mottola, S. Toth, I. Frattin, E. Lara, L.M. Gutiérrez, P.J. Lin, Z.Y. Kolokolova, L. Sierks, H. Naletto, G. Lamy, P.L. Rodrigo, R. Koschny, D. Davidsson, B. Barucci, M.A. Bertaux, J.-L. Bodewits, D. Cremonese, G. da Deppo, V. Debei, S. de Cecco, M. Deller, J. Fornasier, S. Ip, W.-H. Keller, H.U. Lazzarin, M. López-Moreno, J.J. Marzari, F. Shi, X. Instituto de Astrofísica de Andalucía CSIC c/ Glorieta de la Astronomía s/n Granada18008 Spain Department of Physics and Astronomy ‘G. Galilei’ University of Padova Vicolo dell’ Osservatorio 3 PadovaI-35122 Italy Max-Planck-Institut für Sonnensystemforschung Justus-von-Liebig-Weg 3 GöttingenD-37077 Germany Osservatorio Astronomico Via Tiepolo 11 TriesteI-34143 Italy INAF - Istituto di Astrofisica e Planetologia Spaziali Via Fosso del Cavaliere 100 RomeI-00133 Italy Universitá degli Studi di Napoli Parthenope Dip. di Scienze e Tecnologie CDN IC4 NaplesI-80143 Italy LESIA Observatoire de Paris PSL Research University CNRS Sorbonne Universités UPMC Univ. Paris 06 Univ. Paris-Diderot Sorbonne Paris Cité 5 place Jules Janssen MeudonF-92195 France Laboratoire de Météorologie Dynamique UPMC Sorbonne Universités Paris France Institut für Planetenforschung Rutherfordstraße 23 Berlin12489 Germany MTA CSFK Konkoly Observatory of the Hungarian Academy of Sciences Konkoly Thege M. ut 15-17. BudapestH1121 Hungary National Central University No.300 Jhongda Rd. Jhongli city Taoyuan County320 Taiwan Planetary Data System Group Department of Astronomy University of Maryland Rm. 1207D Atlantic Bldg. College ParkMD20742 United States Max Planck Institute for Solar System Research Justus-von-Liebig-Weg 3 Göttingen37077 Germany University of Padova Department of Physics and Astronomy "Galileo Galilei" Via Marzolo 8 Padova35131 Italy "G. Colombo" Via Venezia 15 Padova35131 Italy CNR-IFN UOS Padova LUXOR Via Trasea 7 Padova35131 Italy Laboratoire Atmosphères Milieux et Observations Spatiales CNRS Université de Versailles Saint-Quentin-en-Yvelines 11 Boulevard dAlembert Guyancourt78280 France Centro de Astrobiología CSIC-INTA Torrejón de ArdozMadrid28850 Spain International Space Science Institute Hallerstrasse 6 Bern3012 Switzerland Science Support Office European Space Research and Technology Centre/ESA Keplerlaan 1 Postbus 299 Noord

The phase function of the dust coma of comet 67P has been determined from Rosetta/OSIRIS images (Bertini et al. 2017). This function show a deep minimum at phase angles near 100◦, and a strong backscattering enhancement. These two properties cannot be reproduced by regular models of cometary dust, most of them based on wavelength-sized and randomly-oriented aggregate particles. We show, however, that an ensamble of oriented elongated particles of a wide variety of aspect ratios, with radii r &10 µm, and whose long axes are perpendicular to the direction of the solar radiation, are capable of reproducing the observed phase function. These particles must be absorbing, with an imaginary part of the refractive index of about 0.1 to match the expected geometric albedo, and with porosity in the 60-70% range. Copyright © 2018, The Authors. All rights reserved.

关键词： Dust

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