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arXiv 2017年

作者： Corbet, Robin H.D. Coley, Joel B. Krimm, Hans A. University of Maryland Baltimore CountyMD21250 United States CRESST/Mail Code 662 X-ray Astrophysics Laboratory NASA Goddard Space Flight Center GreenbeltMD20771 United States Maryland Institute College of Art 1300 W Mt Royal Ave BaltimoreMD21217 United States NASA Postdoctoral Program Astroparticle Physics Laboratory Code 661 NASA Goddard Space Flight Center Greenbelt Rd. MD20771 United States CRESST/Astroparticle Physics Laboratory Code 661 NASA Goddard Space Flight Center Greenbelt Rd. MD20771 United States Universities Space Research Association 10211 Wincopin Circle Suite 500 ColumbiaMD21044 United States National Science Foundation

We present an investigation of long-term modulation in the X-ray light curves of five little-studied candidate high-mass X-ray binaries using the Swift Burst Alert Telescope. IGRJ14488-5942 and AX J1700.2-4220 show strong modulation at periods of 49.6 and 44 days, respectively, which are interpreted as orbital periods of Be star systems. For IGRJ14488-5942, observations with Swift X-ray Telescope show a hint of pulsations at 33.4 s. For AX J1700.2-4220, 54 s pulsations were previously found with XMM-Newton. Swift J1816.7-1613 exhibits complicated behavior. The strongest peak in the power spectrum is at a period near 150 days, but this conflicts with a determination of a period of 118.5 days by La Parola et al. (2014). AX J1820.5-1434 has been proposed to exhibit modulation near 54 days, but the extended BAT observations suggest modulation at slightly longer than double this at approximately 111 days. There appears to be a long-term change in the shape of the modulation near 111 days, which may explain the apparent discrepancy. The X-ray pulsar XTE J1906+090, which was previously proposed to be a Be star system with an orbital period of ∼ 30 days from pulse timing, shows peaks in the power spectrum at 81 and 173 days. The origins of these periods are unclear, although they might be the orbital period and a superorbital period respectively. For all five sources, the long-term variability, together with the combination of orbital and proposed pulse periods, suggests that the sources contain Be star mass donors. Copyright © 2017, The Authors. All rights reserved.

关键词： Modulation

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OGLE-2017-BLG-1130: The first binary gravitational microlens detected from spitzer only

arXiv

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arXiv 2018年

作者： Wang, Tianshu Novati, S. Calchi Udalski, A. Gould, A. Mao, Shude Zang, W. Beichman, C. Bryden, G. Carey, S. Gaudi, B.S. Henderson, C.B. Shvartzvald, Y. Yee, J.C. Mroz, P. Poleski, R. Skowron, J. Szymanski, M.K. Soszynski, I. Kozlowski, S. Pietrukowicz, P. Ulaczyk, K. Pawlak, M. Albrow, M.D. Chung, S.-J. Han, C. Hwang, K.-H. Jung, Y.K. Ryu, Y.-H. Shin, I.-G. Zhu, W. Cha, S.-M. Kim, D.-J. Kim, H.-W. Kim, S.-L. Lee, C.-U. Lee, D.-J. Lee, Y. Park, B.-G. Pogge, R.W. Physics Department and Tsinghua Centre for Astrophysics Tsinghua University Beijing100084 China IPAC Caltech Mail Code 100-22 1200 E. California Blvd. PasadenaCA91125 United States Spitzer Team Warsaw University Observatory Al. Ujazdowskie 4 Warszawa00-478 Poland OGLE collaboration Korea Astronomy and Space Science Institute Daejon34055 Korea Republic of Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States Max-Planck-Institute for Astronomy Konigstuhl 17 Heidelberg69117 Germany KMTnet National Astronomical Observatories Chinese Academy of Sciences 20A Datun Road Chaoyang District Beijing100012 China Jodrell Bank Centre for Astrophysics School of Physics and Astronomy University of Manchester Oxford Road ManchesterM139PL United Kingdom Department of Physics Zhejiang University Hangzhou310058 China NASA Exoplanet Science Institute California Institute of Technology MS 100-22 PasadenaCA91125 United States Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive PasadenaCA91109 United States Spitzer Science Center California Institute of Technology MS 220-6 PasadenaCA United States NASA Postdoctoral Program Fellow Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States Department of Astronomy Ohio State University 140 W.18th Ave. ColumbusOH43210 United States Warsaw University Observatory Al. Ujazdowskie 4 Warszawa00-478 Poland University of Canterbury Department of Physics and Astronomy Private Bag 4800 Christchurch8020 New Zealand Korea University of Science and Technology Daejeon34113 Korea Republic of Department of Physics Chungbuk National University Cheongju28644 Korea Republic of Canadian Institute for Theoretical Astrophysics University of Toronto 60 St George Street TorontoONM5S3H8 Canada School of Space Research Kyung Hee University Yongin Kyeonggi17104 Korea Republic of

We analyze the binary gravitational microlensing event OGLE-2017-BLG-1130 (mass ratio q ∼ 0.45), the first published case in which the binary anomaly was only detected by the Spitzer Space Telescope. This event provides strong evidence that some binary signals can be missed by observations from the ground alone but detected by Spitzer. We therefore invert the normal procedure, first finding the lens parameters by fitting the space-based data and then measuring the microlensing parallax using ground-based observations. We also show that the normal four-fold spacebased degeneracy in the single-lens case can become a weak eight-fold degeneracy in binary-lens events. Although this degeneracy is resolved in event OGLE-2017-BLG-1130, it might persist in other events. Copyright © 2018, The Authors. All rights reserved.

关键词： Geometrical optics

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Gamma-ray burst models in light of the GRB 170817a - GW170817 connection

arXiv

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arXiv 2018年

作者： Veres, P. Mészáros, P. Goldstein, A. Fraija, N. Connaughton, V. Burns, E. Preece, R.D. Hamburg, R. Wilson-Hodge, C.A. Briggs, M.S. Kocevski, D. Center for Space Plasma and Aeronomic Research University of Alabama in Huntsville 320 Sparkman Drive HuntsvilleAL35899 United States Department of Physics Pennsylvania State University University ParkPA16802 United States Department of Astronomy & Astrophysics Pennsylvania State University University ParkPA16802 United States Center for Particle and Gravitational Astrophysics Pennsylvania State University University ParkPA16802 United States Science and Technology Institute Universities Space Research Association HuntsvilleAL35805 United States Nstituto de Astronomía Universidad Nacional Autónoma de México Circuito Exterior C.U. A. Postal 70-264 México D.F.04510 Mexico NASA Postdoctoral Program Fellow Goddard Space Flight Center GreenbeltMD20771 United States Space Science Department University of Alabama in Huntsville 320 Sparkman Drive HuntsvilleAL35899 United States ST12 NASA/Marshall Space Flight Center Astrophysics Office HuntsvilleAL35812 United States Center for Space Plasma and Aeronomic Research University of Alabama in Huntsville 320 Sparkman Drive HuntsvilleAL35899

For the first time, a short gamma-ray burst (GRB) was unambiguously associated with a gravitational wave (GW) observation from a binary neutron star (NS) merger. This allows us to link the details of the central engine properties to GRB emission models. We find that photospheric models (both dissipative and non-dissipative variants) have difficulties accounting for the observations. Internal shocks give the most natural account of the observed peak energy, viewing angle and total energy. We also show that a simple external shock model can reproduce the observed GRB pulse with parameters consistent with those derived from the afterglow modeling. We find a simple cocoon shock breakout model is in mild tension with the observed spectral evolution, however it cannot be excluded based on gamma-ray data alone. Future joint observations of brighter GRBs will pose even tighter constraints on prompt emission models. Copyright © 2018, The Authors. All rights reserved.

关键词： Gravity waves

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OGLE-2017-BLG-0482Lb: A microlensing super -Earth orbiting a low -Mass host star

arXiv

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arXiv 2018年

作者： Han, C. Hirao, Y. Udalski, A. Lee, C.-U. Bozza, V. Gould, A. Abe, F. Barry, R. Bond, I.A. Bennett, D.P. Bhattacharya, A. Donachie, M. Evans, P. Fukui, A. Itow, Y. Kawasaki, K. Koshimoto, N. Li, M.C.A. Ling, C.H. Matsubara, Y. Miyazaki, S. Munakata, H. Muraki, Y. Nagakane, M. Ohnishi, K. Ranc, C. Rattenbury, N. Saito, T. Sharan, A. Sullivan, D.J. Sumi, T. Suzuki, D. Tristram, P.J. Yamada, T. Yonehara, A. Mróz, P. Poleski, R. Kozlowski, S. Pietrukowicz, P. Skowron, J. Ulaczyk, K. Pawlak, M. Rybicki, K. Iwanek, P. Albrow, M.D. Chung, S.-J. Hwang, K.-H. Jung, Y.K. Kim, D. Kim, W.-T. Kim, H.-W. Ryu, Y.-H. Shin, I.-G. Shvartzvald, Y. Yee, J.C. Zhu, W. Cha, S.-M. Kim, S.-L. Kim, D.-J. Lee, D.-J. Lee, Y. Park, B.-G. Pogge, R.W. Department of Physics Chungbuk National University Cheongju28644 Korea Republic of Department of Earth and Space Science Graduate School of Science Osaka University ToyonakaOsaka560-0043 Japan Warsaw University Observatory Al. Ujazdowskie 4 Warszawa00-478 Poland Korea Astronomy and Space Science Institute Daejon34055 Korea Republic of I-84084 Italy Istituto Nazionale di Fisica Nucleare Sezione di Napoli Via Cintia NapoliI-80126 Italy Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States Max Planck Institute for Astronomy Königstuhl 17 HeidelbergD-69117 Germany Institute for Space-Earth Environmental Research Nagoya University Nagoya464-8601 Japan Code 667 NASA Goddard Space Flight Center GreenbeltMD20771 United States Institute of Natural and Mathematical Sciences Massey University Auckland0745 New Zealand Deptartment of Physics University of Notre Dame 225 Nieuwland Science Hall Notre DameIN46556 United States Dept. of Physics University of Auckland Private Bag 92019 Auckland New Zealand Okayama Astrophysical Observatory National Astronomical Observatory of Japan AsakuchiOkayama719-0232 Japan Nagano National College of Technology Nagano381-8550 Japan Tokyo Metroplitan College of Industrial Technology Tokyo116-8523 Japan School of Chemical and Physical Sciences Victoria University Wellington New Zealand Institute of Space and Astronautical Science Japan Aerospace Exploration Agency Kanagawa252-5210 Japan 019 Mt. John University Observatory P.O. Box 56 Lake Tekapo8770 New Zealand Department of Physics Faculty of Science Kyoto Sangyo University Kyoto603-8555 Japan University of Canterbury Department of Physics and Astronomy Private Bag 4800 Christchurch8020 New Zealand Korea University of Science and Technology 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States Department of Physics

We report the discovery of a planetary system in which a super-earth orbits a late M-dwarf host. The planetary system was found from the analysis of the microlensing event OGLE-2017-BLG-0482, wherein the planet signal appears as a short-term anomaly to the smooth lensing light curve produced by the host. Despite its weak signal and short duration, the planetary signal was firmly detected from the dense and continuous coverage by three microlensing surveys. We find a planet/host mass ratio of q ∼ 1.4 × 10−4. We measure the microlens parallax πE from the long-term deviation in the observed lensing light curve, but the angular Einstein radius θE cannot be measured because the source trajectory did not cross the planet-induced caustic. Using the measured event timescale and the microlens parallax, we find that the masses of the planet and the host are Mp = 9.0+−94..05 M and Mhost = 0.20+−00..2010 M, respectively, and the projected separation between them is a= 1.8+−00..67 au. The estimated distance to the lens is DL = 5.8−+21..18 kpc. The discovery of the planetary system demonstrates that microlensing provides an important method to detect low-mass planets orbiting low-mass stars. Copyright © 2018, The Authors. All rights reserved.

关键词： Geometrical optics

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Erratum: 'Evolution of Intrinsic Scatter in the SFR–Stellar Mass Correlation at 0.5

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The Astrophysical Journal Letters 2018年第2期864卷

作者： Peter Kurczynski Eric Gawiser Viviana Acquaviva Eric F. Bell Avishai Dekel Duilia F. de Mello Henry C. Ferguson Jonathan P. Gardner Norman A. Grogin Yicheng Guo Philip F. Hopkins Anton M. Koekemoer David C. Koo Seong-Kook Lee Bahram Mobasher Joel R. Primack Marc Rafelski Emmaris Soto Harry I. Teplitz Department of Physics and Astronomy Rutgers University Piscataway NJ 08854 USA New York City College of Technology Brooklyn NY 11201 USA Department of Astronomy University of Michigan Ann Arbor MI 48109 USA Center for Astrophysics and Planetary Science Racah Institute of Physics The Hebrew University Jerusalem 91904 Israel Laboratory for Observational Cosmology Astrophysics Science Division Code 665 Goddard Space Flight Center Greenbelt MD 20771 USA Department of Physics The Catholic University of America Washington DC 20064 USA Space Telescope Science Institute 3700 San Martin Drive Baltimore MD 21218 USA UCO/Lick Observatory Department of Astronomy and Astrophysics University of California Santa Cruz CA USA TAPIR Mailcode 350-17 California Institute of Technology Pasadena CA 91125 USA Department of Astronomy and Theoretical Astrophysics Center University of California Berkeley Berkeley CA 94720 USA Center for the Exploration of the Origin of the Universe Department of Physics and Astronomy Seoul National University Seoul 151-742 Republic of Korea Department of Physics and Astronomy University of California Riverside CA USA Department of Physics University of California Santa Cruz CA 95064 USA NASA Postdoctoral Program Fellow. Infrared Processing and Analysis Center MS 100-22 Caltech Pasadena CA 91125 USA

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MOA-2015-BLG-337: A planetary system with a low-Mass brown dwarf/planetary boundary host,or a brown dware binary

arXiv

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arXiv 2018年

作者： Miyazaki, S. Sumi, T. Bennett, D.P. Gould, A. Udalski, A. Koshimoto, N. Nagakane, M. Rattenbury, N. Abe, F. Bhattacharya, A. Barry, R. Donachie, M. Fukui, A. Hirao, Y. Itow, Y. Kawasaki, K. Li, M.C.A. Ling, C.H. Matsubara, Y. Matsuo, T. Muraki, Y. Ohnishi, K. Ranc, C. Saito, T. Sharan, A. Shibai, H. Suematsu, H. Suzuki, D. Sullivan, D.J. Tristram, P.J. Yamada, T. Yonehara, A. Koz Lowski, S. Mróz, P. Pawlak, M. Poleski, R. Pietrukowicz, P. Skowron, J. Soszynski, I. Albrow, M.D. Chung, S.-J. Han, C. Jung, Y.K. Hwang, K.-H. Ryu, Y.-H. Shin, I.-G. Shvartzvald, Y. Yee, J.C. Zang, W. Zhu, W. Cha, S.-M. Kim, D.-J. Kim, H.-W. Kim, S.-L. Lee, D.-J. Lee, Y. Park, B.-G. Pogge, R.W. Department of Earth and Space Science Graduate School of Science Osaka University 1-1 Machikaneyama Toyonaka Osaka560-0043 Japan MOA collaboration 3Department of Physics University of Notre Dame Notre DameIN46556 United States Laboratory for Exoplanets and Stellar Astrophysics NASA/Goddard Space Flight Center GreenbeltMD20771 United States Korea Astronomy and Space Science Institute Daejon34055 Korea Republic of Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States Max-Planck-Institute for Astronomy Königstuhl 17 Heidelberg69117 Germany KMTNet collaboration Warsaw University Observatory Al. Ujazdowskie 4 Warszawa00-478 Poland OGLE collaboration 11Institute of Information and Mathematical Sciences Massey University North Shore Mail Centre Private Bag 102-904 Auckland New Zealand Department of Physics University of Auckland Private Bag 92019 Auckland New Zealand Institute for Space-Earth Environmental Research Nagoya University Nagoya464-8601 Japan Okayama Astrophysical Observatory National Astronomical Observatory 3037-5 Honjo Kamogata Asakuchi Okayama719-0232 Japan Institute for Space-Earth Environmental Research Nagoya University Nagoya464-8601 Japan Nagano National College of Technology Nagano381-8550 Japan Tokyo Metropolitan College of Industrial Technology Tokyo116-8523 Japan Institute of Space and Astronautical Science Japan Aerospace Exploration Agency 3-1-1 Yoshinodai Chuo Sagamihara Kanagawa252-5210 Japan School of Chemical and Physical Sciences Victoria University Wellington New Zealand University of Canterbury Mt. John Observatory P.O. Box 56 Lake Tekapo8770 New Zealand Department of Physics Faculty of Science Kyoto Sangyo University Kyoto603-8555 Japan Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States University of Canterbury Department of Physics and Astronomy Private Bag 4800 Christchurch8020 New Zealand Korea University of Sci

We report the discovery and the analysis of the short timescale binary-lens microlensing event, MOA-2015-BLG-337. The lens system could be a planetary system with a very low mass host, around the brown dwarf/planetary mass boundary, or a brown dwarf binary. We found two competing models that explain the observed light curves with companion/host mass ratios of q ∼ 0.01 and ∼ 0.17, respectively. A significant finite source effect in the best-fit planetary model (q ∼ 0.01) reveals a small angular Einstein radius of θE 0.03 mas which favors a low mass lens. We obtain the posterior probability distribution of the lens properties from a Bayesian analysis. The results for the planetary models strongly depend on a power-law index in planetary mass regime, αpl, in the assumed mass function. In summary, there are two solutions of the lens system: (1) a brown dwarf/planetary mass boundary object orbited by a super-Neptune (the planetary model with αpl = 0.49) and (2) a brown dwarf binary (the binary model). If the planetary models are correct, this system can be one of a new class of planetary system, having a low host mass and also a planetary mass ratio (q Copyright © 2018, The Authors. All rights reserved.

关键词： Probability distributions

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The intrinsic characteristics of galaxies on the SFR-M∗ plane at 1.2

arXiv

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arXiv 2017年

作者： Lee, Bomee Giavalisco, Mauro Whitaker, Katherine Williams, Christina C. Ferguson, Henry C. Acquaviva, Viviana Koekemoer, Anton M. Straughn, Amber N. Guo, Yicheng Kartaltepe, Jeyhan S. Lotz, Jennifer Pacifici, Camilla Croton, Darren J. Somerville, Rachel S. Lu, Yu Department of Astronomy University of Massachusetts AmherstMA01003 United States Infrared Processing and Analysis Center California Institute of Technology PasadenaCA91125 United States Department of Physics University of Connecticut StorrsCT06269 United States Hubble Fellow Steward Observatory University of Arizona 933 N. Cherry Ave. TucsonAZ85721 United States Space Telescope Science Institute 3700 San Martin Drive BaltimoreMD21218 United States Department of Physics CUNY NYC College of Technology 300 Jay Street BrooklynNY11201 United States Goddard Space Flight Center Code 665 GreenbeltMD20771 United States UCO/Lick Observatory Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Department of Physics and Astronomy University of Missouri ColumbiaMO65211 United States School of Physics and Astronomy Rochester Institute of Technology 84 Lomb Memorial Drive RochesterNY14623 United States NASA Postdoctoral Program Fellow Centre for Astrophysics & Supercomputing Swinburne University of Technology PO Box 218 HawthornVIC3122 Australia Department of Physics and Astronomy Rutgers State University of New Jersey NJ08854 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States Observatories Carnegie Institution for Science 813 Santa Barbara Street PasadenaCA91101 United States

We use the deep CANDELS observations in the GOODS North and South fields to revisit the correlations between stellar mass (M∗), star–formation rate (SFR) and morphology, and to introduce a fourth dimension, the mass-weighted stellar age, in galaxies at 1.2 ∗, SFR, and stellar age thanks to an improved SED fitting procedure that allows various star formation history for each galaxy. Like others, we find that the slope of the Main Sequence (MS) of star formation in the (M∗;SFR) plane bends at high mass. We observe clear morphological differences among galaxies across the MS, which also correlate with stellar age. At all redshifts, galaxies that are quenching or quenched, and thus old, have high Σ1 (the projected density within the central 1 kpc), while younger, star–forming galaxies span a much broader range of Σ1, which includes the high values observed for quenched galaxies, but also extends to much lower values. As galaxies age and quench, the stellar age and the dispersion of Σ1 for fixed values of M∗ shows two different regimes, one, at the low–mass end, where quenching might be driven by causes external to the galaxies;the other, at the high–mass end, where quenching is driven by internal causes, very likely the mass given the low scatter of Σ1 (mass quenching). We suggest that the monotonic increase of central density as galaxies grow is one manifestation of a more general phenomenon of structural transformation that galaxies undergo as they evolve. Copyright © 2017, The Authors. All rights reserved.

关键词： Galaxies

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The γ-ray spectrum of the core of Centaurus A as observed with H.E.S.S. and Fermi-LAT

arXiv

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arXiv 2018年

作者： Abdalla, H. Abramowski, A. Aharonian, F. Benkhali, F. Ait Angüner, E.O. Arakawa, M. Armand, C. Arrieta, M. Backes, M. Balzer, A. Barnard, M. Becherini, Y. Tjus, J. Becker Berge, D. Bernhard, S. Bernlöhr, K. Blackwell, R. Böttcher, M. Boisson, C. Bolmont, J. Bonnefoy, S. Bordas, P. Bregeon, J. Brun, F. Brun, P. Bryan, M. Büchele, M. Bulik, T. Capasso, M. Caroff, S. Carosi, A. Casanova, S. Cerruti, M. Chakraborty, N. Chaves, R.C.G. Chen, A. Chevalier, J. Colafrancesco, S. Condon, B. Conrad, J. Davids, I.D. Decock, J. Deil, C. Devin, J. deWilt, P. Dirson, L. Djannati-Ataï, A. Donath, A. O’C. Drury, L. Dyks, J. Edwards, T. Egberts, K. Emery, G. Ernenwein, J.-P. Eschbach, S. Farnier, C. Fegan, S. Fernandes, M.V. Fiasson, A. Fontaine, G. Funk, S. Füßling, M. Gabici, S. Gallant, Y.A. Garrigoux, T. Gaté, F. Giavitto, G. Glawion, D. Glicenstein, J.F. Gottschall, D. Grondin, M.-H. Hahn, J. Haupt, M. Hawkes, J. Heinzelmann, G. Henri, G. Hermann, G. Hinton, J.A. Hofmann, W. Hoischen, C. Holch, T.L. Holler, M. Horns, D. Ivascenko, A. Iwasaki, H. Jacholkowska, A. Jamrozy, M. Jankowsky, D. Jankowsky, F. Jingo, M. Jouvin, L. Jung-Richardt, I. Kastendieck, M.A. Katarzyński, K. Katsuragawa, M. Katz, U. Kerszberg, D. Khangulyan, D. Khélifi, B. King, J. Klepser, S. Klochkov, D. Kluźniak, W. Komin, Nu. Kosack, K. Krakau, S. Kraus, M. Krüger, P.P. Laffon, H. Lamanna, G. Lau, J. Lefaucheur, J. Lemière, A. Lemoine-Goumard, M. Lenain, J.-P. Leser, E. Lohse, T. Lorentz, M. Liu, R. López-Coto, R. Lypova, I. Malyshev, D. Marandon, V. Marcowith, A. Mariaud, C. Marx, R. Maurin, G. Maxted, N. Mayer, M. Meintjes, P.J. Meyer, M. Mitchell, A.M.W. Moderski, R. Mohamed, M. Mohrmann, L. Morå, K. Moulin, E. Murach, T. Nakashima, S. de Naurois, M. Ndiyavala, H. Niederwanger, F. Niemiec, J. Oakes, L. O’Brien, P. Odaka, H. Ohm, S. Ostrowski, M. Oya, I. Padovani, M. Panter, M. Parsons, R.D. Pekeur, N.W. Pelletier, G. Perennes, C. Petrucci, P.-O. Centre for Space Research North-West University Potchefstroom2520 South Africa Universität Hamburg Institut für Experimentalphysik Luruper Chaussee 149 HamburgD 22761 Germany Max-Planck-Institut für Kernphysik P.O. Box 103980 HeidelbergD 69029 Germany Dublin Institute for Advanced Studies 31 Fitzwilliam Place Dublin 2 Ireland National Academy of Sciences of the Republic of Armenia Marshall Baghramian Avenue 24 Yerevan0019 Armenia Instytut Fizyki JĄdrowej PAN ul. Radzikowskiego 152 Kraków31-342 Poland Department of Physics Rikkyo University 3-34-1 Nishi-Ikebukuro Toshima-ku Tokyo171-8501 Japan Laboratoire d’Annecy de Physique des Particules Université Savoie Mont-Blanc CNRS/IN2P3 Annecy-le-VieuxF-74941 France LUTH Observatoire de Paris PSL Research University CNRS Université Paris Diderot 5 Place Jules Janssen Meudon92190 France University of Namibia Department of Physics Private Bag 13301 Windhoek Namibia GRAPPA Anton Pannekoek Institute for Astronomy University of Amsterdam Science Park 904 Amsterdam1098 XH Netherlands Department of Physics and Electrical Engineering Linnaeus University Växjö351 95 Sweden Institut für Theoretische Physik Lehrstuhl IV: Weltraum und Astrophysik Ruhr-Universität Bochum BochumD 44780 Germany DESY ZeuthenD-15738 Germany Institut für Astro- und Teilchenphysik Leopold-Franzens-Universität Innsbruck InnsbruckA-6020 Austria School of Physical Sciences University of Adelaide Adelaide5005 Australia 4 place Jussieu Paris Cedex 5F-75252 France Laboratoire Univers et Particules de Montpellier Université Montpellier CNRS/IN2P3 CC 72 Place Eugène Bataillon Montpellier Cedex 5F-34095 France Université Bordeaux CNRS/IN2P3 Centre d’Études Nucléaires de Bordeaux Gradignan Gradignan33175 France IRFU CEA Université Paris-Saclay Gif-sur-YvetteF-91191 France Friedrich-Alexander-Universität Erlangen-Nürnberg Erlangen Centre for Astroparticle Physics Erwin-Rommel-Str. 1 ErlangenD 91058 Germany Astronomica

Centaurus A (Cen A) is the nearest radio galaxy discovered as a very-high-energy (VHE;100 GeV-100 TeV) γ-ray source by the High Energy Stereoscopic System (H.E.S.S.). It is a faint VHE γ-ray emitter, though its VHE flux exceeds both the extrapolation from early Fermi-LAT observations as well as expectations from a (misaligned) single-zone synchrotron-self Compton (SSC) description. The latter satisfactorily reproduces the emission from Cen A at lower energies up to a few GeV. New observations with H.E.S.S., comparable in exposure time to those previously reported, were performed and eight years of Fermi-LAT data were accumulated to clarify the spectral characteristics of the γ-ray emission from the core of Cen A. The results allow us for the first time to achieve the goal of constructing a representative, contemporaneous γ-ray core spectrum of Cen A over almost five orders of magnitude in energy. Advanced analysis methods, including the template fitting method, allow detection in the VHE range of the core with a statistical significance of 12σ on the basis of 213 hours of total exposure time. The spectrum in the energy range of 250 GeV-6 TeV is compatible with a power-law function with a photon index Γ = 2.52 ± 0.13stat ± 0.20sys. An updated Fermi-LAT analysis provides evidence for spectral hardening by ∆Γ 0.4 ± 0.1 at γ-ray energies above 2.8+1.0−0.6 GeV at a level of 4.0σ. The fact that the spectrum hardens at GeV energies and extends into the VHE regime disfavour a single-zone SSC interpretation for the overall spectral energy distribution (SED) of the core and is suggestive of a new γ-ray emitting component connecting the high-energy emission above the break energy to the one observed at VHE energies. The absence of significant variability at both GeV and TeV energies does not yet allow disentanglement of the physical 1 nature of this component, though a jet-related origin is possible and a simple two-zone SED model fit is provided to this end. Copyright © 2018,

关键词： Gamma rays

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Pale orange dots: The impact of organic haze on the habitability and detectability of earthlike exoplanets

arXiv

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arXiv 2017年

作者： Arney, Giada N. Meadows, Victoria S. Domagal-Goldman, Shawn D. Deming, Drake Robinson, Tyler D. Tovar, Guadalupe Wolf, Eric T. Schwieterman, Edward University of Washington Astronomy Department Box 351580 U.W. SeattleWA98195 United States NASA Astrobiology Institute Virtual Planetary Laboratory Box 351580 U.W. SeattleWA98195 University of Washington Astrobiology Program Box 351580 U.W. SeattleWA98195 NASA Goddard Space Flight Center 8800 Greenbelt Road GreenbeltMD20771 United States NASA Postdoctoral Program Universities Space Research Association ColumbiaMD United States University of Maryland Department of Astronomy College ParkMD20742 United States Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States University of Colorado Boulder Laboratory for Astrophysics and Space Physics 1234 Innovation Drive BoulderCO80303 United States University of California at Riverside RiversideCA United States Blue Marble Space Institute of Science 1200 Westlake Ave N Suite 1006 SeattleWA98109

Hazes are common in known planet atmospheres, and geochemical evidence suggests early Earth occasionally supported an organic haze with significant environmental and spectral consequences. The UV spectrum of the parent star drives organic haze formation through methane photochemistry. We use a 1D photochemical-climate model to examine production of fractal organic haze on Archean Earth-analogs in the habitable zonesof several stellar types: the modern and early Sun, AD Leo (M3.5V), GJ 876 (M4V), Ε Eridani (K2V), and σ Boötis (F2V). For Archean-like atmospheres, planets orbiting stars with the highest UV fluxes do not form haze due to the formation of photochemical oxygen radicals that destroy haze precursors. Organic hazes impact planetary habitability via UV shielding and surface cooling, but this cooling is minimized around M dwarfs whose energy is emitted at wavelengths where organic hazes are relatively transparent. We generate spectra to test the detectability of haze. For 10 transits of a planet orbiting GJ 876 observed by the James Webb Space Telescope, haze makes gaseous absorption features at wavelengths 5σ. A haze absorption feature can be detected at 5σ near 6.3 µm, but higher signal-to-noise is needed to distinguish haze from adjacent absorbers. For direct imaging of a planet at 10 parsecs using a coronagraphic 10-meter class ultraviolet-visible-near infrared telescope, a UV-blue haze absorption feature would be strongly detectable at >12σ in 200 hours. Copyright © 2017, The Authors. All rights reserved.

关键词： Signal to noise ratio

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OGLE-2016-BLG-1266: A probable brown-dwarf/planet binary at the deuterium fusion limit

arXiv

引用

arXiv 2018年

作者： Albrow, M.D. Yee, J.C. Udalski, A. Novati, S. Calchi Carey, S. Henderson, C.B. Beichman, C. Bryden, G. Gaudi, B.S. Shvartzvald, Y. Szymański, M.K. Mróz, P. Skowron, J. Poleski, R. Soszyński, I. Kozlowski, S. Pietrukowicz, P. Ulaczyk, K. Pawlak, M. Chung, S.-J. Gould, A. Han, C. Hwang, K.-H. Jung, Y.K. Ryu, Y.-H. Shin, I.-G. Zhu, W. Cha, S.-M. Kim, D.-J. Kim, H.-W. Kim, S.-L. Lee, C.-U. Lee, D.-J. Lee, Y. Park, B.-G. Pogge, R.W. School of Physical and Chemical Sciences University of Canterbury Private Bag 4800 Christchurch New Zealand Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States Warsaw University Observatory Al. Ujazdowskie 4 Warszawa00-478 Poland IPAC Mail Code 100-22 Caltech 1200 E. California Blvd. PasadenaCA91125 United States Spitzer Science Center MS 220-6 California Institute of Technology PasadenaCA United States Jet Propulsion Laboratory California Institute of Technology 4800 Oak Grove Drive PasadenaCA91109 United States NASA Exoplanet Science Institute California Institute of Technology PasadenaCA91125 United States Department of Astronomy Ohio State University 140 W.18th Ave. ColumbusOH43210 United States NASA Postdoctoral Program Korea Astronomy and Space Science Institute Daejon34055 Korea Republic of Korea University of Science and Technology 217 Gajeong-ro Yuseong-gu Daejeon34113 Korea Republic of Max-Planck-Institute for Astronomy Königstuhl 17 Heidelberg69117 Germany Department of Physics Chungbuk National University Cheongju28644 Korea Republic of Canadian Institute for Theoretical Astrophysics University of Toronto 60 St. George Street TorontoONM5S 3H8 Canada School of Space Research Kyung Hee University Yongin Kyeonggi17104 Korea Republic of

We report the discovery, via the microlensing method, of a new very-low-mass binary system. By combining measurements from Earth and from the Spitzer telescope in Earth-trailing orbit, we are able to measure the microlensing parallax of the event, and find that the lens likely consists of an (12.0 ± 0.6)MJ + (15.7 ± 1.5)MJ super-Jupiter / brown-dwarf pair. The binary is located at a distance of (3.08 ± 0.18) kpc in the Galactic Plane, and the components have a projected separation of (0.43 ± 0.03) AU. Two alternative solutions with much lower likelihoods are also discussed, an 8- and 6-MJ model and a 90- and 70-MJ model. Although disfavored at the 3-σ and 5-σ levels, these alternatives cannot be rejected entirely. We show how the more-massive of these models could be tested with future direct imaging. Copyright © 2018, The Authors. All rights reserved.

关键词： Geometrical optics

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