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Detection of CMB-Cluster Lensing using Polarization Data from SPTpol

Physical Review Letters 2019年第18期123卷 181301-181301页

作者： S. Raghunathan S. Patil E. Baxter B. A. Benson L. E. Bleem T. M. Crawford G. P. Holder T. McClintock C. L. Reichardt T. N. Varga N. Whitehorn P. A. R. Ade S. Allam A. J. Anderson J. E. Austermann S. Avila J. S. Avva D. Bacon J. A. Beall A. N. Bender F. Bianchini S. Bocquet D. Brooks D. L. Burke J. E. Carlstrom J. Carretero F. J. Castander C. L. Chang H. C. Chiang R. Citron M. Costanzi A. T. Crites L. N. da Costa S. Desai H. T. Diehl J. P. Dietrich M. A. Dobbs P. Doel S. Everett A. E. Evrard C. Feng B. Flaugher P. Fosalba J. Frieman J. Gallicchio J. García-Bellido E. Gaztanaga E. M. George T. Giannantonio A. Gilbert R. A. Gruendl J. Gschwend N. Gupta G. Gutierrez T. de Haan N. W. Halverson N. Harrington J. W. Henning G. C. Hilton D. L. Hollowood W. L. Holzapfel K. Honscheid J. D. Hrubes N. Huang J. Hubmayr K. D. Irwin T. Jeltema M. Carrasco Kind L. Knox N. Kuropatkin O. Lahav A. T. Lee D. Li M. Lima A. Lowitz M. A. G. Maia J. L. Marshall J. J. McMahon P. Melchior F. Menanteau S. S. Meyer R. Miquel L. M. Mocanu J. J. Mohr J. Montgomery C. Corbett Moran A. Nadolski T. Natoli J. P. Nibarger G. Noble V. Novosad R. L. C. Ogando S. Padin A. A. Plazas C. Pryke D. Rapetti A. K. Romer A. Roodman A. Carnero Rosell E. Rozo J. E. Ruhl E. S. Rykoff B. R. Saliwanchik E. Sanchez J. T. Sayre V. Scarpine K. K. Schaffer M. Schubnell S. Serrano I. Sevilla-Noarbe C. Sievers G. Smecher M. Smith M. Soares-Santos A. A. Stark K. T. Story E. Suchyta M. E. C. Swanson G. Tarle C. Tucker K. Vanderlinde T. Veach J. De Vicente J. D. Vieira V. Vikram G. Wang W. L. K. Wu V. Yefremenko Y. Zhang Department of Physics and Astronomy University of California Los Angeles California 90095 USA School of Physics University of Melbourne Parkville VIC 3010 Australia Department of Physics and Astronomy University of Pennsylvania Philadelphia Pennsylvania 19104 USA Fermi National Accelerator Laboratory MS209 P.O. Box 500 Batavia Illinois 60510 USA Kavli Institute for Cosmological Physics University of Chicago 5640 South Ellis Avenue Chicago Illinois 60637 USA Department of Astronomy and Astrophysics University of Chicago 5640 South Ellis Avenue Chicago Illinois 60637 USA High Energy Physics Division Argonne National Laboratory 9700 S. Cass Avenue Argonne Illinois 60439 USA Astronomy Department University of Illinois at Urbana-Champaign 1002 W. Green Street Urbana Illinois 61801 USA Department of Physics University of Illinois Urbana-Champaign 1110 W. Green Street Urbana Illinois 61801 USA Canadian Institute for Advanced Research CIFAR Program in Gravity and the Extreme Universe Toronto Ontario M5G 1Z8 Canada Department of Physics University of Arizona Tucson Arizona 85721 USA Max Planck Institute for Extraterrestrial Physics Giessenbachstrasse Garching 85748 Germany Universitäts-Sternwarte Fakultät für Physik LudwigMaximilians Universität München Scheinerstr. 1 München 81679 Germany Cardiff University Cardiff CF10 3XQ United Kingdom Fermi National Accelerator Laboratory P. O. Box 500 Batavia Illinois 60510 USA NIST Quantum Devices Group 325 Broadway Mailcode 817.03 Boulder Colorado 80305 USA Instituto de Fisica Teorica UAM/CSIC Universidad Autonoma de Madrid 28049 Madrid Spain Department of Physics University of California Berkeley California 94720 USA Institute of Cosmology & Gravitation University of Portsmouth Dennis Sciama Building Burnaby Road Portsmouth PO1 3FX United Kingdom Faculty of Physics Ludwig-Maximilians-Universität Scheinerstr. 1 Munich 81679 Germany Department of Physics & Astronomy University College London Gower

We report the first detection of gravitational lensing due to galaxy clusters using only the polarization of the cosmic microwave background (CMB). The lensing signal is obtained using a new estimator that extracts the lensing dipole signature from stacked images formed by rotating the cluster-centered Stokes QU map cutouts along the direction of the locally measured background CMB polarization gradient. Using data from the SPTpol 500 deg2 survey at the locations of roughly 18 000 clusters with richness λ≥10 from the Dark Energy Survey (DES) Year-3 full galaxy cluster catalog, we detect lensing at 4.8σ. The mean stacked mass of the selected sample is found to be (1.43±0.40)×1014M⊙ which is in good agreement with optical weak lensing based estimates using DES data and CMB-lensing based estimates using SPTpol temperature data. This measurement is a key first step for cluster cosmology with future low-noise CMB surveys, like CMB-S4, for which CMB polarization will be the primary channel for cluster lensing measurements.

关键词： Cosmic microwave background Gravitational lenses Galaxy clusters

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QUANTIFYING FEEDBACK FROM NARROW LINE REGION OUTFLOWS IN NEARBY ACTIVE GALAXIES. I. SPATIALLY RESOLVED MASS OUTFLOW RATES FOR THE SEYFERT 2 GALAXY MARKARIAN 573†★

arXiv

引用

arXiv 2018年

作者： Revalski, M. Crenshaw, D.M. Kraemer, S.B. Fischer, T.C. Schmitt, H.R. Machuca, C. Department of Physics and Astronomy Georgia State University 25 Park Place Suite 605 AtlantaGA30303 United States Institute for Astrophysics and Computational Sciences Department of Physics Catholic University of America WashingtonDC20064 United States Astrophysics Science Division Goddard Space Flight Center Code 665 GreenbeltMD20771 United States Naval Research Laboratory WashingtonDC20375 United States Department of Astronomy University of Wisconsin–Madison 475 North Charter Street MadisonWI53707 United States National Science Foundation Graduate Research Fellow DGE1550139 James Webb Space Telescope NASA Postdoctoral Program Fellow

We present the first spatially resolved mass outflow rate measurements (M·out) of the optical emission line gas in the narrow line region (NLR) of a Seyfert 2 galaxy, Markarian 573. Using long slit spectra and [O III] imaging from the Hubble Space Telescope and Apache Point Observatory in conjunction with emission line diagnostics and Cloudy photoionization models, we find a peak outflow rate of M·out ≈ 3.4 ± 0.5 M☉ yr−1 at a distance of 210 pc from the central supermassive black hole (SMBH). The outflow extends to distances of 600 pc from the nucleus with a total mass and kinetic energy of M ≈ 2.2 × 106M☉ and E ≈ 5.1 × 1054 erg, revealing the outflows to be more energetic than those in the lower luminosity Seyfert 1 galaxy NGC 4151 (Crenshaw et al. 2015). The peak outflow rate is an order of magnitude larger than the mass accretion and nuclear outflow rates, indicating local in-situ acceleration of the circumnuclear NLR gas. We compare these results to global techniques that quantify an average outflow rate across the NLR, and find the latter are subject to larger uncertainties. These results indicate that spatially resolved observations are critical for probing AGN feedback on scales where circumnuclear star formation occurs. Subject headings: galaxies: active – galaxies: individual (Mrk 573) – galaxies: kinematics and dynamics – galaxies: Seyfert – ISM: jets and outflows Copyright © 2018, The Authors. All rights reserved.

关键词： Galaxies

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Sensitivity of gravitational wave searches to the full signal of intermediate mass black hole binaries during the LIGO O1 science run

arXiv

引用

arXiv 2017年

作者： Bustillo, Juan Calderón Salemi, Francesco Canton, Tito Dal Jani, Karan P. Center for Relativistic Astrophysics School of Physics Georgia Institute of Technology AtlantaGA30332 United States Callinstrasse 38 Hannover Germany NASA Postdoctoral Program Fellow Goddard Space Flight Center GreenbeltMD20771 United States

The sensitivity of gravitational wave searches for binary black holes is estimated via the injection and posterior recovery of simulated gravitational wave signals in the detector data streams. When a search reports no detections, the estimated sensitivity is then used to place upper limits on the coalescence rate of the target source. In order to obtain correct sensitivity and rate estimates, the injected waveforms must be faithful representations of the real signals. Up to date, however, injected waveforms have neglected radiation modes of order higher than the quadrupole, potentially biasing sensitivity and coalescence rate estimates. In particular, higher-order modes are known to have a large impact in the gravitational waves emitted by intermediate mass black holes binaries. In this work we evaluate the impact of this approximation in the context of two search algorithms run by the LIGO Scientific Collaboration in their search for intermediate mass black hole binaries in the O1 LIGO Science Run data: a matched-filter based pipeline and a coherent un-modeled one. To this end we estimate the sensitivity of both searches to simulated signals including and omitting higher-order modes. We find that omission of higher-order modes leads to biases in the sensitivity estimates which depend on the masses of the binary, the search algorithm and the required level of significance for detection. In addition, we compare the sensitivity of the two search algorithms across the studied parameter space. We conclude that the most recent LIGO-Virgo upper limits on the rate of coalescence of intermediate mass black hole binaries are conservative for the case of highly asymmetric binaries. However, the tightest upper limits, placed for nearly-equal-mass sources, remain unchanged due to the small contribution of higher modes to the corresponding sources. Copyright © 2017, The Authors. All rights reserved.

关键词： Learning algorithms

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Detecting ocean glint on exoplanets using multiphase mapping

arXiv

引用

arXiv 2019年

作者： Yaeger, Jacob Lustig Meadows, Victoria S. Mendoza, Guadalupe Tovar Schwieterman, Edward W. Fujii, Yuka Luger, Rodrigo Robinson, Tyler D. Astronomy Department University of Washington Box 951580 SeattleWA98195 United States Nasa Astrobiology Institute Virtual Planetary Laboratory Team United States Astrobiology Program University of Washington 3910 15th Ave. NE Box 351580 SeattleWA98195 United States Nasa Postdoctoral Fellow Department of Earth Sciences University of California RiversideCA92521 United States Nasa Astrobiology Institute Alternative Earths Team University of California RiversideCA92521 United States Blue Marble Space Institute of Science 1001 4th Ave Suite 3201 SeattleWA98154 United States Earth-Life Science Institute Tokyo Institute of Technology Tokyo152-8550 Japan Nasa Goddard Institute for Space Studies New YorkNY10025 United States Center for Computational Astrophysics Flatiron Institute New YorkNY10010 United States Department of Physics Astronomy Northern Arizona University FlagstaffAZ86011 United States

Rotational mapping and specular reection (glint) are two proposed methods to directly detect liquid water on the surface of habitable exoplanets. However, false positives for both methods may prevent the unambiguous detection of exoplanet oceans. We use simulations of Earth as an exoplanet to introduce a combination of multiwavelength, multiphase, time-series direct-imaging observations and accompanying analyses that may improve the robustness of exoplanet ocean detection by spatially mapping the ocean glint signal. As the planet rotates, the glint spot appears to \blink as Lambertian scattering continents interrupt the specular reection from the ocean. This manifests itself as a strong source of periodic variability in crescent-phase disk-integrated reected light curves. We invert these light curves to constrain the longitudinal slice maps and apparent albedo of multiple surfaces at both quadrature and crescent phase. At crescent phase, the retrieved apparent albedo of ocean-bearing longitudinal slices is increased by a factor of 5, compared to the albedo at quadrature phase, due to the contribution from glint. The land-bearing slices exhibit no significant change in apparent albedo with phase. The presence of forward-scattering clouds in our simulated observation increases the overall reectivity toward crescent, but we find that clouds do not correlate with any specific surfaces, thereby allowing for the phase-dependent glint effect to be interpreted as distinct from cloud scattering. Retrieving the same longitudinal map at quadrature and crescent phases may be used to tie changes in the apparent albedo with phase back to specific geographic surfaces (or longstanding atmospheric features), although this requires ideal geometries. We estimate that crescent-phase time-dependent glint measurements are feasible for between 1 and 10 habitable zone exoplanets orbiting the nearest G, K, and M dwarfs using a space-based, high-contrast, direct-imaging telescope with a diam

关键词： Orbits

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Empirical estimate of the shape of the upstream heliopause from IBEX-Lo helium measurements: Preliminary results

arXiv

引用

arXiv 2017年

作者： Isenberg, Philip A. Kucharek, Harald Park, Jeewoo Space Science Center Department of Physics University of New Hampshire Morse Hall 8 College Road DurhamNH03824 United States NASA Postdoctoral Program Fellow Goddard Space Flight Center GreenbeltMD20771 United States

We present a simplified model of the outer heliosheath to help interpret the observations of interstellar neutral helium by the IBEX-Lo instruments. We assume that the measured particles are composed of the superposition of a primary beam population, with the properties of the local interstellar medium, and a secondary population, created by charge exchange between the primary beam neutrals and the ions that have been deflected as they approach the heliopause. We extract information on the large-scale shape of the heliopause by comparing the helium flux measured at IBEX along four different look directions with simple models of deflected plasma flow around hypothetical obstacles of different aspect ratios to the flow. As a first step in this paper, we model the deflected plasma flow with the analytical solutions for compressible gas flow around a series of oblate ellipsoidal obstacles. Our comparisons between the model results and the observations indicate that the heliopause is very blunt in the vicinity of the heliospheric nose, especially compared to a Rankine half-body or cometary shape. The upstream heliopause seems to be highly elongated in the directions parallel to the interstellar magnetic field, and relatively more compact and symmetric in the directions transverse to that field. The IBEX-Lo helium observations are not consistent with a heliopause elongated in directions parallel to the solar rotation axis. Copyright © 2017, The Authors. All rights reserved.

关键词： Helium

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Quantifying feedback from narrow line region outflows in nearby active galaxies. II. spatially resolved mass outflow rates for the QSO2 markarian 34

arXiv

引用

arXiv 2018年

作者： Revalski, M. Dashtamirova, D. Crenshaw, D.M. Kraemer, S.B. Fischer, T.C. Schmitt, H.R. Gnilka, C.L. Schmidt, J. Elvis, M. Fabbiano, G. Storchi-Bergmann, T. Maksym, W.P. Gandhi, P. Department of Physics and Astronomy Georgia State University 25 Park Place AtlantaGA30303 United States Institute for Astrophysics and Computational Sciences Department of Physics Catholic University of America WashingtonDC20064 United States Astrophysics Science Division Goddard Space Flight Center Code 665 GreenbeltMD20771 United States Naval Research Laboratory WashingtonDC20375 United States Designer/Developer for the Astrophysics Source Code Library Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States Departamento de Astronomia Universidade Federal Do Rio Grande Do Sul if CP 15051 Porto Alegre RS91501-970 Brazil Department of Physics and Astronomy University of Southampton SouthamptonSO17 3RT United Kingdom James Webb Space Telescope NASA Postdoctoral Program Fellow

We present spatially resolved mass outow rate measurements (Mout) for the narrow line region of Markarian 34, the nearest Compton-thick type 2 quasar (QSO2). Spectra obtained with the Hubble Space Telescope and at Apache Point Observatory reveal complex kinematics, with distinct signatures of outow and rotation within 2 kpc of the nucleus. Using multi-component photoionization models, we find that the outow contains a total ionized gas mass of M ≈ 1.6 × 106Mo. Combining this with the kinematics yields a peak outow rate of Mout≈ 2.0 ± 0.4 Mo yr-1at a distance of 470 pc from the nucleus, with a spatially integrated kinetic energy of E ≈ 1:4 × 1055erg. These outows are more energetic than those observed in Mrk 573 and NGC 4151, supporting a correlation between luminosity and outow strength even though they have similar peak outow rates. The mix of rotational and outowing components suggests that spatially resolved observations are required to determine accurate outow parameters in systems with complex kinematics. (See appended erratum for updated values.). Copyright © 2018, The Authors. All rights reserved.

关键词： Kinematics

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Detecting binary compact-object mergers with gravitational waves: Understanding and improving the sensitivity of the pycbc search

arXiv

引用

arXiv 2017年

作者： Nitz, Alexander H. Dent, Thomas Canton, Tito D.A.L. Fairhurst, Stephen Brown, Duncan A. HannoverD-30167 Germany Department of Physics Syracuse University SyracuseNY13244 United States NASA Postdoctoral Program Fellow Goddard Space Flight Center GreenbeltMD20771 United States School of Physics and Astronomy Cardiff University Cardiff United Kingdom Kavli Institute for Theoretical Physics University of California at Santa Barbara Santa BarbaraCA93106 United States

We present an improved search for binary compact-object mergers using a network of ground-based gravitational-wave detectors. We model a volumetric, isotropic source population and incorporate the resulting distribution over signal amplitude, time delay, and coalescence phase into the ranking of candidate events. We describe an improved modeling of the background distribution, and demonstrate incorporating a prior model of the binary mass distribution in the ranking of candidate events. We find a ∼ 10% and ∼ 20% increase in detection volume for simulated binary neutron star and neutron star-binary black hole systems, respectively, corresponding to a reduction of the false alarm rates assigned to signals by between one and two orders of magnitude. Copyright © 2017, The Authors. All rights reserved.

关键词： Gravity waves

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Evidence for Late-stage Eruptive Mass-loss in the Progenitor to SN2018gep, a Broad-lined Ic Supernova: Pre-explosion Emission and a Rapidly Rising Luminous Transient

arXiv

引用

arXiv 2019年

作者： Ho, Anna Y.Q. Goldstein, Daniel A. Schulze, Steve Khatami, David K. Perley, Daniel A. Ergon, Mattias Gal-Yam, Avishay Corsi, Alessandra Andreoni, Igor Barbarino, Cristina Bellm, Eric C. Blagorodnova, Nadia Bright, Joe S. Burns, E. Cenko, S. Bradley Cunningham, Virginia De, Kishalay Dekany, Richard Dugas, Alison Fender, Rob P. Fransson, Claes Fremling, Christoffer Goldstein, Adam Graham, Matthew J. Hale, David Horesh, Assaf Hung, Tiara Kasliwal, Mansi M. M. Kuin, N. Paul Kulkarni, S.R. Kupfer, Thomas Lunnan, Ragnhild Masci, Frank J. Ngeow, Chow-Choong Nugent, Peter E. Ofek, Eran O. Patterson, Maria T. Petitpas, Glen Rusholme, Ben Sai, Hanna Sfaradi, Itai Shupe, David L. Sollerman, Jesper Soumagnac, Maayane T. Tachibana, Yutaro Taddia, Francesco Walters, Richard Wang, Xiaofeng Yao, Yuhan Zhang, Xinhan Cahill Center for Astrophysics California Institute of Technology MC 249-17 1200 E California Boulevard PasadenaCA91125 United States Department of Particle Physics and Astrophysics Weizmann Institute of Science 234 Herzl St Rehovot76100 Israel Department of Astronomy University of California BerkeleyCA94720 United States Astrophysics Research Institute Liverpool John Moores University IC2 Liverpool Science Park 146 Brownlow Hill LiverpoolL3 5RF United Kingdom The Oskar Klein Centre & Department of Astronomy Stockholm University AlbaNova StockholmSE-106 91 Sweden Department of Physics and Astronomy Texas Tech University Box 1051 LubbockTX79409-1051 United States DIRAC Institute Department of Astronomy University of Washington 3910 15th Avenue NE SeattleWA98195 United States Department of Astrophysics IMAPP Radboud University Nijmegen Netherlands Department of Physics University of Oxford Denys Wilkinson Building Keble Road OxfordOX1 3RH United Kingdom NASA Postdoctoral Program Fellow Goddard Space Flight Center GreenbeltMD20771 United States Astrophysics Science Division NASA Goddard Space Flight Center Mail Code 661 GreenbeltMD20771 United States Joint Space-Science Institute University of Maryland College ParkMD20742 United States Astronomy Department University of Maryland College ParkMD20742 United States Caltech Optical Observatories California Institute of Technology MC 11-17 1200 E. California Blvd. PasadenaCA91125 United States Division of Physics Mathematics and Astronomy California Institute of Technology PasadenaCA91125 United States Science and Technology Institute Universities Space Research Association HuntsvilleAL35805 United States Racah Institute of Physics Hebrew University Jerusalem91904 Israel Department of Astronomy and Astrophysics University of California Santa CruzCA95064 United States Mullard Space Science Laboratory University College London Holmbury St. Mary Dorking SurreyRH5 6NT Un

We present detailed observations of ZTF18abukavn (SN2018gep), discovered in high-cadence data from the Zwicky Transient Facility as a rapidly rising (1.4 ±0.1 mag/hr) and luminous (Mg,peak = −20 mag) transient. It is spectroscopically classified as a broad-lined stripped-envelope supernova (Ic-BL SN). The high peak luminosity (Lbol & 3×1044 erg s−1), the short rise time (trise = 3 day in g-band), and the blue colors at peak (g−r ∼ −0.4) all resemble the high-redshift Ic-BL iPTF16asu, as well as several other unclassified fast transients. The early discovery of SN2018gep (within an hour of shock breakout) enabled an intensive spectroscopic campaign, including the highest-temperature (Teff & 40, 000K) spectra of a stripped-envelope SN. A retrospective search revealed luminous (Mg ∼ Mr ≈ −14 mag) emission in the days to weeks before explosion, the first definitive detection of precursor emission for a Ic-BL. We find a limit on the isotropic gamma-ray energy release Eγ,iso 10 day) light curve requires an additional energy source, which could be the radioactive decay of Ni-56. Copyright © 2019, The Authors. All rights reserved.

关键词： Shock waves

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KMT-2016-BLG-1107: A new hollywood-planet close/wide degeneracy

arXiv

引用

arXiv 2018年

作者： Hwang, Kyu-Ha Ryu, Yoon-Hyun Kim, Hyoun-Woo Albrow, Michael D. Chung, Sun-Ju Gould, Andrew Han, Cheongho Jung, Youn Kil Shin, In-Gu Shvartzvald, Yossi Yee, Jennifer C. Zang, Weicheng Cha, Sang-Mok Kim, Dong-Jin Kim, Seung-Lee Lee, Chung-Uk Lee, Dong-Joo Lee, Yongseok Park, Byeong-Gon Pogge, Richard W. Korea Astronomy and Space Science Institute Daejon34055 Korea Republic of University of Canterbury Department of Physics and Astronomy Private Bag 4800 Christchurch8020 New Zealand Korea University of Science and Technology Daejeon34113 Korea Republic of Max-Planck-Institute for Astronomy Königstuhl 17 Heidelberg69117 Germany Department of Astronomy Ohio State University 140 W. 18th Ave. ColumbusOH43210 United States Department of Physics Chungbuk National University Cheongju28644 Korea Republic of Harvard-Smithsonian Center for Astrophysics 60 Garden St. CambridgeMA02138 United States IPAC Mail Code 100-22 Caltech 1200 E. California Blvd. PasadenaCA91125 United States NASA Postdoctoral Program Fellow Physics Department and Tsinghua Centre for Astrophysics Tsinghua University Beijing100084 China School of Space Research Kyung Hee University Yongin Kyeonggi17104 Korea Republic of

We show that microlensing event KMT-2016-BLG-1107 displays a new type of degeneracy between wide-binary and close-binary Hollywood events in which a giant-star source envelops the planetary caustic. The planetary anomaly takes the form of a smooth, two-day "bump" far out on the falling wing of the light curve, which can be interpreted either as the source completely enveloping a minor-image caustic due to a close companion with mass ratio q = 0.036, or partially enveloping a major-image caustic due to a wide companion with q = 0.004. The best estimates of the companion masses are both in the planetary regime (3.3+3−1..58 Mjup and 0.090+0−0..096037 Mjup) but differ by an even larger factor than the mass ratios due to different inferred host masses. We show that the two solutions can be distinguished by high-resolution imaging at first light on next-generation ("30m") telescopes. We provide analytic guidance to understand the conditions under which this new type of degeneracy can appear. Copyright © 2018, The Authors. All rights reserved.

关键词： Giant stars

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ALBEDOS, EQUILIBRIUM TEMPERATURES, AND SURFACE TEMPERATURES OF HABITABLE PLANETS

arXiv

引用

arXiv 2018年

作者： Del Genio, Anthony D. Kiang, Nancy Y. Way, Michael J. Amundsen, David S. Sohl, Linda E. Fujii, Yuka Chandler, Mark Aleinov, Igor Colose, Christopher M. Guzewich, Scott D. Kelley, Maxwell NASA Goddard Institute for Space Studies 2880 Broadway New YorkNY10025 United States Department of Applied Physics and Applied Mathematics Columbia University New YorkNY10027 United States Center for Climate Systems Research Columbia University New YorkNY10027 United States Earth-Life Science Institute Tokyo Institute of Technology Ookayama Meguro Tokyo152-8550 Japan NASA Postdoctoral Program Goddard Institute for Space Studies New YorkNY10025 United States NASA Goddard Space Flight Center GreenbeltMD20771 United States SciSpace LLC 2880 Broadway New YorkNY10025 United States

The potential habitability of known exoplanets is often categorized by a nominal equilibrium temperature assuming a Bond albedo of either ~0.3, similar to Earth, or 0. As an indicator of habitability, this leaves much to be desired, because albedos of other planets can be very different, and because surface temperature exceeds equilibrium temperature due to the atmospheric greenhouse effect. We use an ensemble of 3-dimensional general circulation model simulations to show that for a range of habitable planets, much of the variability of Bond albedo, equilibrium temperature, and even surface temperature can be predicted with useful accuracy from incident stellar flux and stellar temperature, two known external parameters for every confirmed exoplanet. Earth’s Bond albedo is near the minimum possible for habitable planets orbiting G stars, because of increasing contributions from clouds and sea ice/snow at higher and lower instellations, respectively. For habitable M star planets, Bond albedo is usually lower than Earth’s because of near-IR H2O absorption, except at high instellation where clouds are important. We apply the relationships derived from this behavior to several known exoplanets to derive zeroth-order estimates of their potential habitability. More expansive multivariate statistical models that include currently non-observable parameters suggest that greenhouse gas variations could account for significant variance in albedo and surface temperature, while orbital and surface features can have significant but not clearly consistent effects. We discuss how emerging information from global climate models might resolve some degeneracies and help focus scarce observing resources on the most promising planets. Copyright © 2018, The Authors. All rights reserved.

关键词： Surface properties

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