• A Warm Layer in the Nightside Mesosphere of Mars

      Nakagawa, Hiromu; Jain, Sonal K.; Schneider, Nicholas M.; Montmessin, Franck; Yelle, Roger V.; Jiang, Fayu; Verdier, Loic; Kuroda, Takeshi; Yoshida, Nao; Fujiwara, Hitoshi; et al. (AMER GEOPHYSICAL UNION, 2020-02-17)
      We report a new set of stellar occultation measurements for nightside temperature profiles made by the Mars Atmosphere and Volatile EvolutioN/Imaging Ultraviolet Spectrograph that provide evidence for a recurring layer of warm air between 70 and 90 km altitudes in the nightside mesosphere of Mars during L-s = 0-180 degrees in Martian Year 33-34. The nightside profiles reveal a recurring peak of atmospheric temperature around 80 km over the equator to the middle latitudes in the northern hemisphere. The predictions of the Mars Climate Database have a warm layer with much smaller amplitudes. The observed peak amplitudes are larger than those predicted by the model by up to 90 K. Wavenumber-3 structures are seen in the warm layer that are potentially signatures of thermal tides or stationary planetary waves, with amplitudes two times larger than predicted.
    • Warming and precipitation addition interact to affect plant spring phenology in alpine meadows on the central Qinghai-Tibetan Plateau

      Ganjurjav, Hasbagan; Gornish, Elise S.; Hu, Guozheng; Schwartz, Mark W.; Wan, Yunfan; Li, Yue; Gao, Qingzhu; Univ Arizona, Sch Nat Resources & Environm (ELSEVIER, 2020-06-15)
      Temperature and precipitation are primary regulators of plant phenology. However, our knowledge of how these factors might interact to affect plant phenology is incomplete. The Qinghai-Tibetan Plateau, a cold and high region, has experienced no consistent changes in spring phenology, despite a significant warming trend. We conducted a manipulative experiment of warming and precipitation addition in an alpine meadow on the Qinghai-Tibetan Plateau in 2015 (cold and wet), 2016 (warm and dry) and 2017 (mild and very wet). We found that warming increased annual variability of plant spring phenology. Warming delayed green up of all monitored species in 2016, advanced green up of early flowering species in 2015, and did not alter green up in 2017. For example, green up of the shallow rooted Kobresia pygmaea advanced 8 (+/- 2) days in 2015 and was delayed by 23 (+/- 3) days in a dry year (2016) under warming compared with control. Early spring precipitation addition can offset the delaying effects of warming in a dry year on the Qinghai-Tibetan Plateau. Under warming plus precipitation addition, community average green up advanced compared to control plots in 2015 and 2016, and community average flowering advanced for all three years. In 2016, flowering of K. pygmaea (an early flowering species) advanced under warming plus precipitation addition compared to control while flowering of other species did not change. Our results highlight that annual variation of soil moisture condition plays a critical role in determining the magnitude and direction of spring phenology response to warming. We provide insights in how plant spring phenology might change in a warmer future in the presence or absence of precipitation increase.
    • Was 49b: An Overmassive AGN in a Merging Dwarf Galaxy?

      Secrest, Nathan J.; Schmitt, Henrique R.; Blecha, Laura; Rothberg, B.; Fischer, Jacqueline; Univ Arizona, LBT Observ (IOP PUBLISHING LTD, 2017-02-17)
      We present a combined morphological and X-ray analysis of Was. 49, an isolated, dual-AGN system notable for the presence of a dominant AGN, Was 49b, in the disk of the primary galaxy, Was 49a, at a projected radial distance of 8. kpc from the nucleus. Using X-ray data from Chandra, the Nuclear Spectroscopic Telescope Array, and Swift, we find that this AGN has a bolometric luminosity of L-bol similar to 10(45) erg s(-1), with a black hole mass of M-BH = 1.3(-0.9)(+10)M(circle dot) . Despite the large mass, our analysis of optical data from the Discovery Channel Telescope shows that the supermassive black hole (SMBH) is hosted by a stellar counterpart with a mass of only 5.6(-2.6)(+4.9)M(circle dot), which makes the SMBH potentially larger than expected from SMBH-galaxy scaling relations, and the stellar counterpart exhibits a morphology that is consistent with dwarf elliptical galaxies. Our analysis of the system in the r and K bands indicates that Was. 49 is a minor merger, with the mass ratio of Was 49b to Was 49a between similar to 1:7 and similar to 1:15. This is in contrast with findings that the most luminous merger-triggered AGNs are found in major mergers and that minor mergers predominantly enhance AGN activity in the primary galaxy.
    • Was Aztec and Mixtec turquoise mined in the American Southwest?

      Thibodeau, Alyson M.; López Luján, Leonardo; Killick, David J.; Berdan, Frances F.; Ruiz, Joaquin; Univ Arizona, Sch Anthropol; Univ Arizona, Dept Geosci (AMER ASSOC ADVANCEMENT SCIENCE, 2018-06)
      Archaeologists have long suggested that prehispanic states in Mesoamerica acquired turquoise through long-distance exchange with groups living in what is now the American Southwest and adjacent parts of northern Mexico. To test this hypothesis, we use lead and strontium isotopic ratios to investigate the geologic provenance of 43 Mesoamerican turquoise artifacts, including 38 mosaic tiles from offerings within the Sacred Precinct of Tenochtitlan (the Mexica or Aztec capital) and 5 tiles associated with Mixteca-style mosaics currently held by the Smithsonian's National Museum of the American Indian. Most of these artifacts have isotopic signatures that differ from turquoise deposits in the American Southwest, but closely match copper deposits and crustal rocks in Mesoamerica. We thus conclude that turquoise used by the Aztecs and Mixtecs likely derives from Mesoamerican sources and was not acquired through long-distance exchange with the Southwest.
    • WASP-52b. The effect of starspot correction on atmospheric retrievals

      Bruno, Giovanni; Lewis, Nikole K; Alam, Munazza K; López-Morales, Mercedes; Barstow, Joanna K; Wakeford, Hannah R; Sing, David; Henry, Gregory W; Ballester, Gilda E; Bourrier, Vincent; et al. (OXFORD UNIV PRESS, 2019-11-18)
      We perform atmospheric retrievals on the full optical to infrared (0.3-5 mu m) transmission spectrum of the inflated hot Jupiter WASP-52b by combining HST/STIS, WFC3 IR, and Spitzer/IRAC observations. As WASP-52 is an active star that shows both out-of-transit photometric variability and star-spot crossings during transits, we account for the contribution of non-occulted active regions in the retrieval. We recover a 0.1-10x solar atmospheric composition, in agreement with core accretion predictions for giant planets, and no significant contribution of aerosols. We also obtain a <3000K temperature for the star-spots, a measure which is likely affected by the models used to fit instrumental effects in the transits, and a 5 per cent star-spot fractional coverage, compatible with expectations for the host star's spectral type. Such constraints on the planetary atmosphere and on the activity of its host star will inform future JWST GTO observations of this target.
    • Water and carbon dioxide distribution in the 67P/Churyumov-Gerasimenko coma from VIRTIS-M infrared observations

      Migliorini, A.; Piccioni, G.; Capaccioni, F.; Filacchione, G.; Bockelée-Morvan, D.; Erard, S.; Leyrat, C.; Combi, M. R.; Fougere, N.; Crovisier, J.; et al. (EDP SCIENCES S A, 2016-04-12)
      Context. Studying the coma environment of comet 67P/Churyumov-Gerasimenko (67P) is one of the primary scientific goals of the VIRTIS experiment on the ESA Rosetta mission. Aims. The distribution and variability of water vapour and carbon dioxide in the comet's coma are needed to estimate their production rate, abundances in the nucleus, and the spatial distribution of the active regions. Methods. Infrared emission lines from vibrational bands of water and carbon dioxide at 2.67 and 4.27 mu m, respectively, were observed by the VIRTIS-M imaging channel and mapped from close to the nucleus up to similar to 10 km altitude with a resolution of similar to 40 m/px. A dataset consisting of 74 observations in the 1 5 mu m spectral range acquired from 8 to 14 April 2015 when 67P was at a heliocentric distance of 1.9 AU is analysed in this work. A statistical correlation between the gas distribution and the surface's active regions was performed. Results. The maximum H2O emission is observed within 3 km from the nucleus and is mainly concentrated above two active regions, Aten-Babi and Seth-Hapi, while the CO2 distribution appears more uniform with significant emissions coming from both the "head" and southern latitude regions. In the equatorial region, the column densities of both species decrease with altitude, although CO2 decreases more rapidly than H2O. The calculated CO2/H2O column density ratios above Aten-Babi and Seth-Hapi are 2.4 +/- 0.6% and 3.0 +/- 0.7%, respectively. A value equal to 3.9 +/- 1.0% is observed at equatorial latitudes in the region encompassing Imothep. Conclusions. VIRTIS-M has mapped the distribution of water vapour and carbon dioxide around the nucleus of 67P with unprecedented spatial resolution. The different water and carbon dioxide outgassing above the surface, seen in the VIRTIS-M data, might be indicative of a different thermal history of the northern and southern hemispheres of 67P.
    • Water on Mars, With a Grain of Salt: Local Heat Anomalies Are Required for Basal Melting of Ice at the South Pole Today

      Sori, Michael M.; Bramson, Ali M.; Univ Arizona, Lunar & Planetary Lab (AMER GEOPHYSICAL UNION, 2019-02-12)
      Recent analysis of radar data from the Mars Express spacecraft has interpreted bright subsurface radar reflections as indicators of local liquid water at the base of the south polar layered deposits (SPLD). However, the physical and geological conditions required to produce melting at this location were not quantified. Here we use thermophysical models to constrain parameters necessary to generate liquid water beneath the SPLD. We show that no concentration of salt is sufficient to melt ice at the base of the SPLD in the present day under typical Martian conditions. Instead, a local enhancement in the geothermal heat flux of >72 mW/m(2) is required, even under the most favorable compositional considerations. This heat flow is most simply achieved via the presence of a subsurface magma chamber emplaced 100 s of kyr ago. Thus, if the liquid water interpretation of the observations is correct, magmatism on Mars may have been active extremely recently.
    • Water Production Rates and Activity of Interstellar Comet 2I/Borisov

      Xing, Zexi; Bodewits, Dennis; Noonan, John; Bannister, Michele T.; Univ Arizona, Lunar & Planetary Lab (IOP PUBLISHING LTD, 2020-04-27)
      We observed the interstellar comet 2I/Borisov using the Neil Gehrels Swift Observatory's Ultraviolet/Optical Telescope. We obtained images of the OH gas and dust surrounding the nucleus at six epochs spaced before and after perihelion (-2.56 to 2.54 au). Water production rates increased steadily before perihelion from (7.0 1.5) x 10(26) molecules s(-1) on 2019 November 1, to (10.7 1.2) x 10(26) molecules s(-1) on December 1. This rate of increase in water production rate is quicker than that of most dynamically new comets and at the slower end of the wide range of Jupiter-family comets. After perihelion, the water production rate decreased to (4.9 0.9) x 10(26) molecules s(-1) on December 21, which is much more rapidly than that of all previously observed comets. Our sublimation model constrains the minimum radius of the nucleus to 0.37 km, and indicates an active fraction of at least 55% of the surface. A(0)f rho calculations show a variation between 57.5 and 105.6 cm with a slight trend peaking before the perihelion, lower than previous and concurrent published values. The observations confirm that 2I/Borisov is carbon-chain depleted and enriched in NH2 relative to water.
    • Water splitting activity of oxygen-containing groups in graphene oxide catalyst in bipolar membranes

      Martínez, Rodrigo J.; Farrell, James; Univ Arizona, Dept Chem & Environm Engn (ELSEVIER, 2019-09-15)
      Graphene oxide (GO) is a very effective catalyst for splitting water into H+ and OH− ions in bipolar membranes. This research investigated the catalytic activity of six oxygenated functional groups in GO for water splitting. Møller-Plesset second order perturbation method (MP2) simulations were performed to calculate activation barriers for proton acceptance and release reactions with and without an applied electric field. The relative catalytic activity for the functional groups on GO was independent of the electric field intensity and dielectric constant. The catalytic activity for accepting and releasing a proton linearly correlated with the pKa of the functional groups. The edge carboxylate site had the highest catalytic activity for water splitting, and had activation barriers that were 0.2 to 0.4 kcal/mol higher than a model tertiary amine. This suggests that the high catalytic activity of GO results from a high catalytic site density, as opposed to a chemical effect.
    • Water splitting promoted by electronically conducting interlayer material in bipolar membranes

      Chen, Yingying; Martínez, Rodrigo J.; Gervasio, Don; Baygents, James C.; Farrell, James; Univ Arizona, Dept Chem & Environm Engn (SPRINGER, 2019-11-06)
      Bipolar membranes are used in a variety of industrial applications to split water into hydronium and hydroxide ions. This research investigated the hypothesis that an electronically conducting material between the anion and cation exchange membranes can increase the rate of water splitting by increasing the electric field intensity in the mobile ion depleted region. Bipolar membranes were constructed with electronically conducting (graphene and carbon nanotubes) and electronically insulating (graphene oxide) interlayer materials of varying thickness. All three interlayer materials decreased the voltage required for water splitting compared to a bipolar membrane with no interlayer material. Quantum chemistry simulations were used to determine the catalytic effect of proton accepting and proton releasing sites on the three interlayer materials. Neither graphene nor carbon nanotubes had catalytic sites for water splitting. Thicker layers of graphene oxide resulted in decreased rates of water splitting at each applied potential. This effect can be attributed to a diminished electric field in the mobile ion depleted region with increasing catalyst layer thickness. In contrast, membrane performance with the electronically conducting graphene and carbon nanotube interlayers was independent of the interlayer thickness. An electrostatic model was used to show that interlayer electronic conductance can increase the electric field intensity in the mobile ion depleted region as compared to an electronically insulating material. Thus, including electronically conducting material in addition to a traditional catalyst may be a viable strategy for improving the performance of bipolar membranes.
    • Water Supply and Ancient Society in the Lake Balkhash Basin: Runoff Variability along the Historical Silk Road

      Panyushkina, Irina P.; Macklin, Mark G.; Toonen, Willem H. J.; Meko, David M.; University of Arizona, Laboratory of Tree-Ring Research (SPRINGER, 2019-02-28)
      Expansion of agricultural practices from the Fertile Crescent to China during the mid and late Holocene are believed to have shaped the early network of Silk Road routes and possibly regulated the dynamics of trade and exchange in the urban oases along the Silk Road throughout its existence. While the impacts of climate change on the Silk Road are more or less documented for the medieval period, they remain poorly understood for early history of the Silk Road, especially in Central Asia. We analyze hydroclimatic proxies derived from fluvial stratigraphy, geochronology, and tree-ring records that acted on various time scales in the Lake Balkhash Basin to learn how changes in water supply could have influenced the early farmers in the Semirechye region of southern Kazakhstan. Our approach aims to identify short-term and long-term variability of regional runoff and to compare the hydrological data with cultural dynamics coupled with the archaeological settlement pattern and agricultural production. The reconstructed runoff variability underscore the contribution of winter precipitation driven by the interaction between the Arctic oscillation and the Siberian High-Pressure System, to Central Asian river discharge. We show that Saka people of the Iron Age employed extensive ravine agriculture on the alluvial fans of the Tian Shan piedmont, where floodwater farming peaked between 400 BC and 200 BC. The early Silk Road farmers on the alluvial fans favored periods of reduced flood flows, river stability and glacier retreat in the Tian Shan Mountains. Moreover, they were able to apply simple flow control structures to lead water across the fan surface. It is very unlikely that changes in water supply ever significantly constricted agricultural expansion in this region.
    • Water, Law, and Development in Chile/California Cooperation, 1960–70s

      Bauer, Carl; Catalán, Luis; University of Arizona (PERGAMON-ELSEVIER SCIENCE LTD, 2017-02)
      During 1963-78 the governments and the top universities of Chile and California undertook three programs of binational development assistance and cooperation. The programs built on a long historical relationship between the two regions, marked by their striking similarities in physical geography and natural resources, despite being 1,000s of miles apart on opposite sides of the Equator. The first program was for technical development assistance to Chile in the framework of the Alliance for Progress, and involved the three governments of Chile, California, and the United States. Water resources and river basin development planning were a primary emphasis, and led to building Chile's largest dual-purpose reservoir (Colbun). The second program was for graduate-level academic exchange and involved the two leading public university systems, the University of Chile and the University of California. This comprehensive program was funded for more than a decade by the Ford Foundation, with agriculture, natural sciences, and engineering the dominant fields. The third program was a separate effort to reform Chilean legal education, led by Stanford Law School and funded by the Ford Foundation. This Chile Law Program was a leading international example of the "law and development" movement in the 1960s, which overlapped closely with the early years of the "law and society" movement in the U.S. Both university and law school programs ended after the Chilean military coup in 1973. What were the impacts of these programs on water, law, and society in both Chile and California? What lessons can we learn today from those historical experiences? We answer these questions with an historical overview and synthesis of diverse documents and evidence. In focusing on water, law, and society, we aim to contribute to the interdisciplinary synthesis of different fields of development studies.
    • The Water-Energy-Food Nexus: A systematic review of methods for nexus assessment

      Albrecht, Tamee R; Crootof, Arica; Scott, Christopher A; Univ Arizona, Sch Geog & Dev (IOP Publishing, 2018-04)
      The water-energy-food (WEF) nexus is rapidly expanding in scholarly literature and policy settings as a novel way to address complex resource and development challenges. The nexus approach aims to identify tradeoffs and synergies of water, energy, and food systems, internalize social and environmental impacts, and guide development of cross-sectoral policies. However, while the WEF nexus offers a promising conceptual approach, the use of WEF nexus methods to systematically evaluate water, energy, and food interlinkages or support development of socially and politically-relevant resource policies has been limited. This paper reviews WEF nexus methods to provide a knowledge base of existing approaches and promote further development of analytical methods that align with nexus thinking. The systematic review of 245 journal articles and book chapters reveals that (a) use of specific and reproducible methods for nexus assessment is uncommon (less than one-third); (b) nexus methods frequently fall short of capturing interactions among water, energy, and food—the very linkages they conceptually purport to address; (c) assessments strongly favor quantitative approaches (nearly three-quarters); (d) use of social science methods is limited (approximately one-quarter); and (e) many nexus methods are confined to disciplinary silos—only about one-quarter combine methods from diverse disciplines and less than one-fifth utilize both quantitative and qualitative approaches. To help overcome these limitations, we derive four key features of nexus analytical tools and methods—innovation, context, collaboration, and implementation—from the literature that reflect WEF nexus thinking. By evaluating existing nexus analytical approaches based on these features, we highlight 18 studies that demonstrate promising advances to guide future research. This paper finds that to address complex resource and development challenges, mixed-methods and transdisciplinary approaches are needed that incorporate social and political dimensions of water, energy, and food; utilize multiple and interdisciplinary approaches; and engage stakeholders and decision-makers.
    • A wave-bending structure at Ka-band using 3D-printed metamaterial

      Wu, Junqiang; Liang, Min; Xin, Hao; Univ Arizona, Dept Elect & Comp Engn (AMER INST PHYSICS, 2018-03-30)
      Three-dimensional printing technologies enable metamaterials of complex structures with arbitrary inhomogeneity. In this work, a 90 degrees wave-bending structure at the Ka-band (26.5-40 GHz) based on 3D-printed metamaterials is designed, fabricated, and measured. The wave-bending effect is realized through a spatial distribution of varied effective dielectric constants. Based on the effective medium theory, different effective dielectric constants are accomplished by special, 3D-printable unit cells, which allow different ratios of dielectric to air at the unit cell level. In contrast to traditional, metallic-structure-included metamaterial designs, the reported wave-bending structure here is all dielectric and implemented by the polymer-jetting technique, which features rapid, low-cost, and convenient prototyping. Both simulation and experiment results demonstrate the effectiveness of the wave-bending structure. Published by AIP Publishing.
    • Wave-Function Engineering for Spectrally Uncorrelated Biphotons in the Telecommunication Band Based on a Machine-Learning Framework

      Cui, Chaohan; Arian, Reeshad; Guha, Saikat; Peyghambarian, N.; Zhuang, Quntao; Zhang, Zheshen; Univ Arizona, James C Wyant Coll Opt Sci; Univ Arizona, Dept Elect & Comp Engn; Univ Arizona, Dept Math & Computat Sci; Univ Arizona, Dept Mat Sci & Engn (AMER PHYSICAL SOC, 2019-09-30)
      Indistinguishable single photons are key ingredients for a plethora of quantum-information-processing applications, ranging from quantum communications to photonic quantum computing. A mainstream platform to produce indistinguishable single photons over a wide spectral range is based on biphoton generation through spontaneous parametric down-conversion in nonlinear crystals. The purity of the biphotons produced is, however, limited by their spectral correlations. Here we present a design recipe, based on a machine-learning framework, for the engineering of biphoton joint spectral amplitudes over a wide spectral range. By customizing the poling profile of the KTiOPO4 crystal, we show, numerically, that spectral purities of 99.22%, 99.99%, and 99.82%, respectively, can be achieved in the 1310-, 1550-, and 1600-nm bands after applying a moderate 8-nm filter. The machine-learning framework thus enables the generation of near-indistinguishable single photons over the entire telecommunication band without resorting to the KTiOPO4 crystal's group-velocity-matching wavelength window near 1582 nm.
    • Wavefront analysis from its slope data

      Mahajan, Virendra N.; Acosta, Eva; Univ Arizona, Coll Opt Sci (SPIE-INT SOC OPTICAL ENGINEERING, 2017-08-30)
      In the aberration analysis of a wavefront over a certain domain, the polynomials that are orthogonal over and represent balanced wave aberrations for this domain are used. For example, Zernike circle polynomials are used for the analysis of a circular wavefront. Similarly, the annular polynomials are used to analyze the annular wavefronts for systems with annular pupils, as in a rotationally symmetric two-mirror system, such as the Hubble space telescope. However, when the data available for analysis are the slopes of a wavefront, as, for example, in a Shack-Hartmann sensor, we can integrate the slope data to obtain the wavefront data, and then use the orthogonal polynomials to obtain the aberration coefficients. An alternative is to find vector functions that are orthogonal to the gradients of the wavefront polynomials, and obtain the aberration coefficients directly as the inner products of these functions with the slope data. In this paper, we show that an infinite number of vector functions can be obtained in this manner. We show further that the vector functions that are irrotational are unique and propagate minimum uncorrelated additive random noise from the slope data to the aberration coefficients.
    • Wavelength Tunable Ho3+-Doped ZBLAN Fiber Lasers in the 1.2-mu m Wavelength Region

      Ma, Yunxiu; Zhu, Xiushan; Yang, Luyun; Zhang, Xinzheng; Norwood, R. A.; Peyghambarian, N.; Univ Arizona, Coll Opt Sci (IEEE-INST ELECTRICAL ELECTRONICS ENGINEERS INC, 2018-08-15)
      Wavelength tunability of continuous-wave holmium doped ZrF4-BaF2-LaT3-AlF3-NaF fiber lasers operating in the 1.2-arm wavelength region was investigated with a Littrow configuration. A wavelength tuning range of 1184-1198 nm was obtained from the fiber output port of the laser. The spectral width was measured to be around 0.02 nm over the entire tunable range and a maximum output power of 81.6 mW at 1192 nm was obtained at a pump power of 1.97 W. The wavelength tunable range was found to be limited by the transmission of the fiber-optic wavelength division multiplexer and coupler. A broader wavelength tuning range of 1177-1201 nm was obtained with a simpler fiber laser construction from the zero-order diffraction output of the bulk grating.
    • A wavelength-dispersive instrument for characterizing fluorescence and scattering spectra of individual aerosol particles on a substrate

      Huffman, Donald R.; Swanson, Benjamin E.; Huffman, J. Alex; Univ Arizona, Dept Phys (COPERNICUS GESELLSCHAFT MBH, 2016-08-23)
      We describe a novel, low-cost instrument to acquire both elastic and inelastic (fluorescent) scattering spectra from individual supermicron-size particles in a multi-particle collection on a microscope slide. The principle of the device is based on a slitless spectroscope that is often employed in astronomy to determine the spectra of individual stars in a star cluster but had not been applied to atmospheric particles. Under excitation, most commonly by either a 405 nm diode laser or a UV light-emitting diode (LED), fluorescence emission spectra of many individual particles can be determined simultaneously. The instrument can also acquire elastic scattering spectra from particles illuminated by a white-light source. The technique also provides the ability to detect and rapidly estimate the number fraction of fluorescent particles that could contaminate a collection of non-fluorescent material, even without analyzing full spectra. Advantages and disadvantages of using black-and-white cameras compared to color cameras are given. The primary motivation for this work has been to develop an inexpensive technique to characterize fluorescent biological aerosol particles, especially particles such as pollen and mold spores that can cause allergies. An example of an iPhone-enabled device is also shown as a means for collecting data on biological aerosols at lower cost or by utilizing citizen scientists for expanded data collection.
    • Weak lensing measurement of the mass–richness relation of SDSS redMaPPer clusters

      Simet, Melanie; McClintock, Tom; Mandelbaum, Rachel; Rozo, Eduardo; Rykoff, Eli; Sheldon, Erin; Wechsler, Risa H.; Univ Arizona, Dept Phys (OXFORD UNIV PRESS, 2017-04-21)
      We perform a measurement of the mass-richness relation of the redMaPPer galaxy cluster catalogue using weak lensing data from the Sloan Digital Sky Survey (SDSS). We have carefully characterized a broad range of systematic uncertainties, including shear calibration errors, photo-z biases, dilution by member galaxies, source obscuration, magnification bias, incorrect assumptions about cluster mass profiles, cluster centring, halo triaxiality and projection effects. We also compare measurements of the lensing signal from two independently produced shear and photometric redshift catalogues to characterize systematic errors in the lensing signal itself. Using a sample of 5570 clusters from 0.1 <= z <= 0.33, the normalization of our power-law mass versus. relation is log(10)[M-200m/ h-M-1(circle dot)] = 14.344 +/- 0.021 (statistical) +/- 0.023 (systematic) at a richness lambda= 40, a 7 per cent calibration uncertainty, with a power-law index of 1.33(- 0.10)(+0.09) (1 sigma). The detailed systematics characterization in this work renders it the definitive weak lensing mass calibration for SDSS redMaPPer clusters at this time.
    • Weak lensing reveals a tight connection between dark matter halo mass and the distribution of stellar mass in massive galaxies

      Huang, Song; Leauthaud, Alexie; Hearin, Andrew; Behroozi, Peter; Bradshaw, Christopher; Ardila, Felipe; Speagle, Joshua; Tenneti, Ananth; Bundy, Kevin; Greene, Jenny; et al. (OXFORD UNIV PRESS, 2019-12-05)
      Using deep images from the Hyper Suprime-Cam (HSC) survey and taking advantage of its unprecedented weak lensing capabilities, we reveal a remarkably tight connection between the stellar mass distribution of massive central galaxies and their host dark matter halo mass. Massive galaxies with more extended stellar mass distributions tend to live in more massive dark matter haloes. We explain this connection with a phenomenological model that assumes, (1) a tight relation between the halo mass and the total stellar content in the halo, (2) that the fraction of in situ and ex situ mass at r <10 kpc depends on halo mass. This model provides an excellent description of the stellar mass functions (SMFs) of total stellar mass (M-star(max)) and stellar mass within inner 10 kpc (M-star(10)) and also reproduces the HSC weak lensing signals of massive galaxies with different stellar mass distributions. The best-fitting model shows that halo mass varies significantly at fixed total stellar mass (as much as 0.4 dex) with a clear dependence on M-star(10). Otu' two-parameter M-star(max) -M-star(10) description provides a more accurate picture of the galaxy halo connection at the high-mass end than the simple stellar halo mass relation (SHMR) and opens a new window to connect the assembly history of haloes with those of central galaxies. The model also predicts that the ex situ component dominates the mass profiles of galaxies at r < 10 kpc for log M-star >= 11,7. The code used for this paper is available online haps://github.com/dr-guangfou/asap