Now showing items 525-544 of 871

    • NuSTAR observation of GRO J1744−28 at low mass accretion rate 

      König, O.; Fürst, F.; Kretschmar, P.; Ballhausen, R.; Sokolova-Lapa, E.; Dauser, T.; Sánchez-Fernández, C.; Hemphill, P. B.; Wolff, M. T.; Pottschmidt, K.; Wilms, J. (2020-09-16)
      We present the spectral analysis of the LMXB GRO J1744-28 using ∼29 ks of NuSTAR data taken in 2017 February at a low luminosity of 3.2×10³⁶ erg/s (3-50 keV). The continuum spectrum is modeled with an absorbed power-law ...
    • NuSTAR perspective on high-redshift MeV blazars 

      Marcotulli, L.; Paliya, V.; Ajello, M.; Kaur, A.; Marchesi, S.; Rajagopal, M.; Hartmann, D.; Gasparrini, D.; Ojha, R.; Madejski, G. (The American Astronomical Society, 2020-02-04)
      With bolometric luminosities exceeding 10⁴⁸ erg s⁻¹, powerful jets and supermassive black holes at their center, MeV blazars are some of the most extreme sources in the Universe. Recently, the Fermi-Large Area Telescope ...
    • Observation of Low-Contrast All-Optical Switching in Si₃N₄ Microdisks Based on the Zeno Effect 

      Hendrickson, S. M.; Weiler, C. N.; Camacho, R. M.; Rakich, P. T.; Young, A. I.; Shaw, M. J.; Pittman, T. B.; Franson, J.D.; Jacobs, B. C. (OSA Publishing, 2012-06)
      Low-contrast all-optical Zeno switching has been demonstrated in a Silicon Nitride microdisk resonator surrounded by hot Rubidium vapor. The device is based on the suppression of the cavity field buildup due to non-degenerate ...
    • Observation of Two-Photon Absorption at Low Power Levels Using Tapered Optical Fibers in Rubidium Vapor 

      Hendrickson, S. M.; Lai, M. M.; Pittman, T.B.; Franson, J.D. (American Physical Society (APS), 2010-10-19)
      Nonlinear optical effects can be enhanced in tapered optical fibers with diameters less than the wavelength of the propagating light. Here we report on the observation of two-photon absorption using tapered fibers in ...
    • Observational constraints on glyoxal production from isoprene oxidation and its contribution to organic aerosol over the Southeast United States 

      Li, Jingyi; Mao, Jingqiu; Min, Kyung‐Eun; Washenfelder, Rebecca A.; Brown, Steven S.; Kaiser, Jennifer; Keutsch, Frank N.; Volkamer, Rainer; Wolfe, Glenn M.; Hanisco, Thomas F.; Pollack, Ilana B.; Ryerson, Thomas B.; Graus, Martin; Gilman, Jessica B.; Lerner, Brian M.; Warneke, Carsten; Gouw, Joost A. de; Middlebrook, Ann M.; Liao, Jin; Welti, André; Henderson, Barron H.; McNeill, V. Faye; Hall, Samuel R.; Ullmann, Kirk; Donner, Leo J.; Paulot, Fabien; Horowitz, Larry W. (AGU Pubication, 2016-07-31)
      We use a 0‐D photochemical box model and a 3‐D global chemistry‐climate model, combined with observations from the NOAA Southeast Nexus (SENEX) aircraft campaign, to understand the sources and sinks of glyoxal over the ...
    • Observational Insights into Aerosol Formation from Isoprene 

      Worton, David R.; Surratt, Jason D.; LaFranch, Brian W.; Chan, Arthur W. H.; Zhao, Yunliang; Weber, Robin J.; Park, Jeong-Hoo; Gilman, Jessica B.; Gouw, Joost de; Park, Changhyoun; Schade, Gunnar; Beaver, Melinda; Clair, Jason M. St.; Crounse, John; Wennberg, Paul; Wolfe, Glenn M.; Harrold, Sara; Thornton, Joel A.; Farmer, Delphine K.; Docherty, Kenneth S.; Cubison, Michael J.; Jimenez, Jose-Luis; Frossard, Amanda A.; Russel, Lynn M.; Kristensen, Kasper; Glasius, Marianne; Mao, Jingqiu; Ren, Xinrong; Brune, William; Browne, Eleanor C.; Pusede, Sally E.; Cohen, Ronald C.; Seinfeld, John H.; Goldstein, Allen H. (ACS Publications, 2013-10-15)
      Atmospheric photooxidation of isoprene is an important source of secondary organic aerosol (SOA) and there is increasing evidence that anthropogenic oxidant emissions can enhance this SOA formation. In this work, we use ...
    • An observationally constrained evaluation of the oxidative capacity in the tropical western Pacific troposphere 

      Nicely, Julie M; Anderson, Daniel C.; Canty, Timothy P.; Salawitch, Ross J.; Wolfe, Glenn M.; Apel, Eric C.; Arnold, Steve R.; Atlas, Elliot L.; Blake, Nicola J.; Bresch, James F.; Campos, Teresa L.; Dickerson, Russell R.; Duncan, Bryan; Emmons, Louisa K.; Evans, Matthew J.; Fernandez, Rafael P.; Flemming, Johannes; Hall, Samuel R.; Hanisco, Thomas F.; Honomichl, Shawn B.; Hornbrook, Rebecca S.; Huijnen, Vincent; Kaser, Lisa; Kinnison, Douglas E.; Lamarque, Jean‐Francois; Mao, Jingqiu; Monks, Sarah A.; Montzka, Denise D.; Pan, Laura L.; Riemer, Daniel D.; Saiz‐Lopez, Alfonso; Steenrod, Stephen D.; H. Stell, Meghan; Tilmes, Simone; Turquety, Solene; Ullmann, Kirk; Weinheimer, Andrew J. (AGU Pubication, 2016-06-05)
      Hydroxyl radical (OH) is the main daytime oxidant in the troposphere and determines the atmospheric lifetimes of many compounds. We use aircraft measurements of O₃, H₂O, NO, and other species from the Convective Transport ...
    • Observations of a GX 301−2 Apastron Flare with the X-Calibur Hard X-Ray Polarimeter Supported by NICER, the Swift XRT and BAT, and Fermi GBM 

      Abarr, Q.; Baring, M.; Beheshtipour, B.; Beilicke, M.; de Geronimo, G.; Dowkontt, P.; Errando, M.; Guarino, V.; Iyer, N.; Kislat, F.; Kiss, M.; Kitaguchi, T.; Krawczynski, H.; Lanzi, J.; Li, S.; Lisalda, L.; Okajima, T.; Pearce, M.; Press, L.; Rauch, B.; Stuchlik, D.; Takahashi, H.; Tang, J.; Uchida, N.; West, A.; Jenke, P.; Krimm, H.; Lien, A.; Malacaria, C.; Miller, J.M.; Wilson-Hodge, C. (2020-01-13)
      The accretion-powered X-ray pulsar GX301−2 was observed with the balloon-borne X-Calibur hard X-ray polarimeter during late December 2018, with contiguous observations by the NICER X-ray telescope, the Swift X-ray Telescope ...
    • Observations of atmosphere-biosphere exchange of total and speciated peroxynitrates: nitrogen fluxes and biogenic sources of peroxynitrates 

      Min, K.-E.; Pusede, S. E.; Browne, E. C.; LaFranchi, B. W.; Wooldridge, P. J.; Wolfe, G. M.; Harrold, S. A.; Thornton, J. A.; Cohen, R. C. (Copernicus Publications, 2012-10-29)
      Peroxynitrates are responsible for global scale transport of reactive nitrogen. Recent laboratory observations suggest that they may also play an important role in delivery of nutrients to plant canopies. We measured eddy ...
    • Observations of elevated formaldehyde over a forest canopy suggest missing sources from rapid oxidation of arboreal hydrocarbons 

      Choi, W.; Faloona, I. C.; Bouvier-Brown, N. C.; McKay, M.; Goldstein, A. H.; Mao, J.; Brune, W. H.; LaFranchi, B. W.; Cohen, R. C.; Wolfe, G. M.; Thornton, J. A.; Sonnenfroh, D. M.; Millet, D. B. (Copernicus Publications, 2010-09-17)
      To better understand the processing of biogenic VOCs (BVOCs) in the pine forests of the US Sierra Nevada, we measured HCHO at Blodgett Research Station using Quantum Cascade Laser Spectroscopy (QCLS) during the Biosphere ...
    • Observations of glyoxal and formaldehyde as metrics for the anthropogenic impact on rural photochemistry 

      DiGangi, J. P.; Henry, S. B.; Kammrath, A.; Boyle, E. S.; Kaser, L.; Schnitzhofer, R.; Graus, M.; Turnipseed, A.; Park, J. H.; Weber, R. J.; Hornbrook, R. S.; Cantrell, C. A.; Maudlin III, R. L.; Kim, S.; Nakashima, Y.; Wolfe, G. M.; Kajii, Y.; Apel, E.C.; Goldstein, A. H.; Guenther, A.; Karl, T.; Hansel, A.; Keutsch, F. N. (Copernicus, 2012-10-22)
      We present simultaneous fast, in-situ measurements of formaldehyde and glyoxal from two rural campaigns, BEARPEX 2009 and BEACHON-ROCS, both located in Pinus Ponderosa forests with emissions dominated by biogenic volatile ...
    • Observations of M31 and M33 with the Fermi Large Area Telescope: A Galactic Center Excess in Andromeda? 

      Mirabal, N.; et al. (IOP, 2017-02-23)
      The Fermi Large Area Telescope (LAT) has opened the way for comparative studies of cosmic rays (CRs) and high-energy objects in the Milky Way (MW) and in other, external, star-forming galaxies. Using 2 yr of observations ...
    • Observations of VOC emissions and photochemical products over US oil- and gas-producing regions using high-resolution H₃O⁺ CIMS (PTR-ToF-MS) 

      Koss, Abigail; Yuan, Bin; Warneke, Carsten; Gilman, Jessica B.; Lerner, Brian M.; Veres, Patrick R.; Peischl, Jeff; Eilerman, Scott; Wild, Rob; Brown, Steven S.; Thompson, Chelsea R.; Ryerson, Thomas; Hanisco, Thomas; Wolfe, Glenn M.; St. Clair, Jason M.; Thayer, Mitchell; Keutsch, Frank N.; Murphy, Shane; Gouw, Joost de (Copernicus Publications, 2017-08-16)
      VOCs related to oil and gas extraction operations in the United States were measured by H₃O⁺ chemical ionization time-of-flight mass spectrometry (H₃O⁺ ToF-CIMS/PTR-ToF-MS) from aircraft during the Shale Oil and Natural ...
    • Observing atmospheric formaldehyde (HCHO) from space: validation and intercomparison of six retrievals from four satellites (OMI, GOME2A, GOME2B, OMPS) with SEAC4RS aircraft observations over the southeast US 

      Zhu, Lei; Jacob, Daniel J.; Kim, Patrick S.; Fisher, Jenny A.; Yu, Karen; Travis, Katherine R.; Mickley, Loretta J.; Yantosca, Robert M.; Sulprizio, Melissa P.; Smedt, Isabelle De; Abad, Gonzalo González; Chance, Kelly; Li, Can; Ferrare, Richard; Fried, Alan; Hair, Johnathan W.; Hanisco, Thomas F.; Richter, Dirk; Scarino, Amy Jo; Walega, James; Weibring, Petter; Wolfe, Glenn M. (EGU Publications, 2016-11-01)
      Formaldehyde (HCHO) column data from satellites are widely used as a proxy for emissions of volatile organic compounds (VOCs), but validation of the data has been extremely limited. Here we use highly accurate HCHO aircraft ...
    • Ocean stratification and sea-ice cover in Barents and Kara seas modulate sea-air methane flux: satellite evidence 

      Yurganov, Leonid N; Carroll, Dustin; Zhang, Hong (Wiley, 2020-08-25)
      The diverse range of mechanisms driving the Arctic amplification are not completely understood and, moreover, the role of the greenhouse gas methane in Arctic warming remains unclear. Strong sources of methane at the ocean ...
    • On the Measurement of the Lense-Thirring effect Using the Nodes of the LAGEOS Satellites in reply to "On the reliability of the so-far performed tests for measuring the Lense-Thirring effect with the LAGEOS satellites" by L. Iorio 

      Ciufolini, I.; Pavlis, E. (Elsevier, 2005-05-02)
      In this paper, we provide a detailed description of our recent analysis and determination of the frame-dragging effect obtained using the nodes of the satellites LAGEOS and LAGEOS 2, in reply to the paper “On the reliability ...
    • On the Nature of the High-Energy Rollover in 1H 0419-577 

      Turner, T, J.; Reeves, J. N.; Braito, V,; Costa, M. (Oxford Academic, 2018)
      A NuSTAR/Swift observation of the luminous Seyfert 1 galaxy 1H 0419-577 taken during 2015 reveals one of the most extreme high energy cut-offs observed to date from an AGN - an origin due to thermal Comptonization would ...
    • On the possibility of measuring relativistic gravitational effects with a LAGEOS-LAGEOS II-OPTIS-mission 

      Iorio, Lorenzo; Ciufolini, Ignazio; Pavlis, Erricos C.; Schiller, Stephan; Dittus, Hansjörg; Lämmerzahl, Claus (IOP, 2004-03-23)
      A space mission, OPTIS, has been proposed for testing the foundations of special relativity and post-Newtonian gravitation in the field of the Earth. The constraints posed on the original OPTIS orbital geometry would allow ...
    • On the X-ray Spectral Energy Distributions of Star-Forming Galaxies: the 0.3–30 keV Spectrum of the Low-Metallicity Starburst Galaxy VV 114 

      Garofali, Kristen; Lehmer, Bret D.; Basu-Zych, Antara; West, Lacey A.; Wik, Daniel; Yukita, Mihoko; Vulic, Neven; Ptak, Andrew; Hornschemeier, Ann (2020-09-18)
      Binary population synthesis combined with cosmological models suggest that X-ray emission from star-forming galaxies, consisting primarily of emission from X-ray binaries (XRBs) and the hot interstellar medium (ISM), could ...
    • Optical activity of the flaring gamma-ray blazar PKS 0458-02 

      Pursimo, Tapio; Ojha, Roopesh; Kiaeerad, Fatemeh (2012-09-20)