Now showing items 21-40 of 883

    • Advection-dominated accretion and the black hole event horizon 

      Narayan, Ramesh; McClintock, Jeffrey E. (Elsevier BV, 2008)
      As the luminosity of an accreting black hole drops to a few percent of Eddington, the spectrum switches from the familiar soft state to a hard state that is well-described by a distended and tenuous advection-dominated ...
    • The Afterglow and Early-type Host Galaxy of the Short GRB 150101B at Z = 0.1343 

      Fong, W.; Margutti, R.; Chornock, R.; Berger, Edo; Shappee, B. J.; Levan, A. J.; Tanvir, N. R.; Smith, N.; Milne, P. A.; Laskar, T.; Fox, D. B.; Lunnan, R.; Blanchard, P. K.; Hjorth, J.; Wiersema, K.; van der Horst, A. J.; Zaritsky, D. (American Astronomical Society, 2016)
      We present the discovery of the X-ray and optical afterglows of the short-duration GRB 150101B, pinpointing the event to an early-type host galaxy at z = 0.1343±0.0030. This makes GRB 150101B the most nearby shortGRB with ...
    • The Afterglow and Environment of the Short Grb 111117a 

      Margutti, R; Berger, Edo; Fong, W; Zauderer, B; Cenko, S. B.; Greiner, J.; Soderberg, Alicia M.; Cucchiara, A.; Rossi, A.; Klose, S.; Schmidl, S.; Milisavljevic, Danny; Sanders, Nathan Edward (IOP Publishing, 2012)
      We present multi-wavelength observations of the afterglow of the short GRB 111117A, and follow-up observations of its host galaxy. From rapid optical and radio observations we place limits of r & 25.5 mag at δt ≈ 0.55 d ...
    • The Afterglow and Ulirg Host Galaxy of the Dark Short Grb 120804a 

      Berger, Edo; Zauderer, B; Levan, A.; Margutti, R.; Laskar, T.; Fong, W.; Mangano, V.; Fox, D. B.; Tunnicliffe, R. L.; Chornock, R.; Tanvir, N. R.; Menten, K. M.; Hjorth, J.; Roth, K.; Dupuy, T. J. (IOP Publishing, 2013)
      We present the optical discovery and sub-arcsecond optical and X-ray localization of the afterglow of the short GRB 120804A, as well as optical, near-IR, and radio detections of its host galaxy. X-ray observations with ...
    • Alien Maps of an Ocean-Bearing World 

      Cowan, Nicolas B.; Agol, Eric; Meadows, Victoria S.; Robinson, Tyler; Livengood, Timothy A.; Deming, Drake; Lisse, Carey M.; A'Hearn, Michael F.; Wellnitz, Dennis D.; Seager, Sara; Charbonneau, David (Institute of Physics, 2009)
      When Earth-mass extrasolar planets first become detectable, one challenge will be to determine which of these worlds harbor liquid water, a widely used criterion for habitability. Some of the first observations of these ...
    • Alignment between Protostellar Outflows and Filamentary Structure 

      Stephens, Ian W.; Dunham, Michael M.; Myers, Philip C.; Pokhrel, Riwaj; Sadavoy, Sarah Ilana; Vorobyov, Eduard I.; Tobin, John J; Pineda, Jaime E.; Offner, Stella S. R.; Lee, Katherine I.; Kristensen, Lars E.; Jørgensen, Jes K.; Goodman, Alyssa; Bourke, Tyler L.; Arce, Héctor G.; Plunkett, Adele L. (American Astronomical Society, 2017)
      We present new Submillimeter Array (SMA) observations of CO(2-1) outflows toward young, embedded protostars in the Perseus molecular cloud as part of the Mass Assembly of Stellar Systems and their Evolution with the SMA ...
    • All-Weather Calibration of Wide-Field Optical and NIR Surveys 

      Burke, David L.; Saha, Abhijit; Claver, Jenna; Axelrod, T.; Claver, Chuck; DePoy, Darren; Ivezić, Željko; Jones, Lynne; Smith, R. Chris; Stubbs, Christopher William (IOP Publishing, 2013)
      The science goals for ground-based large-area surveys, such as the Dark Energy Survey, Pan-STARRS, and the Large Synoptic Survey Telescope, require calibration of broadband photometry that is stable in time and uniform ...
    • ALMA Observations of the Host Galaxy of GRB 090423 at Z = 8.23: Deep Limits on Obscured Star formation 630 Million Years after the Big Bang. 

      Berger, Edo; Zauderer, B. A.; Chary, R.-R.; Laskar, T.; Chornock, R.; Tanvir, N. R.; Stanway, E. R.; Levan, A. J.; Levesque, E. M.; Davies, J. E. (IOP Publishing, 2014)
      We present rest-frame far-infrared (FIR) and optical observations of the host galaxy of GRB 090423 at z = 8.23 from the Atacama Large Millimeter Array (ALMA) and the Spitzer Space Telescope, respectively. The host remains ...
    • ALMA reveals a candidate hot and compact disc around the O-type protostar IRAS 16547-4247 

      Zapata, L. A.; Palau, A.; Galvan-Madrid, R.; Rodriguez, L. F.; Garay, G.; Moran, James M.; Franco-Hernandez, R. (Oxford University Press (OUP), 2015)
      We present high angular resolution (∼ 0.3′′) submillimeter continuum (0.85 mm) and line observations of the O-type protostar IRAS 16547−4247 carried out with the Atacama Large Millimeter/Submillimeter Array (ALMA). In the ...
    • An ALMA Survey of DCN/H13CN and DCO+/H13CO+in Protoplanetary Disks 

      Huang, Jane; Oberg, Karin; Qi, Chunhua; Aikawa, Yuri; Andrews, Sean; Furuya, Kenji; Guzman, Viviana; Loomis, Ryan; van Dishoeck, Ewine; Wilner, David (American Astronomical Society, 2017-01-31)
      The deuterium enrichment of molecules is sensitive to their formation environment. Constraining patterns of deuterium chemistry in protoplanetary disks is therefore useful for probing how material is inherited or reprocessed ...
    • The Anatomy of the Column Density Probability Distribution Function (N-PDF) 

      Chen, Hope; Burkhart, Blakesley; Goodman, Alyssa; Collins, David (American Astronomical Society, 2018-06-04)
      The column density probability distribution function (N-PDF) of Giant Molecular Clouds (GMCs) has been used as a diagnostic of star formation. Simulations and analytic predictions have suggested that the N-PDF is composed ...
    • Anchoring Magnetic Fields in Turbulent Molecular Clouds 

      Li, Hua-bai; Dowell, C. Darren; Goodman, Alyssa; Hildebrand, Roger; Novak, Giles (American Astronomical Society, 2009)
      One of the key problems in star formation research is to determine the role of magnetic fields. Starting from the atomic intercloud medium which has density \(n_H \sim \ 1 \ cm^{–3}\), gas must accumulate from a volume ...
    • Angular Momentum in Disk Wind Revealed in the Young Star MWC 349A 

      Zhang, Qizhou; Claus, Brian; Watson, Linda; Moran, James (American Astronomical Society, 2017)
      Disk winds are thought to play a critical role in star birth. As winds extract excess angular momentum from accretion disks, matter in the disk can be transported inward to the star to fuel mass growth. However, the ...
    • The Angular Momentum of Magnetized Molecular Cloud Cores: A Two-Dimensional-Three-Dimensional Comparison 

      Dib, Sami; Hennebelle, Patrick; Pineda, Jaime E.; Csengeri, Timea; Bontemps, Sylvain; Audit, Edouard; Goodman, Alyssa (Institute of Physics Publishing, Inc., 2010)
      In this work, we present a detailed study of the rotational properties of magnetized and self-gravitating dense molecular cloud cores formed in a set of two very high resolution three-dimensional molecular cloud simulations ...
    • Angular Momentum Transport in Convectively Unstable Shear Flows 

      Käpylä, Petri J.; Brandenburg, Axel; Korpi, Maarit J.; Snellman, Jan E.; Narayan, Ramesh (IOP Publishing, 2010)
      Angular momentum transport due to hydrodynamic turbulent convection is studied using local three-dimensional numerical simulations employing the shearing box approximation. We determine the turbulent viscosity from nonrotating ...
    • Anisotropic Hyperfine Interactions Limit the Efficiency of Spin-Exchange Optical Pumping of 3He Nuclei 

      Tscherbul, T. V.; Zhang, Peng; Sadeghpour, Hossein R.; Dalgarno, Alexander (American Physical Society (APS), 2011)
      We use accurate ab initio and quantum scattering calculations to demonstrate that the maximum He3 spin polarization that can be achieved in spin-exchange collisions with potassium (K39) and silver (Ag107) atoms is limited ...
    • Antenna-coupled TES bolometer arrays for BICEP2/Keck and SPIDER 

      Orlando, Abigail Claire; Aikin, R. W.; Amiri, M.; Bock, J. J.; Bonetti, J. A.; Brevik, J. A.; Burger, B.; Chattopadthyay, G.; Day, P. K.; Filippini, J. P.; Golwala, S. R.; Halpern, M.; Hasselfield, M.; Hilton, G. C.; Irwin, K. D.; Kenyon, M.; Kovac, John M; Kuo, C. L.; Lange, A. E.; LeDuc, H. G.; Llombart, N.; Nguyen, H. T.; Ogburn, R. W.; Reintsema, C. D.; Runyan, M. C.; Staniszewski, Z.; Sudiwala, R.; Teply, G.; Trangsrud, A. R.; Turner, A. D.; Wilson, P. (SPIE, 2010)
      BICEP2/Keck and SPIDER are cosmic microwave background (CMB) polarimeters targeting the B-mode polarization induced by primordial gravitational waves from inflation. They will be using planar arrays of polarization sensitive ...
    • Antenna-coupled TES Bolometers used in BICEP2, Keck Array, and SPIDER 

      Ade, P. A. R.; Aikin, R. W.; Amiri, M.; Barkats, D.; Benton, S. J.; Bischoff, Colin A.; Bock, J. J.; Bonetti, J. A.; Brevik, J. A.; Buder, I; Bullock, E.; Chattopadhyay, G.; Davis, G.; Day, P. K.; Dowell, C. D.; Duband, L.; Filippini, J. P.; Fliescher, S.; Golwala, S. R.; Halpern, M.; Hasselfield, M.; Hildebrandt, S. R.; Hilton, G. C.; Hristov, V.; Hui, H.; Irwin, K. D.; Jones, W. C.; Karkare, Kirit Sukrit; Kaufman, J. P.; Keating, B. G.; Kefeli, S.; Kernasovskiy, S. A.; Kovac, John M; Kuo, C. L.; LeDuc, H. G.; Leitch, E. M.; Llombart, N.; Lueker, M.; Mason, P.; Megerian, K.; Moncelsi, L.; Netterfield, C. B.; Nguyen, H. T.; O’Brient, R.; IV, R. W. Ogburn; Orlando, A.; Pryke, C; Rahlin, A. S.; Reintsema, C. D.; Richter, S.; Runyan, M. C.; Schwarz, R.; Sheehy, C. D.; Staniszewski, Z. K.; Sudiwala, R. V.; Teply, G. P.; Tolan, J. E.; Trangsrud, A.; Tucker, R. S.; Turner, A. D.; Vieregg, A. G.; Weber, A.; Wiebe, D. V.; Wilson, P.; Wong, C; Yoon, K. W.; Zmuidzinas, J.; undefined, undefined (IOP Publishing, 2015)
      We have developed antenna-coupled transition-edge sensor (TES) bolometers for a wide range of cosmic microwave background (CMB) polarimetry experiments, including BICEP2, Keck Array, and the balloon borne SPIDER. These ...
    • ASCA observations of two steep soft X-ray quasars 

      Fiore, F.; Matt, G.; Cappi, M.; Elvis, Martin S.; Leighly, K. M.; Nicastro, F.; Piro, L.; Siemiginowska, Aneta L.; Wilkes, Belinda Jane (Oxford University Press (OUP), 1998)
      Steep soft X-ray (0.1-2 keV) quasars share several unusual properties: narrow Balmer lines, strong FeII emission, large and fast X-ray variability, rather steep 2-10 keV spectrum. These intriguing objects have been suggested ...
    • An Astrometric Search for a Sub-stellar Companion of the M8.5 Dwarf TVLM 513–46546 Using Very Long Baseline Interferometry 

      Forbrich, Jan; Berger, Edo; Reid, Mark Jonathan (IOP Publishing, 2013)
      We conducted multi-epoch VLBI observations to search for astrometric reflex motion caused by a sub-stellar companion of the M8.5 dwarf TVLM 513–46546. The observations yield an absolute parallax corresponding to a distance ...