Now showing items 886-905 of 934

    • Variability and Proper Motion of X-ray Knots in the Jet of Centaurus A 

      Snios, Bradford; Wykes, Sarka; Nulsen, Paul E. J.; Kraft, Ralph P.; Meyer, Eileen T.; Birkinshaw, Mark; Worrall, Diana M.; Hardcastle, Martin J.; Roediger, Elke; Forman, William R.; Jones, Christine (2019-01-22)
      We report results from Chandra observations analyzed for evidence of variability and proper motion in the X-ray jet of Centaurus A. Using data spanning 15 years, collective proper motion of 11.3±3.3 mas yr We report results ...
    • Variability of Upstream Proton Cyclotron Wave Properties and Occurrence at Mars observed by MAVEN 

      Romeo, O. M.; Romanelli, N.; Espley, J. R.; Mazelle, C.; DiBraccio, G. A.; Gruesbeck, J. R.; Halekas, J. S. (American Geophysical Union, 2020-12-11)
      The presence of plasma waves upstream from the Martian bow shock, with frequencies near the local proton cyclotron frequency in the spacecraft frame, constitutes, in principle, an indirect signature for the existence of ...
    • The variable and non-variable X-ray absorbers in Compton-thin type-II Active Galactic Nuclei 

      Laha, Sibasish; Markowitz, Alex G.; Krumpe, Mirko; Nikutta, Robert; Rothschild, Richard; Saha, Tathagata (2020-05-12)
      We have conducted an extensive X-ray spectral variability study of a sample of 20 Compton-thin type II galaxies using broad band spectra from XMM-Newton, Chandra, and Suzaku. The aim is to study the variability of the ...
    • Velocity-dependent optical forces and Maxwell’s demon 

      Franson, J. D. (Nature, 2019-09-24)
      An atom placed in a focused laser beam will experience a dipole force due to the gradient in the interaction energy, which is analogous to the well-known optical tweezers effect. This force will be dependent on the velocity ...
    • VERITAS and Fermi-LAT Observations of TeV Gamma-Ray Sources Discovered by HAWC in the 2HWC Catalog 

      Ojha, Roopesh; et al. (The American Astronomical Society, 2018-10-05)
      The High Altitude Water Cherenkov (HAWC) collaboration recently published their 2HWC catalog, listing 39 very high energy (VHE; >100 GeV) gamma-ray sources based on 507 days of observation. Among these, 19 sources are not ...
    • VERITAS Discovery of VHE Emission from the Radio Galaxy 3C 264: A Multi-Wavelength Study 

      A. Archer; et al (2020-05-06)
      The radio source 3C 264, hosted by the giant elliptical galaxy NGC 3862, was observed with VERITAS between February 2017 and May 2019. These deep observations resulted in the discovery of very-high-energy (VHE; E >100 GeV) ...
    • Vertical Dependence of Horizontal Variation of Cloud Microphysics: Observations from theACE-ENA field campaign and implications for warm rain simulation in climate models 

      Zhang, Zhibo; Song, Qianqian; Mechem, David; Larson, Vincent; Wang, Jian; Liu, Yangang; Witte, Mikael; Dong, Xiquan; Wu, Peng (Copernicus Publications, 2020-08-11)
      In the current global climate models (GCM), the nonlinearity effect of subgrid cloud variations on the parameterization of warm rain process, e.g., the autoconversion rate, is often treated by multiplying the resolved-scale ...
    • Vertical profiles of droplet size distributions derived from cloud-side observations by the research scanning polarimeter: Tests on simulated data 

      Alexandrov, Mikhail D.; Miller, Daniel J.; Rajapakshe, Chamara; Fridlind, Ann; Diedenhoven, Bastiaan van; Cairns, Brian; Ackerman, Andrew S.; Zhang, Zhibo (Elsevier, 2020-02-25)
      The Research Scanning Polarimeter (RSP) is an airborne along-track scanner measuring the polarized and total reflectances with high angular resolution. It allows for accurate characterization of liquid water cloud droplet ...
    • VERY HIGH ENERGY γ-RAYS FROM THE UNIVERSE'S MIDDLE AGE: DETECTION OF THE z = 0.940 BLAZAR PKS 1441+25 WITH MAGIC 

      Ojha, R.; Mirabal, N.; et al. (IOP, 2015-12-15)
      The flat-spectrum radio quasar PKS 1441+25 at a redshift of z = 0.940 is detected between 40 and 250 GeV with a significance of 25.5σ using the MAGIC telescopes. Together with the gravitationally lensed blazar QSO B0218+357 ...
    • Vetting of 384 TESS Objects of Interest with TRICERATOPS and Statistical Validation of 12 Planet Candidates 

      Giacalone, Steven; Dressing, Courtney D.; Jensen, Eric L. N.; Collins, Karen A.; Ricker, George R.; Vanderspek, Roland; Seager, S.; Winn, Joshua N.; Jenkins, Jon M.; Barclay, Thomas; Barkaoui, Khalid; Cadieux, Charles; Charbonneau, David; Collins, Kevin I.; Conti, Dennis M.; Doyon, René; Evans, Phil; Ghachoui, Mourad; Gillon, Michaël; Guerrero, Natalia M.; Hart, Rhodes; Jehin, Emmanuël; Kielkopf, John F.; McLean, Brian; Murgas, Felipe; Palle, Enric; Parviainen, Hannu; Pozuelos, Francisco J.; Relles, Howard M.; Shporer, Avi; Socia, Quentin; Stockdale, Chris; Tan, Thiam-Guan; Torres, Guillermo; Twicken, Joseph D.; Waalkes, William C.; Waite, Ian A. (IOP Publishing, 2020-12-11)
      We present TRICERATOPS, a new Bayesian tool that can be used to vet and validate TESS Objects of Interest (TOIs). We test the tool on 68 TOIs that have been previously confirmed as planets or rejected as astrophysical false ...
    • Viewpoint: Equilibration in Quantum Systems 

      Deffner, Sebastian (American Physical Society, 2019-11-13)
      Two research groups show that specific contributions to entropy may be the key to understanding how and when quantum systems equilibrate.
    • Violating Bell’s inequality using a number state and a beam splitter 

      Shringarpure, S.U.; Franson, J.D. (2019-11-06)
      Passing a photon number state through a balanced beam splitter will produce an entangled state in which the phases of the two output modes are highly correlated. We show that Bell’s inequality can be violated using this ...
    • Violation of Bell’s Inequality with Photons from Independent Sources 

      Pittman, T.B.; Franson, J.D. (American Physical Society (APS), 2003-06-19)
      We report a violation of Bell’s inequality using one photon from a parametric down-conversion source and a second photon from an attenuated laser beam. The two photons were entangled at a beam splitter using the postselection ...
    • Virtual Telescope for X-ray Observations: VTXO 

      Krizmanic, John
      Precision formation flying of a OpticsSat with X-ray Phase Fresnel Lens (PFL) Optics and a DetectorSat with an X-ray camera forming a 1 km focal length X-ray telescope with 55 milli-arcsecond angular resolution and 8 arcsecond FoV
    • Viscoelasticity Enhances Nanometer-Scale Slip in Gigahertz-Frequency Liquid Flows 

      Chakraborty, Debadi; Uthe, Brian; Malachosky, Edward W.; Pelton, Matthew; Sader, John E. (ACS Publications, 2021-03-31)
      The interaction between flowing liquids and solid surfaces underpins many physical phenomena and technologies, such as the ability of an airfoil to generate lift and the mixing of liquids for industrial applications. These ...
    • Visualizing Heterogeneity of Monodisperse CdSe Nanocrystals by Their Assembly into Three-Dimensional Supercrystals 

      Shevchenko, Elena V.; Podsiadlo, Paul; Wu, Xiaohua; Lee, Byeongdu; Rajh, Tijana; Morin, Rachel; Pelton, Matthew (ACS Publications, 2020-10-19)
      We show that the self-assembly of monodisperse CdSe nanocrystals synthesized at lower temperature (∼310 °C) into three-dimensional supercrystals results in the formation of separate regions within the supercrystals that ...
    • VLBA Polarimetry: A Faraday Screen in 3C 273 

      Ojha, Roopesh; Homan, Daniel C.; Wardle, John F. C.; Roberts, David H.; Aller, Hugh D.; Aller, Margo F.; Hughes, Philip A. (Astronomical Society of the Pacific Conference Series, 2005)
      The polarization of superluminal radio components moving at the base of the VLBI jet in 3C273 are tracked as part of a six epoch monitoring campaign at 15 and 22 GHz. The components rise sharply in fractional polarization ...
    • VLBA Snap-Shot Imaging of Scintillating Sources 

      Ojha, Roopesh; Lovell, James E.; Jauncey, David L.; Kedziora-Chudczer, Lucyna; Bignall, Hayley E.; Reynolds, John E.; Tzioumis, Anastasios K.; Macquart, Jean-Pierre; Fey, Alan L.; Johnston, Kenneth J. (Astronomical Society of the Pacific Conference Series, 2005)
      We present VLBA snap-shot images of weak scintillating sources and compare their morphologies with those of strong scintillating sources imaged by the USNO astrometry program. It is now clear that interstellar scintillation ...
    • VLBA Snapshot Imaging Survey of Scintillating Sources 

      Ojha, Roopesh; Fey, Alan L.; Lovell, James E. J.; Jauncey, David L.; Johnston, Kenneth J. (IOP, 2004-10-01)
      We present 8.4 GHz Very Long Baseline Array (VLBA) observations of 75 extragalactic radio sources drawn from the scintillating sources discovered in the Microarcsecond Scintillation-induced Variability survey. This survey ...
    • VLBI Monitoring of the bright γ-ray blazar PKS 0537−441 

      Hungwe, F.; Ojha, R.; Kadler, M.; Booth, R.; Blanchard, J.; Lovell, J.; Muller, C.; Bock, M.; TANAMI team (2010-06-10)
      One of the defining characteristics of BL Lacertae objects is their strong variability across the electromagnetic spectrum. PKS 0537-441 is one such object and is one of the most luminous blazars from radio to gamma-ray ...