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  • Astrophysics  (4)
  • Aircraft Design, Testing and Performance  (1)
  • GEOPHYSICS
  • 2015-2019  (5)
  • 1965-1969
  • 2017  (5)
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  • 2015-2019  (5)
  • 1965-1969
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  • 1
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    Multiwavelength Characterization of an ACT-Selected, Lensed Dusty Star-Forming Galaxy at zeta 2.64 (2017)
    In:  Other Sources
    Details
    Publication Date: 2019-07-13
    Description: We present C I(21) and multi-transition C-12 O observations of a dusty star-forming galaxy, ACT J2029+0120,which we spectroscopically confirm to lie at zeta = 2.64. We detect CO(3-2), CO(5-4), CO(7-6), CO(8-7), and C I(2-1) at high significance, tentatively detect HCO+(4-3), and place strong upper limits on the integrated strength of dense gas tracers (HCN(4-3) and CS(7-6)). Multi-transition CO observations and dense gas tracers can provide valuable constraints on the molecular gas content and excitation conditions in high-redshift galaxies. We therefore use this unique data set to construct a CO spectral line energy distribution (SLED) of the source, which is most consistent with that of a ULIRG Seyfert or QSO host object in the taxonomy of the Herschel Comprehensive ULIRG Emission Survey. We employ RADEX models to fit the peak of the CO SLED, inferring a temperature of T approximately 117 K and n(sub H2) approximately 10(exp5) cm(exp -3), most consistent with a ULIRGQSO object and the presence of high-density tracers. We also find that the velocity width of the C I line is potentially larger than seen in all CO transitions forth is object, and that the L'(sub Ci(2-1))/L'(sub CO(3-2))ratio is also larger than seen in other lensed and unlensed submillimeter galaxies and QSO hosts; if confirmed, this anomaly could be an effect of differential lensing of a shocked molecular outflow.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN46867 , The Astrophysical Journal (ISSN 0004-637X) (e-ISSN 1538-4357); 844; 2; 110
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  • 2
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    Bayesian Treatment of Prospective LISA Parameter Estimation for Massive Black Hole Mergers (2017)
    In:  Other Sources
    Details
    Publication Date: 2019-07-27
    Description: A full understanding of LISA (Laser Interferometer Space Antenna)'s science capability will require accurate models of incident waveform signals and the instrumental response. While Fisher matrix analysis is useful for some estimates, a full Bayesian treatment is needed for important cases at the limit of LISA's capability. We will apply fast analysis algorithms enabling accurate treatment with EOB (effective-one-body) waveforms and the full-featured LISA response to study the significance of higher spherical harmonics and mergers in LISA analysis.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN56728 , International LISA (Laser Interferometer Space Antenna) Symposium; 5ý9 Sep. 2016; Zurich; Switzerland|Journal of Physics: Conference Series; 840; 1; 012051
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  • 3
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    SpaRibs Geometry Parameterization for Wings with Multiple Sections using Single Design (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: The SpaRibs topology of an aircraft wing has a significant effect on its structural behavior and stability as well as the flutter performance. The development of additive manufacturing techniques like Electron Beam Free Form Fabrication (EBF3) has made it feasible to manufacture aircraft wings with curvilinear spars, ribs (SpaRibs) and stiffeners. In this article a new global-local optimization framework for wing with multiple sections using curvilinear SpaRibs is described. A single design space is used to parameterize the SpaRibs geometry. This method has been implemented using MSC-PATRAN to create a broad range of SpaRibs topologies using limited number of parameters. It ensures C0 and C1 continuities in SpaRibs geometry at the junction of two wing sections with airfoil thickness gradient discontinuity as well as mesh continuity between all structural components. This method is advantageous in complex multi-disciplinary optimization due to its potential to reduce the number of design variables. For the global-local optimization the local panels are generated by an algorithm which is totally based on a set algebra on the connectivity matrix data. The great advantage of this method is that it is completely independent of the coordinates of the nodes of the finite element model. It is also independent of the order in which the elements are distributed in the FEM. The code is verified by optimizing of the CRM Baseline model at trim condition at Mach number equal to 0.85 for five different angle of attack (-2deg, 0deg,2deg,4deg and 6deg). The final weight of the wing is 19,090.61 lb. This value is comparable to that obtained by Qiang et al. 6 (19,269 lb).
    Keywords: Aircraft Design, Testing and Performance
    Type: AFRC-DAA-TN37932 , AIAA SciTech 2017; Jan 09, 2017 - Jan 13, 2017; Grapevine, TX; United States
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  • 4
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    Prompt Electromagnetic Transients from Binary Black Hole Mergers (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Binary black hole (BBH) mergers provide a prime source for current and future interferometric gravitational wave observatories. Massive BBH mergers may often take place in plasma-rich environments, leading to the exciting possibility of a concurrent electromagnetic (EM) signal observable by traditional astronomical facilities. However, many critical questions about the generation of such counterparts remain unanswered. We explore mechanisms that may drive EM counterparts with magnetohydrodynamic simulations treating a range of scenarios involving equal-mass black-hole binaries immersed in an initially homogeneous fluid with uniform, orbitally aligned magnetic fields. We find that the time development of Poynting luminosity, which may drive jetlike emissions, is relatively insensitive to aspects of the initial configuration. In particular, over a significant range of initial values, the central magnetic field strength is effectively regulated by the gas flow to yield a Poynting luminosity of 1 0 Exp 45) 10(exp 46) (sub 13) M(sub 8)(exp 2) erg s(exp 1), with BBH mass scaled to M(sub 8) M / ( 10 8 M ) and ambient density 13 / ( 10(exp 13) g cm(sub 3)). We also calculate the direct plasma synchrotron emissions processed through geodesic ray-tracing. Despite lensing effects and dynamics, we find the observed synchrotron flux varies little leading up to merger.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN54261 , Physical Review D - Particles, Fields, Gravitation and Cosmology (ISSN 1550-7998) (e-ISSN 1550-2368); 96; 12; 123003
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  • 5
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    Prompt Electromagnetic Transients from Binary Black Hole Mergers (2017)
    In:  CASI
    Details
    Publication Date: 2019-07-13
    Description: Binary black hole (BBH) mergers provide a prime source for current and future interferometric GW observatories. Massive BBH mergers may often take place in plasma-rich environments, leading to the exciting possibility of a concurrent electromagnetic (EM) signal observable by traditional astronomical facilities. However, many critical questions about the generation of such counterparts remain unanswered. We explore mechanisms that may drive EM counterparts with magnetohydrodynamic simulations treating a range of scenarios involving equal-mass black-hole binaries immersed in an initially homogeneous fluid with uniform, orbitally aligned magnetic fields. We find that the time development of Poynting luminosity, which may drive jet-like emissions, is relatively insensitive to aspects of the initial configuration. In particular, over a significant range of initial values, the central magnetic field strength is effectively regulated by the gas flow to yield a Poynting luminosity of 10(exp 45) - 10(exp 46) (p-13) M(sub 8)(exp 2) erg/s, with BBH mass scaled to M(sub 8) defined to be equal to M=(10(exp 8) solar mass) and ambient density p -13 defined to be equal to p/(10(exp -13) g/cu.cm). We also calculate the direct plasma synchrotron emissions processed through geodesic ray-tracing. Despite lensing effects and dynamics, we find the observed synchrotron flux varies little leading up to merger.
    Keywords: Astrophysics
    Type: GSFC-E-DAA-TN51364 , Physical Review D - Particles, Fields, Gravitation and Cosmology (ISSN 1550-7998) (e-ISSN 1550-2368); 96; 12; 123003
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