Browsing Institutt for teoretisk astrofysikk by Title

Now showing items 764-783 of 1278

  • Non-Gaussianity in the CMB: : directional analysis and application of needlets 
    Rudjord, Øystein (Doctoral thesis / Doktoravhandling, 2010)
  • Non-linear dynamics of the minimal theory of massive gravity 
    Hagala, Robert; De Felice, Antonio; Mota, David; Mukohyama, Shinji (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    We investigate cosmological signatures of the minimal theory of massive gravity (MTMG). To this aim, we simulate the normal branch of the MTMG by employing the R AMSES N -body code and extending it with an effective ...
  • Non-linear phenomenology of disformally coupled quintessence 
    Llinares, Claudio; Hagala, Robert; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The quintessence model is one of the simplest and better known alternatives to Einstein’s theory for gravity. The properties of the solutions have been studied in great detail in the background, linear and non-linear ...
  • Non-local contribution from small scales in galaxy–galaxy lensing: comparison of mitigation schemes 
    Prat, J.; Zacharegkas, G.; Park, Y.; MacCrann, N.; Switzer, E.R.; Pandey, S.; Chang, C.; Blazek, J.; Miquel, R.; Alarcon, A.; Alves, O.; Amon, A.; Andrade-Oliveira, F.; Bechtol, K.; Becker, M.R.; Bernstein, G.M.; Chen, R.; Choi, A.; Camacho, H.; Campos, A.; Carnero Rosell, A.; Carrasco Kind, M.; Cawthon, R.; Cordero, J.; Crocce, M.; Davis, C.; DeRose, J.; Diehl, H.T.; Dodelson, S.; Doux, C.; Drlica-Wagner, A.; Eckert, K.; Eifler, T.F.; Elvin-Poole, J.; Everett, S.; Fang, X.; Ferté, A.; Fosalba, P.; Friedrich, O.; Gatti, M.; Giannini, G.; Gruen, D.; Gruendl, R.A.; Harrison, I.; Hartley, W.G.; Herner, K.; Huang, H.; Huff, E.M.; Jarvis, M.; Krause, E.; Kuropatkin, N.; Leget, P.-F.; McCullough, J.; Myles, J.; Navarro-Alsina, A.; Porredon, A.; Raveri, M.; Rollins, R.P.; Roodman, A.; Rosenfeld, R.; Ross, A.J.; Rykoff, E.S.; Sánchez, C.; Sanchez, J.; Secco, L.F.; Sevilla-Noarbe, I.; Sheldon, E.; Shin, T.; Troxel, M.A.; Tutusaus, I.; Varga, T.N.; Yanny, B.; Yin, B.; Zhang, Y.; Zuntz, Joseph; Aguena, M.; Allam, S.; Annis, J.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D.L.; Carretero, J.; Costanzi, M.; Pereira, M.E.S.; De Vicente, J.; Desai, S.; Ferrero, Ismael; Flaugher, B.; Gerdes, D.W.; Gutierrez, G.; Hinton, S.R.; Hollowood, D.L.; Honscheid, K.; James, D.J.; Lima, M.; Menanteau, F.; Mena-Fernández, J.; Palmese, A.; Paterno, M.; Paz-Chinchón, F.; Pieres, A.; Plazas Malagón, A.A.; Rodriguez-Monroy, M.; Sanchez, E.; Schubnell, M.; Smith, M.; Soares-Santos, M.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; To, C.; Weaverdyck, N.; Weller, J. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    ABSTRACT Recent cosmological analyses with large-scale structure and weak lensing measurements, usually referred to as 3 × 2pt, had to discard a lot of signal to noise from small scales due to our inability to ...
  • Non-LTE Calculations of the Fe I 6173 Å Line in a Flaring Atmosphere 
    hong, Jie; Ding, M. D.; Li, Ying; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    The Fe i 6173 Å line is widely used in the measurements of vector magnetic fields by instruments including the Helioseismic and Magnetic Imager (HMI). We perform non-local thermodynamic equilibrium calculations of this ...
  • Non-LTE line formation of Fe in late-type stars – IV. Modelling of the solar centre-to-limb variation in 3D 
    Lind, K.; Amarsi, A. M.; Asplund, M.; Barklem, P. S.; Bautista, M.; Bergemann, M.; Collet, R.; Kiselman, D.; Leenaarts, Jorrit; Mendes Domingos Pereira, Tiago (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Our ability to model the shapes and strengths of iron lines in the solar spectrum is a critical test of the accuracy of the solar iron abundance, which sets the absolute zero-point of all stellar metallicities. We use an ...
  • Non-metric Quintessence 
    Tayfeh, Bagheri F. (Master thesis / Masteroppgave, 2013)
    The existence of dark energy in the universe is hypothesized to explain the accelerated expansion of today’s universe and the inflationary expansion of very early universe; accelerated expansion of today’s universe is ...
  • Non-thermal electrons from solar nanoflares In a 3D radiative MHD simulation 
    Bakke, Helle; Frogner, Lars; Gudiksen, Boris Vilhelm (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    Context: We introduce a model for including accelerated particles in pure magnetohydrodynamics (MHD) simulations of the solar atmosphere. Aims: We show that the method is viable and produces results that enhance the realism ...
  • Nonequilibrium ionization and ambipolar diffusion in solar magnetic flux emergence processes 
    Nóbrega Siverio, Daniel Elias; Moreno-Insertis, Fernando; Martinez-Sykora, Juan; Carlsson, Mats; Szydlarski, Mikolaj Marcin (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Context. Magnetic flux emergence from the solar interior has been shown to be a key mechanism for unleashing a wide variety of phenomena. However, there are still open questions concerning the rise of the magnetized plasma ...
  • Non–equilibrium ionization of metals in 3D numerical models of the solar atmosphere 
    Olluri, Kosovare (Doctoral thesis / Doktoravhandling, 2014)
    De siste par tiårene har avanserte forskningssatellitter og rombaserte observatorier gitt oss innsikt i en svært dynamisk solatmosfære, hvor lokale variable som temperatur og tetthet endres på korte tidsskalaer. Disse ...
  • Novel approach toward the large-scale stable interacting dark-energy models and their astronomical bounds 
    Yang, Weiqiang; Pan, Supriya; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017 American Physical Society
  • Nucleosynthesis Predictions and High-Precision Deuterium Measurements 
    Riemer-Sørensen, Signe; Jenssen, Espen Sem (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
  • Null test for interactions in the dark sector 
    Von Marttens, Rodrigo F.; Marra, Valerio; Casarini, Luciano; Gonzalez, J. E.; Alcaniz, Jailson S (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Since there is no known symmetry in nature that prevents a nonminimal coupling between the dark energy (DE) and cold dark matter (CDM) components, such a possibility constitutes an alternative to standard cosmology, with ...
  • Numerical dependencies of the galactic dynamo in isolated galaxies with SPH 
    Wissing, Robert Bleckert Nils Håkan; Shen, Sijing (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Simulating and evolving magnetic fields within global galaxy simulations provides a large tangled web of numerical complexity due to the vast amount of physical processes involved. Understanding the numerical dependencies ...
  • A numerical model for heating by nanoflares in 3D MHD simulations of the solar atmosphere 
    Frogner, Lars (Master thesis / Masteroppgave, 2018)
    Solar flares play a key role in the dynamics of the solar atmosphere. They occur with a wide range of energies, from the largest X-class flares representing some of the most violent releases of energy in the solar system, ...
  • Numerical radiative transfer using a multigrid method 
    Bjørgen, Johan Pires (Master thesis / Masteroppgave, 2014)
    Solving the non-LTE radiative transfer problem in stellar atmospheres is computationally demanding. There is therefore an interest to investigate new methods to solve this problem effectively. A numerical method, multigrid, ...
  • Numerical Simulations and Observations of Mg II in the Solar Chromosphere 
    Hansteen, Viggo Haraldson; Martinez-Sykora, Juan; Carlsson, Mats; De Pontieu, Bart Walter; Gošić, Milan; Bose, Souvik (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    The Mg ii h and k lines are among the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest, as it is the lowest region of the Sun's atmosphere where the magnetic ...
  • NUMERICAL SIMULATIONS of CORONAL HEATING THROUGH FOOTPOINT BRAIDING 
    Hansteen, Viggo; Guerreiro, Nuno Miguel Rodrigues; De Pontieu, Bart Walter; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    Advanced three-dimensional (3D) radiative MHD simulations now reproduce many properties of the outer solar atmosphere. When including a domain from the convection zone into the corona, a hot chromosphere and corona are ...
  • NUMERICAL SIMULATIONS OF SPICULE ACCELERATION 
    Guerreiro, Nuno Miguel Rodrigues; Carlsson, Mats; Hansteen, Viggo (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)
    Observations in the Hα line of hydrogen and the H and K lines of singly ionized calcium on the solar limb reveal the existence of structures with jet-like behavior, usually designated as spicules. The driving mechanism for ...
  • Numerical studies of a plasma diode with external forcing 
    Rekaa, Vegard Lundby; Pecseli, Hans; Trulsen, Jan Karsten (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    With reference to laboratory Q-machine studies we analyze the dynamics of a plasma diode under external forcing. Assuming a strong axial magnetic field, the problem is analyzed in one spatial dimension by a particle-in-cell ...