Browsing Institutt for teoretisk astrofysikk by Title

Now showing items 805-824 of 1279

  • On the active region bright grains observed in the transition region imaging channels of IRIS 
    Skogsrud, Håkon; Rouppe, Van Der Voort Luc; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)
    The Interface Region Imaging Spectrograph (IRIS) provides spectroscopy and narrow band slit-jaw (SJI) imaging of the solar chromosphere and transition region at unprecedented spatial and temporal resolutions. Combined with ...
  • On the dynamics of spicules and mass flows in the solar atmosphere 
    Bose, Souvik (Doctoral thesis / Doktoravhandling, 2021)
    The atmosphere of the Sun is envisioned as composed of inherently complex, non-homogeneous, and dynamic layers. A detailed understanding of the physical processes involved in these layers is still lacking. For example, it ...
  • On the generation of solar spicules and Alfvenic waves 
    Martinez-Sykora, Juan; De Pontieu, Bart Walter; Hansteen, Viggo; Rouppe van der Voort, Luc; Carlsson, Mats; Mendes Domingos Pereira, Tiago (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2017)
    In the lower solar atmosphere, the chromosphere is permeated by jets known as spicules, in which plasma is propelled at speeds of 50 to 150 kilometers per second into the corona. The origin of the spicules is poorly ...
  • On the Identification of Small-Scaled Heating Events in MHD Simulations of the Solar Corona 
    Kanella, Charalambos (Doctoral thesis / Doktoravhandling, 2018)
    The identification of small-scale 3-D heating events in numerical simulations brought us a step closer to solve one of the biggest mysteries in astrophysics. The identification of small scale 3-D heating events in the ...
  • On the importance of Ca II photoionization by the hydrogen lyman transitions in solar flare models 
    Osborne, Christopher M. J.; Heinzel, Petr; Kašparová, Jana; Fletcher, Lyndsay (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    ABSTRACT The forward fitting of solar flare observations with radiation–hydrodynamic simulations is a common technique for learning about energy deposition and atmospheric evolution during these explosive events. ...
  • On the multi-threaded nature of solar spicules 
    Skogsrud, Håkon; Rouppe, Van Der Voort Luc; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
    A dominant constituent in the dynamic chromosphere is spicules. Spicules at the limb appear as relatively small and dynamic jets that are observed to stick out everywhere. Many papers emphasize the important role spicules ...
  • On the Observability of Individual Population III Stars and Their Stellar-mass Black Hole Accretion Disks through Cluster Caustic Transits 
    Windhorst, Rogier A.; Timmes, F.X.; Wyithe, J. Stuart B.; Alpaslan, Mehmet; Andrews, Stephen K.; Coe, Daniel; Diego, Jose M.; Dijkstra, Mark; Driver, Simon P.; Kelly, Patrick L.; Kim, Duho (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We summarize panchromatic Extragalactic Background Light data to place upper limits on the integrated near-infrared surface brightness (SB) that may come from Population III stars and possible accretion disks around their ...
  • On the Occurrence of Thermal Nonequilibrium in Coronal Loops 
    Froment, Clara; Auchère, F.; Mikic, Z.; Aulanier, G.; Bocchialini, Karine; Buchlin, E.; Solomon, J.; Soubrie, E. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    Long-period EUV pulsations, recently discovered to be common in active regions, are understood to be the coronal manifestation of thermal nonequilibrium (TNE). The active regions previously studied with EIT/Solar and ...
  • On the Origin of the Magnetic Energy in the Quiet Solar Chromosphere 
    Martinez-Sykora, Juan; Hansteen, Viggo; Gudiksen, Boris Vilhelm; Carlsson, Mats; De Pontieu, Bart Walter; Gošić, Milan (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    The presence of magnetic field is crucial in the transport of energy through the solar atmosphere. Recent ground-based and space-borne observations of the quiet Sun have revealed that magnetic field accumulates at photospheric ...
  • ON THE TEMPORAL EVOLUTION OF SPICULES OBSERVED WITH IRIS, SDO, AND HINODE 
    Skogsrud, Håkon; Rouppe, Van Der Voort Luc; De Pontieu, Bart Walter; Mendes Domingos Pereira, Tiago (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    Spicules are ubiquitous, fast moving jets observed off-limb in chromospheric spectral lines. Combining the recently launched Interface Region Imaging Spectrograph with the Solar Dynamics Observatory and Hinode, we have a ...
  • On the theory of dark matter superfluidity 
    Valberg, Pål (Master thesis / Masteroppgave, 2018)
    The ''theory of dark matter superfluidity'' \cite{berezhiani2015theory} is reproduced in SI units with the inclusion of intermediate, and precise, steps in the calculations. By use of another measure of the mean interparticle ...
  • On the Variability of the Solar Mean Magnetic Field: Contributions from Various Magnetic Features on the Surface of the Sun 
    Bose, Souvik; Nagaraju, K (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    The solar mean magnetic field (SMMF) is referred to as the disk-averaged line-of-sight (LOS) magnetic field that also reflects the polarity imbalance of the magnetic field on the Sun. The origin of the SMMF has been debated ...
  • Optical validation and characterisation of Planck PSZ1 sources at the Canary Islands observatories: II. Second year of ITP13 observations 
    Barrena, R.; Ferragamo, A.; Rubiño-Martín, J. A.; Streblyanska, A.; Aguado-Barahona, A.; Tramonte, D.; Génova-Santos, R. T.; Hempel, A.; Lietzen, H.; Aghanim, Nabila; Arnaud, Monique; Böhringer, H.; Chon, G.; Dahle, Håkon; Douspis, M.; Lasenby, A. N.; Mazzotta, P.; Melin, J. B.; Pointecouteau, E.; Pratt, G. W.; Rossetti, M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    We report new galaxy clusters previously unknown included in the first Planck Sunyaev–Zeldovich (SZ) sources catalogue, the PSZ1. The results presented here were achieved during the second year of a two-year observational ...
  • Optical validation and characterization of Planck PSZ1 sources at the Canary Islands observatories: I. First year of ITP13 observations 
    Barrena, R.; Streblyanska, A.; Ferragamo, A.; Rubiño-Martín, J. A.; Aguado-Barahona, A.; Tramonte, D.; Génova-Santos, R. T.; Hempel, A.; Lietzen, H.; Aghanim, Nabila; Arnaud, M.; Böhringer, H.; Chon, G.; Démoclès, J.; Dahle, Håkon; Douspis, M.; Lasenby, A. N.; Mazzotta, P.; Melin, J. B.; Pointecouteau, E.; Pratt, G. W.; Rossetti, M.; van der Burg, R. F. J. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We have identified new clusters and characterized previously unknown Planck Sunyaev–Zeldovich (SZ) sources from the first Planck catalogue of SZ sources (PSZ1). The results presented here correspond to an optical follow-up ...
  • Optical variability of quasars with 20-yr photometric light curves 
    Stone, Zachary; Shen, Yue; Burke, Colin J; Chen, Yu-Ching; Yang, Qian; Liu, Xin; Gruendl, R.A.; Adamów, M.; Andrade-Oliveira, F.; Annis, J.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D.L.; Carnero Rosell, Rosell; Carrasco Kind, Kind; Carretero, J.; Da Costa, L N; Pereira, M.E.S.; De Vicente, Vicente; Desai, S.; Diehl, H.T.; Doel, P.; Ferrero, Ismael; Friedel, D.N.; Frieman, J.; García-Bellido, J.; Gaztanaga, E.; Gruen, D.; Gutierrez, G.; Hinton, S.R.; Hollowood, D.L.; Honscheid, K.; James, D.J.; Kuehn, K.; Kuropatkin, N.; Lidman, C.; Maia, M.A.G.; Menanteau, F.; Miquel, R.; Morgan, R.; Paz-Chinchón, F.; Pieres, A.; Plazas Malagón, Malagon; Rodriguez-Monroy, M.; Sanchez, E.; Scarpine, V.; Serrano, S.; Sevilla-Noarbe, I.; Smith, M.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; To, C. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    ABSTRACT We study the optical gri photometric variability of a sample of 190 quasars within the SDSS Stripe 82 region that have long-term photometric coverage during ∼1998−2020 with SDSS, PanSTARRS-1, the Dark ...
  • Optimized Large-scale CMB Likelihood and Quadratic Maximum Likelihood Power Spectrum Estimation 
    Gjerløw, Eirik; Colombo, L. P. L.; Eriksen, Hans Kristian Kamfjord; Górski, Krzysztof M.; Gruppuso, A.; Jewell, J. B.; Plaszczynski, S; Wehus, Ingunn Kathrine (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    We revisit the problem of exact cosmic microwave background (CMB) likelihood and power spectrum estimation with the goal of minimizing computational costs through linear compression. This idea was originally proposed for ...
  • Origin of Metals around Galaxies. I. Catalogs of Metal-line Absorption Doublets from High-resolution Quasar Spectra 
    Mas Ribas, Lluis; Riemer-Sørensen, Signe; Hennawi, Joseph F; Miralda-Escudé, Jordi; O'Meara, John M.; Pérez-Ràfols, Ignasi; Murphy, Michael T.; Webb, John K. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present the first paper of the series Origin of Metals around Galaxies, which aims to explore the origin of the metals observed in the circumgalactic and intergalactic media. In this work we extract and build catalogs ...
  • The origin of the [CII] emission in high-redshift galaxies 
    Warraich, Jessie Harvir Kaur (Master thesis / Masteroppgave, 2021)
    The ionized carbon [CII] λ ∼ 158 µm emission line is an important tool in tracing the interstellar medium (ISM) of galaxies, especially at high redshift. The line is one of the dominant coolants of cool gas and, as the ...
  • Origins, distribution and kinematics of circumgalactic O VI around star forming L* galaxies 
    Spilker, Andri Karoline Lunøe (Master thesis / Masteroppgave, 2018)
    Analysing the state of the art, zoom-in simulation "Eris", we study the distribution, origins and kinematics of O~VI gas around star forming L* galaxies. A detailed comparison to observations from the COS-halo survey is ...
  • Oscillations on Width and Intensity of Slender Ca II H Fibrils from Sunrise/SuFI 
    Gafeira, Ricardo; Jafarzadeh, Shahin; Solanki, S. K.; Lagg, A.; van Noort, M.; Barthol, P.; Blanco Rodriguez, J.; del Toro Iniesta, J. C.; Gandorfer, A.; Gizon, L; Hirzberger, J.; Knölker, M.; Orozco Suarez, D.; Riethmüller, T. L.; Schmidt, W. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
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