Browsing Institutt for teoretisk astrofysikk by Title

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  • Tracing the signatures of a quiet Sun nanoflare 
    Robinson, Rebecca Anne; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Context. Nanoflare-scale reconnection events are difficult to detect, and even when they are detected, it is tricky to reconstruct the details and trigger mechanisms that power them. However, numerical models of nanoflare-scale ...
  • Trans-Planckian anisotropies in the cosmic microwave background 
    Groeneboom, Nicolaas Ervik (Master thesis / Masteroppgave, 2007)
  • Transverse motions in sunspot super-penumbral fibrils 
    Morton, Richard J.; Mooroogen, K; de Jorge Henriques, Vasco Manuel (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Sunspots have played a key role in aiding our understanding of magnetohydrodynamic (MHD) wave phenomena in the Sun’s atmosphere, and it is well known they demonstrate a number of wave phenomena associated with slow MHD ...
  • Transverse Oscillations in Slender Ca II H Fibrils Observed with Sunrise/SuFI 
    Jafarzadeh, Shahin; Solanki, S. K.; Gafeira, Ricardo; 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)
    We present observations of transverse oscillations in slender Ca ii H fibrils (SCFs) in the lower solar chromosphere. We use a 1 hr long time series of high- (spatial and temporal-) resolution seeing-free observations in ...
  • Transverse Wave Induced Kelvin-Helmholtz Rolls in Spicules 
    Antolin, Patrick; Schmit, D.; Pereira, Tiago Mendes Domingos; De Pontieu, Bart Walter; De Moortel, I. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    In addition to their jet-like dynamic behavior, spicules usually exhibit strong transverse speeds, multi-stranded structure, and heating from chromospheric to transition region temperatures. In this work we first analyze ...
  • TREVR2: Illuminating fast N log_2 N radiative transfer 
    Wadsley, James W.; Baumschlager, Bernhard; Shen, Sijing (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
    ABSTRACT We present trevr2 (Tree-based REVerse Ray Tracing 2), a fast, general algorithm for computing the radiation field, suitable for both particle and mesh codes. It is designed to self-consistently evolve ...
  • Turnaround radius as a probe of cosmologyRestricted Access 
    Børvind, Marius Bjerke (Master thesis / Masteroppgave, 2023)
  • Turnaround radius in ΛCDM and dark matter cosmologies with shear and vorticity 
    Del Popolo, Antonino; Chan, Man Ho; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    We determine the relationship between the turnaround radius, Rt, and mass, Mt, in Λ CDM , and in dark energy scenarios, using an extended spherical collapse model taking into account the effects of shear and vorticity. We ...
  • Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere 
    Martinez-Sykora, Juan; De Pontieu, Bart Walter; Carlsson, Mats; Hansteen, Viggo; Nobrega-Siverio, Daniel; Gudiksen, Boris Vilhelm (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ...
  • The Ubiquitous Imprint of Radiative Acceleration in the Mean Absorption Spectrum of Quasar Outflows 
    Mas Ribas, Lluis; Mauland-Hus, Renate (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Observational evidence revealing the main mechanisms that accelerate quasar outflows has proven difficult to obtain due to the complexity of the absorption features that this gas produces in the spectra of the emission ...
  • Ultra-high-resolution observations of persistent null-point reconnection in the solar corona 
    Cheng, X.; Priest, E.R.; Li, H.T.; Chen, J.; Aulanier, Guillaume; Chitta, L.P.; Wang, Y.L.; Peter, H.; Zhu, X.S.; Xing, C.; Ding, M.D.; Solanki, S.K.; Berghmans, D.; Teriaca, L.; Aznar Cuadrado, R.; Zhukov, A.N.; Guo, Y.; Long, D.; Harra, L.; Smith, P.J.; Rodriguez, L.; Verbeeck, C.; Barczynski, K.; Parenti, S. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract Magnetic reconnection is a key mechanism involved in solar eruptions and is also a prime possibility to heat the low corona to millions of degrees. Here, we present ultra-high-resolution extreme ultraviolet ...
  • Ultra-high-resolution observations of plasmoid-mediated magnetic reconnection in the deep solar atmosphere 
    Rouppe van der Voort, Luc; Van Noort, Michiel; de la Cruz Rodriguez, Jaime (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Context. Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs. Aims. To effectively trace magnetic reconnection ...
  • Ultracool dwarfs candidates based on 6 yr of the Dark Energy Survey data 
    dal Ponte, M.; Santiago, B.; Carnero Rosell, A.; De Paris, L.; Pace, A.B.; Bechtol, K.; Abbott, T.M.C.; Aguena, M.; Allam, S.; Alves, O.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D.L.; Carrasco Kind, M.; Carretero, J.; Conselice, C.; Costanzi, M.; Desai, S.; De Vicente, J.; Doel, P.; Everett, S.; Ferrero, Ismael; Flaugher, B.; Frieman, J.; García-Bellido, J.; Gerdes, D.W.; Gruendl, R.A.; Gruen, D.; Gutierrez, G.; Hinton, S.R.; Hollowood, D.L.; James, D.J.; Kuehn, K.; Kuropatkin, N.; Marshall, J.L.; Mena-Fernández, J.; Menanteau, F.; Miquel, R.; Ogando, R.L.C.; Palmese, A.; Paz-Chinchón, F.; Pereira, M.E.S.; Plazas Malagón, A.A.; Pieres, A.; Raveri, M.; Rodriguez-Monroy, M.; Sanchez, E.; Scarpine, V.; Schubnell, M.; Sevilla-Noarbe, I.; Smith, M.; Soares-Santos, M.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; Thomas, D.; To, C.; Weaverdyck, N. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    ABSTRACT We present a sample of 19 583 ultracool dwarf candidates brighter than z ≤23 selected from the Dark Energy Survey DR2 coadd data matched to VHS DR6, VIKING DR5, and AllWISE covering ∼ 480 deg2. The ...
  • Umbral chromospheric fine structure and umbral flashes modelled as one: The corrugated umbra 
    de Jorge Henriques, Vasco Manuel; Nelson, Chris J.; Rouppe van der Voort, Luc; Mathioudakis, Mihalis (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Context. The chromosphere of the umbra of sunspots features an assortment of dynamic fine structures that are poorly understood and often studied separately. Small-scale umbral brightenings (SSUBs), umbral microjets, spikes ...
  • Understanding the extreme luminosity of DES14X2fna 
    Grayling, Matthew; Gutiérrez, Claudia P.; Sullivan, Mark; Wiseman, Philip; Vincenzi, Maria; González-Gaitán, Santiago; Tucker, B. E.; Galbany, Lluís; Kelsey, Lisa; Lidman, Chris; Swann, E.; Smith, Mathew; Frohmaier, Christopher; Carollo, Daniela; Glazebrook, K.; Lewis, Geraint F.; Möller, Anais; Hinton, Samuel R.; Uddin, S. A.; Abbott, Timothy M. C.; Aguena, Michel; Avila, Santiago; Bertin, Emmanuel; Bhargava, S.; Brooks, D.; Carnero Rosell, Aurelio; Carrasco Kind, Matias; Carretero, Jorge; Costanzi, Matteo; da Costa, Luiz N.; De Vicente, Juan; Desai, S.; Diehl, Herman T.; Doel, Peter; Everett, Spencer; Ferrero, Ismael; Fosalba, Pablo; Frieman, Josh; García-Bellido, Juan; Gaztañaga, Enrique; Gruen, Daniel; Gruendl, Robert A.; Gschwend, Julia; Gutierrez, G.; Hoyle, B.; Kuehn, Kyler; Kuropatkin, Nikolay; Lima, M.; MacCrann, Niall; Marshall, Jennifer L.; Martini, Paul; Miquel, Ramon; Morgan, R.; Palmese, Antonella; Paz-Chinchón, Francisco; Plazas, Andrés A.; Romer, A. K.; Sánchez, Carles; Sanchez, E.; Scarpine, Vic; Serrano, S.; Sevilla-Noarbe, Ignacio; Soares-Santos, Marcelle; Suchyta, Eric; Tarlé, Gregory; Thomas, Daniel; To, Chun-Hao; Varga, Tamas Norbert; Walker, Alistair R.; Wilkinson, Reese D. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    ABSTRACT We present DES14X2fna, a high-luminosity, fast-declining Type IIb supernova (SN IIb) at redshift z = 0.0453, detected by the Dark Energy Survey (DES). DES14X2fna is an unusual member of its class, with ...
  • Understanding the heating mechanism of the solar active region atmosphere in chromosphere 
    Yalim, Mehmet Sarp; Zank, Gary; Beck, Christian; Choudhary, Debi Prasad; Prasad, Avijeet; Hu, Qiang; Frisse, Makayla (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract Understanding the mechanisms underlying the heating of the solar atmosphere is a fundamental problem in solar physics. In this paper, we present an overview of our research on understanding the heating ...
  • A UNIFIED COMPUTATIONAL MODEL for SOLAR and STELLAR FLARES 
    Allred, Joel C.; Kowalski, Adam F.; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    We present a unified computational framework that can be used to describe impulsive flares on the Sun and on dMe stars. The models assume that the flare impulsive phase is caused by a beam of charged particles that is ...
  • Unified description of screened modified gravity 
    Brax, P; Davis, A.-C.; Li, Baojiu; Winther, Hans Arnold (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    We consider modified gravity models driven by a scalar field whose effects are screened in high density regions due to the presence of nonlinearities in its interaction potential and/or its coupling to matter. Our approach ...
  • Unifying static analysis of gravitational structures with a scale-dependent scalar field gravity as an alternative to dark matter 
    Salzano, Vincenzo; Mota, David; Capoziello, S.; Napolitano, N. R. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
    Aims: We investigated the gravitational effects of a scalar field within scalar-tensor gravity as an alternative to dark matter. Motivated by chameleon, symmetron, and f(R)-gravity models, we studied a phenomenological ...
  • Universal predictions of screened modified gravity on cluster scales 
    Gronke, Max Balthasar; Mota, David; Winther, Hans Arnold (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    Modified gravity models require a screening mechanism to be able to evade the stringent constraints from local gravity experiments and, at the same time, give rise to observable astrophysical and cosmological signatures. ...