Browsing Institutt for teoretisk astrofysikk by Title
Now showing items 513-532 of 1258
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(Master thesis / Masteroppgave, 2013)The gravitational redshift in clusters of galaxies can be measured to probe gravity as was first done by Wojtak et al. (2011). Using N -body simulations we are able to analyze the gravitational redshift profiles for the ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)Aims: We investigate the gravitational redshift in clusters of galaxies in the symmetron and Hu-Sawicky f(R) models. The characteristic feature of both models is the screening mechanism that hides the fifth force in dense ...
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)The Lambda-Cold Dark Matter (ΛCDM) model agrees with most of the cosmological observations, but has some hindrances from observed data at smaller scales such as galaxies. Recently, Berezhiani and Khoury proposed a new ...
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(Chapter / Bokkapittel / PublishedVersion; Peer reviewed, 2023)The Lambda-Cold Dark Matter (ΛCDM) model agrees with most of the cosmological observations, but has some hindrances from observed data at smaller scales such as galaxies. Recently, Berezhiani and Khoury proposed a new ...
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)The evolution of the virial overdensity Δvir for ΛCDM and seven dynamical dark-energy models is investigated in the extended spherical collapse model (SCM). Here the virialization process is naturally achieved by introducing ...
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(Master thesis / Masteroppgave, 2013)Modified gravity theories are a popular research field in the hope that they could explain some of the unanswered questions in cosmology, for example how the universe starts, evolves and ends. One way to test proposed ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)Screened modified gravity predicts potentially large signatures in the peculiar velocity field that makes it an interesting probe to test gravity on cosmological scales. We investigate the signatures induced by the Symmetron ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)Recent studies have identified the potential for coronal wave heating to balance radiative losses in a transversely oscillating low-density loop undergoing resonant absorption, phase mixing and the Kelvin–Helmholtz ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)The heating of the Sun's chromosphere remains poorly understood. While progress has been made on understanding what drives the quiet-Sun internetwork chromosphere, chromospheric heating in strong magnetic field regions ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)We use coordinated observations with the Interface Region Imaging Spectrograph (IRIS) and the Swedish 1 m Solar Telescope to identify the disk counterpart of type II spicules in upper-chromospheric and transition region ...
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(Master thesis / Masteroppgave, 2010)
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)We studied the physical parameters of the penumbra in a large and fully developed sunspot, one of the largest over the last two solar cycles, by using full-Stokes measurements taken at the photospheric Fe i 617.3 nm and ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)We present a new 3D magnetohydrodynamic (MHD) heliospheric model for space-weather forecasting driven by boundary conditions defined from white-light observations of the solar corona. The model is based on the MHD code ...
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(Doctoral thesis / Doktoravhandling, 2007)Doktorgradsavhandlingen beskriver et programvarebibliotek utviklet av Øystein Olsen ved Institutt for teoretisk astrofysikk. Programvaren har blitt brukt til å finne regioner med stabile og ustabile baner rundt asteroider ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)We present high-resolution, high-cadence observations of six, fine-scale, on-disk jet-like events observed by the High-resolution Coronal Imager 2.1 (Hi-C 2.1) during its sounding-rocket flight. We combine the Hi-C 2.1 ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)Abstract Since the very beginning of astronomy the location of objects on the sky has been a fundamental observational quantity that has been taken for granted. While precise two dimensional positional information is easy ...
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(Master thesis / Masteroppgave, 2011)Spicules are relatively small, narrow and elongated structures that stick out above the edge of the solar disk. They are very dynamic and appear as jets that shoot out into the outer solar atmosphere. Up until recently, ...
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)We report detection of oscillations in brightness temperature, size and horizontal velocity of three small bright features in the chromosphere of a plage/enhanced-network region. The observations, which were taken with ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)We characterize waves in small magnetic elements and investigate their propagation in the lower solar atmosphere from observations at high spatial and temporal resolution. We use the wavelet transform to analyze oscillations ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)Using high-cadence observations from the Hydrogen-alpha Rapid Dynamics camera imaging system on the Dunn Solar Telescope, we present an investigation of the statistical properties of transverse oscillations in spicules ...