Browsing Institutt for teoretisk astrofysikk by Title
Now showing items 719-738 of 1243
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2011)We introduce the N-body simulation technique to follow structure formation in linear and nonlinear regimes for the extended quintessence models (scalar-tensor theories in which the scalar field has a self-interaction ...
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(Master thesis / Masteroppgave, 2014)Neutrinos are very weakly interacting particles with a low mass. In fact, the mass of the neutrinos has not yet been determined by experiments or observations. Still, neutrinos are a good candidate for some of the dark ...
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)Foreground components in the Cosmic Microwave Background (CMB) are sparse in a needlet representation, due to their specific morphological features (anisotropy, non-Gaussianity). This leads to the possibility of applying ...
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(Master thesis / Masteroppgave, 2021)Synthetic spectra calculated from model solar atmospheres are central to our understanding of the connection between the observed intensity and the solar atmosphere. To obtain synthetic profiles in the general case, we ...
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(Journal article / Tidsskriftartikkel / SubmittedVersion, 2017)Recent constrains on the sum of neutrino masses inferred by analyzing cosmological data, show that detecting a non-zero neutrino mass is within reach of forthcoming cosmological surveys. Such a measurement will imply a ...
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(Master thesis / Masteroppgave, 2016)The universe is full of stuff we cannot see, neither directly or indirectly. We do not understand the nature of the mysterious dark matter and how it interacts with normal matter. Big Bang Nucleosynthesis (BBN) provides ...
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(Master thesis / Hovedoppgave, 2002)Five years (1992-1997, ~2650 images) of optical observations of the gravitational lens system QSO 0957+561 were analyzed using a new photometry package developed by Jan Teuber and me. My supervisor was Prof. Rolf Stabell, ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)The origin of the disk and spheroid of galaxies has been a key open question in understanding their morphology. Using the high-resolution cosmological simulation New Horizon, we explore kinematically decomposed disk and ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)© 2017. The American Astronomical Society. All rights reserved.
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(Doctoral thesis / Doktoravhandling, 2023)The Sun, our nearest star, serves as an invaluable reference for the study of solar-like stars, due to the availability of many spatiotemporally resolved solar spectra. Amongst several spectral lines, some of the strongest ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)We present a new perturbative approach to ‘constrained Ly α radiative transfer’ (RT) through the circum- and intergalactic medium (CGM and IGM). We constrain the H I content and kinematics of the CGM and IGM in a physically ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)The existence of multiple active galactic nuclei (AGNs) at small projected distances on the sky is due to either the presence of multiple, inspiraling supermassive black holes, or to gravitational lensing of a single AGN. ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)In this Letter, we introduce the nonlinear partial differential equation ∂2τπ∝(→∇π)2 showing a new type of instability. Such equations appear in the effective field theory (EFT) of dark energy for the k-essence model as ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)ABSTRACT Standard sirens (SS) are the gravitational wave analogue of the astronomical standard candles, and can provide powerful information about the dynamics of the Universe up to very high z values. In this ...
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)Thanks to the release of the extraordinary EHT image of shadow attributed to the M87* supermassive black hole (SMBH), we have a novel window to assess the validity of fundamental physics in the strong-field regime. Motivated ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)The ionization state of the gas in the dynamic solar chromosphere can depart strongly from the instantaneous statistical equilibrium commonly assumed in numerical modeling. We improve on earlier simulations of the solar ...
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(Doctoral thesis / Doktoravhandling, 2017)
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(Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2019)This is an overview of non-equilibrium aspects of the formation of solar continua and lines affecting the contributions by magnetic network and plage to spectrally resolved solar irradiance. After a brief summary of these ...
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(Doctoral thesis / Doktoravhandling, 2010)
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(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 ...