Browsing Institutt for teoretisk astrofysikk by Title
Now showing items 499-518 of 599
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)We investigate the efficiency of screening mechanisms in the hybrid metric-Palatini gravity. The value of the field is computed around spherical bodies embedded in a background of constant density. We find a thin shell ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)It is shown that extensions to general relativity, which introduce a strongly coupled scalar field, can be viable if the interaction has a nonconformal form. Such disformal coupling depends upon the gradients of the scalar ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)We present a formalism to study screening mechanisms in modified theories of gravity through perturbative methods in different cosmological scenarios. We consider Einstein-frame posed theories that are recast as Jordan-frame ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)We report the discovery of a unique gravitational lens system, SDSS J2222+2745, producing five spectroscopically confirmed images of a zs = 2.82 quasar lensed by a foreground galaxy cluster at zl = 0.49. We also present ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)© 2017 The Authors Published by Oxford University Press on behalf of the Royal Astronomical Society
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(Doctoral thesis / Doktoravhandling, 2010)
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(Master thesis / Masteroppgave, 2012)The Q/U-Imaging ExperimenT (QUIET) is a ground-based coherent polarimeter experiment, primarily targeting the detection of low-l B-mode polarization in the CMB. Such modes are a signature of primordial tensor perturbations, ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)The space-time evolution of an initial step-like plasma density variation is studied. We give particular attention to formulate the problem in a way that opens for the possibility of realizing the conditions experimentally. ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)Context: The solar chromosphere and the lower transition region are believed to play a crucial role in the heating of the solar corona. Models that describe the chromosphere (and the lower transition region), accounting ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)The measurement of the large-scale B-mode polarization in the cosmic microwave background (CMB) is a fundamental goal of future CMB experiments. However, because of unprecedented sensitivity, future CMB experiments will ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)Scalar fields are crucial components in high energy physics and extensions of general relativity. The fact that they are not observed in the Solar System may be due to a mechanism which screens their presence in high dense ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2013)Sunspot chromospheres display vigorous oscillatory signatures when observed using chromospheric diagnostics such as the strong Ca II lines and Hα. New high-resolution sunspot observations from the Swedish 1 m Solar Telescope ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)Dynamical jets are generally found on light bridges (LBs), which are key to studying sunspot decay. So far, their formation mechanism is not fully understood. In this paper, we used state-of-the-art observations from the ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)A dense forest of slender bright fibrils near a small solar active region is seen in high-quality narrowband Ca ii H images from the SuFI instrument onboard the Sunrise balloon-borne solar observatory. The orientation of ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)We present spatially resolved Echelle spectroscopy of an intervening Mg II–Fe II–Mg I absorption-line system detected at zabs = 0.73379 towards the giant gravitational arc PSZ1 G311.65–18.48. The absorbing gas is associated ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)We present a comprehensive method to analyze small-scale heating events in detail in a 3D magnetohydrodynamics simulation for quiet-Sun conditions. The method determines the number, volume, and some general geometric ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)Context. Small-scale heating events (SSHEs) are believed to play a fundamental role in understanding the process responsible for heating of the solar corona, the pervading redshifts in the transition region, and the ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)© 2017. The American Astronomical Society. All rights reserved.
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)© 2017. The American Astronomical Society. All rights reserved.