Now showing items 585-602 of 602

• (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 ...
• (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 ...
• (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 ...
• (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 ...
• (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. ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
We present a new flexible Bayesian framework for directly inferring the fraction of neutral hydrogen in the intergalactic medium (IGM) during the Epoch of Reionization (EoR, z ~ 6–10) from detections and non-detections of ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
Lyα is a powerful astrophysical probe. Not only is it ubiquitous at high redshifts, it is also a resonant line, making Lyα photons scatter. This scattering process depends on the physical conditions of the gas through which ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2014)
New and advanced space-based observing facilities continue to lower the resolution limit and detect solar coronal loops in greater detail. We continue to discover even finer substructures within coronal loop cross-sections, ...
• (Master thesis / Masteroppgave, 2010)
The statistical analysis of the Cosmic Microwave Background radiation to make estimates of the Power Spectrum is a comutationally heavy operation, involving large covariance matrices. In this thesis I explore the possibility ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
The Vainshtein mechanism, present in many models of gravity, is very effective at screening dark matter haloes such that the fifth force is negligible and general relativity is recovered within their Vainshtein radii. ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
Context: The reionisation of the Universe is a process that is thought to have ended around z ~ 6, as inferred from spectroscopy of distant bright background sources, such as quasars (QSO) and gamma-ray burst (GRB) afterglows. ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
Solar “magnetic tornadoes” are produced by rotating magnetic field structures that extend from the upper convection zone and the photosphere to the corona of the Sun. Recent studies show that these kinds of rotating features ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
We present a mass estimate of the Planck-discovered cluster PLCK G100.2-30.4, derived from a weak lensing analysis of deep Subaru griz images. We perform a careful selection of the background galaxies using the multi-band ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
Spicules are the most ubuiquitous type of jets in the solar atmosphere. The advent of high-resolution imaging and spectroscopy from the Interface Region Imaging Spectrograph (IRIS) and ground-based observatories has revealed ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
We analyze observations from the Interface Region Imaging Spectrograph of the Mg ii k line, the Mg ii UV subordinate lines, and the O i 135.6 $\mathrm{nm}$ line to better understand the solar plage chromosphere. We also ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
Spectral observations of the solar transition region (TR) and corona show broadening of spectral lines beyond what is expected from thermal and instrumental broadening. The remaining non-thermal broadening is significant ...
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
© 2017 American Institute of Physics.
• (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
Recently, a modified theory of gravity was presented, which consists of the superposition of the metric Einstein-Hilbert Lagrangian with an f(R) term constructed à la Palatini. The theory possesses extremely interesting ...