Late time accelerated expansion of the universe is usually considered to be the result of dark energy, and the standard model of cosmology implements the cosmological constant as the drive of the acceleration of the universe. ...

The ''theory of dark matter superfluidity'' \cite{berezhiani2015theory} is reproduced in SI units with the inclusion of intermediate, and precise, steps in the calculations. By use of another measure of the mean interparticle ...

Analysing the state of the art, zoom-in simulation "Eris", we study the distribution, origins and kinematics of O~VI gas around star forming L* galaxies. A detailed comparison to observations from the COS-halo survey is ...

The nuclide 187Re beta-decays to 187Os with a half-life of approximately 41.6 Gyr. The long half-life and simple relation between 187Re and 187Os makes the ratio a good candidate for a cosmic clock. In order to "use the ...

Solar flares play a key role in the dynamics of the solar atmosphere. They occur with a wide range of energies, from the largest X-class flares representing some of the most violent releases of energy in the solar system, ...

The Planck satellite has provided a multitude of data images of the full microwave sky, or sky maps, since it saw first light in 2009. Its observations of the Cosmic Microwave Background (CMB) data has been paramount in ...

In the 2015 Planck Isotropy and Statistics article, the dipolar asymmetry previously found in the WMAP data (Hansen et al. 2009) was found to extend to the smallest scales. While the statistical significance of this anomaly ...

We perform an investigation of quadru- and octopolar asymmetry in the CMB data by expanding the on the study of alignment and angular clustering of the dipole components of the CMB power distribution across multipoles l = ...

In order to estimate the mass of supermassive black holes found in the centres of active galactic nuclei (AGNs) from spectroscopic data, the contamination from the light emitted by the stars in the surrounding host galaxy ...

Following the discovery of the late-time acceleration, a multitude of extensions to General Relativity have been developed, seeking to shed light on this new phenomenon. Some of these models involve couplings to ordinary ...

The Next Generation Transit Survey (NGTS) is an ongoing wide-field exoplanet transit survey at ESO Paranal Observatory, Chile. It is searching for Neptune and super-Earth size planets around nearby stars using 12 robotic ...

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 ...

Several decades ago it was discovered that the outer layers of the Sun are much hotter than the photosphere. The mechanism or mechanisms heating the outer solar layers are not known, so this is known as the coronal heating ...

Recent observations support a significantly reduced visibility of Lyman-α (Lyα) flux from galaxies at redshifts z > 6. This is surprising considering that the visibility of Lyα flux has been observed to increase up towards ...

Spherical collapse is a crude, but useful toy model for structure formation in an expanding universe. Previous works have looked at this model in ΛCDM with massive neutrinos, where the primary findings were that massive ...

If dark matter, after it has become non-relativistic, scatters elastically with a relativistic heat bath particle, then the resulting pressure leads to acoustic oscillations that suppress the growth of overdensities in the ...

The Planck Sunyaev-Zeldovich Cluster catalogue provides an all-sky set of SZ detected galaxy clusters, which is the first of its kind. SZ signals are independent of redshift which allows a greater volume of space to be ...

In 2013 a new metric called TARDIS was introduced. This metric was published by Tippet and Tsang, and described a time machine. This thesis uses numerical methods to explore properties of this new metric. We start by ...

The ΛCDM model used in modern cosmology has major theoretical problems. To attempt to solve these many modified gravity theories have been proposed. We calculate velocity statistics (streaming pair-wise velocities and the ...

In this thesis, we investigate statistical properties of the redshift zero matter distribution in disformal gravity through N-body simulations. The disformal model studied here is a conformally coupled field in a symmetron ...

In this thesis we have implemented a basic radiative transfer code to model the radial Lyα scattering rate around the epoch when the first stars and galaxies start forming, and ionizing their surroundings. The model, builds ...

Magnetic bright points (MBPs) are small-scale (generally kG) magnetic features, ubiqui- tous in the lower solar atmosphere, and are a manifestation of solar magnetism. They represent the cross-sections of thin flux tubes ...

In this thesis we investigate a dynamical cosmological constant called the quintessence. Quintessence is a scalar field varying in both space and time following a chosen potential. To explain the coincidence problem, e.g. ...

In this thesis chromospheric features called Penumbral Microjets (PMJs) are investigated in a sunspot. Observations of high resolution in space, time and wavelength from the Swedish 1-meter Solar Telescope (SST) are used ...

Studier av vekselvirkningsmodeller for baryonsk materie, mørk materie og mørk energi. Hovedfokus på stabilitet for universmodeller, sammenligning med observasjonelle data og konsekvenser for strukturformasjoner.

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 ...

Solving the non-LTE radiative transfer problem in stellar atmospheres is computationally demanding. There is therefore an interest to investigate new methods to solve this problem effectively. A numerical method, multigrid, ...

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 ...

We investigate cosmologies where the accelerated expansion of the universe is driven by a fluid with an anisotropic equation of state. If dark energy equation of state is anisotropic, the expansion rate of the universe ...

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 ...

The existence of dark energy in the universe is hypothesized to explain the accelerated expansion of today’s universe and the inflationary expansion of very early universe; accelerated expansion of today’s universe is ...

The solar corona has a temperature of order 1 MK, which is almost 200 times the temperature of the underlying surface. This fact has puzzled solar physicists for more than six decades. As of today, most solar physicists ...

Inflation is a much discussed topic within the field of cosmology; it represents a time in the history of the Universe where a very rapid, exponential expansion was taking place. This expansion is needed in order for the ...

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, ...

The inverse-C shape of the bisector from the chromospheric Ca triplet spectral lines is a little understood phenomena. This spectral signature can give valuble information about the chromosphere, which is the least understood ...

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, ...

This thesis is a study of the dynamics and virialization of cosmic structures in the framework of flat cosmological models where the properties of the dark energy component plays an important role in the global and local ...

There have been many reports on anomalies in the CMB from different research groups. In this work statistical tests using the gradients of the CMB temperature, applied to the seven year WMAP data, have been investigated. ...

The standard model of cosmology has proven to be a great success. Through measurements of the Cosmic Microwave Background radiation, cosmologists have been able to constrain parameters such as the age and geometry of the ...

The existence of dark matter is a well established fact both due to galaxy rotation curves and also due to the CMB temperature anisotropies and the matter power spectra. According to the $\Lambda$CDM model, the so called ...

Neutrino cosmology is a very interesting field of research, where properties of some of the smallest constituents of the universe are probed by the very largest structures of the universe; large scale structures of the ...

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 ...

The theory of inflation gives certain predictions for the amount of primordial gravitational waves compared to the amount of density perturbations. These predictions are, in principle, verifiable through observation of the ...

The solar chromosphere is a region where the thermodynamics are out of equilibrium, and realistic values of temperature and electron densities here are difficult to obtain. Hydrogen, being the most abundant element in solar ...

We investigate scalar-field theories with a field-dependent coupling to matter and show the existence of a chameleon mechanism. The thin-shell solutions for a spherical body are found, and used to investigate the consequences ...

In this thesis the correlation between star formation and dynamical state of a statistical well defined selection of galaxy clusters have been studied. From simulations and theory it is expected strong correlations between ...

The cosmic microwave background (CMB) radiation at 2.7 K is the leftover radiation from the Big Bang. By studying this radiation we can extract much information about the universe we live in. CMB experiments over the last ...

I have investigated the total energy of Friedmann-Robertson-Walker universes. This is an interesting issue, because if the energy of the universe turns out not to be conserved, it will be in conflict with our common ...

En mulig forklaring på at universet gikk inn i en fase av akselerert ekspansjon for 5-6 milliarder år siden, er at energitettheten i universet inneholder et bidrag fra et dynamisk skalarfelt. Problemet med denne forklaringen ...

In between the Cosmic Microwave Background (CMB) and the instrument there are other sources of radiation, called foregrounds. The foregrounds radiate in the same frequency bands as the background, and cause contamination ...

Observations of the Cosmic Microwave Background is impaired by other astrophysical sources that also radiate in the microwave spectrum. These other, non-CMB sources are known as foregrounds. In this thesis, three different ...

Observations of how matter is distributed on different length scales in the universe are an important test of cosmological models. For example, such observations can give an upper limit for the mass of neutrinos: As the ...

The solar chromosphere has previously been thought to be a homogenic layer of the solar atmosphere, but better observations have made it evident that the chromosphere is a highly dynamic area. Spicules are structures ...

Systematic anomalies that seem to follow the first ionisation potential (FIP) of the minor, heavy elements at the sun, have been found when comparing the observed elemental abundances in the upper solar atmosphere with the ...

In-situ observations together with spectroscopic measurements show that the elemental abundance in the solar atmosphere varies from the photosphere to solar wind. An enrichment for low First Ionisation Potential elements ...

Gravitational lensing has played an important role in cosmology since the discovery of the first gravitational lensing system in 1979 (Walsh et al.), where the quasar QSO 0957+561 can be seen in two images. Such multiple ...

Two galaxy clusters, Abell 1351 and Abell 1995, are examined using weak gravitational lensing techniques. Mass maps are created, and the clusters' density and shear profiles are compared to theoretical predictions. Gravitational ...