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(Doctoral thesis / Doktoravhandling, 2024)
In my thesis, I investigated local (ultra-)luminous infrared galaxies, typically identified as galaxy mergers. These galaxies are fascinating due to their intense star formation and active galactic nuclei, which can lead ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
ABSTRACT
While proper orbital elements are currently available for more than 1 million asteroids, taxonomical information is still lagging behind. Surveys like SDSS-MOC4 provided preliminary information for more ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2024)
We present a cross-correlation analysis between 1´resolution total intensity and polarization observations from the Atacama Cosmology Telescope (ACT) at 150 and 220 GHz and 15'' mid-infrared photometry from the Wide-field ...
(Doctoral thesis / Doktoravhandling, 2023)
The cosmic microwave background is one of the most prominent sources of cosmological information. Modern cosmological theories rely upon both small- and large-scale observations of the CMB. As a necessity, these observations ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The Euclid mission will conduct an extragalactic survey over 15 000 deg 2 of the extragalactic sky. The spectroscopic channel of the Near-Infrared Spectrometer and Photometer (NISP) has a resolution of R ~ 450 for its blue ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The solar atmosphere is highly dynamic, and observing the small-scale features is valuable for interpretations of the underlying physical processes. The contrasts and magnitude of the observable signatures of ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The intensity of radiation from the solar atmosphere at millimetre wavelengths is closely related to the plasma temperature, and the formation height of the radiation is wavelength dependent. It follows from this ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Local primordial non-Gaussianity (PNG) is a promising observable of the underlying physics of inflation, characterized by flocNL. We present the methodology to measure flocNL from the Dark Energy Survey (DES) data using ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT We present the deconvolved distribution estimator (DDE), an extension of the voxel intensity distribution (VID), in the context of future observations proposed as part of the CO Mapping Array Project (COMAP). The ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The Square Kilometre Array Observatory (SKAO) is perhaps the most ambitious radio telescope envisaged yet. It will enable unprecedented studies of the Sun, corona and heliosphere and help to answer many of the outstanding ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Nanoflare heating through small-scale magnetic reconnection events is one of the prime candidates to explain heating of the solar corona. However, direct signatures of nanoflares are difficult to determine, and ...
(Doctoral thesis / Doktoravhandling, 2023)
Understanding the mechanisms responsible for heating the solar atmosphere from a few thousand Kelvin in the photosphere to millions of degrees in the corona is a major challenge in solar physics. A number of potential ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The theoretical basis of dark energy remains unknown and could signify a need to modify the laws of gravity on cosmological scales. In this study, we investigate how the clustering and motions of galaxies can be used as ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Doctoral thesis / Doktoravhandling, 2023)
The study of the cosmic microwave background (CMB) radiation is a pillar of modern cosmology that enables us to understand the history, the evolution of structures, and the global shape (topology) of the Universe. This ...
(Doctoral thesis / Doktoravhandling, 2023)
The oldest radiation in the universe is the Cosmic Microwave Background (CMB) radiation. Analysing the CMB is like analysing a baby picture of the Universe, and gives us unique information on what the Universe looked like ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Waves and oscillations have been observed in the Sun’s atmosphere for over half a century. While such phenomena have readily been observed across the entire electromagnetic spectrum, spanning radio to gamma-ray sources, ...
(Master thesis / Masteroppgave, 2023)
(Master thesis / Masteroppgave, 2023)
Turnaround radius as a probe of cosmology Restricted Access
(Master thesis / Masteroppgave, 2023)
(Doctoral thesis / Doktoravhandling, 2023)
The theme of this thesis has been the use of forward modeling to study the formation of spectral lines in the solar atmosphere, with a particular focus on the chromospheric Ca II 854.2 nm line which is important for magnetic ...
(Master thesis / Masteroppgave, 2023)
(Master thesis / Masteroppgave, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
Extreme, young stellar populations are considered to be the primary contributor to cosmic reionization. How the Lyman continuum (LyC) escapes these galaxies remains highly elusive, and it is challenging ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The gravitational lens system PS J0147+4630 (Andromeda’s Parachute) consists of four quasar images ABCD and a lensing galaxy. We obtained r -band light curves of ABCD in the 2017−2022 period from monitoring with two 2 m ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The ultra-faint dwarf galaxy Reticulum II (Ret II) exhibits a unique chemical evolution history, with
% of its stars strongly enhanced in r-process elements. We present deep Hubble Space Telescope photometry of Ret II and ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Aims. We analyse the signature and origin of transient structures embedded in the slow solar wind, and observed by the Wide-Field Imager for Parker Solar Probe (WISPR) during its first ten passages close to the Sun. WISPR ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The Solar Orbiter mission completed its first remote-sensing observation windows in the spring of 2022. On 2 April 2022, an M-class flare followed by a filament eruption was seen both by the instruments on board ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Oscillations are abundant in the solar corona. Coronal loop oscillations are typically studied using highly idealised models of magnetic flux tubes. In order to improve our understanding of coronal oscillations, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Material outgassing in a vacuum leads to molecular contamination, a well-known problem in spaceflight. Water is the most common contaminant in cryogenic spacecraft, altering numerous properties of optical systems. Too much ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We have investigated the cosmological constraints that can be expected from measurement of the cross-correlation of galaxies with cosmic voids identified in the Euclid spectroscopic survey, which will include spectroscopic ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Optical polarimeters are typically calibrated using measurements of stars with known and stable polarization parameters. However, there is a lack of such stars available across the sky. Many of the currently ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
Gravitationally lensed supernovae (LSNe) are important probes of cosmic expansion, but they remain rare and difficult to find. Current cosmic surveys likely contain 5–10 LSNe in total while next-generation ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Wavelength-dependent atmospheric effects impact photometric supernova flux measurements for ground-based observations. We present corrections on supernova flux measurements from the Dark Energy Survey Supernova Program's ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We present a Bayesian calibration algorithm for cosmic microwave background (CMB) observations as implemented within the global end-to-end B EYOND P LANCK framework and applied to the Planck Low Frequency Instrument (LFI) ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The Extreme Ultraviolet Imager (EUI) on board Solar Orbiter consists of three telescopes: the two High Resolution Imagers, in EUV (HRI EUV ) and in Lyman- α (HRI Lya ), and the Full Sun Imager (FSI). Solar Orbiter/EUI ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
In most cosmological models, the equation of state of the dark matter is assumed to be zero, which means that the dark matter is pressure-less or cold. While this hypothesis is based on the abundance of ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
LiteBIRD is a planned JAXA-led cosmic microwave background (CMB) B -mode satellite experiment aiming for launch in the late 2020s, with a primary goal of detecting the imprint of primordial inflationary gravitational waves. ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract The present work is a numerical follow-up on our published experimental paper on shock ignition of aluminium particle clouds in the low-temperature regime. The in-house multi-phase regularized smoothed particle ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
The S -index is a measure of emission in the Ca ii H and K lines and is a widely used proxy of stellar magnetic activity. It has been assumed until now that the S -index is mainly affected by bright plage ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The BeyondPlanck and Cosmoglobe collaborations have implemented the first integrated Bayesian end-to-end analysis pipeline for CMB experiments. The primary long-term motivation for this work is to develop a common analysis ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
Understanding the physical processes that trigger solar flares is paramount to help with forecasting space weather and mitigating the effects on our technological infrastructure. A previously unknown ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
We present the first systematic follow-up of Planck Sunyaev–Zeldovich effect (SZE) selected candidates down to signal-to-noise (S/N) of 3 over the 5000 deg2 covered by the Dark Energy Survey. Using the ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
Clusters of galaxies trace the most non-linear peaks in the cosmic density field. The weak gravitational lensing of background galaxies by clusters can allow us to infer their masses. However, galaxies ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Coronal rain is the most dramatic cooling phenomenon of the solar corona. Recent observations in the visible and UV spectrum have shown that coronal rain is a pervasive phenomenon in active regions. Its strong ...
(Doctoral thesis / Doktoravhandling, 2023)
The cosmic microwave background (CMB) is not just the oldest light in the Universe but also the oldest polarized light. By measuring its patterns, we can learn large amounts of information about the origin of the Universe ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The measurement of the absolute neutrino mass scale from cosmological large-scale clustering data is one of the key science goals of the Euclid mission. Such a measurement relies on precise modelling of the impact of ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
Recent cosmological analyses with large-scale structure and weak lensing measurements, usually referred to as 3 × 2pt, had to discard a lot of signal to noise from small scales due to our inability to ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The Laser Interferometer Space Antenna (LISA) will be a transformative experiment for gravitational wave astronomy, and, as such, it will offer unique opportunities to address many key astrophysical questions in a completely ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We describe the B EYOND P LANCK project in terms of our motivation, methodology, and main products, and provide a guide to a set of companion papers that describe each result in more detail. Building directly on experience ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We describe the correction procedure for Analog-to-Digital Converter (ADC) differential non-linearities (DNL) adopted in the Bayesian end-to-end B EYOND P LANCK analysis framework. This method is nearly identical to that ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The flare activity of the Sun has been studied for decades, using both space- and ground-based telescopes. The former have mainly focused on the corona, while the latter have mostly been used to investigate the conditions ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
Reverberation mapping measurements have been used to constrain the relationship between the size of the broad-line region and luminosity of active galactic nuclei (AGN). This R–L relation is used to ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Recent cosmic shear studies have shown that higher-order statistics (HOS) developed by independent teams now outperform standard two-point estimators in terms of statistical precision thanks to their sensitivity to the ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
The Slow Solar Wind Connection Solar Orbiter Observing Plan (Slow Wind SOOP) was developed to utilize the extensive suite of remote-sensing and in situ instruments on board the ESA/NASA Solar Orbiter ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Using the Planck Low Frequency Instrument (LFI) and WMAP data within the global Bayesian B EYOND P LANCK framework, we constrained the polarized foreground emission between 30 and 70 GHz. We combined, for the first time, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
Coronal mass ejections are explosive plasma phenomena prevalently occurring on the Sun and probably on other magnetically active stars. However, how their pre-eruptive configuration evolves toward the ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
This work focusses on the pilot run of a simulation campaign aimed at investigating the spectroscopic capabilities of the Euclid Near-Infrared Spectrometer and Photometer (NISP), in terms of continuum and emission line ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The kinematic and thermal Sunyaev-Zel’dovich (kSZ and tSZ) effects probe the abundance and thermodynamics of ionized gas in galaxies and clusters. We present a new hybrid estimator to measure the kSZ effect by combining ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
We perform a search for galaxy–galaxy strong lens systems using a convolutional neural network (CNN) applied to imaging data from the first public data release of the DECam Local Volume Exploration Survey, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
The solar atmosphere is filled with clusters of hot small-scale loops commonly known as coronal bright points (CBPs). These ubiquitous structures stand out in the Sun by their strong X-ray and/or ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
We have systematically investigated ultraviolet (UV) emission from molecular hydrogen (H2) using the Interface Region Imaging Spectrograph (IRIS), during three X-ray flares of C5.1, C9.7, and X1.0 classes ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We present a high sensitivity, ground-based spectral line survey of low- J carbon monoxide (CO( J up → J up − 1) with J up = 1, 2, 3) and neutral carbon [CI] 3 P 1 − 3 P 0 ([CI](1–0)) in 36 local ultra-luminous infrared ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT
We present the luminosity functions and host galaxy properties of the Dark Energy Survey (DES) core-collapse supernova (CCSN) sample, consisting of 69 Type II and 50 Type Ibc spectroscopically and ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
ABSTRACT We present spatially resolved H α properties of 21 type 1 AGN host galaxies at z ∼ 2 derived from the SUPER survey. These targets were observed with the adaptive optics capabilities of the SINFONI spectrograph, a ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. White-light continuum observations of solar flares often have coronal counterparts, including the classical ‘white-light prominence’ (WLP) phenomenon.
Aims. Coronal emissions by flares, seen in the white-light ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. In the solar spectrum, the Balmer series line H ε is a weak blend on the wing of Ca II H. Recent high-resolution H ε spectroheliograms reveal a reversed granulation pattern and in some cases, even unique structures. ...
(Master thesis / Masteroppgave, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The Mg ii h and k lines are among the best diagnostic tools of the upper solar chromosphere. This region of the atmosphere is of particular interest, as it is the lowest region of the Sun's atmosphere where the magnetic ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
We have developed an algorithm to identify solar spicules in the first ever systematic survey of on-disk spicules exclusively using Mg ii spectral observations. Using this algorithm we identify 2021 ...
(Doctoral thesis / Doktoravhandling, 2023)
Nanoflares are tiny, energetic explosions on the Sun—and we accidentally simulated one. This work focuses on the development and characteristics of a nanoflare-scale magnetic reconnection event that was simulated using our ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Magnetic reconnection in the deep solar atmosphere can give rise to enhanced emission in the Balmer hydrogen lines, a phenomenon referred to as Ellerman bombs.
Aims. To effectively trace magnetic reconnection ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Observations of center-to-limb variations (CLVs) of spectral lines and continua provide a good test for the accuracy of models with a solar and stellar atmospheric structure and spectral line formation. They are ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
The ponderomotive force has been suggested to be the main mechanism to produce the so-called first ionization potential (FIP) effect—the enrichment of low-FIP elements observed in the outer solar atmosphere, ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
Our understanding of magnetic reconnection (MR) under chromospheric conditions remains limited. Recent observations have demonstrated the important role of ion–neutral interactions in the dynamics of the ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The European Space Agency's Euclid mission will provide high-quality imaging for about 1.5 billion galaxies. A software pipeline to automatically process and analyse such a huge amount of data in real time is being developed ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
LiteBIRD, the Lite (Light) satellite for the study of B-mode polarization and Inflation from cosmic background Radiation Detection, is a space mission for primordial cosmology and fundamental physics. The Japan Aerospace ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
We present Atacama Large Millimetre/submillimetre Array (ALMA) CO(1–0) observations of the nearby infrared luminous (LIRG) galaxy pair IRAS 05054+1718 (also known as CGCG 468-002), as well as a new analysis of X-ray data ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract To recognize gravitational wave lensing events and being able to differentiate between similar lens models will be of crucial importance once one will be observing several lensing events of gravitational waves per ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The Copernican principle, the notion that we are not at a special location in the Universe, is one of the cornerstones of modern cosmology. Its violation would invalidate the Friedmann-Lemaître-Robertson-Walker ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Euclid ’s photometric galaxy cluster survey has the potential to be a very competitive cosmological probe. The main cosmological probe with observations of clusters is their number count, within which the halo mass function ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Fabry–Pérot interferometers (FPIs) have become very popular in solar observations because they offer a balance between cadence, spatial resolution, and spectral resolution through a careful design of the spectral ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Abstract
The element abundances in the solar corona and solar wind are often different from those of the solar photosphere, typically with a relative enrichment of elements with low first ionization potential ...
(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 ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Cosmological constraints from key probes of the Euclid imaging survey rely critically on the accurate determination of the true redshift distributions, n ( z ), of tomographic redshift bins. We determine whether the mean ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Within the extension of theΛCDMmodel, allowing for the presence of neutrinos or warm dark matter, we develop the analytical cosmological perturbation theory. It covers all spatial scales where the weak gravitational field ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
The Euclid space telescope will survey a large dataset of cosmic voids traced by dense samples of galaxies. In this work we estimate its expected performance when exploiting angular photometric void clustering, galaxy weak ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The smallest extreme-ultraviolet (EUV) brightening events that were detected so far, called campfires, have recently been uncovered by the High Resolution EUV telescope (HRI EUV ), which is part of the Extreme ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. The H α line, one of the most studied chromospheric diagnostics, is a tracer of magnetic field structures, while the intensity of its line core provides an estimate of the mass density. The interpretation of H α ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context. Low-altitude nanoflares are among the candidates for atmospheric heating in the quiet Sun’s corona. Low-altitude twisted magnetic fields may be involved in such events, as they are in larger flares. But for ...
(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
Context . Three-dimensional non-local thermodynamical equilibrium (NLTE) radiative transfer calculations are a fundamental tool for a detailed spectral analysis in stellar atmospheres, but require vast amounts of computer ...