Browsing Institutt for teoretisk astrofysikk by Title
Now showing items 4-23 of 1243
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)Coronal bright points (CBPs) are ubiquitous structures in the solar atmosphere composed of hot small-scale loops observed in extreme-ultraviolet (EUV) or X-rays in the quiet Sun and coronal holes. They are key elements to ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)Context. Magnetic reconnection is a fundamental mechanism in astrophysics. A common challenge in mimicking this process numerically in particular for the Sun is that the solar electrical resistivity is small compared to ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)We present the first linear polarization measurements from the 2015 long-duration balloon flight of Spider, which is an experiment that is designed to map the polarization of the cosmic microwave background (CMB) on degree ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)We present a constraint on the tensor-to-scalar ratio, r, derived from measurements of cosmic microwave background (CMB) polarization B-modes with “delensing,” whereby the uncertainty on r contributed by the sample variance ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)We have demonstrated that the transition region adaptive conduction (TRAC) method permits fast and accurate numerical solutions of the field-aligned hydrodynamic equations, successfully removing the influence of numerical ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)ABSTRACT Type Ia supernovae (SNe Ia) are used as standardizable candles to measure cosmological distances, but differences remain in their corrected luminosities which display a magnitude step as a function of ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)In this paper, we study the effective field theory (EFT) of dark energy (DE) for the k-essence model beyond linear order. Using particle-mesh N-body simulations that consistently solve the DE evolution on a grid, we find ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)In recent decades our understanding of solar active regions (ARs) has improved substantially due to observations made with better angular resolution and wider spectral coverage. While prior AR observations have shown that ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)ABSTRACT We demonstrate that highly accurate joint redshift–stellar mass probability distribution functions (PDFs) can be obtained using the Random Forest (RF) machine learning (ML) algorithm, even with few ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)ABSTRACT Current post-processing techniques for the correction of atmospheric seeing in solar observations – such as Speckle interferometry and Phase Diversity methods – have limitations when it comes to their ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)We review and compare two different cosmic microwave background (CMB) dipole estimators discussed in the literature and assess their performances through Monte Carlo simulations. The first method amounts to simple template ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)Context. Penumbral microjets (PMJs) are short-lived, jet-like objects found in the penumbra of sunspots. They were first discovered in chromospheric lines and have later also been shown to exhibit signals in transition ...
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(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 ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)We present a new analytical equation of state (EOS), which correctly models high pressure theory and fits well to the experimental data of ɛ-Fe, SiO2, Mg2, and the Earth. The cold part of the EOS is modeled after the Varpoly ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)Observed FeO/MgO ratios in the Moon and Earth are inconsistent with simulations done with a single homogeneous silicate layer. In this paper we use a newly developed equation of state to perform smoothed particle hydrodynamics ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)Abstract The Interface Region Imaging Spectrograph (IRIS) has been obtaining near- and far-ultraviolet images and spectra of the solar atmosphere since July 2013. IRIS is the highest resolution observatory to provide ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)The umbral regions of sunspots and pores in the solar photosphere are generally dominated by 3 mHz oscillations, which are due to p -modes penetrating the magnetic region. In these locations, wave power is also significantly ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)The magnetic field governs the corona; hence, it is a crucial parameter to measure. Unfortunately, existing techniques for estimating its strength are limited by strong assumptions and limitations. These techniques include ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)Context. A new and hitherto unknown cosmic microwave background (CMB) foreground has recently been detected. A systematic decrease in CMB temperatures around nearby large spiral galaxies points to an unknown interaction ...
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(Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)Although thousands of galaxy mergers are known, only a handful of sub-kiloparsec-scale supermassive black hole (SMBH) pairs have been confirmed so far, leaving a huge gap between the observed and predicted numbers of such ...