Browsing Institutt for teoretisk astrofysikk by Title

Now showing items 117-136 of 1257

  • The cause of spatial structure in solar He i 1083 nm multiplet images 
    Leenaarts, Jorrit; Golding, Thomas Peter; Carlsson, Mats; Libbrecht, Tine; Joshi, Jayant (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2016)
    Context. The He i 1083 nm is a powerful diagnostic for inferring properties of the upper solar chromosphere, in particular for the magnetic field. The basic formation of the line in one-dimensional models is well understood, ...
  • Center-to-limb variation of spectral lines and continua observed with SST/CRISP and SST/CHROMIS 
    Pietrow, A.G.M.; Kiselman, D.; Andriienko, O.; Petit dit de la Roche, D. J. M.; Díaz Baso, Carlos José; Calvo, F. (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 ...
  • Chameleon fields and Gravitational waves 
    Ninive, Per Harald (Master thesis / Masteroppgave, 2009)
    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 ...
  • Chameleon model with field-dependent couplings 
    Winther, Hans Arnold (Master thesis / Masteroppgave, 2010)
    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 ...
  • CHANDRA and XMM-NEWTON OBSERVATIONS OF THE MERGING CLUSTER OF GALAXIES PLCK G036.7+14.9 
    Zhang, B; David, L. P.; Jones, C.; Andrade-Santos, F.; O'Sullivan, E.; Dahle, Håkon; Nulsen, P. E. J.; Clarke, T. E.; Pointecouteau, E; Pratt, G. W.; Arnaud, M.; Vrtilek, J. M.; Ji, L.; van Weeren, R. J.; Kraft, R. P.; Kong, X. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    We present Chandra and XMM-Newton observations of PLCK G036.7+14.9 from the Chandra–Planck Legacy Program. The high resolution X-ray observations reveal two close (~72'' = 193 kpc in projection) subclusters, G036N and ...
  • Chandra measurements of a complete sample of X-ray luminous galaxy clusters: The luminosity-mass relation 
    Giles, P. A.; Maughan, B. J.; Dahle, Håkon; Bonamente, M.; Landry, D.; Jones, C.; Joy, M.; Murray, S. S.; van der Pyl, N. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    We present the results of work involving a statistically complete sample of 34 galaxy clusters, in the redshift range 0.15 ≤ z ≤ 0.3 observed with Chandra. We investigate the luminosity–mass (LM) relation for the cluster ...
  • Characterising coronal turbulence using snapshot imaging of radio bursts in 80–200 MHz 
    Mohan, Atul (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2021)
    Context. Metrewave solar type-III radio bursts offer a unique means to study the properties of turbulence across coronal heights. Theoretical models have shown that the apparent intensity and size of the burst sources ...
  • Characteristic Features of Gravitational Wave Lensing as Probe of Lens Mass Model 
    Cremonese, Paolo; Mota, David; Salzano, Vincenzo (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 ...
  • Characteristic functions for cosmological cross-correlations 
    Breysse, Patrick C.; Chung, Dongwoo T.; Ihle, Håvard Tveit (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    ABSTRACT We introduce a novel unbiased, cross-correlation estimator for the one-point statistics of cosmological random fields. One-point statistics are a useful tool for analysis of highly non-Gaussian density ...
  • Characterization and formation of on-disk spicules in the Ca II K and Mg II k spectral lines 
    Bose, Souvik; de Jorge Henriques, Vasco Manuel; Joshi, Jayant; Rouppe van der Voort, Luc (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    We characterize, for the first time, type-II spicules in Ca II K 3934 Å using the CHROMIS instrument at the Swedish 1 m Solar Telescope. We find that their line formation is dominated by opacity shifts with the K3 minimum ...
  • Characterization of shock wave signatures at millimetre wavelengths from Bifrost simulations 
    Eklund, Henrik; Wedemeyer, Sven; Snow, Ben; Jess, David B.; Jafarzadeh, Shahin; Grant, Samuel D. T.; Carlsson, Mats; Szydlarski, Mikolaj Marcin (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Observations at millimetre wavelengths provide a valuable tool to study the small-scale dynamics in the solar chromosphere. We evaluate the physical conditions of the atmosphere in the presence of a propagating shock wave ...
  • Characterizing the intracluster light over the redshift range 0.2 < z < 0.8 in the DES-ACT overlap 
    Golden-Marx, Jesse B.; Zhang, Y.; Ogando, R.L.C.; Allam, S.; Tucker, D.L.; Miller, C.J.; Hilton, M.; Mutlu-Pakdil, B.; Abbott, T.M.C.; Aguena, M.; Alves, O.; Andrade-Oliveira, F.; Annis, J.; Bacon, D.; Bertin, E.; Bocquet, S.; Brooks, D.; Burke, D.L.; Carnero Rosell, A.; Carrasco Kind, M.; Castander, F.J.; Conselice, C.; Costanzi, M.; da Costa, L.N.; Pereira, M.E.S.; De Vicente, J.; Desai, S.; Doel, P.; Everett, S.; Ferrero, Ismael; Flaugher, B.; Frieman, J.; García-Bellido, J.; Gerdes, D.W.; Gruen, D.; Gruendl, R.A.; Gutierrez, G.; Hinton, S.R.; Hollowood, D.L.; Honscheid, K.; James, D.J.; Kuehn, K.; Kuropatkin, N.; Lahav, O.; Marshall, J.L.; Melchior, P.; Mena-Fernández, J.; Miquel, R.; Mohr, J.J.; Palmese, A.; Paz-Chinchón, F.; Pieres, A.; Plazas Malagón, A.A.; Prat, J.; Raveri, M.; Rodriguez-Monroy, M.; Romer, A.K.; Sanchez, E.; Scarpine, V.; Sevilla-Noarbe, I.; Sifón, C.; Smith, M.; Suchyta, E.; Swanson, M.E.C.; Tarle, G.; Vincenzi, M.; Weaverdyck, N.; Yanny, B. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    ABSTRACT We characterize the properties and evolution of bright central galaxies (BCGs) and the surrounding intracluster light (ICL) in galaxy clusters identified in the Dark Energy Survey and Atacama Cosmology ...
  • Characterizing Ultraviolet Bursts in a Solar Coronal Hole using Machine Learning Techniques 
    Faber, Jonas Thoen (Master thesis / Masteroppgave, 2022)
    The Interface Region Imaging Spectrograph (IRIS) provides simultaneous imaging and spectral data of the chromosphere and transition region (TR) with great spatial, spectral and temporal resolution. A Solar coronal hole ...
  • Charged Black Hole Mergers: Emissions, Orbital Evolution, Gravitational Waveform and Observer Bias 
    Christiansen, Øyvind (Master thesis / Masteroppgave, 2020)
    Gravitational waveforms from mergers or close-encounters of astrophysical compact bodies provide a new and separate window into high energy physics and dark objects. Although there is a zoo of theoretical compact objects ...
  • Charged black hole mergers: Orbit circularisation and chirp mass bias 
    Christiansen, Øyvind; Jiménez, Jose Beltrán; Mota, David (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2021)
    We consider the inspiral of black holes carrying U(1) charge that is not electromagnetic, but corresponds to some dark sector. In the weak-field, low-velocity regime, the components follow Keplerian orbits. We investigate ...
  • Chemical Analysis of the Brightest Star of the Cetus II Ultrafaint Dwarf Galaxy Candidate 
    Webber, K.B.; Hansen, T.T.; Marshall, J.L.; Simon, J.D.; Pace, A.B.; Mutlu-Pakdil, B.; Drlica-Wagner, A.; Martínez-Vázquez, C.E.; Aguena, M.; Allam, S.S.; Alves, O.; Bertin, E.; Brooks, D.; Carnero Rosell, A.; Carretero, J.; da Costa, L.N.; De Vicente, J.; Doel, P.; Ferrero, Ismael; Friedel, D.; Frieman, J.; García-Bellido, J.; Giannini, G.; Gruen, D.; Gruendl, R.A.; Hinton, S.R.; Hollowood, D.L.; Honscheid, K.; Kuehn, K.; Mena-Fernández, J.; Menanteau, F.; Miquel, R.; Ogando, R.L.C.; Pereira, M.E.S.; Pieres, A.; Plazas Malagón, A.A.; Sanchez, E.; Santiago, B.; Smith, J. Allyn; Smith, M.; Suchyta, E.; Tarle, G.; To, C.; Weaverdyck, N.; Yanny, B. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2023)
    Abstract We present a detailed chemical abundance analysis of the brightest star in the ultrafaint dwarf (UFD) galaxy candidate Cetus II from high-resolution Magellan/MIKE spectra. For this star, DES J011740.53-173053, ...
  • Chemical Analysis of the Ultrafaint Dwarf Galaxy Grus II. Signature of High-mass Stellar Nucleosynthesis 
    Hansen, Terese T.; Marshall, Jennifer L.; Simon, J. D.; Li, Ting S.; Bernstein, R. A.; Pace, A. B.; Ferguson, P.; Nagasawa, D. Q.; Kuehn, Kyler; Carollo, Daniela; Geha, Marla; James, David; Walker, Alistair; Diehl, H. T.; Aguena, M.; Allam, S.; Avila, S.; Bertin, E.; Brooks, David; Buckley-Geer, E.; Burke, David L.; Carnero Rosell, A.; Carrasco Kind, Matias; Carretero, J.; Costanzi, M.; Da Costa, L. N.; Desai, S.; De Vicente, J.; Doel, P.; Eckert, Kathleen; Eifler, T. F.; Everett, S.; Ferrero, Ismael; Frieman, J.; García-Bellido, Juan; Gaztanaga, E.; Gerdes, David W.; Gruen, Daniel; Gruendl, Robert A.; Gschwend, J.; Gutierrez, G.; Hinton, Samuel R.; Hollowood, Devon L.; Honscheid, K.; Kuropatkin, N.; Maia, M. A. G.; March, M.; Miquel, Ramon; Palmese, Antonella; Paz-Chinchón, Francisco; Plazas, Andrés A.; Sanchez, E.; Santiago, B.; Scarpine, V.; Serrano, S.; Smith, Mathew; Soares-Santos, Marcelle; Suchyta, E.; Swanson, M. E. C.; Tarle, G.; Varga, T. N.; Wilkinson, R. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
  • Chemical enrichment of stars due to accretion from the ISM during the Galaxy's assembly 
    Shen, Sijing; Kulkarni, Girish; Madau, Piero; Mayer, Lucio (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    Using the Eris zoom-in cosmological simulation of assembly of a Milky Way analogue, we study the chemical enrichment of stars due to accretion of metal-enriched gas from the interstellar medium (ISM) during the Galaxy's ...
  • Chromospheric counterparts of solar transition region unresolved fine structure loops 
    Mendes Domingos Pereira, Tiago; Rouppe van der Voort, Luc; Hansteen, Viggo; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    Low-lying loops have been discovered at the solar limb in transition region temperatures by the Interface Region Imaging Spectrograph (IRIS). They do not appear to reach coronal temperatures, and it has been suggested that ...
  • Chromospheric emission from nanoflare heating in RADYN simulations 
    Bakke, Helle; Carlsson, Mats; Rouppe van der Voort, Luc; Gudiksen, Boris Vilhelm; Polito, V.; Testa, Paola; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2022)
    Context. Heating signatures from small-scale magnetic reconnection events in the solar atmosphere have proven to be difficult to detect through observations. Numerical models that reproduce flaring conditions are essential ...