Now showing items 41-60 of 735

  • Jimenez, Jose Beltran; Golovnev, A.; Karčiauskas, Mindaugas; Koivisto, Tomi Sebastian (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2012)
    The bimetric variational principle is a subtle reinterpretation of general relativity that assumes the spacetime connection to be generated by an independent metric. Unlike the so-called Palatini formalism that promotes ...
  • Khodadi, Mohsen; Allahyari, Alireza; Vagnozzi, Sunny; Mota, David (Journal article / Tidsskriftartikkel / AcceptedVersion; Peer reviewed, 2020)
    Searching for violations of the no-hair theorem (NHT) is a powerful way to test gravity, and more generally fundamental physics, particularly with regards to the existence of additional scalar fields. The first observation ...
  • Hansteen, Viggo; Archontis, Vasilis; Mendes Domingos Pereira, Tiago; Carlsson, Mats; Rouppe van der Voort, Luc; Leenaarts, Jorrit (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    A spectacular manifestation of solar activity is the appearance of transient brightenings in the far wings of the Hα line, known as Ellerman bombs (EBs). Recent observations obtained by the Interface Region Imaging ...
  • Hagstotz, Steffen; Gronke, Max Balthasar; Mota, David; Baldi, Marco (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
    Searches for modified gravity in the large-scale structure try to detect the enhanced amplitude of density fluctuations caused by the fifth force present in many of these theories. Neutrinos, on the other hand, suppress ...
  • Salzano, Vincenzo; Mota, David; Capoziello, S.; Donahue, Megan (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2017)
    © 2017 American Physical Society
  • Chintzoglou, G.; De Pontieu, Bart Walter; Martinez-Sykora, Juan; Pereira, Tiago Mendes Domingos; Vourlidas, A.; Beltran, Samuel Tun (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present results from an observing campaign in support of the VAULT2.0 sounding rocket launch on 2014 September 30. VAULT2.0 is a Lyα (1216 Å) spectroheliograph capable of providing spectroheliograms at high cadence. Lyα ...
  • McGreer, Ian D; Clément, Benjamin; Mainali, Ramesh; Stark, Daniel P.; Gronke, Max Balthasar; Dijkstra, Mark; Fan, Xiaohui; Bian, Fuyan; Frye, Brenda; Jiang, Linhua; Kneib, Jean-Paul; Limousin, Marceau; Walth, Gregory (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2018)
    We present a detailed study of an unusually bright, lensed galaxy at z = 5.424 discovered within the CFHTLS imaging survey. With an observed flux ofiAB =23.0, J141446.82+544631.9 is one of the brightest galaxies known at ...
  • Rigby, J. R.; Bayliss, M. B.; Gladders, M. D.; Sharon, K.; Wuyts, E; Dahle, Håkon; Johnson, T.; Peña-Guerrero, M. (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2015)
    We measure [C iii] 1907, C iii] 1909 Å emission lines in 11 gravitationally lensed star-forming galaxies at z ~ 1.6–3, finding much lower equivalent widths than previously reported for fainter lensed galaxies. While it is ...
  • Wang, Deng; Mota, David (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Motivated by the discrepancy in measurements of H0 between local and global probes, we investigate whether teleparallel gravities could be a better model to describe the present-day observations or at least to alleviate ...
  • Polito, Vanessa; Testa, Paola; De Pontieu, Bart Walter (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2019)
  • González Manrique, Sergio Javier; Quintero Noda, Carlos; Kuckein, Christoph; Ruiz Cobo, Basilio; Carlsson, Mats (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    We examine the capabilities of a fast and simple method to infer line-of-sight (LOS) velocities from observations of the photospheric Si  I 10 827 Å line. This spectral line is routinely observed together with the chromospheric ...
  • Joshi, Reetika; Chandra, Ramesh; Schmieder, Brigitte; Moreno-Insertis, Fernando; Aulanier, Guillaume; Nóbrega Siverio, Daniel Elias; Devi, Pooja (Journal article / Tidsskriftartikkel / PublishedVersion; Peer reviewed, 2020)
    Context. Hot coronal jets are a basic observed feature of the solar atmosphere whose physical origin is still actively debated. Aims. We study six recurrent jets that occurred in active region NOAA 12644 on April 4, 2017. ...
  • 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, ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...
  • 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 ...