Search Results - "Björnsson, Gunnlaugur"

Gamma-Ray Burst Host Galaxies: Specific Star Formation Rate versus Metallicity by Björnsson, Gunnlaugur

“…The observed properties of long gamma-ray burst (GRB) host galaxies show them to often be of a rather low metallicity and/or of high specific star formation…”
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Afterglow Light Curves and Broken Power Laws: A Statistical Study by Jóhannesson, Gudlaugur, Björnsson, Gunnlaugur, Gudmundsson, Einar H

“…In gamma-ray burst research, it is quite common to fit the afterglow light curves with a broken power law to interpret the data. We apply this method to a…”
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Dark Energy and the Observable Universe by Gudmundsson, Einar H, Björnsson, Gunnlaugur

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Host galaxies of gamma-ray bursts and their cosmological evolution by Courty, Stéphanie, Björnsson, Gunnlaugur, Gudmundsson, Einar H.

“…ABSTRACT We use numerical simulations of large‐scale structure formation to explore the cosmological properties of gamma‐ray burst (GRB) host galaxies. Among…”
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Polarimetric Constraints on the Optical Afterglow Emission from GRB 990123 by Hjorth, Jens, Björnsson, Gunnlaugur, Andersen, Michael I., Caon, Nicola, Cairós, Luz Marina, Castro-Tirado, Alberto J., María Rosa Zapatero Osorio, Pedersen, Holger, Costa, Enrico

“…Polarization of the optical emission from GRB 990123 was measured on 24.17 January 1999 universal time with the Nordic Optical Telescope. An upper limit of…”
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Energy Injection in Gamma-Ray Burst Afterglow Models by Jóhannesson, Gudlaugur, Björnsson, Gunnlaugur, Gudmundsson, Einar H

“…We extend the standard fireball model, widely used to interpret gamma-ray burst (GRB) afterglow light curves, to include energy injections and apply the model…”
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Gamma-Ray Burst Host Galaxies: Specific Star Formation Rate vs. Metallicity by Björnsson, Gunnlaugur

“…ApJ 887, 219 (2019) The observed properties of long gamma-ray burst (GRB) host galaxies show them to often be of a rather low metallicity and/or of high…”
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Cosmological observations in a closed universe by Björnsson, Gunnlaugur, Gudmundsson, Einar H.

“…We investigate how a closed Friedmann-Robertson-Walker universe would appear to astronomers living at different cosmic epochs. For this purpose we apply the…”
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The Afterglow and Complex Environment of the Optically Dim Burst GRB 980613 by Hjorth, Jens, Thomsen, Bjarne, Nielsen, Svend R, Andersen, Michael I, Holland, Stephen T, Fynbo, Johan U, Pedersen, Holger, Jaunsen, Andreas O, Halpern, Jules P, Fesen, Robert, Gorosabel, Javier, Castro-Tirado, Alberto, McMahon, Richard G, Hoenig, Michael D, Björnsson, Gunnlaugur, Amati, Lorenzo, Tanvir, Nial R, Natarajan, Priyamvada

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Low-energy electrons in GRB afterglow models by Jóhannesson, Guðlaugur, Björnsson, Gunnlaugur

“…Observations of gamma-ray burst (GRB) afterglows have long provided the most detailed information about the origin of this spectacular phenomena. The model…”
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The Polarization Variability in the Optical Afterglow of GRB 990712 by Björnsson, Gunnlaugur, Lindfors, Elina J

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Optically thin accretion disks in the Kerr metric by Bjornsson, G.

“…We calculate the structure of an effectively optically thin and geometrically thin accretion disk in the Kerr geometry, including electron-positron pairs. We…”
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Hot Accretion Disks Revisited by Bjoernsson, Gunnlaugur, Abramowicz, Marek A., Chen, Xingming, Lasota, Jean-Pierre

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Polarization in GRB Afterglows by Björnsson, Gunnlaugur

“…Polarization has been observed in a number of GRB afterglows. We briefly review the models that have been proposed to account for the observed polarization…”
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Accretion Disks Phase Transitions: 2-D or Not 2-D? by Abramowicz, Marek A., Björnsson, Gunnlaugur, Igumenshchev, Igor V.

“…Abstract We argue that the proper way to treat thin-thick accretion-disk transitions should take into account the 2-D nature of the problem. We illustrate the…”
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On the stability of electron–positron pair equilibria and the X-ray variability of active galactic nuclei by Björnsson, Gunnlaugur, Svensson, Roland

“…We perform a detailed linear stability analysis of pair equilibria in homogeneous, static two-temperature plasma clouds. We consider the case in which…”
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Luminosity Functions of Gamma-Ray Burst Afterglows by Jóhannesson, Guðlaugur, Björnsson, Gunnlaugur, Gudmundsson, Einar H

“…Aims: Use the standard fireball model to create virtual populations of gamma-ray burst afterglows and study their luminosity functions. Methods: We randomly…”
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Afterglow Light Curves and Broken Power Laws: A Statistical Study by Jóhannesson, Gudlaugur, Björnsson, Gunnlaugur, Gudmundsson, Einar H

“…Astrophys.J. 640 (2006) L5-L8 In gamma-ray burst research it is quite common to fit the afterglow light curves with a broken power law to interpret the data…”
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The afterglow and complex environment of the optically dim burst GRB 980613 by Hjorth, Jens, Thomsen, Bjarne, Nielsen, Svend R, Andersen, Michael I, Holland, Stephen T, Fynbo, Johan U, Pedersen, Holger, Jaunsen, Andreas O, Halpern, Jules P, Fesen, Robert, Gorosabel, Javier, Castro-Tirado, Alberto, McMahon, Richard G, Hoenig, Michael D, Björnsson, Gunnlaugur, Amati, Lorenzo, Tanvir, Nial R, Natarajan, Priyamvada

“…Astrophys.J. 576 (2002) 113-119 We report the identification of the optical afterglow of GRB 980613 in R- and I-band images obtained between 16 and 48 hours…”
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A study of electron-positron pair equilibria in models of compact X- and gamma-ray sources by Bjornsson, Gunnlaugur

“…This thesis studies thermal electron-positron pair equilibria in two temperature models of compact $X$- and $\gamma$-ray sources. The radiation field is taken…”
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