Academic interests
Theoretical physics and cosmology with focus on gravitation, including general relativity and modified gravity. My research can be found at Inspire, arXiv or Orcid. My reviews are tracked at Publons.
Current teaching:
Background
- PhD in Cosmology, Institute of Theoretical Astrophysics (University of Oslo), 2014.
Thesis title: Cosmologies with Gauge Vector Interactions.
- Master in theoretical physics, University of Oslo, 2010.
Awards
Publications
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Normann, Ben David; Ricciardone, Angelo; Hervik, Sigbjørn & Thorsrud, Mikjel
(2022).
A study of inhomogeneous massless scalar gauge fields in cosmology.
International Journal of Modern Physics, Conference Series.
ISSN 2010-1945.
p. 1378–1883.
doi:
10.1142/9789811258251_0199.
Full text in Research Archive
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Thorsrud, Mikjel
(2015).
Quintessence with Kaluza-Klein type couplings to matter and an isotropy-violating vector field,
The Thirteenth Marcel Grossmann Meeting: On Recent Developments in Theoretical and Experimental General Relativity, Astrophysics, and Relativistic Field Theories.
World Scientific.
ISSN 978-981-4612-14-2.
p. 1561–1563.
doi:
10.1142/9789814623995_0224.
Show summary
We study the dynamics of a scalar field with Kaluza-Klein type couplings to cold dark matter and an isotropy-violating vector field. The vector coupling, f2(ϕ)F2, has been studied thoroughly in the context of inflation recently. We generalize the model to a dark energy context and study the cosmological consequences. We find a rich set of exact anisotropic power-law solutions and identify a strong vector coupling regime where the anisotropy is controllable and all solutions are close to the ΛCDM limit.
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View all works in Cristin
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Thorsrud, Mikjel
(2019).
Gravitasjon på skrivebordet.
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Thorsrud, Mikjel
(2018).
Shear-Free Cosmological Solutions And Their Stability.
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Thorsrud, Mikjel
(2015).
Horndeski’s Vector-Tensor Theory.
Show summary
Horndeski formulated a most general vector-tensor theory that reduces to ordinary electrodynamics in a flat spacetime, in which the dynamical equations are of second order and the vector field respects the gauge symmetry. The theory is remarkably simple containing only a single free parameter which controls the strength of the vector's coupling to gravity. In this talk I will give a short introduction to the theory and report on our attempts to understand its stability and phenomenological consequences, focusing mainly on a cosmological context.
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Urban, Federico; Mota, David & Thorsrud, Mikjel
(2014).
Bubble observers in Bubbland [ARISF, Paris, pp. 255-258 (2014)].
Show summary
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Thorsrud, Mikjel
(2013).
Inflation with vector interactions.
Show summary
Vector fields are usually assumed to decay away exponentially fast during inflation and therefore ignored. Nevertheless, with an appropriate coupling to the inflaton, vectors may play an interesting role. In this talk I will first give an introduction to inflation with the f^2F^2 interaction and review some of its rich phenomenology. Next I will focus on the role of super horizon vector fluctuations and their contribution to the primordial power spectrum. Contrary to the contribution from the background vector, their contribution is not deterministically determined by background parameters. Instead the huge cosmic variance associated with large scale fluctuations requires a stochastic approach and the prediction is in terms of a probability distribution function (PDF) which we estimate by Monte-Carlo simulations.
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Thorsrud, Mikjel
(2013).
Cosmologies in Horndeski's vector-tensor theory.
Show summary
In 1976 Horndeski formulated a most general vector-tensor theory in which the vector field respects the gauge symmetry and the resulting dynamical equations are of second order. In a flat spacetime background the theory reduces to ordinary electrodynamics. The theory is remarkably simple containing only a single free parameter which controlst he strength of the vector's coupling to gravity. Until very recently, the cosmological consequences of this theory remained unexplored. In this talk I will introduce you to the theory and tell you about our attempts to understand its consequences in a cosmological context.
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Thorsrud, Mikjel
(2012).
Doubly Coupled Quintessence.
Show summary
Motivated by the couplings of the dilaton in four-dimensional effective actions, we investigate the cosmological consequences of a scalar field coupled both to matter and a Maxwell-type vector field. The vector field has a background isotropy-violating component. New anisotropic scaling solutions which can be responsible for the matter and dark energy dominated epochs are identified and explored. For a large parameter region the universe expands almost isotropically. Using that the CMB quadrupole is extremely sensitive to shear, we constrain the ratio of the matter coupling to the vector coupling to be less than 10-5. Moreover, we identify a large parameter region, corresponding to a strong vector coupling regime, yielding exciting and viable cosmologies close to the LCDM limit.
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Thorsrud, Mikjel
(2012).
Dynamical System Approach to Non-minimal Matter Couplings.
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Thorsrud, Mikjel
(2012).
Quintessence with Kaluza-Klein type couplings to matter and an isotropy-violating vector field.
Show summary
We study the dynamics of a scalar field with Kaluza-Klein type couplings to cold dark matter and an isotropy-violating vector field. The vector coupling, f2(ϕ)F2, has been studied thoroughly in the context of inflation recently. We generalize the model to a dark energy context and study the cosmological consequences. We find a rich set of exact anisotropic power-law solutions and identify a strong vector coupling regime where the anisotropy is controllable and all solutions are close to the ΛCDM limit.
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Thorsrud, Mikjel
(2011).
Inflation with Stable Anisotropic Hair.
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Thorsrud, Mikjel
(2011).
Stability of Anisotropic Inflation.
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Thorsrud, Mikjel
(2014).
Cosmologies with Gauge Vector Interactions.
Akademika forlag.
ISSN 1501-7710.
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View all works in Cristin
Published June 12, 2018 4:17 PM
- Last modified Oct. 18, 2021 4:10 PM
