Change search
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf
Cosmic tests of massive gravity
Stockholm University, Faculty of Science, Department of Physics. (Cosmology, Particle Astrophysics and String Theory group)
2015 (English)Doctoral thesis, comprehensive summary (Other academic)
Abstract [en]

Massive gravity is an extension of general relativity where the graviton, which mediates gravitational interactions, has a non-vanishing mass. The first steps towards formulating a theory of massive gravity were made by Fierz and Pauli in 1939, but it took another 70 years until a consistent theory of massive gravity was written down. This thesis investigates the phenomenological implications of this theory, when applied to cosmology. In particular, we look at cosmic expansion histories, structure formation, integrated Sachs-Wolfe effect and weak lensing, and put constraints on the allowed parameter range of the theory. This is done by using data from supernovae, the cosmic microwave background, baryonic acoustic oscillations, galaxy and quasar maps and galactic lensing.

The theory is shown to yield both cosmic expansion histories, galactic lensing and an integrated Sachs-Wolfe effect consistent with observations. For the structure formation, however, we show that for certain parameters of the theory there exists a tension between consistency relations for the background and stability properties of the perturbations. We also show that a background expansion equivalent to that of general relativity does not necessarily mean that the perturbations have to evolve in the same way.

Place, publisher, year, edition, pages
Stockholm: Department of Physics, Stockholm University , 2015. , 104 p.
Keyword [en]
Modified gravity, massive gravity, cosmology, dark energy, dark matter
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Physics
Identifiers
URN: urn:nbn:se:su:diva-113076ISBN: 978-91-7649-049-5 (print)OAI: oai:DiVA.org:su-113076DiVA: diva2:782791
Public defence
2015-02-20, sal FD5, AlbaNova Universitetscentrum, Roslagstullsbacken 21, Stockholm, 13:00 (English)
Opponent
Supervisors
Note

At the time of the doctoral defense, the following papers were unpublished and had a status as follows: Paper 5: Manuscript. Paper 6: Manuscript.

Available from: 2015-01-29 Created: 2015-01-22 Last updated: 2015-08-24Bibliographically approved
List of papers
1. Cosmological solutions in bimetric gravity and their observational tests
Open this publication in new window or tab >>Cosmological solutions in bimetric gravity and their observational tests
Show others...
2012 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 3, 042- p.Article in journal (Refereed) Published
Abstract [en]

We obtain the general cosmological evolution equations for a classically consistent theory of bimetric gravity. Their analytic solutions are demonstrated to generically allow for a cosmic evolution starting out from a matter dominated FLRW universe and relaxing towards a de Sitter (anti-de Sitter) phase at late cosmic time. In particular, we examine a subclass of models which contain solutions that are able to reproduce the expansion history of the cosmic concordance model inspite of the nonlinear couplings of the two metrics. This is demonstrated explicitly by fitting these models to observational data from Type Ia supernovae, Cosmic Microwave Background and Baryon Acoustic Oscillations. In the appendix we comment on the relation to massive gravity.

Keyword
modified gravity, dark energy theory
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Theoretical Physics
Identifiers
urn:nbn:se:su:diva-83245 (URN)10.1088/1475-7516/2012/03/042 (DOI)000302949600042 ()
Available from: 2012-12-06 Created: 2012-12-06 Last updated: 2017-12-07Bibliographically approved
2. Growth histories in bimetric massive gravity
Open this publication in new window or tab >>Growth histories in bimetric massive gravity
Show others...
2012 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 12, 021- p.Article in journal (Refereed) Published
Abstract [en]

We perform cosmological perturbation theory in Hassan-Rosen bimetric gravity for general homogeneous and isotropic backgrounds. In the de Sitter approximation, we obtain decoupled sets of massless and massive scalar gravitational fluctuations. Matter perturbations then evolve like in Einstein gravity. We perturb the future de Sitter regime by the ratio of matter to dark energy, producing quasi-de Sitter space. In this more general setting the massive and massless fluctuations mix. We argue that in the quasi-de Sitter regime, the growth of structure in bimetric gravity differs from that of Einstein gravity.

Keyword
modified gravity, cosmological parameters from LSS, dark energy theory
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-87679 (URN)10.1088/1475-7516/2012/12/021 (DOI)000312959800021 ()
Funder
Swedish Research Council
Note

AuthorCount:5;

Available from: 2013-02-15 Created: 2013-02-14 Last updated: 2017-12-06Bibliographically approved
3. Strong lensing constraints on bimetric massive gravity
Open this publication in new window or tab >>Strong lensing constraints on bimetric massive gravity
2013 (English)In: Journal of High Energy Physics (JHEP), ISSN 1126-6708, E-ISSN 1029-8479, no 10, 031- p.Article in journal (Refereed) Published
Abstract [en]

We derive dynamical and gravitational lensing properties of local sources in the Hassan-Rosen bimetric gravity theory. Observations of elliptical galaxies rule out values of the effective length-scale of the theory, in units of the Hubble radius, in the interval 10(-6). lambda(g) = rH less than or similar to 10(-3), unless the proportionality constant between the metrics at the background level is far from unity, in which case general relativity is effectively restored for local sources. In order to have background solutions resembling the concordance cosmological model, without fine-tuning of the parameters of the model, we are restricted to the upper interval, or lambda(g) /gamma H similar to 1, for which the Vainshtein mechanism is expected to restore general relativity for local sources. Except for a limited range of parameter values, the Hassan-Rosen theory is thus consistent with the observed lensing and dynamical properties of elliptical galaxies.

Keyword
Classical Theories of Gravity, Black Holes
National Category
Physical Sciences
Identifiers
urn:nbn:se:su:diva-95746 (URN)10.1007/JHEP10(2013)031 (DOI)000325222700002 ()
Note

AuthorCount:2;

Available from: 2013-11-06 Created: 2013-11-04 Last updated: 2017-12-06Bibliographically approved
4. Cosmic expansion histories in massive bigravity with symmetric matter coupling
Open this publication in new window or tab >>Cosmic expansion histories in massive bigravity with symmetric matter coupling
2015 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 1, 006Article in journal (Refereed) Published
Abstract [en]

We study the cosmic expansion history of massive bigravity with a viable matter coupling which treats both metrics on equal footing. We derive the Friedmann equation for the effective metric through which matter couples to the two metrics, and study its solutions. For certain parameter choices, the background cosmology is identical to that of LCDM. More general parameters yield dynamical dark energy, which can still be in agreement with observations of the expansion history. We study specific parameter choices of interest, including minimal models, maximally-symmetric models, and a candidate partially-massless theory.

Keyword
modified gravity, dark energy theory
National Category
Astronomy, Astrophysics and Cosmology
Research subject
Physics
Identifiers
urn:nbn:se:su:diva-112949 (URN)10.1088/1475-7516/2015/01/006 (DOI)000349283000006 ()
Available from: 2015-01-19 Created: 2015-01-19 Last updated: 2017-12-05Bibliographically approved
5. Cosmological viability of massive gravity with generalized matter coupling
Open this publication in new window or tab >>Cosmological viability of massive gravity with generalized matter coupling
Show others...
2015 (English)In: Journal of Cosmology and Astroparticle Physics, ISSN 1475-7516, E-ISSN 1475-7516, no 4, 027Article in journal (Refereed) Published
Abstract [en]

There is a no-go theorem forbidding flat and closed FLRW solutions in massive gravity on a flat reference metric, while open solutions are unstable. Recently it was shown that this no-go theorem can be overcome if at least some matter couples to a hybrid metric composed of both the dynamical and the fixed reference metric. We show that this is not compatible with the standard description of cosmological sources in terms of effective perfect fluids, and the predictions of the theory become sensitive either to the detailed field-theoretical modelling of the matter content or to the presence of additional dark degrees of freedom. This is a serious practical complication. Furthermore, we demonstrate that viable cosmological background evolution with a perfect fluid appears to require the presence of fields with highly contrived properties. This could be improved if the equivalence principle is broken by coupling only some of the fields to the composite metric, but viable self-accelerating solutions due only to the massive graviton are difficult to obtain. These problems can be avoided by giving the reference metric dynamics.

Keyword
modified gravity, dark energy theory
National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-112950 (URN)10.1088/1475-7516/2015/04/027 (DOI)000355742500028 ()
Available from: 2015-01-19 Created: 2015-01-19 Last updated: 2017-12-05Bibliographically approved
6. Integrated Sachs-Wolfe effect in massive bigravity
Open this publication in new window or tab >>Integrated Sachs-Wolfe effect in massive bigravity
Show others...
(English)Manuscript (preprint) (Other academic)
Abstract [en]

We study the Integrated Sachs-Wolfe (ISW) effect in ghost-free, massive bigravity, where only one metric couples to matter. We focus on the infinite-branch bigravity (IBB) model which exhibits viable cosmic expansion histories and stable linear perturbations, while the cosmological constant is set to zero and the late-time accelerated expansion of the Universe is due solely to the gravitational interaction terms. The ISW contribution to the CMB auto-correlation power spectrum is predicted, as well as the cross-correlation between the CMB temperature anisotropies and the large-scale structure. We use ISW amplitudes as observed in the WMAP 9-year temperature data together with galaxy and AGN data provided by the WISE mission, in order to compare the theoretical predictions to the observations. The ISW amplitudes in IBB are found to be larger than the corresponding ones in the standard LCDM model by roughly a factor of 1.5, but are still consistent with the observations.

National Category
Astronomy, Astrophysics and Cosmology
Identifiers
urn:nbn:se:su:diva-112951 (URN)
Available from: 2015-01-19 Created: 2015-01-19 Last updated: 2016-01-29Bibliographically approved

Open Access in DiVA

fulltext(2339 kB)228 downloads
File information
File name FULLTEXT01.pdfFile size 2339 kBChecksum SHA-512
5dced83964d84deb728413c75343d1b44d978abd39a76728526598bff7a29decdcabe392db83759908eb836455de12469585338aab1960e93162121071e94aa7
Type fulltextMimetype application/pdf

Search in DiVA

By author/editor
Enander, Jonas
By organisation
Department of Physics
Astronomy, Astrophysics and Cosmology

Search outside of DiVA

GoogleGoogle Scholar
Total: 228 downloads
The number of downloads is the sum of all downloads of full texts. It may include eg previous versions that are now no longer available

isbn
urn-nbn

Altmetric score

isbn
urn-nbn
Total: 722 hits
CiteExportLink to record
Permanent link

Direct link
Cite
Citation style
  • apa
  • ieee
  • modern-language-association-8th-edition
  • vancouver
  • Other style
More styles
Language
  • de-DE
  • en-GB
  • en-US
  • fi-FI
  • nn-NO
  • nn-NB
  • sv-SE
  • Other locale
More languages
Output format
  • html
  • text
  • asciidoc
  • rtf