Constraining the shape of the CMB: A peak-by-peak analysis

We investigate f (R) theories of gravity within the Palatini approach and show how one can determine the expansion history, H(a), for an arbitrary choice of f (R). As an example, we consider cosmological constraints on such theories arising from the supernova type Ia, large-scale structure formation, and cosmic microwave background observations. We find that the best fit to the data is a nonnull leading order correction to the Einstein gravity. However, the current data exhibits no significant trend toward such corrections compared to the concordance ΛCDM model. Our results show that the oft-considered 1/R models are not compatible with the data. The results demonstrate that background expansion alone can act as a good discriminator between modified gravity models when multiple data sets are used.

show abstract

“…The CMBR shift parameter (Bond et al 1997;Melchiorri et al 2003;Odman et al 2003) in a spatially flat universe is given by…”

Section: Cmbr Shift Parametermentioning

confidence: 99%

Cosmological constraints on f(R) gravity theories within the Palatini approach

Amarzguioui¹,

Elgarøy

Mota³

et al. 2006

A&A

261

260

View full text Add to dashboard Cite

show abstract

“…[26,43] Koivisto and Mota placed observational constraints using the Gold data set of Supernova Ia [44] together with the CMB shift parameter data [45]. The parameter λ is constrained to be 3.5 < ∼ λ < ∼ 4.5 at the 90% .…”

Section: Cosmological Dynamicsmentioning

confidence: 99%

String-inspired cosmology: a late time transition from a scaling matter era to a dark energy universe caused by a Gauss–Bonnet coupling

Tsujikawa

Sami

2007

J. Cosmol. Astropart. Phys.

108

100

View full text Add to dashboard Cite

The Gauss-Bonnet (GB) curvature invariant coupled to a scalar field φ can lead to an exit from a scaling matter-dominated epoch to a late-time accelerated expansion, which is attractive to alleviate the coincident problem of dark energy. We derive the condition for the existence of cosmological scaling solutions in the presence of the GB coupling for a general scalar-field Lagrangian density p(φ, X), where X = −(1/2)(∇φ) 2 is a kinematic term of the scalar field. The GB coupling and the Lagrangian density are restricted to be in the form f (φ) ∝ e λφ and p = Xg(Xe λφ ), respectively, where λ is a constant and g is an arbitrary function. We also derive fixed points for such a scaling Lagrangian with a GB coupling f (φ) ∝ e µφ and clarify the conditions under which the scaling matter era is followed by a de-Sitter solution which can appear in the presence of the GB coupling. Among scaling models proposed in the current literature, we find that the models which allow such a cosmological evolution are an ordinary scalar field with an exponential potential and a tachyon field with an inverse square potential, although the latter requires a coupling between dark energy and dark matter.

show abstract

“…The CMB shift parameter determines the shift of the peaks in the CMB power spectrum when cosmological parameters are varied [14,15,16]. It is given by…”

Section: Constraints On Braneworld Loiteringmentioning

confidence: 99%

Loitering universe models in light of the CMB

Elgarøy

Mota

Multamäki³

2005

Phys. Rev. D

View full text Add to dashboard Cite

Spatially flat loitering universe models have recently been shown to arise in the context of brane world scenarios. Such models allow more time for structure formation to take place at high redshifts, easing, e.g., the tension between the observed and predicted evolution of the quasar population with redshift. While having the desirable effect of boosting the growth of structures, we show that in such models the position of the first peak in the power spectrum of the cosmic microwave background anisotropies severely constrain the amount of loitering at high redshifts.

show abstract

Constraining the shape of the CMB: A peak-by-peak analysis

Cited by 45 publications

References 57 publications

Cosmological constraints on f(R) gravity theories within the Palatini approach

Cosmological constraints on f(R) gravity theories within the Palatini approach

String-inspired cosmology: a late time transition from a scaling matter era to a dark energy universe caused by a Gauss–Bonnet coupling

Loitering universe models in light of the CMB

Contact Info

Product

Resources

About