Cosmological Constraints from Galaxy Clustering

Percival, Will J.

doi:10.1007/978-3-540-71013-4_6

Cited by 3 publications

(3 citation statements)

References 61 publications

(58 reference statements)

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“…The last decade of observations of large scale structure [8,9,[20][21][22][23], the search for type Ia supernovae (SNIa) [5][6][7]10] and the measurements of the CMB anisotropies [3,24,25] are very well explained by assuming that two dark components govern the dynamics of the…”

Section: Discussionmentioning

confidence: 99%

“…the so-called "cosmological constant problem" [11,12], prompted cosmologists to investigate alternatives to the cosmological constant, mainly in the form of a dynamic component dubbed Dark Energy (DE) [13][14][15][16][17][18]. By now, many independent observations support both the existence of a CDM component and that of a separate DE [5][6][7][8][9][10][19][20][21][22][23][24][25][26].…”

Section: Introductionmentioning

confidence: 99%

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Unified Dark Matter scalar field models with fast transition

Bertacca

Bruni

Piattella

et al. 2011

J. Cosmol. Astropart. Phys.

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Abstract:We investigate the general properties of Unified Dark Matter (UDM) scalar field models with Lagrangians with a non-canonical kinetic term, looking specifically for models that can produce a fast transition between an early Einstein-de Sitter CDM-like era and a later Dark Energy like phase, similarly to the barotropic fluid UDM models in JCAP1001(2010)014. However, while the background evolution can be very similar in the two cases, the perturbations are naturally adiabatic in fluid models, while in the scalar field case they are necessarily non-adiabatic. The new approach to building UDM Lagrangians proposed here allows to escape the common problem of the fine-tuning of the parameters which plague many UDM models. We analyse the properties of perturbations in our model, focusing on the the evolution of the effective speed of sound and that of the Jeans length. With this insight, we can set theoretical constraints on the parameters of the model, predicting sufficient conditions for the model to be viable. An interesting feature of our models is that what can be interpreted as w DE can be < −1 without violating the null energy conditions.

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

Unified Dark Matter scalar field models with fast transition

Bertacca

Bruni

Piattella

et al. 2011

J. Cosmol. Astropart. Phys.

View full text Add to dashboard Cite

show abstract

“…The main alternative to the cosmological constant is a more general dynamic component called Dark Energy (DE) [11][12][13]. Many independent observations support both the existence of a CDM component and that of a separate DE [10,[14][15][16][17][18][19][20][21][22].…”

Section: Introductionmentioning

confidence: 99%

Unified Dark Matter models with fast transition

Piattella

Bertacca

Bruni

et al. 2010

J. Cosmol. Astropart. Phys.

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We investigate the general properties of Unified Dark Matter (UDM) fluid models where the pressure and the energy density are linked by a barotropic equation of state (EoS) p = p(ρ) and the perturbations are adiabatic. The EoS is assumed to admit a future attractor that acts as an effective cosmological constant, while asymptotically in the past the pressure is negligible. UDM models of the dark sector are appealing because they evade the so-called "coincidence problem" and "predict" what can be interpreted as w DE ≈ −1, but in general suffer the effects of a non-negligible Jeans scale that wreak havoc in the evolution of perturbations, causing a large Integrated Sachs-Wolfe effect and/or changing structure formation at small scales. Typically, observational constraints are violated, unless the parameters of the UDM model are tuned to make it indistinguishable from ΛCDM. Here we show how this problem can be avoided, studying in detail the functional form of the Jeans scale in adiabatic UDM perturbations and introducing a class of models with a fast transition between an early Einstein-de Sitter CDM-like era and a later ΛCDM-like phase. If the transition is fast enough, these models may exhibit satisfactory structure formation and CMB fluctuations. To consider a concrete case, we introduce a toy UDM model and show that it can predict CMB and matter power spectra that are in agreement with observations for a wide range of parameter values.

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Large-scale distribution of mass versus light from baryon acoustic oscillations: measurement in the final SDSS-III BOSS Data Release 12

Soumagnac

Sabiu

Barkana

et al. 2019

Monthly Notices of the Royal Astronomical Society

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Baryon Acoustic Oscillations (BAOs) in the early Universe are predicted to leave an as yet undetected signature on the relative clustering of total mass versus luminous matter. This signature, a modulation of the relative large-scale clustering of baryons and dark matter, offers a new angle to compare the large scale distribution of light versus mass. A detection of this effect would provide an important confirmation of the standard cosmological paradigm and constrain alternatives to dark matter as well as non-standard fluctuations such as Compensated Isocurvature Perturbations (CIPs). The first attempt to measure this effect in the SDSS-III BOSS Data Release 10 CMASS sample remained inconclusive but allowed to develop a method, which we detail here and use to conduct the second observational search. When using the same model as in our previous study and including CIPs in the model, the DR12 data are consistent with a null-detection, a result in tension with the strong evidence previously measured with the DR10 data. This tension remains when we use a more realistic model taking into account our knowledge of the survey flux limit, as the data then privilege a zero effect. In the absence of CIPs, we obtain a null detection consistent with both the absence of the effect and the amplitude predicted in previous theoretical studies. This shows the necessity of more accurate data in order to prove or disprove the theoretical predictions.

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Cosmological Constraints from Galaxy Clustering

Cited by 3 publications

References 61 publications

Unified Dark Matter scalar field models with fast transition

Unified Dark Matter scalar field models with fast transition

Unified Dark Matter models with fast transition

Large-scale distribution of mass versus light from baryon acoustic oscillations: measurement in the final SDSS-III BOSS Data Release 12

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