Do you want to publish a course? Click here

On cosmological signatures of baryons-dark energy elastic couplings

172   0   0.0 ( 0 )
 Publication date 2020
  fields Physics
and research's language is English




Ask ChatGPT about the research

We consider a scenario where dark energy and baryons are dynamically coupled without any energy transfer. In this scenario, the background cosmology is unaffected and, at the perturbations level, the coupling only appears through the corresponding Euler equations of dark energy and baryons. We then explore some phenomenological consequences of this scenario and their signatures in several cosmological observables. In particular, we show its ability to suppress the growth of cosmic structures. We also constrain the parameters of the model with cosmological data and show that an interaction of dark energy with baryons on cosmological scales is mildly favoured.



rate research

Read More

We consider a cosmological model where dark matter and dark energy feature a coupling that only affects their momentum transfer in the corresponding Euler equations. We perform a fit to cosmological observables and confirm previous findings within these scenarios that favour the presence of a coupling at more than $3sigma$. This improvement is driven by the Sunyaev-Zeldovich data. We subsequently perform a forecast for future J-PAS data and find that clustering measurements will permit to clearly discern the presence of an interaction within a few percent level with the uncoupled case at more than $10sigma$ when the complete survey, covering $8500$ sq. deg., is considered. We found that the inclusion of weak lensing measurements will not help to further constrain the coupling parameter. For completeness, we compare to forecasts for DESI and Euclid, which provide similar discriminating power.
We study cosmological models involving scalar fields coupled to radiation and discuss their effect on the redshift evolution of the cosmic microwave background temperature, focusing on links with varying fundamental constants and dynamical dark energy. We quantify how allowing for the coupling of scalar fields to photons, and its important effect on luminosity distances, weakens current and future constraints on cosmological parameters. In particular, for evolving dark energy models, joint constraints on the dark energy equation of state combining BAO radial distance and SN luminosity distance determinations, will be strongly dominated by BAO. Thus, to fully exploit future SN data one must also independently constrain photon number non-conservation arising from the possible coupling of SN photons to the dark energy scalar field. We discuss how observational determinations of the background temperature at different redshifts can, in combination with distance measures data, set tight constraints on interactions between scalar fields and photons, thus breaking this degeneracy. We also discuss prospects for future improvements, particularly in the context of Euclid and the E-ELT and show that Euclid can, even on its own, provide useful dark energy constraints while allowing for photon number non-conservation.
We reconsider the dynamics of the Universe in the presence of interactions in the cosmological dark sector. A class of interacting models is introduced via a real function $fleft(rright)$ of the ratio $r$ between the energy densities of the (pressureless) cold dark matter (CDM) and dark energy (DE). The subclass of models for which the ratio $r$ depends only on the scale factor is shown to be equivalent to unified models of the dark sector, i.e. models for which the CDM and DE components can be combined in order to form a unified dark fluid. For specific choices of the function $fleft(rright)$ we recover several models already studied in the literature. We analyse various special cases of this type of interacting models using a suitably modified version of the CLASS code combined with MontePython in order to constrain the parameter space with the data from supernova of type SNe Ia (JLA), the Hubble constant $H_{0}$, cosmic chronometers (CC), baryon acoustic oscilations (BAO) and data from the Planck satellite (Planck TT). Our analysis shows that even if data from the late Universe ($H_{0}$, SNe Ia and CC) indicate an interaction in the dark sector, the data related to the early Universe (BAO and Planck TT) constrain this interaction substantially, in particular for cases in which the background dynamics is strongly affected.
134 - Johannes Noller 2020
Gravitational wave (GW) constraints have recently been used to significantly restrict models of dark energy and modified gravity. New bounds arising from GW decay and GW-induced dark energy instabilities are particularly powerful in this context, complementing bounds from the observed speed of GWs. We discuss the associated linear cosmology for Horndeski gravity models surviving these combined bounds and compute the corresponding cosmological parameter constraints, using CMB, redshift space distortion, matter power spectrum and BAO measurements from the Planck, SDSS/BOSS and 6dF surveys. The surviving theories are strongly constrained, tightening previous bounds on cosmological deviations from $Lambda{}$CDM by over an order of magnitude. We also comment on general cosmological stability constraints and the nature of screening for the surviving theories, pointing out that a raised strong coupling scale can ensure compatibility with gravitational wave constraints, while maintaining a functional Vainshtein screening mechanism on solar system scales. Finally, we discuss the quasi-static limit as well as (constraints on) related observables for near-future surveys.
A large number of cosmological parameters have been suggested for obtaining information on the nature of dark energy. In this work, we study the efficacy of these different parameters in discriminating theoretical models of dark energy, using both currently available supernova (SNe) data, and simulations of future observations. We find that the current data does not put strong constraints on the nature of dark energy, irrespective of the cosmological parameter used. For future data, we find that the although deceleration parameter can accurately reconstruct some dark energy models, it is unable to discriminate between different models of dark energy, therefore limiting its usefulness. Physical parameters such as the equation of state of dark energy, or the dark energy density do a good job of both reconstruction and discrimination if the matter density is known to high accuracy. However, uncertainty in matter density reduces the efficacy of these parameters. A recently proposed parameter, Om(z), constructed from the first derivative of the SNe data, works very well in discriminating different theoretical models of dark energy, and has the added advantage of not being dependent on the value of matter density. Thus we find that a cosmological parameter constructed from the first derivative of the data, for which the theoretical models of dark energy are sufficiently distant from each other, and which is independent of the matter density, performs the best in reconstructing dark energy from SNe data.
comments
Fetching comments Fetching comments
Sign in to be able to follow your search criteria
mircosoft-partner

هل ترغب بارسال اشعارات عن اخر التحديثات في شمرا-اكاديميا