Parametrizing growth in dark energy and modified gravity models

It is well-known that an extremely accurate parametrization of the growth function of matter density perturbations in $\Lambda$CDM cosmology, with errors below $0.25 \%$, is given by $f(a)=\Omega_{m}^{\gamma} \,(a)$ with $\gamma \simeq 0.55$. In this work, we show that a simple modification of this expression also provides a good description of growth in modified gravity theories. We consider the model-independent approach to modified gravity in terms of an effective Newton constant written as $\mu(a,k)=G_{eff}/G$ and show that $f(a)=\beta(a)\Omega_{m}^{\gamma} \,(a)$ provides fits to the numerical solutions with similar accuracy to that of $\Lambda$CDM. In the time-independent case with $\mu=\mu(k)$, simple analytic expressions for $\beta(\mu)$ and $\gamma(\mu)$ are presented. In the time-dependent (but scale-independent) case $\mu=\mu(a)$, we show that $\beta(a)$ has the same time dependence as $\mu(a)$. As an example, explicit formalae are provided in the DGP model. In the general case, for theories with $\mu(a,k)$, we obtain a perturbative expansion for $\beta(\mu)$ around the General Relativity case $\mu=1$ which, for $f(R)$ theories, reaches an accuracy below $1 \%$. Finally, as an example we apply the obtained fitting functions in order to forecast the precision with which future galaxy surveys will be able to measure the $\mu$ parameter.Comment: 12 pages, 12 figures. New section on applications to forecasts for galaxy surveys and new references included. Matches version published in PR

The building of a modern district seen from the perspective of its open spaces: Huerta del rey (Valladolid)

Huerta del Rey es un barrio residencial de Valladolid “de bloques y torres” en el que se han ido superponiendo en distintos estratos los puntos doctrinales del Movimiento Moderno, las expectativas del Ayuntamiento y las transformaciones que han hecho sus habitantes de este espacio, en un proceso que se dilata desde mediados hasta finales del siglo XX. Fruto de tal proceso, unas veces controlado y otras fortuito, su espacio libre ha ido adquiriendo espesor y carácter. Aunque la valoración actual del barrio no es unánime, frente a la agresividad de que se suele acusar hoy a los espacios libres de propuestas materializadas de forma rigurosa desde postulados de la Carta de Atenas, éste ha conseguido adquirir una gran coherencia formal y social. El artículo evidencia a partir de la historia urbanística del barrio el carácter paralelo de las diversas concepciones institucionales, sociales y disciplinares, que se han cernido sobre él y la contribución de cada una de ellas en la resultante final, que no definitivaHuerta del Rey is a residential district of Valladolid comprising tower blocks and high-rise buildings. In it the doctrines of the Modernist Movement, the expectations of the City Council and the adjustments made by those living in the area have gradually been superposed in different strata. This was a process that ran over the period from the middle of the twentieth century through until its end. As an outcome of this process, sometimes controlled, sometimes haphazard, its open spaces have gained depth and character. Although current assessments of the district are not unanimous, it has managed to achieve considerable formal and social coherence, in contrast with the aggressiveness which nowadays is attributed to the open spaces established by projects slavishly following the guidelines of the Athens Charter. This paper gives evidence from the town-planning history of the district to show the parallel nature of the various institutional, social and disciplinary concepts that have been applied to it and the contribution made by each to the final, though not definitive, resul

Testing for gravitational preferred directions with galaxy and lensing surveys

We analyze the sensitivity of galaxy and weak-lensing surveys to detect preferred directions in the gravitational interaction. We consider general theories of gravity involving additional vector degrees of freedom with non-vanishing spatial components in the background. We use a model-independent parametrization of the perturbations equations in terms of four effective parameters, namely, the standard effective Newton constant G(eff) and slip parameter gamma for scalar modes and two new parameters mu(Q) and mu(h) for vector and tensor modes respectively, which are required when preferred directions are present. We obtain the expressions for the multipole galaxy power spectrum in redshift space and for the weak-lensing shear, convergence and rotation spectra in the presence of preferred directions. By performing a Fisher matrix forecast analysis, we estimate the sensitivity of a future Euclid-like survey to detect this kind of modification of gravity. We finally compare with the effects induced by violations of statistical isotropy in the primordial power spectrum and identify the observables which could discriminate between them

The Fisher gAlaxy suRvey cOde (FARO\texttt{FARO})

The Fisher gAlaxy suRvey cOde ($\texttt{FARO}$) is a new public Python code that computes the Fisher matrix for galaxy surveys observables. The observables considered are the linear multitracer 3D galaxy power spectrum, the linear convergence power spectrum for weak lensing, and the linear multitracer power spectrum for the correlation between galaxy distribution and convergence. The code allows for tomographic and model-independent analysis in which, for scale-independent growth, the following functions of redshift $A_a (z) \equiv \sigma_{8}(z) \, b_a (z)$, $R(z) \equiv \sigma_{8}(z) \, f(z)$, $L(z) \equiv \Omega_{m} \, \sigma_{8}(z) \, \Sigma (z)$ and $E(z) \equiv H(z)/H_0$, together with the function of scale $\hat{P}(k)$, are taken as free parameters in each redshift and scale bins respectively. In addition, a module for change of variables is provided to project the Fisher matrix on any particular set of parameters required. The code is built to be as fast as possible and user-friendly. As an application example, we forecast the sensitivity of future galaxy surveys like DESI, Euclid, J-PAS and LSST and compare their performance on different redshift and scale ranges.Comment: https://www.ucm.es/iparcos/far

Modified gravity or imperfect dark matter: a model-independent discrimination

We analyze how to parametrize general modifications of the dark matter perturbations equations in a model-independent way. We prove that a general model with an imperfect and non-conserved dark matter fluid with bulk and shear viscosities and heat flux in a modified gravity scenario can be described with five general functions of time and scale. We focus on the sub-Hubble regime within the quasi-static approximation and calculate the observable power spectra of the galaxy distribution, galaxy velocities and weak lensing and find that these observables are only sensitive to three combinations of the initial five functions. Deviations of these three observable functions with respect to $\mathrm{\Lambda CDM}$ give us different characteristic signals which allow us to determine in which cases it is possible to discriminate a modification of gravity from an imperfect or non-conserved dark matter. Finally, we perform a Fisher forecast analysis for these three parameters and show an example for a particular model with shear viscosity

J-PAS: forecasts on dark energy and modified gravity theories

The next generation of galaxy surveys will allow us to test one of the most fundamental assumptions of the standard cosmology, i.e. that gravity is governed by the general theory of relativity (GR). In this paper, we investigate the ability of the Javalambre Physics of the AcceleratingUniverseAstrophysical Survey (J-PAS) to constrainGR and its extensions. Based on the J-PAS information on clustering and gravitational lensing, we perform a Fisher matrix forecast on the effective Newton constant, mu, and the gravitational slip parameter, eta, whose deviations from unity would indicate a breakdown of GR. Similar analysis is also performed for the DESI and Euclid surveys and compared to J-PAS with two configurations providing different areas, namely an initial expectation with 4000 deg(2) and the future best case scenario with 8500 deg(2). We show that J-PAS will be able to measure the parameters mu and eta at a sensitivity of 2-7 per cent, and will provide the best constraints in the interval z = 0.3-0.6, thanks to the large number of ELGs detectable in that redshift range. We also discuss the constraining power of J-PAS for dark energy models with a time-dependent equation-of-state parameter of the type w(a) = w(0) + w(a)(1 - a), obtaining Delta w(0) = 0.058 and Delta w(a) = 0.24 for the absolute errors of the dark energy parameters

J-PAS: forecasts for dark matter-dark energy elastic couplings

© 2021 IOP Publishing Artículo firmado por más de 10 autores We thank Wilmar Cardona for useful discussions on the fit to different datasets. JBJ, DB, DF and FATP acknowledge support from the Atraccion del Talento Cientifico en Salamanca programme, from project PGC2018-096038-B-I00 by Spanish Ministerio de Ciencia, Innovacion y Universidades and Ayudas del Programa XIII by USAL. DF acknowledges support from the programme Ayudas para Financiar la Contratacion Predoctoral de Personal Investigador (ORDEN EDU/601/2020) funded by Junta de Castilla y Leon and European Social Fund. This work has been supported by the MINECO (Spain) projects FIS201678859-P and PID2019-107394GB-I00 (AEI/FEDER, UE). LRA acknowledges financial support from CNPq (306696/2018-5) and FAPESP (2015/17199-0). JA is supported by CNPq (Grants No. 310790/2014-0 and 400471/2014-0) and FAPERJ (Grant No. 233906). SB acknowledges PGC2018-097585-B-C22, MINECO/FEDER, UE of the Spanish Ministerio de Economia, Industriay Competitividad. CEFCA researchers acknowledge support from the project PGC2018-097585-B-C21. SC is supported by CNPq (Grants No. 307467/2017-1 and420641/2018-1). R.A.D. acknowledges support from the Conselho Nacional de Desenvolvimento Cientifico e Tecnologico -CNPq through BPgrant 308105/2018-4, and the Financiadora de Estudos e Projetos -FINEP grants REF. 1217/13 -01.13.0279.00 and REF 0859/10-01.10.0663.00 and also FAPERJ PRONEX grant E-26/110.566/2010 for hardware funding support for the J-PAS project through the National Observatory of Braziland Centro Brasileiro de Pesquisas Fisicas. VM thanks CNPq (Brazil) and FAPES (Brazil) for partial financial support. This project has received funding from the European Union's Horizon 2020 research and innovation programme under the Marie Sklodowska-Curie grant agreement No 888258. CMdO acknowledges support from Brazilian agencies CNPq (grant 312333/2014-5) and FAPESP (grant 2009/54202-8. IAA researchers acknowledge financial support from the State Agency for Research of the Spanish MCIU through the "Center of Excellence Severo Ochoa" award to the Instituto de Astrofisica de Andalucia (SEV-2017-0709). LSJ acknowledges support from Brazilian agencies CNPq (grant 304819/2017-4) and FAPESP (grant 2012/00800-4).; This paper has gone through internal review by the J-PAS collaboration. Based on observations made with the JST/T250 telescope and JPCam at the Observatorio Astrofisico de Javalambre (OAJ), in Teruel, owned, managed, and operated by the Centro de Estudios de Fisica del Cosmos de Aragon (CEFCA). We acknowledge the OAJ Data Processing and Archiving Unit (UPAD) for reducing and calibrating the OAJ data used in this work. Funding for the J-PAS Project has been provided by the Governments of Spain and Aragon through the Fondo de Inversion de Teruel, European FEDER funding and the Spanish Ministry of Science, Innovation and Universities, and by the Brazilian agencies FINEP, FAPESP, FAPERJ and by the National Observatory of Brazil. Additional funding was also provided by the Tartu Observatory and by the J-PAS Chinese Astronomical Consortium.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 3a. This improvement is mainly driven by cluster counts from Planck Sunyaev-Zeldovich data that we include as a certain prior. 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 10o(-) 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.Depto. de Física TeóricaFac. de Ciencias FísicasTRUEUnión Europea. H2020Ministerio de Economía y Competitividad (MINECO)/ FEDERMinisterio de Economía y Competitividad (MINECO)Ministerio de Ciencia e Innovación (MICINN)Centros de Excelencia Severo Ochoa (MICINN)pu

On the dark energy rest frame and the CMB

Dark energy is usually parametrized as a perfect fluid with negative pressure and a certain equation of state. Besides, it is supposed to interact very weakly with the rest of the components of the universe and, as a consequence, there is no reason to expect it to have the same large-scale rest frame as matter and radiation. Thus, apart from its equation of state $w$ and its energy density $\Omega_{DE}$ one should also consider its velocity as a free parameter to be determined by observations. This velocity defines a cosmological preferred frame, so the universe becomes anisotropic and, therefore, the CMB temperature fluctuations will be affected, modifying mainly the dipole and the quadrupole.Comment: 4 pages. Contribution to the proceedings of Spanish Relativity Meeting 2008, Salamanca, Spain, 15-19 September 200

Anaerobic co-digestion of municipal sewage sludge and fruit/vegetable waste: effect of different mixtures on digester stability and methane yield

There are different options for the management of fruit and vegetable wastes (FVWs), but the most environmental-friendly is the anaerobic digestion, because it allows an optimum recovery of materials and energy from the two by-products: biogas and digestate. Nevertheless, in many cases there are economic and technical problems that cause the selection of other alternatives. Frequently these wastes are produced in large quantities but only during few weeks of the year. In these cases, this is the most important economic problem, because large digesters that would be used only for short time periods every year would be required. In addition, a close control of the pH of the digester is required for this kind of residues, for which the hydrolysis is usually faster than the methanogenesis, so large concentrations of fatty acids should be prevented to maintain the adequate pH value for anaerobic digestion that should be neutral or slightly alkaline. Both problems can be simultaneously overcome by the co-digestion with other residues that are produced throughout the year. Among the benefits of co-digestion, one of the most important is the improvement in the feedstock characteristics, since it may allow a more equilibrate composition resulting in a better performance of the digester in treatment capacity, and a better quality of biogas and digestate. The co-digestion with other substrates with a complementary composition that are produced throughout the year and that are already managed by anaerobic digestion is probably the optimum management option. For these cases, if the existing anaerobic digester is oversized and allows the introduction of additional volumes of wastes, the mean retention time of the digestate should be maintained. Therefore, the anaerobic co-digestion of fruit and vegetable waste (FVW) and municipal sewage sludge (MSS) under mesophilic condition and a constant hydraulic retention time (20 d) is studied. The effects on digester performance of the FVW:MSS ratio and the organic loading rate (OLR) were examined. The OLR is the mass of volatile solids fed per volume of digestate and day.Universidad de Málaga. Campus de Excelencia Internacional Andalucía Tech

El Plan General de Valladolid de 1984. En los orígenes de un nuevo modelo urbano

The expansive development cycle through Spanish cities have gone in last decades has its origin in the period of time between final seventies and early eighties, concurrently with political, economic and social important changes, and in urban discipline too. This research analyses that period through the case of Valladolid, comparing the city then existing to the spatial proposals from the Master Plan 1984.This plan proposed a new urban model oriented towards a radial-concentric expansion that has marked the city development until today and that was built on the analysis of the growth and transformation of Valladolid in the previous decades. This transformation was based on the addition of fragmentary actions and the social segregation, in default of an effective and inclusive, global urban model.El ciclo de desarrollo expansivo que las ciudades españolas han experimentado en las últimas décadas tuvo su origen en el periodo comprendido entre finales de los setenta y principios de los ochenta, coincidiendo con importantes cambios políticos, económicos y sociales, y también en la propia disciplina urbanística. La investigación analiza ese periodo a través del caso de Valladolid, confrontando la realidad urbana existente entonces con las propuestas espaciales del Plan General de 1984.Este plan propuso un nuevo modelo urbano de expansión radio-concéntrica que ha marcado el desarrollo de la ciudad hasta la actualidad, y que se construyó a partir del análisis del crecimiento y transformación de Valladolid en las décadas anteriores. Un desarrollo que se había basado en la suma de actuaciones fragmentarias y en la segregación social, en ausencia de un modelo urbano global que fuese eficaz e inclusivo