A5004695575- Galaxies: Formation, Evolution, Phenomena
- Cosmology and Gravitation Theories
- Astronomy and Astrophysical Research
- Stellar, planetary, and galactic studies
- Dark Matter and Cosmic Phenomena
- Astrophysics and Star Formation Studies
- Black Holes and Theoretical Physics
- Astrophysics and Cosmic Phenomena
- Gamma-ray bursts and supernovae
- Neutrino Physics Research
- Particle physics theoretical and experimental studies
- Radio Astronomy Observations and Technology
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Astronomical Observations and Instrumentation
- Solar and Space Plasma Dynamics
- Astrophysical Phenomena and Observations
- History and Developments in Astronomy
- Pulsars and Gravitational Waves Research
- Advanced Thermodynamics and Statistical Mechanics
- Astro and Planetary Science
- Computational Physics and Python Applications
- Relativity and Gravitational Theory
- Tribology and Lubrication Engineering
- Atmospheric Ozone and Climate
Universitat de Barcelona
2015-2024
Institució Catalana de Recerca i Estudis Avançats
2015-2024
Institut Català de Ciències del Clima
2010-2024
Universidad Politécnica de Madrid
2023
Universidad Científica del Sur
2022
Universidad Carlos III de Madrid
2020
Baker Hughes (United States)
2020
Universidad Autónoma de Madrid
2007-2020
Harvard University
2014-2018
Institute for Advanced Study
2016-2018
We develop a formalism to characterize the shape and redshift evolution of dark energy potential. Our makes use quantities similar horizon-flow parameters in inflation is general enough that can deal with multiscalar quintessence scenarios, exotic matter components, higher-order curvature corrections General Relativity. show how potential be recovered nonparametrically using this we present approximations analogous ones relevant slow-roll inflation. Since presently available data do not...
Deriving the expansion history of Universe is a major goal modern cosmology. To date, most accurate measurements have been obtained with Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO), providing evidence for existence transition epoch at which rate changes from decelerated to accelerated. However, these results within framework specific cosmological models that must be implicitly or explicitly assumed in measurement. It therefore crucial obtain accelerated independently...
We propose to use relative galaxy ages as a means of constraining cosmological parameters. By measuring the age difference between two ensembles passively evolving galaxies at somewhat different redshifts, one could determine derivative redshift with respect cosmic time, dz/dt. At high z ~ 1-2, this measurement would constrain equation state dark energy, while low ≲ 0.2, it Hubble constant, H0. Furthermore, we show that d2z/dt2 directly tracks energy; thus, measurements quantity redshifts...
We present new determinations of the cosmic expansion history from red-envelope galaxies. have obtained for this purpose high-quality spectra with Keck-LRIS spectrograph galaxies in 24 galaxy clusters redshift range 0.2 < z 1.0. complement these Keck high-quality, publicly available archival SPICES and VVDS surveys. improve over our previous measurements Simon et al. (2005) by providing two history: H(z) = 97 +- 62 km/sec/Mpc at 0.5 90 40 0.8. discuss uncertainty determination that arises...
We present new improved constraints on the Hubble parameter H ( z ) in redshift range 0.15 < 1.1, obtained from differential spectroscopic evolution of early-type galaxies as a function redshift. extract large sample ∼ 11000) several surveys, spanning almost 8 billion years cosmic lookback time (0.15 1.42). select most massive, red elliptical galaxies, passively evolving and without signature ongoing star formation. Those can be used standard chronometers, firstly proposed by Jimenez...
We have assembled a compilation of observational Hubble parameter measurements estimated with the differential evolution cosmic chronometers, in redshift range 0<z<1.75. This sample has been used, combination CMB data and most recent estimate constant H_0, to derive new constraints on several cosmological parameters. The are very useful break some degeneracies present CMB-only analysis, constrain possible deviations from standard (minimal) flat \Lambda CDM model. H(z) especially valuable...
Abstract The detection of the accelerated expansion Universe has been one major breakthroughs in modern cosmology. Several cosmological probes (Cosmic Microwave Background, Supernovae Type Ia, Baryon Acoustic Oscillations) have studied depth to better understand nature mechanism driving this acceleration, and they are being currently pushed their limits, obtaining remarkable constraints that allowed us shape standard model. In parallel that, however, percent precision achieved recently...
Abstract The evolution of differential ages passive galaxies at different redshifts (cosmic chronometers) has been proved to be a method potentially able constrain the Hubble parameter in cosmology-independent way, but systematic uncertainties must carefully evaluated. In this paper, we compute contribution full covariance matrix due choice initial mass function, stellar library, and metallicity, exploring variety population synthesis models. Through simulations redshift range 0 < z 1.5,...
The weak radio source LBDS 53W091 is associated with a very faint (R ≈ 24.5) red - K 5.8) galaxy. Long spectroscopic integrations the W. M. Keck telescope have provided an absorption-line redshift, z = 1.552 ± 0.002. galaxy has rest frame ultraviolet spectrum similar to that of F6 V star, and single-burst old stellar population matches IR colors, optical energy distribution spectral discontinuities minimum age 3.5 Gyr. We present detailed synthesis analyses observed in order estimate time...
We place tight constraints on the redshift-averaged, effective value of equation state dark energy, w, using only absolute ages Galactic stars and observed position first peak in angular power spectrum CMB. find w<-0.8 at 68% confidence level. If we further consider that w > -1, this finding suggests within our uncertainties, energy is indistinguishable from a classical vacuum term. detect correlation between oldest galaxies their redshift. This opens up possibility measuring w(z) by...
We present the results of a moped analysis ∼3 × 105 galaxy spectra from Sloan Digital Sky Survey Data Release 3 (SDSS DR3), with number improvements in data, modelling and compared our previous DR1. The include: galaxies theoretical models at higher spectral resolution Å, better calibrated an extended list excluded emission lines wider range dust models. new estimates cosmic star formation rate (SFR), evolution stellar mass density function fossil record. In contrast to earlier work show no...
The observed abundance of high-redshift galaxies and clusters contains precious information about the properties initial perturbations. We present a method to compute analytically number density objects as function mass redshift for range physically motivated non-Gaussian models. In these models non-Gaussianity can be dialed from zero is assumed small. probability smoothed dark matter field we extend Press Schechter approach mildly fields. directly related parameter thus physical processes...
We introduce VErsatile SPectral Analysis (VESPA): a new method which aims to recover robust star formation and metallicity histories from galactic spectra. VESPA uses the full spectral range construct galaxy history synthetic models. investigate use of an adaptative parametrization grid reliable on galaxy-by-galaxy basis. Our goal is robustness as opposed high resolution histories, designed return time only where data demand it. In this paper we detail present our findings when apply real...
We use the latest Planck constraints, and in particular constraints on derived parameters (Hubble constant age of Universe) for local universe compare them with measurements same quantities. propose a way to quantify whether cosmological from two different experiments are tension or not. Our statistic, T, is an evidence ratio therefore can be interpreted widely used Jeffrey's scale. find that framework ΛCDM model, inferred dimensional, joint, posterior distribution Hubble Universe "strong"...
We exploit cosmological-model independent measurements of the expansion history Universe to provide a cosmic distance ladder. These are supernovae type Ia used as standard candles (at redshift between 0.01 and 1.3) baryon acoustic oscillations redshifts 0.1 0.8) rulers. calibrate (anchor) ladder in two ways: first using local $H_0$ value an anchor at $z$ = 0 (effectively calibrating candles) secondly microwave background-inferred sound-horizon scale (giving ruler length) inverse Both methods...
Recent anomalies found in cosmological datasets such as the low multipoles of Cosmic Microwave Background or redshift amplitude and growth clustering measured by e.g., abundance galaxy clusters space distortions surveys, have motivated explorations models beyond standard $\Lambda$CDM. Of particular interest are where general relativity (GR) is modified on large scales. Here we consider deviations from $\Lambda$CDM+GR within context Horndeski gravity, which most theory gravity with second...
The authors introduce a new actor in the current drama of Hubble tension (conflicting measurements ${H}_{0}$), namely age Universe ${t}_{\text{U}}$, as determined by oldest globular clusters, and show that if local are correct, resolution implies modification cosmological standard model $\mathrm{\ensuremath{\Lambda}}$CDM early late Universe. Once systematic uncertainties reduced, measuring ${t}_{\text{U}}$ will discriminate between viable solutions for ${H}_{0}$ tension, i.e. changing or...
Abstract The local supercluster acts as a gravity deflection source for cosmic background neutrinos. This by changes the neutrino helicity and therefore has important consequences ground based tritium capture experiments aimed at determining if is Dirac or Majorana. Here we explore effect of using two simulations from DEMNUni suite characterised very different mass resolutions, they are both filled with 2048 3 dark matter particles (and an equal number massive particles) but have comoving...
The annihilation rate of weakly interacting cold dark matter particles at the galactic center could be greatly enhanced by growth a density spike around central supermassive black hole (SBH). Here we discuss effects hierarchical mergers on spike. Mergers between halos containing SBHs lead to formation SBH binaries which transfer energy particles, lowering their density. predicted flux photons from is several orders magnitude smaller than in models that ignore and mergers. Measurement...
We reexamine the issue of cosmological parameter estimation in light current and upcoming high-precision measurements cosmic microwave background power spectrum. Physical quantities which determine spectrum are reviewed, their connection to familiar parameters is explicated. present a set physical parameters, analytic functions usual upon depends linearly (or with some other simple dependence) over wide range values. With such spectra can be estimated high accuracy negligible computational...
We present a method for radical linear compression of data sets where the are dependent on some number M parameters. show that, if noise in is independent parameters, we can form combinations which contain as much information about all parameters entire set, sense that Fisher matrices identical; i.e. lossless. explore how these compressed numbers fare when and method, though not precisely lossless, increases errors by very modest factor. The general, but illustrate it with problem...
Using moped, we determine non-parametrically the star formation and metallicity history of over 37 000 high-quality galaxy spectra from Sloan Digital Sky Survey (SDSS) early data release. We use entire spectral range, rather than concentrating on specific features, estimate complete without prior assumptions concerning its form (by constructing so-called ‘population boxes’). The main results this initial study are that rate in SDSS galaxies has been decline for ∼6 Gyr; a distribution...