Improved constraints on the expansion rate of the Universe up to z ∼ 1.1 from the spectroscopic evolution of cosmic chronometers

Abstract

Abstract. We present new improved constraints on the Hubble parameter H(z) in the redshift range 0.15 < z < 1.1, obtained from the differential spectroscopic evolution of early-type galaxies as a function of redshift. We extract a large sample of early-type galaxies (∼ 11000) from several spectroscopic surveys, spanning almost 8 billion years of cosmic lookback time (0.15 < z < 1.42). We select the most massive, red elliptical galaxies, passively evolving and without signature of ongoing star formation. Those galaxies can be used as standard cosmic chronometers, as firstly proposed by Jimenez & Loeb (2002), whose differential age evolution as a function of cosmic time directly probesWe analyze the 4000Å break (D4000) as a function of redshift, use stellar population synthesis models to theoretically calibrate the dependence of the differential age evolution on the differential D4000, and estimate the Hubble parameter taking into account both statistical and systematical errors.We provide 8 new measurements of H(z) (see Tab. 4), and determine its change in H(z) to a precision of 5 − 12% mapping homogeneously the redshift range up to z ∼ 1.1; for the first time, we place a constraint on H(z) at z = 0 with a precision comparable with the one achieved for the Hubble constant (about 5-6% at z ∼ 0.2), and covered a redshift range (0.5 < z < 0.8) which is crucial to distinguish many different quintessence cosmologies.These measurements have been tested to best match a ΛCDM model, clearly providing a statistically robust indication that the Universe is undergoing an accelerated expansion. This method shows the potentiality to open a new avenue in constrain a variety of alternative cosmologies, especially when future surveys (e.g. Euclid) will open the possibility to extend it up to z ∼ 2.-1 -

Observational probes of cosmic acceleration

“…This differential approach removes some of the uncertainties in the population synthesis models, but it relies on identifying a population of galaxies at one redshift that is just an aged version of a population at a higher redshift, or accounting for the evolutionary corrections that arise from mergers, low-level star formation, and movement of galaxies into or out of the passive population. The state-of-the art observational study is the analysis of ∼ 11, 000 early-type galaxies from several large surveys by Moresco et al (2012). They report measurements of H(z) in eight bins out to z ≈ 1, with uncertainties of ∼ 5 − 15% per bin including estimated systematic errors.…”

AIC, BIC, Bayesian evidence against the interacting dark energy model

“…We used the observational data of 580 type Ia supernovae (the Union2.1 compilation [56]), 31 observational data points of the Hubble function from [57][58][59][60][61][62][63][64][65][66] collected in [67], the measurements of BAO from the Sloan Digital Sky Survey (SDSS-III) combined with the 2dF Galaxy Redshift Survey [68][69][70][71], the 6dF Galaxy Survey [72,73], and the WiggleZ Dark Energy Survey [74][75][76]. We also used information coming from determinations of the Hubble function using the Alcock-Paczyński test [77,78].…”

Neutrino footprint in large scale structure

“…An accurate cosmic microwave background (CMB) spectrum, both in temperature and polarization has been measured by Planck [1] and WMAP [2]. The expansion history of the Universe has been mapped in several ways: with measurements of the Baryon Acoustic Oscillation (BAO) scale by the Baryon Oscillation Spectroscopic Survey (BOSS) of the Sloan Digital Sky Survey (SDSS) [3] and others [4,5]; by the luminosity distance relation as given by Type 1A supernova data e.g., [6]; via the direct measurement of the Hubble parameter with cosmic chronometers [7,8].Finally, large scale structure (LSS) has been probed by a variety of surveys (galaxies e.g., [9][10][11][12], weak lensing e.g., [13][14][15][16][17], Lyα [18]) with increased sensitivity to the scale and redshift dependences of the matter power spectrum, thanks also to redshift space distortion measurements e.g., [19,20].All this wealth of cosmological data show a consistent ΛCDM model with improved precision on parameters and better control of systematics. If included as a parameter in the model, total neutrino mass bounds have significantly improved in a variety of analysis, yielding an upper bound slightly higher than 100 meV [18,21].…”