Constraining Cosmological Parameters Based on Relative Galaxy Ages

Jiménez, Raúl; Loeb, Abraham

doi:10.1086/340549

Cited by 857 publications

(753 citation statements)

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“…The conflict between the ages of globular clusters and the value of t 0 in a decelerating universe was one of the significant early arguments for cosmic acceleration, and a number of authors have employed ages of high-redshift galaxies or clusters of galaxies as a constraint on dark energy models (e.g., Lima and Alcaniz 2000;Jimenez et al 2003;Capozziello et al 2004). Jimenez and Loeb (2002) proposed using differential ages of galaxies at different redshifts to measure, in effect, H(z). Observational studies thus far have concentrated on the massive ellipticals, as these have the fewest complications (dust, ongoing star formation).…”

Section: Galaxy Agesmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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The accelerating expansion of the universe is the most surprising cosmological discovery in many decades, implying that the universe is dominated by some form of "dark energy" with exotic physical properties, or that Einstein's theory of gravity breaks down on cosmological scales. The profound implications of cosmic acceleration have inspired ambitious efforts to understand its origin, with experiments that aim to measure the history of expansion and growth of structure with percent-level precision or higher. We review in detail the four most well established methods for making such measurements: Type Ia supernovae, baryon acoustic oscillations (BAO), weak gravitational lensing, and the abundance of galaxy clusters. We pay particular attention to the systematic uncertainties in these techniques and to strategies for controlling them at the level needed to exploit "Stage IV" dark energy facilities such as BigBOSS, LSST, Euclid, and WFIRST. We briefly review a number of other approaches including redshift-space distortions, the Alcock-Paczynski effect, and direct measurements of the Hubble constant H 0 . We present extensive forecasts for constraints on the dark energy equation of state and parameterized deviations from General Relativity, achievable with Stage III and Stage IV experimental programs that incorporate supernovae, BAO, weak lensing, and cosmic microwave background data. We also show the level of precision required for clusters or other methods to provide constraints competitive with those of these fiducial programs. We emphasize the value of a balanced program that employs several of the most powerful methods in combination, both to cross-check systematic uncertainties and to take advantage of complementary information. Surveys to probe cosmic acceleration produce data sets that support a wide range of scientific investigations, and they continue the longstanding astronomical tradition of mapping the universe in ever greater detail over ever larger scales.

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Section: Galaxy Agesmentioning

confidence: 99%

Observational probes of cosmic acceleration

et al. 2013

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“…For review, including a discussion on systematic uncertainties and possible source of errors, see [36]. The differential age method has been proposed in [37]. It has been shown in this reference, that by measuring the age differences between two ensembles of passively evolving galaxies at somewhat different redshifts, it is possible to obtain the derivative dz/dt and this quantity is directly related to H(z),…”

Section: H(z)mentioning

confidence: 99%

Constraining the cosmic deceleration-acceleration transition with type Ia supernova, BAO/CMB and H(z) data

Santos

Reis

Waga

2016

J. Cosmol. Astropart. Phys.

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Abstract. We revisit the kink-like parametrization of the deceleration parameter q(z) [1], which considers a transition, at redshift z t , from cosmic deceleration to acceleration. In this parametrization the initial, at z z t , value of the q-parameter is q i , its final, z = −1, value is q f and the duration of the transition is parametrized by τ . By assuming a flat space geometry we obtain constraints on the free parameters of the model using recent data from type Ia supernovae (SN Ia), baryon acoustic oscillations (BAO), cosmic microwave background (CMB) and the Hubble parameter H(z). The use of H(z) data introduces an explicit dependence of the combined likelihood on the present value of the Hubble parameter H 0 , allowing us to explore the influence of different priors when marginalizing over this parameter. We also study the importance of the CMB information in the results by considering data from WMAP7, WMAP9 (Wilkinson Microwave Anisotropy Probe -7 and 9 years) and Planck 2015. We show that the contours and best fit do not depend much on the different CMB data used and that the considered new BAO data is responsible for most of the improvement in the results. Assuming a flat space geometry, q i = 1/2 and expressing the present value of the deceleration parameter q 0 as a function of the other three free parameters, we obtain z t = 0.67 +0.10 −0.08 , τ = 0.26 +0.14 −0.10 and q 0 = −0.48 +0.11 −0.13 , at 68% of confidence level, with an uniform prior over H 0 . If in addition we fix q f = −1, as in flat ΛCDM, DGP and Chaplygin quartessence that are special models described by our parametrization, we get z t = 0.66 +0.03 −0.04 , τ = 0.33 +0.04 −0.04 and q 0 = −0.54 +0.05 −0.07 , in excellent agreement with flat ΛCDM for which τ = 1/3. We also obtain for flat wCDM, another dark energy model described by our parametrization, the constraint on the equation of state parameter −1.22 < w < −0.78 at more than 99% confidence level.

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“…But recent analyses of the two-point correlation function of the cosmic microwave background (Melia 2014;Copi et al 2015), as well as the Om(z i , z j ) and Omh 2 (z i , z j ) diagnostics applied to measurements of the Hubble expansion rate H(z) (Shafieloo, Sahni & Starobinsky 2012; Sahni, Shafieloo & Starobinsky 2014), appear to have revealed significant tension between its predictions and recent measurements (see, e.g. Zheng et al 2016).In this paper, we directly address the problems highlighted by the various analyses carried out with the H(z) data, which apparently do not confirm the anticipated transition from early deceleration E-mail: kyleaf@email.arizona.edu (KL); melia@physics.arizona.eduto more recent acceleration in the cosmic expansion rate (Jimenez & Loeb 2002;Moresco et al 2016a). With this type of work, one typically compiles a unified sample of H(z) versus redshift measurements based on various approaches, including the determination of differential ages using cosmic chronometers (Moresco et al 2016b) and the inference of a characteristic distance scale revealed in baryon acoustic oscillations (BAOs; see, e.g.…”

mentioning

confidence: 83%

“…to more recent acceleration in the cosmic expansion rate (Jimenez & Loeb 2002;Moresco et al 2016a). With this type of work, one typically compiles a unified sample of H(z) versus redshift measurements based on various approaches, including the determination of differential ages using cosmic chronometers (Moresco et al 2016b) and the inference of a characteristic distance scale revealed in baryon acoustic oscillations (BAOs; see, e.g.…”

Section: Introductionmentioning

confidence: 99%

Analysing H(z) data using two-point diagnostics

Leaf

Melia

2017

Monthly Notices of the Royal Astronomical Society

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Measurements of the Hubble constant H(z) are increasingly being used to test the expansion rate predicted by various cosmological models. But the recent application of two-point diagnostics, such as Om(z i , z j ) and Omh 2 (z i , z j ), has produced considerable tension between CDM's predictions and several observations, with other models faring even worse. Part of this problem is attributable to the continued mixing of truly model-independent measurements using the cosmic-chronometer approach, and model-dependent data extracted from baryon acoustic oscillations. In this paper, we advance the use of two-point diagnostics beyond their current status, and introduce new variations, which we call h(z i , z j ), that are more useful for model comparisons. But we restrict our analysis exclusively to cosmic-chronometer data, which are truly model independent. Even for these measurements, however, we confirm the conclusions drawn by earlier workers that the data have strongly non-Gaussian uncertainties, requiring the use of both 'median' and 'mean' statistical approaches. Our results reveal that previous analyses using two-point diagnostics greatly underestimated the errors, thereby misinterpreting the level of tension between theoretical predictions and H(z) data. Instead, we demonstrate that as of today, only Einstein-de Sitter is ruled out by the two-point diagnostics at a level of significance exceeding ∼3σ . The R h = ct universe is slightly favoured over the remaining models, including Lambda cold dark matter and Chevalier-Polarski-Linder, though all of them (other than Einstein-de Sitter) are consistent to within 1σ with the measured mean of the h(z i , z j ) diagnostics.Key words: galaxies: distances and redshifts -galaxies: evolution -large-scale structure of Universe -cosmology: observations -cosmology: theory. I N T RO D U C T I O NLambda cold dark matter ( CDM) has done reasonably well accounting for a broad range of data and is therefore correctly viewed as the current standard model of cosmology (see, e.g. Planck Collaboration XXIII 2014). But recent analyses of the two-point correlation function of the cosmic microwave background (Melia 2014;Copi et al. 2015), as well as the Om(z i , z j ) and Omh 2 (z i , z j ) diagnostics applied to measurements of the Hubble expansion rate H(z) (Shafieloo, Sahni & Starobinsky 2012; Sahni, Shafieloo & Starobinsky 2014), appear to have revealed significant tension between its predictions and recent measurements (see, e.g. Zheng et al. 2016).In this paper, we directly address the problems highlighted by the various analyses carried out with the H(z) data, which apparently do not confirm the anticipated transition from early deceleration E-mail: kyleaf@email.arizona.edu (KL); melia@physics.arizona.eduto more recent acceleration in the cosmic expansion rate (Jimenez & Loeb 2002;Moresco et al. 2016a). With this type of work, one typically compiles a unified sample of H(z) versus redshift measurements based on various approaches, including the determination of differ...

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Constraining Cosmological Parameters Based on Relative Galaxy Ages

Cited by 857 publications

References 27 publications

Observational probes of cosmic acceleration

Observational probes of cosmic acceleration

Constraining the cosmic deceleration-acceleration transition with type Ia supernova, BAO/CMB and H(z) data

Analysing H(z) data using two-point diagnostics

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