The Hubble constant determined through an inverse distance ladder including quasar time delays and Type Ia supernovae (original) (raw)
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The Astrophysical Journal, 2022
With the distance sum rule in the Friedmann-Lemaître-Robertson-Walker metric, model-independent constraints on both the Hubble constant H 0 and spatial curvature Ω K can be obtained using strong lensing time-delay data and Type Ia supernova (SN Ia) luminosity distances. This method is limited by the low redshifts of SNe Ia, however. Here, we propose using quasars as distance indicators, extending the coverage to encompass the redshift range of strong lensing systems. We provide a novel and improved method of determining H 0 and Ω K simultaneously. By applying this technique to the time-delay measurements of seven strong lensing systems and the known ultraviolet versus X-ray luminosity correlation of quasars, we constrain the possible values of both H 0 and Ω K , and find that H 0 = 75.3 +3.0 −2.9 km s −1 Mpc −1 and Ω K = −0.01 +0.18 −0.17. The measured Ω K is consistent with zero spatial curvature, indicating that there is no significant deviation from a flat universe. If we use flatness as a prior, we infer that H 0 = 75.3 +1.9 −1.9 km s −1 Mpc −1 , representing a precision of 2.5%. If we further combine these data with the 1048 current Pantheon SNe Ia, our model-independent constraints can be further improved to H 0 = 75.3 +3.0 −2.9 km s −1 Mpc −1 and Ω K = 0.05 +0.16 −0.14. In every case, we find that the Hubble constant measured with this technique is strongly consistent with the value (∼ 74 km s −1 Mpc −1) measured using the local distance ladder, as opposed to the value optimized by Planck.
Physical Review D
We apply two methods, i.e., the Gaussian processes and the non-parametric smoothing procedure, to reconstruct the Hubble parameter H(z) as a function of redshift from 15 measurements of the expansion rate obtained from age estimates of passively evolving galaxies. These reconstructions enable us to derive the luminosity distance to a certain redshift z, calibrate the light-curve fitting parameters accounting for the (unknown) intrinsic magnitude of type Ia supernova (SNe Ia) and construct cosmological model-independent Hubble diagrams of SNe Ia. In order to test the compatibility between the reconstructed functions of H(z), we perform a statistical analysis considering the latest SNe Ia sample, the so-called JLA compilation. We find that, for the Gaussian processes, the reconstructed functions of Hubble parameter versus redshift, and thus the following analysis on SNe Ia calibrations and cosmological implications, are sensitive to prior mean functions. However, for the non-parametric smoothing method, the reconstructed functions are not dependent on initial guess models, and consistently require high values of H0, which are in excellent agreement with recent measurements of this quantity from Cepheids and other local distance indicators.
Journal of Cosmology and Astroparticle Physics, 2016
Deriving the expansion history of the Universe is a major goal of modern cosmology. To date, the most accurate measurements have been obtained with Type Ia Supernovae (SNe) and Baryon Acoustic Oscillations (BAO), providing evidence for the existence of a transition epoch at which the expansion rate changes from decelerated to accelerated. However, these results have been obtained within the framework of specific cosmological models that must be implicitly or explicitly assumed in the measurement. It is therefore crucial to obtain measurements of the accelerated expansion of the Universe independently of assumptions on cosmological models. Here we exploit the unprecedented statistics provided by the Baryon Oscillation Spectroscopic Survey (BOSS, [1, 2, 3]) Data Release 9 to provide new constraints on the Hubble parameter H(z) using the cosmic chronometers approach. We extract a sample of more than 130000 of the most massive and passively evolving galaxies, obtaining five new cosmology-independent H(z) measurements in the redshift range 0.3 < z < 0.5, with an accuracy of ∼11-16% incorporating both statistical and systematic errors. Once combined, these measurements yield a 6% accuracy constraint of H(z = 0.4293) = 91.8 ± 5.3 km/s/Mpc. The new data are crucial to provide the first cosmology-independent determination of the transition redshift at high statistical significance, measuring z t = 0.4 ± 0.1, and to significantly disfavor the null hypothesis of no transition between decelerated and accelerated expansion at 99.9% confidence level. This analysis highlights the wide potential of the cosmic chronometers approach: it permits to derive constraints on the expansion history of the Universe with results competitive with standard probes, and most importantly, being the estimates independent of the cosmological model, it can constrain cosmologies beyondand including-the ΛCDM model.
Monthly Notices of the Royal Astronomical Society, 2020
We present a blind time-delay cosmographic analysis for the lens system DES J0408−5354. This system is extraordinary for the presence of two sets of multiple images at different redshifts, which provide the opportunity to obtain more information at the cost of increased modelling complexity with respect to previously analysed systems. We perform detailed modelling of the mass distribution for this lens system using three band Hubble Space Telescope imaging. We combine the measured time delays, line-of-sight central velocity dispersion of the deflector, and statistically constrained external convergence with our lens models to estimate two cosmological distances. We measure the 'effective' time-delay distance corresponding to the redshifts of the deflector and the lensed quasar D eff t = 3382 +146 −115 Mpc and the angular diameter distance to the deflector D d = 1711 +376 −280 Mpc, with covariance between the two distances. From these constraints on the cosmological distances, we infer the Hubble constant H 0 = 74.2 +2.7 −3.0 km s −1 Mpc −1 assuming a flat CDM cosmology and a uniform prior for m as m ∼ U (0.05, 0.5). This measurement gives the most precise constraint on H 0 to date from a single lens. Our measurement is consistent with that obtained from the previous sample of six
Cosmographic Hubble fits to the supernova data
Physical Review D, 2008
The Hubble relation between distance and redshift is a purely cosmographic relation that depends only on the symmetries of a FLRW spacetime, but does not intrinsically make any dynamical assumptions. This suggests that it should be possible to estimate the parameters defining the Hubble relation without making any dynamical assumptions. To test this idea, we perform a number of interrelated cosmographic fits to the legacy05 and gold06 supernova datasets. Based on this supernova data, the "preponderance of evidence" certainly suggests an accelerating universe. However we would argue that (unless one uses additional dynamical and observational information) this conclusion is not currently supported "beyond reasonable doubt". As part of the analysis we develop two particularly transparent graphical representations of the redshift-distance relation -representations in which acceleration versus deceleration reduces to the question of whether the relevant graph slopes up or down.
Raising the bar: new constraints on the Hubble parameter with cosmic chronometers at z$ sim$2
2015
One of the most compelling tasks of modern cosmology is to constrain the expansion history of the Universe, since this measurement can give insights on the nature of dark energy and help to estimate cosmological parameters. In this letter are presented two new measurements of the Hubble parameter H(z) obtained with the cosmic chronometer method up to zsim2z\sim2zsim2. Taking advantage of near-infrared spectroscopy of the few very massive and passive galaxies observed at z>1.4z>1.4z>1.4 available in literature, the differential evolution of this population is estimated and calibrated with different stellar population synthesis models to constrain H(z), including in the final error budget all possible sources of systematic uncertainties (star formation history, stellar metallicity, model dependencies). This analysis is able to extend significantly the redshift range coverage with respect to present-day constraints, crossing for the first time the limit at zsim1.75z\sim1.75zsim1.75. The new H(z) data are used to estimate the gain in accuracy on cosmological parameters with respect to previous measurements in two cosmological models, finding a small but detectable improvement ($\sim$5 %) in particular on OmegaM\Omega_{M}OmegaM and w0w_{0}w0. Finally, a simulation of a Euclid-like survey has been performed to forecast the expected improvement with future data. The provided constraints have been obtained just with the cosmic chronometers approach, without any additional data, and the results show the high potentiality of this method to constrain the expansion history of the Universe at these redshifts.
Cosmography: Extracting the Hubble series from the supernova data
Cosmography (cosmokinetics) is the part of cosmology that proceeds by making minimal dynamic assumptions. One keeps the geometry and symmetries of FLRW spacetime, at least as a working hypothesis, but does not assume the Friedmann equations (Einstein equations), unless and until absolutely necessary. By doing so it is possible to defer questions about the equation of state of the cosmological fluid, and concentrate more directly on the observational situation. In particular, the "big picture" is best brought into focus by performing a fit of all available supernova data to the Hubble relation, from the current epoch at least back to redshift z ≈ 1.75. We perform a number of interrelated cosmographic fits to the legacy05 and gold06 supernova datasets. We pay particular attention to the influence of both statistical and systematic uncertainties, and also to the extent to which the choice of distance scale and manner of representing the redshift scale affect the cosmological parameters. While the "preponderance of evidence" certainly suggests an accelerating universe, we would argue that (based on the supernova data) this conclusion is not currently supported "beyond reasonable doubt". As part of the analysis we develop two particularly transparent graphical representations of the redshift-distance relationrepresentations in which acceleration versus deceleration reduces to the question of whether the graph slopes up or down. Turning to the details of the cosmographic fits, three issues in particular concern us: First, the fitted value for the deceleration parameter changes significantly depending on whether one performs a χ 2 fit to the luminosity distance, proper motion distance, angular diameter distance, or other suitable distance surrogate. Second, the fitted value for the deceleration parameter changes significantly depending on whether one uses the traditional redshift variable z, or what we shall argue is on theoretical grounds an improved parameterization y = z/(1+z). Third, the published estimates for systematic uncertainties are sufficiently large that they certainly impact on, and to a large extent undermine, the usual purely statistical tests of significance. We conclude that the case for an accelerating universe is considerably less watertight than commonly believed.
An independent determination of the local Hubble constant
Monthly Notices of the Royal Astronomical Society, 2017
The relationship between the integrated Hβ line luminosity and the velocity dispersion of the ionized gas of H ii galaxies and giant H ii regions represents an exciting standard candle that presently can be used up to redshifts z ∼ 4. Locally it is used to obtain precise measurements of the Hubble constant by combining the slope of the relation obtained from nearby (z ≤ 0.2) H ii galaxies with the zero point determined from giant H ii regions belonging to an 'anchor sample' of galaxies for which accurate redshift-independent distance moduli are available. We present new data for 36 giant H ii regions in 13 galaxies of the anchor sample that includes the megamaser galaxy NGC 4258. Our data is the result of the first four years of observation of our primary sample of 130 giant H ii regions in 73 galaxies with Cepheid determined distances. Our best estimate of the Hubble parameter is 71.0 ± 2.8(random) ± 2.1(systematic) km s −1 Mpc −1. This result is the product of an independent approach and, although at present less precise than the latest SNIa results, it is amenable to substantial improvement.