The Megamaser Cosmology Project. Iv. A Direct Measurement of the Hubble Constant From Ugc 3789

Reid, M. J.; Braatz, J. A.; Condon, J. J.; Lo, K. Y.; Kuo, C. Y.; Impellizzeri, C. M. V.; Henkel, C.

doi:10.1088/0004-637x/767/2/154

Cited by 140 publications

(129 citation statements)

References 18 publications

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“…The reason is that the contribution of peculiar velocities (see Sec 2 for the definition of peculiar velocity) to the cosmic flow, which can be ignored at high Redshifts is dominant locally and especially for surveys of limited depth. Interestingly, direct measurement of the Hubble parameter based on masers which targets only sources of very small peculiar velocities favors a low value of the Hubble parameter: H 0 = 68.9 ± 7.1 [19], in good agreement with the CMB-based value.…”

Section: Introductionsupporting

confidence: 64%

Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

Liu¹,

Mohayaee²,

Naselsky³

2016

J. Cosmol. Astropart. Phys.

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Abstract. The existence of critical points for the peculiar velocity field is a natural feature of the correlated vector field. These points appear at the junctions of velocity domains with different orientations of their averaged velocity vectors. Since peculiar velocities are the important cause of the scatter in the Hubble expansion rate, we propose that a more precise determination of the Hubble constant can be made by restricting analysis to a subsample of observational data containing only the zones around the critical points of the peculiar velocity field, associated with voids and saddle points. On large-scales the critical points, where the first derivative of the gravitational potential vanishes, can easily be identified using the density field and classified by the behavior of the Hessian of the gravitational potential. We use high-resolution N-body simulations to show that these regions are stable in time and hence are excellent tracers of the initial conditions. Furthermore, we show that the variance of the Hubble flow can be substantially minimized by restricting observations to the subsample of such regions of vanishing velocity instead of aiming at increasing the statistics by averaging indiscriminately using the full data sets, as is the common approach.

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Section: Introductionsupporting

confidence: 64%

Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

Liu¹,

Mohayaee²,

Naselsky³

2016

J. Cosmol. Astropart. Phys.

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“…26 The estimate labelled "MCP" shows the 25 As noted in Sect. 1, after the submission of this paper Humphreys et al (2013) Reid et al 2013, for a detailed analysis of UGC 3789). The point labelled "RXJ1131-1231" shows the estimate H 0 = 78.7 +4.3 −4.5 km s −1 Mpc −1 derived from gravitational lensing time delay measurements of the system RXJ1131-1231, observed as part of the "COSmological MOnitoring of GRAvitational Lenses" (COSMOGRAIL) project (Suyu et al 2013, see also Courbin et al 2011;Tewes et al 2013).…”

Section: The Hubble Constantmentioning

confidence: 99%

Planck2013 results. XVI. Cosmological parameters

Ade¹,

Aghanim²,

Armitage-Caplan³

et al. 2014

A&A

5,014

163

2,253

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This paper presents the first cosmological results based on Planck measurements of the cosmic microwave background (CMB) temperature and lensing-potential power spectra. We find that the Planck spectra at high multipoles ( > ∼ 40) are extremely well described by the standard spatiallyflat six-parameter ΛCDM cosmology with a power-law spectrum of adiabatic scalar perturbations. Within the context of this cosmology, the Planck data determine the cosmological parameters to high precision: the angular size of the sound horizon at recombination, the physical densities of baryons and cold dark matter, and the scalar spectral index are estimated to be θ * = (1.04147 ± 0.00062) × 10 −2 , Ω b h 2 = 0.02205 ± 0.00028, Ω c h 2 = 0.1199 ± 0.0027, and n s = 0.9603 ± 0.0073, respectively (note that in this abstract we quote 68% errors on measured parameters and 95% upper limits on other parameters). For this cosmology, we find a low value of the Hubble constant, H 0 = (67.3 ± 1.2) km s −1 Mpc −1 , and a high value of the matter density parameter, Ω m = 0.315 ± 0.017. These values are in tension with recent direct measurements of H 0 and the magnituderedshift relation for Type Ia supernovae, but are in excellent agreement with geometrical constraints from baryon acoustic oscillation (BAO) surveys. Including curvature, we find that the Universe is consistent with spatial flatness to percent level precision using Planck CMB data alone. We use high-resolution CMB data together with Planck to provide greater control on extragalactic foreground components in an investigation of extensions to the six-parameter ΛCDM model. We present selected results from a large grid of cosmological models, using a range of additional astrophysical data sets in addition to Planck and high-resolution CMB data. None of these models are favoured over the standard six-parameter ΛCDM cosmology. The deviation of the scalar spectral index from unity is insensitive to the addition of tensor modes and to changes in the matter content of the Universe. We find an upper limit of r 0.002 < 0.11 on the tensor-to-scalar ratio. There is no evidence for additional neutrino-like relativistic particles beyond the three families of neutrinos in the standard model. Using BAO and CMB data, we find N eff = 3.30 ± 0.27 for the effective number of relativistic degrees of freedom, and an upper limit of 0.23 eV for the sum of neutrino masses. Our results are in excellent agreement with big bang nucleosynthesis and the standard value of N eff = 3.046. We find no evidence for dynamical dark energy; using BAO and CMB data, the dark energy equation of state parameter is constrained to be w = −1.13 +0.13 −0.10 . We also use the Planck data to set limits on a possible variation of the fine-structure constant, dark matter annihilation and primordial magnetic fields. Despite the success of the six-parameter ΛCDM model in describing the Planck data at high multipoles, we note that this cosmology does not provide a good fit to the temperature power spectrum at low multipoles. T...

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“…New Milky Way parallax measurements using the spatial scanning capability of HST may achieve this precision even sooner. Discovery of additional galaxies with maser distances (like NGC 4258) may also improve the Cepheid calibration or, if they are in the Hubble flow, may provide a direct determination of the Hubble constant (see Reid et al 2012a for a recent measurement of UGC 3789 and Greenhill et al 2009 for additional candidates). The other key step will be the Cepheid calibration of more Type Ia supernovae, which occur at a rate of one per 2 − 3 years in the range D < 35 Mpc accessible to HST with WFC3.…”

Section: Measurement Of the Hubble Constant At Z ≈mentioning

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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The Megamaser Cosmology Project. Iv. A Direct Measurement of the Hubble Constant From Ugc 3789

Cited by 140 publications

References 18 publications

Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

Critical points of the cosmic velocity field and the uncertainties in the value of the Hubble constant

Planck2013 results. XVI. Cosmological parameters

Observational probes of cosmic acceleration

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