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Adam G Riess - One of the best experts on this subject based on the ideXlab platform.
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a measurement of the Hubble Constant from type ii supernovae
Monthly Notices of the Royal Astronomical Society, 2020Co-Authors: T De Jaeger, Adam G Riess, Benjamin E Stahl, W Zheng, A V Filippenko, L GalbanyAbstract:Progressive increases in the precision of the Hubble-Constant measurement via Cepheid-calibrated Type Ia supernovae (SNe Ia) have shown a discrepancy of $\sim 4.4\sigma$ with the current value inferred from Planck satellite measurements of the cosmic microwave background radiation and the standard $\Lambda$CDM cosmological model. This disagreement does not appear to be due to known systematic errors and may therefore be hinting at new fundamental physics. Although all of the current techniques have their own merits, further improvement in constraining the Hubble Constant requires the development of as many independent methods as possible. In this work, we use SNe II as standardisable candles to obtain an independent measurement of the Hubble Constant. Using 7 SNe II with host-galaxy distances measured from Cepheid variables or the tip of the red giant branch, we derive H$_0= 75.8^{+5.2}_{-4.9}$ km s$^{-1}$ Mpc$^{-1}$ (statistical errors only). Our value favours that obtained from the conventional distance ladder (Cepheids + SNe Ia) and exhibits a difference of 8.4 km s$^{-1}$ Mpc$^{-1}$ from the Planck $+\Lambda$CDM value. Adding an estimate of the systematic errors (2.8 km s$^{-1}$ Mpc$^{-1}$) changes the $\sim 1.7\sigma$ discrepancy with Planck $+\Lambda$CDM to $\sim 1.4\sigma$. Including the systematic errors and performing a bootstrap simulation, we confirm that the local H$_0$ value exceeds the value from the early Universe with a confidence level of 95%. As in this work we only exchange SNe II for SNe Ia to measure extragalactic distances, we demonstrate that there is no evidence that SNe Ia are the source of the H$_0$ tension.
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the megamaser cosmology project xiii combined Hubble Constant constraints
The Astrophysical Journal, 2020Co-Authors: Dominic W Pesce, J A Braatz, Mark J Reid, Adam G Riess, D Scolnic, J J Condon, F GaoAbstract:We present a measurement of the Hubble Constant made using geometric distance measurements to megamaser-hosting galaxies. We have applied an improved approach for fitting maser data and obtained better distance estimates for four galaxies previously published by the Megamaser Cosmology Project: UGC 3789, NGC 6264, NGC 6323, and NGC 5765b. Combining these updated distance measurements with those for the maser galaxies CGCG 074-064 and NGC 4258, and assuming a fixed velocity uncertainty of 250 km s−1 associated with peculiar motions, we constrain the Hubble Constant to be H 0 = 73.9 ± 3.0 km s−1 Mpc−1 independent of distance ladders and the cosmic microwave background. This best value relies solely on maser-based distance and velocity measurements, and it does not use any peculiar velocity corrections. Different approaches for correcting peculiar velocities do not modify H 0 by more than ±1σ, with the full range of best-fit Hubble Constant values spanning 71.8–76.9 km s−1 Mpc−1. We corroborate prior indications that the local value of H 0 exceeds the early-universe value, with a confidence level varying from 95% to 99% for different treatments of the peculiar velocities.
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the local perspective on the Hubble tension local structure does not impact measurement of the Hubble Constant
The Astrophysical Journal, 2019Co-Authors: Darcy W Kenworthy, Adam G Riess, D ScolnicAbstract:We use the largest sample to date of spectroscopic supernova (SN) Ia distances and redshifts to look for evidence in the Hubble diagram of large-scale outflows caused by local voids suggested to exist at z < 0.15. Our sample combines data from the Pantheon sample with the Foundation survey, and the most recent release of light curves from the Carnegie Supernova Project, to create a sample of 1295 SNe over a redshift range of 0.01 < z < 2.26. We make use of an inhomogeneous and isotropic Lemaitre–Tolman–Bondi metric to model a void in the SN Ia distance–redshift relation. We conclude that the SN luminosity distance–redshift relation is inconsistent at the 4–5σ confidence level with large local underdensities (, where the density contrast δ = Δρ/ρ) proposed in some galaxy count studies, and find no evidence of a change in the Hubble Constant corresponding to a void with a sharp edge in the redshift range 0.023 < z < 0.15. With an empirical precision of , we conclude that the distance ladder measurement is not affected by local density contrasts, in agreement with a cosmic variance of , predicted from simulations of large-scale structure. Given that uncertainty in the distance ladder value is , this does not affect the Hubble tension. We derive a 5σ constraint on local density contrasts on scales larger than of . The presence of local structure does not appear to impede the possibility of measuring the Hubble Constant to 1% precision.
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the local perspective on the Hubble tension local structure does not impact measurement of the Hubble Constant
arXiv: Cosmology and Nongalactic Astrophysics, 2019Co-Authors: Darcy W Kenworthy, Adam G Riess, D ScolnicAbstract:We use the largest sample to date of spectroscopic SN Ia distances and redshifts to look for evidence in the Hubble diagram of large scale outflows caused by local voids suggested to exist at z 20%, where the density contrast delta = Delta rho /rho) proposed in some galaxy count studies, and find no evidence of a change in the Hubble Constant corresponding to a void with a sharp edge in the redshift range 0.023
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cepheid calibrations of modern type ia supernovae implications for the Hubble Constant
Astrophysical Journal Supplement Series, 2009Co-Authors: Adam G Riess, Lucas M Macri, Hubert Lampeitl, Stefano Casertano, Henry C Ferguson, Alexei V Filippenko, S Jha, R ChornockAbstract:This is the first of two papers reporting measurements from a program to determine the Hubble Constant to {approx}5% precision from a refurbished distance ladder. We present new observations of 110 Cepheid variables in the host galaxies of two recent Type Ia supernovae (SNe Ia), NGC 1309 and NGC 3021, using the Advanced Camera for Surveys on the Hubble Space Telescope (HST). We also present new observations of the hosts previously observed with HST whose SNe Ia provide the most precise luminosity calibrations: SN 1994ae in NGC 3370, SN 1998aq in NGC 3982, SN 1990N in NGC 4639, and SN 1981B in NGC 4536, as well as the maser host, NGC 4258. Increasing the interval between observations enabled the discovery of new, longer-period Cepheids, including 57 with P>60 days, which extend these period-luminosity (P-L) relations. We present 93 measurements of the metallicity parameter, 12 + log[O/H], measured from H II regions in the vicinity of the Cepheids and show these are consistent with solar metallicity. We find the slope of the seven dereddened P-L relations to be consistent with that of the Large Magellanic Cloud Cepheids and with parallax measurements of Galactic Cepheids, and we address the implications for themore » Hubble Constant. We also present multi-band light curves of SN 2002fk (in NGC 1309) and SN 1995al (in NGC 3021) which may be used to calibrate their luminosities. In the second paper, we present observations of the Cepheids in the H band obtained with the Near-Infrared Camera and Multi-Object Spectrometer on HST, further mitigating systematic errors along the distance ladder resulting from dust and chemical variations. The quality and homogeneity of these SN and Cepheid data provide the basis for a more precise determination of the Hubble Constant.« less
Wendy L Freedman - One of the best experts on this subject based on the ideXlab platform.
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measurements of the Hubble Constant tensions in perspective
The Astrophysical Journal, 2021Co-Authors: Wendy L FreedmanAbstract:Measurement of the distances to nearby galaxies have improved rapidly in recent decades. The ever-present challenge is to reduce systematic effects, especially as greater distances are probed, and the uncertainties become larger. In this paper, we combine several recent calibrations of the Tip of the Red Giant Branch (TRGB) method. These calibrations are internally self-consistent at the 1% level. New Gaia Early Data Release 3 (EDR3) data provide an additional consistency check, at a (lower) 5% level of accuracy, a result of the well-documented Gaia angular covariance bias. The updated TRGB calibration applied to a distant sample of Type Ia supernovae from the Carnegie Supernova Project results in a value of the Hubble Constant of Ho = 69.8 $\pm$ 0.6 (stat) $\pm$ 1.6 (sys) km/s/Mpc. No statistically significant difference is found between the value of Ho based on the TRGB and that determined from measurements of the cosmic microwave background. The TRGB results are also consistent to within 2$\sigma$ with the SHoES and Spitzer plus HST Key Project Cepheid calibrations. The TRGB results alone do not demand additional new physics beyond the standard Lambda-CDM cosmological model. They have the advantage of simplicity of the underlying physics (the core He flash) and small systematic uncertainties (from extinction, metallicity and crowding). Finally, the strengths and weaknesses of both the TRGB and Cepheids are reviewed, and prospects for addressing the current discrepancy with future Gaia, HST and JWST observations are discussed. Resolving this discrepancy is essential for ascertaining if the claimed tension in Ho between the locally-measured and the CMB-inferred value is physically motivated.
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carnegie Hubble program a mid infrared calibration of the Hubble Constant
The Astrophysical Journal, 2012Co-Authors: Wendy L Freedman, Barry F Madore, C R Burns, Victoria Scowcroft, Andy Monson, Eric S Persson, Mark Seibert, Jane R RigbyAbstract:Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 μm with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble Constant. We have established the mid-IR zero point of the Leavitt law (the Cepheid period-luminosity relation) using time-averaged 3.6 μm data for 10 high-metallicity, Milky Way Cepheids having independently measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 μm data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 ± 0.033 (systematic) mag. We re-examine the systematic uncertainties in H 0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H 0 over that obtained by the Hubble Space Telescope Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H 0 = 74.3 with a systematic uncertainty of ±2.1 (systematic) km s–1 Mpc–1, corresponding to a 2.8% systematic uncertainty in the Hubble Constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w 0 = –1.09 ± 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yield w 0 = –1.08 ± 0.10 and a value of N eff = 4.13 ± 0.67, mildly consistent with the existence of a fourth neutrino species.
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carnegie Hubble program a mid infrared calibration of the Hubble Constant
arXiv: Cosmology and Nongalactic Astrophysics, 2012Co-Authors: Wendy L Freedman, Barry F Madore, C R Burns, Victoria Scowcroft, Andy Monson, Eric S Persson, Mark Seibert, Jane R RigbyAbstract:Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 um with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble Constant. We have established the mid-IR zero point of the Leavitt Law (the Cepheid Period-Luminosity relation) using time-averaged 3.6 um data for ten high-metallicity, Milky Way Cepheids having independently-measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 um data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 +/- 0.033 (systematic) mag. We re-examine the systematic uncertainties in H0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H0 over that obtained by the Hubble Space Telescope (HST) Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H0 = 74.3 with a systematic uncertainty of +/-2.1 (systematic) km/s/Mpc, corresponding to a 2.8% systematic uncertainty in the Hubble Constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w0 = -1.09 +/- 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yields w0 = -1.08 +/- 0.10 and a value of N_eff = 4.13 +/- 0.67, mildly consistent with the existence of a fourth neutrino species.
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the Hubble Constant and new discoveries in cosmology
arXiv: Cosmology and Nongalactic Astrophysics, 2012Co-Authors: S H Suyu, Wendy L Freedman, J A Braatz, Stefan Hilbert, Tommaso Treu, R D Blandford, C Blake, F Courbin, J Dunkley, L J GreenhillAbstract:We report the outcome of a 3-day workshop on the Hubble Constant (H_0) that took place during February 6-8 2012 at the Kavli Institute for Particle Astrophysics and Cosmology, on the campus of Stanford University. The participants met to address the following questions. Are there compelling scientific reasons to obtain more precise and more accurate measurements of H_0 than currently available? If there are, how can we achieve this goal? The answers that emerged from the workshop are (1) better measurements of H_0 provide critical independent constraints on dark energy, spatial curvature of the Universe, neutrino physics, and validity of general relativity, (2) a measurement of H_0 to 1% in both precision and accuracy, supported by rigorous error budgets, is within reach for several methods, and (3) multiple paths to independent determinations of H_0 are needed in order to access and control systematics.
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the Hubble Constant
arXiv: Cosmology and Nongalactic Astrophysics, 2010Co-Authors: Wendy L Freedman, Barry F MadoreAbstract:Considerable progress has been made in determining the Hubble Constant over the past two decades. We discuss the cosmological context and importance of an accurate measurement of the Hubble Constant, and focus on six high-precision distance-determination methods: Cepheids, tip of the red giant branch, maser galaxies, surface brightness fluctuations, the Tully-Fisher relation and Type Ia supernovae. We discuss in detail known systematic errors in the measurement of galaxy distances and how to minimize them. Our best current estimate of the Hubble Constant is 73 +/-2 (random) +/-4 (systematic) km/s/Mpc. The importance of improved accuracy in the Hubble Constant will increase over the next decade with new missions and experiments designed to increase the precision in other cosmological parameters. We outline the steps that will be required to deliver a value of the Hubble Constant to 2% systematic uncertainty and discuss the constraints on other cosmological parameters that will then be possible with such accuracy.
Bharat Ratra - One of the best experts on this subject based on the ideXlab platform.
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measuring the Hubble Constant and spatial curvature from supernova apparent magnitude baryon acoustic oscillation and Hubble parameter data
Astrophysics and Space Science, 2019Co-Authors: Changyung Park, Bharat RatraAbstract:Cosmic microwave background (CMB) anisotropy (spatial inhomogeneity) data provide the tightest constraints on the Hubble Constant, matter density, spatial curvature, and dark energy dynamics. Other data, sensitive to the evolution of only the spatially homogeneous part of the cosmological model, such as Type Ia supernova apparent magnitude, baryon acoustic oscillation distance, and Hubble parameter measurements, can be used in conjunction with the CMB data to more tightly constrain parameters. Recent joint analyses of CMB and such non-CMB data indicate that slightly closed spatial hypersurfaces are favored in nonflat untilted inflation models and that dark energy dynamics cannot be ruled out, and favor a smaller Hubble Constant. We show that the constraints that follow from these non-CMB data alone are consistent with those that follow from the CMB data alone and so also consistent with, but weaker than, those that follow from the joint analyses of the CMB and non-CMB data.
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Determining the Hubble Constant from Hubble parameter measurements
The Astrophysical Journal, 2017Co-Authors: Y. Q. Chen, Suresh Kumar, Bharat RatraAbstract:Citation: Chen, Y., Kumar, S., & Ratra, B. (2017). DETERMINING THE Hubble Constant FROM Hubble PARAMETER MEASUREMENTS. Astrophysical Journal, 835(1), 4. doi:10.3847/1538-4357/835/1/86
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determining the Hubble Constant from Hubble parameter measurements
arXiv: Cosmology and Nongalactic Astrophysics, 2016Co-Authors: Y. Q. Chen, Suresh Kumar, Bharat RatraAbstract:We use 28 Hubble parameter, $H(z)$, measurements at intermediate redshifts $0.07 \leq z \leq 2.3$ to determine the present-day Hubble Constant $H_0$ in four cosmological models. We measure $H_0 = 68.3^{ +2.7}_{ -2.6 }, 68.4^{ +2.9 }_{ -3.3 }, 65.0^{ +6.5 }_{ -6.6 }$ and $ 67.9^{ +2.4}_{-2.4}$ km s${}^{-1}$ Mpc${}^{-1}$ (1$\sigma$ errors) in the $\Lambda$CDM (spatially flat and non-flat), $\omega$CDM and $\phi$CDM models, respectively. These measured $H_0$ values are more consistent with the lower values determined from recent cosmic microwave background and baryon acoustic oscillation data, as well as with that found from a median statistics analysis of Huchra's compilation of $H_0$ measurements,but include the higher local measurements of $H_0$ within the 2$\sigma$ confidence limits.
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non gaussian error distribution of Hubble Constant measurements
Publications of the Astronomical Society of the Pacific, 2003Co-Authors: Gang Chen, Richard J Gott, Bharat RatraAbstract:ABSTRACT We construct the error distribution of Hubble Constant ( \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcommand\sfdefault{wncyss} \renewcommand\encodingdefault{OT2} \normalfont \selectfont} \DeclareTextFontCommand{\textcyr}{\cyr} \pagestyle{empty} \DeclareMathSizes{10}{9}{7}{6} \begin{document} \landscape $H_{0}$ \end{document} ) measurements from Huchra’s compilation of 461 measurements of \documentclass{aastex} \usepackage{amsbsy} \usepackage{amsfonts} \usepackage{amssymb} \usepackage{bm} \usepackage{mathrsfs} \usepackage{pifont} \usepackage{stmaryrd} \usepackage{textcomp} \usepackage{portland,xspace} \usepackage{amsmath,amsxtra} \usepackage[OT2,OT1]{fontenc} \newcommand\cyr{ \renewcommand\rmdefault{wncyr} \renewcomm...
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non gaussian error distribution of Hubble Constant measurements
arXiv: Astrophysics, 2003Co-Authors: Gang Chen, Richard J Gott, Bharat RatraAbstract:We construct the error distribution of Hubble Constant ($H_0$) measurements from Huchra's compilation of 461 measurements of $H_0$ and the WMAP experiment central value $H_0$ = 71 km s$^{-1}$ Mpc$^{-1}$. This error distribution is non-Gaussian, with significantly larger probability in the tails of the distribution than predicted by a Gaussian distribution. The 95.4 % confidence limits are 7.0 $\sigma$ in terms of the quoted errors. It is remarkably well described by either a widened $n = 2$ Student's $t$ distribution or a widened double exponential distribution. These conclusions are unchanged if we use instead the central value $H_0$ = 67 km s$^{-1}$ Mpc$^{-1}$ found from a median statistics analysis of a major subset of $H_0$ measurements used here.
C R Burns - One of the best experts on this subject based on the ideXlab platform.
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the carnegie supernova project absolute calibration and the Hubble Constant
The Astrophysical Journal, 2018Co-Authors: C R Burns, Nicholas B Suntzeff, M M Phillips, Emilie Parent, M Stritzinger, K Krisciunas, E Y Hsiao, Carlos Contreras, J Anais, Luis BoldtAbstract:We present an analysis of the final data release of the Carnegie Supernova Project I, focusing on the absolute calibration of the luminosity-decline-rate relation for Type Ia supernovae (SNeIa) using new intrinsic color relations with respect to the color-stretch parameter, $s_{BV}$, enabling improved dust extinction corrections. We investigate to what degree the so-called fast-declining SNeIa can be used to determine accurate extragalactic distances. We estimate the intrinsic scatter in the luminosity-decline-rate relation, and find it ranges from $\pm 0.13$ mag to $\pm 0.18$ mag with no obvious dependence on wavelength. Using the Cepheid variable star data from the SH0ES project (Riess et al., 2016), the SNIa distance scale is calibrated and the Hubble Constant is estimated using our optical and near-infrared sample, and these results are compared to those determined exclusively from a near-infrared sub-sample. The systematic effect of the supernova's host galaxy mass is investigated as a function of wavelength and is found to decrease toward redder wavelengths, suggesting this effect may be due to dust properties of the host. Using estimates of the dust extinction derived from optical and NIR wavelengths, and applying these to H band, we derive a Hubble Constant $H_0 = 73.2 \pm 2.3$ km/s/Mpc, whereas using a simple $B-V$ color-correction applied to B band yields $H_0 = 72.7 \pm 2.1$ km/s/Mpc. Photometry of two calibrating SNeIa from the CSP-II sample, SN2012ht and SN2015F, is presented and used to improve the calibration of the SNIa distance ladder.
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the carnegie supernova project absolute calibration and the Hubble Constant
The Astrophysical Journal, 2018Co-Authors: C R Burns, Nicholas B Suntzeff, M M Phillips, Emilie Parent, M Stritzinger, K Krisciunas, E Y Hsiao, Carlos Contreras, J Anais, Luis BoldtAbstract:We present an analysis of the final data release of the Carnegie Supernova Project I, focusing on the absolute calibration of the luminosity-decline-rate relation for Type Ia supernovae (SNeIa) using new intrinsic color relations with respect to the color-stretch parameter, $s_{BV}$, enabling improved dust extinction corrections. We investigate to what degree the so-called fast-declining SNeIa can be used to determine accurate extragalactic distances. We estimate the intrinsic scatter in the luminosity-decline-rate relation, and find it ranges from $\pm 0.13$ mag to $\pm 0.18$ mag with no obvious dependence on wavelength. Using the Cepheid variable star data from the SH0ES project (Riess et al., 2016), the SNIa distance scale is calibrated and the Hubble Constant is estimated using our optical and near-infrared sample, and these results are compared to those determined exclusively from a near-infrared sub-sample. The systematic effect of the supernova's host galaxy mass is investigated as a function of wavelength and is found to decrease toward redder wavelengths, suggesting this effect may be due to dust properties of the host. Using estimates of the dust extinction derived from optical and NIR wavelengths, and applying these to H band, we derive a Hubble Constant $H_0 = 73.2 \pm 2.3$ km/s/Mpc, whereas using a simple $B-V$ color-correction applied to B band yields $H_0 = 72.7 \pm 2.1$ km/s/Mpc. Photometry of two calibrating SNeIa from the CSP-II sample, SN2012ht and SN2015F, is presented and used to improve the calibration of the SNIa distance ladder.
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carnegie Hubble program a mid infrared calibration of the Hubble Constant
The Astrophysical Journal, 2012Co-Authors: Wendy L Freedman, Barry F Madore, C R Burns, Victoria Scowcroft, Andy Monson, Eric S Persson, Mark Seibert, Jane R RigbyAbstract:Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 μm with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble Constant. We have established the mid-IR zero point of the Leavitt law (the Cepheid period-luminosity relation) using time-averaged 3.6 μm data for 10 high-metallicity, Milky Way Cepheids having independently measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 μm data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 ± 0.033 (systematic) mag. We re-examine the systematic uncertainties in H 0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H 0 over that obtained by the Hubble Space Telescope Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H 0 = 74.3 with a systematic uncertainty of ±2.1 (systematic) km s–1 Mpc–1, corresponding to a 2.8% systematic uncertainty in the Hubble Constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w 0 = –1.09 ± 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yield w 0 = –1.08 ± 0.10 and a value of N eff = 4.13 ± 0.67, mildly consistent with the existence of a fourth neutrino species.
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carnegie Hubble program a mid infrared calibration of the Hubble Constant
arXiv: Cosmology and Nongalactic Astrophysics, 2012Co-Authors: Wendy L Freedman, Barry F Madore, C R Burns, Victoria Scowcroft, Andy Monson, Eric S Persson, Mark Seibert, Jane R RigbyAbstract:Using a mid-infrared calibration of the Cepheid distance scale based on recent observations at 3.6 um with the Spitzer Space Telescope, we have obtained a new, high-accuracy calibration of the Hubble Constant. We have established the mid-IR zero point of the Leavitt Law (the Cepheid Period-Luminosity relation) using time-averaged 3.6 um data for ten high-metallicity, Milky Way Cepheids having independently-measured trigonometric parallaxes. We have adopted the slope of the PL relation using time-averaged 3.6 um data for 80 long-period Large Magellanic Cloud (LMC) Cepheids falling in the period range 0.8 < log(P) < 1.8. We find a new reddening-corrected distance to the LMC of 18.477 +/- 0.033 (systematic) mag. We re-examine the systematic uncertainties in H0, also taking into account new data over the past decade. In combination with the new Spitzer calibration, the systematic uncertainty in H0 over that obtained by the Hubble Space Telescope (HST) Key Project has decreased by over a factor of three. Applying the Spitzer calibration to the Key Project sample, we find a value of H0 = 74.3 with a systematic uncertainty of +/-2.1 (systematic) km/s/Mpc, corresponding to a 2.8% systematic uncertainty in the Hubble Constant. This result, in combination with WMAP7 measurements of the cosmic microwave background anisotropies and assuming a flat universe, yields a value of the equation of state for dark energy, w0 = -1.09 +/- 0.10. Alternatively, relaxing the constraints on flatness and the numbers of relativistic species, and combining our results with those of WMAP7, Type Ia supernovae and baryon acoustic oscillations yields w0 = -1.08 +/- 0.10 and a value of N_eff = 4.13 +/- 0.67, mildly consistent with the existence of a fourth neutrino species.
Daniel E Holz - One of the best experts on this subject based on the ideXlab platform.
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a two per cent Hubble Constant measurement from standard sirens within five years
Nature, 2018Co-Authors: Hsinyu Chen, M Fishbach, Daniel E HolzAbstract:Gravitational-wave detections provide a novel way to determine the Hubble Constant1–3, which is the current rate of expansion of the Universe. This ‘standard siren’ method, with the absolute distance calibration provided by the general theory of relativity, was used to measure the Hubble Constant using the gravitational-wave detection of the binary neutron-star merger, GW170817, by the Laser Interferometer Gravitational-Wave Observatory (LIGO) and Virgo4, combined with optical identification of the host galaxy5,6 NGC 4993. This independent measurement is of particular interest given the discrepancy between the value of the Hubble Constant determined using type Ia supernovae via the local distance ladder (73.24 ± 1.74 kilometres per second per megaparsec) and the value determined from cosmic microwave background observations (67.4 ± 0.5 kilometres per second per megaparsec): these values differ7,8 by about 3σ. Local distance ladder observations may achieve a precision of one per cent within five years, but at present there are no indications that further observations will substantially reduce the existing discrepancies9. Here we show that additional gravitational-wave detections by LIGO and Virgo can be expected to constrain the Hubble Constant to a precision of approximately two per cent within five years and approximately one per cent within a decade. This is because observing gravitational waves from the merger of two neutron stars, together with the identification of a host galaxy, enables a direct measurement of the Hubble Constant independent of the systematics associated with other available methods. In addition to clarifying the discrepancy between existing low-redshift (local ladder) and high-redshift (cosmic microwave background) measurements, a precision measurement of the Hubble Constant is of crucial value in elucidating the nature of dark energy10,11. Gravitational-wave observations of binary neutron-star mergers will enable precision measurements of the Hubble Constant within five years.
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a 2 per cent Hubble Constant measurement from standard sirens within 5 years
arXiv: Cosmology and Nongalactic Astrophysics, 2017Co-Authors: Hsinyu Chen, M Fishbach, Daniel E HolzAbstract:Gravitational wave coalescence events provide an entirely new way to determine the Hubble Constant, with the absolute distance calibration provided by the theory of general relativity. This standard siren method was utilized to measure the Hubble Constant using LIGO-Virgo's detection of the binary neutron-star merger GW170817, as well as optical identifications of the host galaxy, NGC 4993. The novel and independent measurement is of particular interest given the existing tension between the value of the Hubble Constant determined using Type Ia supernovae via the local distance ladder ($73.24 \pm 1.74$) and that from Cosmic Microwave Background observations ($66.93 \pm 0.62$) by $\sim 3$ sigma. Local distance ladder observations may achieve a precision of $1\%$ within 5 years, but at present there are no indications that further observations will substantially reduce the existing discrepancies. In addition to clarifying the discrepancy between existing low and high-redshift measurements, a precision measurement of the Hubble Constant is of crucial value in elucidating the nature of the dark energy. Here we show that LIGO and Virgo can be expected to constrain the Hubble Constant to a precision of $\sim2\%$ within 5 years and $\sim1\%$ within a decade.
