scholarly journals The effects of peculiar velocities in SN Ia environments on the local H0 measurement

2020 ◽  
Vol 500 (3) ◽  
pp. 3728-3742
Author(s):  
Thomas M Sedgwick ◽  
Chris A Collins ◽  
Ivan K Baldry ◽  
Philip A James
Keyword(s):  
Hubble Constant ◽  
Density Parameter ◽  
Host Galaxies ◽  
Peculiar Velocities ◽  
Standard Candle ◽  
Modern Cosmology ◽  
Type Ia ◽  
The Difference ◽  
Ia Supernovae ◽  
Distance Indicators

ABSTRACT The discrepancy between estimates of the Hubble constant (H0) measured from local (z ≲  0.1) scales and from scales of the sound horizon is a crucial problem in modern cosmology. Peculiar velocities (vpec) of standard candle distance indicators can systematically affect local H0 measurements. We here use 2MRS galaxies to measure the local galaxy density field, finding a notable z  <  0.05 underdensity in the SGC-6dFGS region of 27  ±  2 per cent. However, no strong evidence for a ‘Local Void’ pertaining to the full 2MRS sky coverage is found. Galaxy densities are used to measure a density parameter, Δϕ+−, which we introduce as a proxy for vpec that quantifies density gradients along a supernova (SN) line of sight. Δϕ+− is found to correlate with local H0 estimates from 88 Pantheon Type Ia supernovae (SNe Ia; 0.02  <  z  <  0.05). Density structures on scales of ∼50 Mpc are found to correlate strongest with H0 estimates in both the observational data and in mock data from the MDPL2-Galacticus simulation. Using trends of H0 with Δϕ+−, we can correct for the effects of density structure on local H0 estimates, even in the presence of biased vpec. However, the difference in the inferred H0 estimate with and without the peculiar velocity correction is limited to < 0.1  per cent. We conclude that accounting for environmentally induced peculiar velocities of SN Ia host galaxies does not resolve the tension between local and CMB-derived H0 estimates.

scholarly journals Theoretical Light Curves for Type Ia Supernovae and Determination of the Hubble Constant

1999 ◽  
Vol 183 ◽  
pp. 68-68
Author(s):  
Koichi Iwamoto ◽  
Ken'Ichi Nomoto
Keyword(s):  
Hubble Constant ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Maximum Brightness ◽  
Decline Rate ◽  
Type Ia ◽  
Error Bars ◽  
Ia Supernovae ◽  
Distance Indicators

The large luminosity (MV ≈ −19 ∼ −20) and the homogeneity in light curves and spectra of Type Ia supernovae(SNe Ia) have led to their use as distance indicators ultimately to determine the Hubble constant (H0). However, an increasing number of the observed samples from intermediate- and high-z (z ∼ 0.1 − 1) SN Ia survey projects(Hamuy et al. 1996, Perlmutter et al. 1997) have shown that there is a significant dispersion in the maximum brightness (∼ 0.4 mag) and the brighter-slower correlation between the brightness and the postmaximum decline rate, which was first pointed out by Phillips(1993). By taking the correlation into account, Hamuy et al.(1996) gave an estimate of H0 within the error bars half as much as previous ones.

scholarly journals Towards a 1% measurement of the Hubble constant: accounting for time dilation in variable-star light curves

2019 ◽  
Vol 631 ◽  
pp. A165
Author(s):  
Richard I. Anderson
Keyword(s):  
Variable Star ◽  
Hubble Constant ◽  
Light Curves ◽  
Type Ia Supernovae ◽  
Host Galaxies ◽  
Pulsating Stars ◽  
Distant Galaxies ◽  
Type Ia ◽  
Absolute Magnitudes ◽  
Ia Supernovae

Assessing the significance and implications of the recently established Hubble tension requires the comprehensive identification, quantification, and mitigation of uncertainties and/or biases affecting H0 measurements. Here, we investigate the previously overlooked distance scale bias resulting from the interplay between redshift and Leavitt laws in an expanding Universe: Redshift-Leavitt bias (RLB). Redshift dilates oscillation periods of pulsating stars residing in supernova-host galaxies relative to periods of identical stars residing in nearby (anchor) galaxies. Multiplying dilated log P with Leavitt Law slopes leads to underestimated absolute magnitudes, overestimated distance moduli, and a systematic error on H0. Emulating the SH0ES distance ladder, we estimate an associated H0 bias of (0.27 ± 0.01)% and obtain a corrected H0 = 73.70 ± 1.40 km s−1 Mpc−1. RLB becomes increasingly relevant as distance ladder calibrations pursue greater numbers of ever more distant galaxies hosting both Cepheids (or Miras) and type-Ia supernovae. The measured periods of oscillating stars can readily be corrected for heliocentric redshift (e.g. of their host galaxies) in order to ensure H0 measurements free of RLB.

scholarly journals Improving Type Ia supernova characterization through multiwavelength studies of Type Ia supernova host galaxies

2012 ◽  
Vol 8 (S289) ◽  
pp. 328-328
Author(s):  
Brad Tucker ◽  
Brian P. Schmidt ◽  
Peter Garnavich
Keyword(s):  
Stellar Population ◽  
Star Formation Rate ◽  
Formation Rate ◽  
Host Galaxies ◽  
Distance Measurements ◽  
Infrared Observations ◽  
Type Ia Supernova ◽  
Type Ia ◽  
Ia Supernovae ◽  
Distance Indicators

AbstractPast investigations have shown a connection between the properties of Type Ia supernovae (SNe Ia) and their host galaxies. We refine these studies using ultraviolet through mid-infrared observations of both nearby and distant SN Ia hosts. We present new results showing that the properties of SNe Ia, both intrinsic and with respect to their use as distance indicators, appear to depend on a combination of metallicity, stellar age, and star-formation rate of the host. We suggest that the stellar population age and location of the supernova progenitor all can play a roll in using SNe Ia as precision distance indicators, and advocate that a multiwavelength approach is one way to disentangle the different influences, resulting in an improvement of 8% in distance measurements.

scholarly journals Allan Sandage and the distance scale

2012 ◽  
Vol 8 (S289) ◽  
pp. 13-25 ◽  
Author(s):  
G. A. Tammann ◽  
B. Reindl
Keyword(s):  
Large Scale ◽  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Distance Scale ◽  
Type Ia ◽  
The Mean ◽  
Red Giant ◽  
Ia Supernovae ◽  
Distance Indicators ◽  
Local Value

AbstractAllan Sandage returned to the distance scale and the calibration of the Hubble constant again and again during his active life, experimenting with different distance indicators. In 1952 his proof of the high luminosity of Cepheids confirmed Baade's revision of the distance scale (H0 ~ 250 km s−1 Mpc−1). During the next 25 years, he lowered the value to 75 and 55. Upon the arrival of the Hubble Space Telescope, he observed Cepheids to calibrate the mean luminosity of nearby Type Ia supernovae (SNe Ia) which, used as standard candles, led to the cosmic value of H0 = 62.3 ± 1.3 ± 5.0 km s−1 Mpc−1. Eventually he turned to the tip of the red giant branch (TRGB) as a very powerful distance indicator. A compilation of 176 TRGB distances yielded a mean, very local value of H0 = 62.9 ± 1.6 km s−1 Mpc−1 and shed light on the streaming velocities in the Local Supercluster. Moreover, TRGB distances are now available for six SNe Ia; if their mean luminosity is applied to distant SNe Ia, one obtains H0 = 64.6 ± 1.6 ± 2.0 km s−1 Mpc−1. The weighted mean of the two independent large-scale calibrations yields H0 = 64.1 km s−1 Mpc−1 within 3.6%.

scholarly journals Cosmic flows in the nearby Universe: new peculiar velocities from SNe and cosmological constraints

2020 ◽  
Vol 498 (2) ◽  
pp. 2703-2718 ◽  
Author(s):  
Supranta S Boruah ◽  
Michael J Hudson ◽  
Guilhem Lavaux
Keyword(s):  
Velocity Field ◽  
Velocity Fields ◽  
Bulk Flow ◽  
Peculiar Velocity ◽  
Cosmological Constraints ◽  
Peculiar Velocities ◽  
Type Ia ◽  
Galaxy Redshift ◽  
Ia Supernovae ◽  
Distance Indicators

ABSTRACT The peculiar velocity field offers a unique way to probe dark matter density field on large scales at low redshifts. In this work, we have compiled a new sample of 465 peculiar velocities from low redshift ($z$ < 0.067) Type Ia supernovae. We compare the reconstructed velocity field derived from the 2M++ galaxy redshift compilation to the supernovae, the SFI++ and the 2MTF Tully–Fisher distance catalogues. We used a forward method to jointly infer the distances and the velocities of distance indicators by comparing the observations to the reconstruction. Comparison of the reconstructed peculiar velocity fields to observations allows us to infer the cosmological parameter combination fσ8, and the bulk flow velocity arising from outside the survey volume. The residual bulk flow arising from outside the 2M++ volume is inferred to be $171^{+11}_{-11}$ km s−1 in the direction l = 301° ± 4° and b = 0° ± 3°. We obtain fσ8 = 0.400 ± 0.017, equivalent to S8 ≈ σ8(Ωm/0.3)0.55 = 0.776 ± 0.033, which corresponds to an approximately $4{{\ \rm per\ cent}}\,$ statistical uncertainty on the value of fσ8. Our inferred value is consistent with other low redshift results in the literature.

scholarly journals COSMOLOGICAL CONSTRAINTS FOR THE COSMIC DEFECT THEORY

2011 ◽  
Vol 20 (06) ◽  
pp. 1039-1051 ◽  
Author(s):  
NINFA RADICELLA ◽  
MAURO SERENO ◽  
ANGELO TARTAGLIA
Keyword(s):  
Large Scale ◽  
Hubble Constant ◽  
Big Bang ◽  
Nuclear Species ◽  
Type Ia ◽  
Species Abundances ◽  
Age Of The Universe ◽  
Ia Supernovae ◽  
The Big Bang ◽  
The Universe

The cosmic defect theory has been confronted with four observational constraints: primordial nuclear species abundances emerging from the big bang nucleosynthesis; large scale structure formation in the Universe; cosmic microwave background acoustic scale; luminosity distances of type Ia supernovae. The test has been based on a statistical analysis of the a posteriori probabilities for three parameters of the theory. The result has been quite satisfactory and such that the performance of the theory is not distinguishable from that of the ΛCDM theory. The use of the optimal values of the parameters for the calculation of the Hubble constant and the age of the Universe confirms the compatibility of the cosmic defect approach with observations.

scholarly journals Lens modelling of the strongly lensed Type Ia supernova iPTF16geu

2020 ◽  
Vol 496 (3) ◽  
pp. 3270-3280
Author(s):  
E Mörtsell ◽  
J Johansson ◽  
S Dhawan ◽  
A Goobar ◽  
R Amanullah ◽  
...  
Keyword(s):  
Hubble Space Telescope ◽  
Hubble Constant ◽  
Host Galaxy ◽  
Total Probability ◽  
Lens Model ◽  
Density Profiles ◽  
Type Ia Supernova ◽  
Standard Candle ◽  
Type Ia ◽  
Universal Expansion

ABSTRACT In 2016, the first strongly lensed Type Ia supernova (SN Ia), iPTF16geu, at redshift z = 0.409 with four resolved images arranged symmetrically around the lens galaxy at z = 0.2163, was discovered. Here, refined observations of iPTF16geu, including the time delay between images, are used to decrease uncertainties in the lens model, including the the slope of the projected surface density of the lens galaxy, Σ ∝ r1 − η, and to constrain the universal expansion rate H0. Imaging with Hubble Space Telescope provides an upper limit on the slope η, in slight tension with the steeper density profiles indicated by imaging with Keck after iPTF16geu had faded, potentially due to dust extinction not corrected for in host galaxy imaging. Since smaller η implies larger magnifications, we take advantage of the standard candle nature of SNe Ia constraining the image magnifications, to obtain an independent constraint of the slope. We find that a smooth lens density fails to explain the iPTF16geu fluxes, regardless of the slope, and additional substructure lensing is needed. The total probability for the smooth halo model combined with star microlensing to explain the iPTF16geu image fluxes is maximized at 12 per cent for η ∼ 1.8, in excellent agreement with Keck high-spatial-resolution data, and flatter than an isothermal halo. It also agrees perfectly with independent constraints on the slope from lens velocity dispersion measurements. Combining with the observed time delays between the images, we infer a lower bound on the Hubble constant, $H_0 \gtrsim 40\, {\rm km \ s^{-1} Mpc^{-1}}$, at 68.3 per cent confidence level.

scholarly journals First cosmological results using Type Ia supernovae from the Dark Energy Survey: measurement of the Hubble constant

2019 ◽  
Vol 486 (2) ◽  
pp. 2184-2196 ◽  
Author(s):  
E Macaulay ◽  
R C Nichol ◽  
D Bacon ◽  
D Brout ◽  
T M Davis ◽  
...  
Keyword(s):  
Dark Energy ◽  
Hubble Constant ◽  
Type Ia Supernovae ◽  
Distance Measurements ◽  
Dark Energy Survey ◽  
Systematic Uncertainties ◽  
Type Ia ◽  
Ia Supernovae ◽  
Energy Survey ◽  
Inverse Distance

ABSTRACT We present an improved measurement of the Hubble constant (H0) using the ‘inverse distance ladder’ method, which adds the information from 207 Type Ia supernovae (SNe Ia) from the Dark Energy Survey (DES) at redshift 0.018 < z < 0.85 to existing distance measurements of 122 low-redshift (z < 0.07) SNe Ia (Low-z) and measurements of Baryon Acoustic Oscillations (BAOs). Whereas traditional measurements of H0 with SNe Ia use a distance ladder of parallax and Cepheid variable stars, the inverse distance ladder relies on absolute distance measurements from the BAOs to calibrate the intrinsic magnitude of the SNe Ia. We find H0 = 67.8 ± 1.3 km s−1 Mpc−1 (statistical and systematic uncertainties, 68 per cent confidence). Our measurement makes minimal assumptions about the underlying cosmological model, and our analysis was blinded to reduce confirmation bias. We examine possible systematic uncertainties and all are below the statistical uncertainties. Our H0 value is consistent with estimates derived from the Cosmic Microwave Background assuming a ΛCDM universe.

scholarly journals The dependence of Type Ia Supernovae luminosities on their host galaxies

2010 ◽  
pp. no-no ◽  
Author(s):  
M. Sullivan ◽  
A. Conley ◽  
D. A. Howell ◽  
J. D. Neill ◽  
P. Astier ◽  
...  
Keyword(s):  
Type Ia Supernovae ◽  
Host Galaxies ◽  
Type Ia ◽  
Ia Supernovae
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