THE ABSOLUTE MAGNITUDES OF TYPE Ia SUPERNOVAE IN THE ULTRAVIOLET

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.

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A problem with the analysis of type Ia supernovae

Open Astronomy ◽

10.1515/astro-2017-0013 ◽

2017 ◽

Vol 26 (1) ◽

Cited By ~ 2

Author(s):

David F. Crawford

Keyword(s):

Rest Frame ◽

Time Dilation ◽

Light Curves ◽

Type Ia Supernovae ◽

Standard Analysis ◽

Static Universe ◽

Direct Measurements ◽

Type Ia ◽

Absolute Magnitudes ◽

Ia Supernovae

AbstractType Ia supernovae have light curves that have widths and magnitudes that can be used for testing cosmologies and they provide one of the few direct measurements of time dilation. It is shown that the standard analysis that calibrates the light curve against a rest-frame average (such as SALT2) removes all the cosmological information from the calibrated light curves. Consequently type Ia supernovae calibrated with these methods cannot be used to investigate cosmology. The major evidence that supports the hypothesis of a static universe is that the measurements of the widths of the rawlight curves of type Ia supernovae do not show any time dilation. The intrinsicwavelength dependence shown by the SALT2 calibration templates is also consistent with no time dilation. Using a static cosmological model the peak absolute magnitudes of raw type Ia supernovae observations are also independent of redshift. These results support the hypothesis of a static universe.

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Testing the evolution of the absolute magnitude of type Ia supernovae and cosmological parameters

Communications of the Byurakan Astrophysical Observatory ◽

10.52526/25792776-2021.68.2-484 ◽

2021 ◽

pp. 484-489

Author(s):

A. P. Mahtessian ◽

G. S. Karapetian ◽

M. A. Hovhannisyan ◽

V. H. Movsisyan ◽

L. A. Mahtessian

Keyword(s):

Computer Simulations ◽

Cosmological Parameters ◽

Absolute Magnitude ◽

Type Ia Supernovae ◽

Zero Density ◽

Type Ia ◽

The Absolute ◽

Ia Supernovae ◽

The Universe

Computer simulations show that, in estimating cosmological parameters, the best agreement between theory and observation is achieved by assuming the evolution of the absolute magnitude of type Ia supernovae. This requires only 0.3m of evolution for the time corresponding to z = 1. This leads to zero density of hidden energy in the Universe.

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The Absolute Luminosities of the Calan/Tololo Type IA Supernovae

The Astronomical Journal ◽

10.1086/118190 ◽

1996 ◽

Vol 112 ◽

pp. 2391 ◽

Cited By ~ 374

Author(s):

Mario Hamuy ◽

M. M. Phillips ◽

Nicholas B. Suntzeff ◽

Robert A. Schommer ◽

Jose Maza ◽

...

Keyword(s):

Type Ia Supernovae ◽

Type Ia ◽

The Absolute ◽

Ia Supernovae

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Type Ia Supernovae Strongly Interacting with Their Circumstellar Medium

Proceedings of the International Astronomical Union ◽

10.1017/s174392131600510x ◽

2015 ◽

Vol 11 (A29B) ◽

pp. 237-237

Author(s):

Jeffrey M. Silverman ◽

Peter Nugent ◽

Avishay Gal-Yam ◽

D. A. Howell ◽

Mark Sullivan ◽

...

Keyword(s):

Infrared Emission ◽

Type Ia Supernovae ◽

Host Galaxies ◽

Ultraviolet Emission ◽

Maximum Brightness ◽

Type Ia ◽

Hα Emission ◽

Absolute Magnitudes ◽

Ia Supernovae ◽

Circumstellar Medium

AbstractA rare subclass of Type Ia supernovae (SNe Ia) shows evidence of strong interaction with a hydrogen-rich circumstellar medium (CSM); these objects are referred to as SNe Ia-CSM. PTF11kx began life as a SN Ia, but after a month it began to show indications of significant interaction with its CSM. This well-studied object solidified the connection between SNe Ia-CSM and more typical SNe Ia, despite their spectral similarity to Type IIn SNe (which likely come from massive star progenitors, as opposed to the white dwarf progenitors for the SNe Ia-CSM). The spectra of all ~20 known SNe Ia-CSM are dominated by Hα emission (with widths of ~2000 km s−1) and exhibit large Hα/Hβ intensity ratios; moreover, they have an almost complete lack of He I emission (see left panel of Figure 1). They also show possible evidence of dust formation through a decrease in the red wing of Hα 75–100 days past maximum brightness. The absolute magnitudes of SNe Ia-CSM are found to be -21.3 mag ≤ MR ≤ −19 mag (see right panel of Figure 1), and they also show ultraviolet emission at early times and strong infrared emission at late times (but no detected radio or X-ray emission). Finally, the host galaxies of SNe Ia-CSM imply that these objects come from a relatively young stellar population.

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