scholarly journals Search for Double Degenerate Progenitors of Supernovae Type Ia with SPY

2006 ◽  
pp. 134-139
Author(s):  
R. Napiwotzki ◽  
N. Christlieb ◽  
H. Drechsel ◽  
H.-J. Hagen ◽  
U. Heber ◽  
...  
Keyword(s):  
Type Ia ◽  
Supernovae Type Ia

scholarly journals On the Trigonometric Descriptions of Colors

2016 ◽  
Vol 8 (3) ◽  
pp. 5
Author(s):  
Jirí Stavek
Keyword(s):  
Experimental Data ◽  
Transverse Energy ◽  
Gravitational Constant ◽  
Isaac Newton ◽  
Type Ia ◽  
New Interpretation ◽  
The Stability ◽  
Mass Evaporation ◽  
Supernovae Type Ia ◽  
Insight Into

<p class="1Body">An attempt is presented for the description of the spectral colors using the standard trigonometric tools in order to extract more information about photons. We have arranged the spectral colors on an arc of the circle with the radius R = 1 and the central angle θ = π/3 when we have defined cos (θ) = λ<sub>380</sub>/λ<sub>760</sub> = 0.5. Several trigonometric operations were applied in order to find the gravity centers for the scotopic, photopic, and mesopic visions. The concept of the center of gravity of colors introduced Isaac Newton. We have postulated properties of the long-lived photons with the new interpretation of the Hubble (Zwicky-Nernst) constant H<sub>0</sub> = 2.748… * 10<sup>-18</sup> kg kg<sup>-1 </sup>s<sup>-1</sup>, the specific mass evaporation rate (SMER) of gravitons from the source mass. The stability of international prototypes of kilogram has been regularly checked. We predict that those standard kilograms due to the evaporation of gravitons lost 8.67 μg kg<sup>-1</sup> century<sup>-1</sup>. The energy of long-lived photons was trigonometrically decomposed into three parts that could be experimentally tested: longitudinal energy, transverse energy and energy of evaporated gravitons. We tested the properties of the long-lived photons with the experimental data published for the best available standard candles: supernovae Type Ia. There was found a surprising match of those experimental data with the model of the long-lived photons. Finally, we have proposed a possible decomposition of the big G (Newtonian gravitational constant) and the small kappa κ (Einsteinian gravitational constant) in order to get a new insight into the mysterious gravitational force and/or the curvature concept.</p>

scholarly journals The Hubble constant from eight time-delay galaxy lenses

2020 ◽  
Vol 501 (1) ◽  
pp. 784-801 ◽  
Author(s):  
Philipp Denzel ◽  
Jonathan P Coles ◽  
Prasenjit Saha ◽  
Liliya L R Williams
Keyword(s):  
Time Delay ◽  
Hubble Constant ◽  
Free Form ◽  
Microwave Background ◽  
Form Analysis ◽  
Systematic Uncertainties ◽  
Type Ia ◽  
Modelling Strategies ◽  
Supernovae Type Ia

ABSTRACT We present a determination of the Hubble constant from the joint, free-form analysis of eight strongly, quadruply lensing systems. In the concordance cosmology, we find $H_0{} = 71.8^{+3.9}_{-3.3}\, \mathrm{km}\, \mathrm{s}^{-1}\, \mathrm{Mpc}^{-1}{}{}$ with a precision of $4.97{{\ \rm per\ cent}}$. This is in agreement with the latest measurements from supernovae Type Ia and Planck observations of the cosmic microwave background. Our precision is lower compared to these and other recent time-delay cosmography determinations, because our modelling strategies reflect the systematic uncertainties of lensing degeneracies. We furthermore are able to find reasonable lensed image reconstructions by constraining to either value of H0 from local and early Universe measurements. This leads us to conclude that current lensing constraints on H0 are not strong enough to break the ‘Hubble tension’ problem of cosmology.

scholarly journals The influence of line opacity treatment in stella on supernova light curves

2020 ◽  
Vol 499 (3) ◽  
pp. 4312-4324
Author(s):  
Alexandra Kozyreva ◽  
Luke Shingles ◽  
Alexey Mironov ◽  
Petr Baklanov ◽  
Sergey Blinnikov
Keyword(s):  
Radiative Transfer ◽  
Spectral Synthesis ◽  
Broad Band ◽  
Light Curves ◽  
Radiation Hydrodynamics ◽  
Type Ii ◽  
Type Ia ◽  
The Impact ◽  
Supernovae Type Ia

ABSTRACT We systematically explore the effect of the treatment of line opacity on supernova light curves. We find that it is important to consider line opacity for both scattering and absorption (i.e. thermalization, which mimics the effect of fluorescence). We explore the impact of the degree of thermalization on three major types of supernovae: Type Ia, Type II-peculiar, and Type II-plateau. For this we use the radiative transfer code stella and analyse broad-band light curves in the context of simulations done with the spectral synthesis code artis and in the context of a few examples of observed supernovae of each type. We found that the plausible range for the ratio between absorption and scattering in the radiation hydrodynamics code stella is (0.8–1):(0.2–0), i.e. the recommended thermalization parameter is 0.9.

Surveys for Double Degenerate Progenitors of Supernovae Type Ia

2005 ◽  
pp. 153-162
Author(s):  
R. Napiwotzki ◽  
C.A. Karl ◽  
G. Nelemans ◽  
L. Yungelson ◽  
N. Christlieb ◽  
...  
Keyword(s):  
Type Ia ◽  
Supernovae Type Ia

scholarly journals Revealing the True Nature of Hen 2-428

Galaxies ◽  
2018 ◽  
Vol 6 (3) ◽  
pp. 88 ◽  
Author(s):  
Nicole Reindl ◽  
Nicolle Finch ◽  
Veronika Schaffenroth ◽  
Martin Barstow ◽  
Sarah Casewell ◽  
...  
Keyword(s):  
State Of The Art ◽  
True Nature ◽  
Spectroscopic Binary ◽  
Merger Process ◽  
Type Ia ◽  
Non Local ◽  
The Individual ◽  
Supernovae Type Ia ◽  
Central Stars ◽  
Interesting System

The nucleus of Hen 2-428 is a short orbital period (4.2 h) spectroscopic binary, whose status as potential supernovae type Ia progenitor has raised some controversy in the literature. We present preliminary results of a thorough analysis of this interesting system, which combines quantitative non-local thermodynamic (non-LTE) equilibrium spectral modelling, radial velocity analysis, multi-band light curve fitting, and state-of-the art stellar evolutionary calculations. Importantly, we find that the dynamical system mass that is derived by using all available He II lines does not exceed the Chandrasekhar mass limit. Furthermore, the individual masses of the two central stars are too small to lead to an SN Ia in case of a dynamical explosion during the merger process.

scholarly journals Search for progenitors of supernovae type Ia with SPY

2001 ◽  
Vol 322 (5-6) ◽  
pp. 411-418 ◽  
Author(s):  
R. Napiwotzki ◽  
N. Christlieb ◽  
H. Drechsel ◽  
H.-J. Hagen ◽  
U. Heber ◽  
...  
Keyword(s):  
Type Ia ◽  
Supernovae Type Ia

scholarly journals Genetic algorithms and supernovae type Ia analysis

2009 ◽  
Vol 2009 (05) ◽  
pp. 006-006 ◽  
Author(s):  
Charalampos Bogdanos ◽  
Savvas Nesseris
Keyword(s):  
Genetic Algorithms ◽  
Type Ia ◽  
Supernovae Type Ia

scholarly journals Large Scale Structure Among z ∼ 2 Quasars as a Cosmological Standard Ruler

2002 ◽  
Vol 199 ◽  
pp. 54-55 ◽  
Author(s):  
B.F. Roukema ◽  
G.A. Mamon
Keyword(s):  
Power Spectrum ◽  
Cosmological Constant ◽  
Confidence Limit ◽  
Large Scale ◽  
Density Parameter ◽  
Confidence Limits ◽  
Microwave Background ◽  
Type Ia ◽  
Supernovae Type Ia ◽  
Quasar Distribution

The peak in the power spectrum at ≈ 130h−1 Mpc at low redshifts provides a standard ruler in comoving space. This scale is shown to be present in the observed quasar distribution at z ∼ 2. This implies strong constraints on the density parameter, Ω0, and weaker constraints on the cosmological constant, λ0. Independently of λ0 (in the range λ0 ∊ [0, 1]), the constraint is 0.1 < Ω0 < 0.45 (68% confidence limit).Combination of the power spectrum peak method with very independent results from the supernovae Type Ia method yields Ω0 = (0.30 ± 0.11) + (0.57 ± 0.11)(λ0 −0.7), 0.55 < λ0 < 0.95, (68% confidence limits) without assuming Ω0 + λ0 = 1. This supports the almost flat, perturbed Friedmann-Lemaître-Robertson-Walker model, independently of any cosmic microwave background observations.

scholarly journals Observational effects of varying speed of light in quadratic gravity cosmological models

2018 ◽  
Vol 15 (05) ◽  
pp. 1850084
Author(s):  
Azam Izadi ◽  
Shadi Sajedi Shacker ◽  
Gonzalo J. Olmo ◽  
Robi Banerjee
Keyword(s):  
Causal Structure ◽  
Affine Connection ◽  
Structure Constant ◽  
Distance Modulus ◽  
Speed Of Light ◽  
Quadratic Gravity ◽  
Type Ia ◽  
Theories Of Gravity ◽  
Definition Of ◽  
Supernovae Type Ia

We study different manifestations of the speed of light in theories of gravity where metric and connection are regarded as independent fields. We find that for a generic gravity theory in a frame with locally vanishing affine connection, the usual degeneracy between different manifestations of the speed of light is broken. In particular, the space-time causal structure constant ([Formula: see text]) may become variable in that local frame. For theories of the form [Formula: see text], this variation in [Formula: see text] has an impact on the definition of the luminosity distance (and distance modulus), which can be used to confront the predictions of particular models against Supernovae type Ia (SN Ia) data. We carry out this test for a quadratic gravity model without cosmological constant assuming (i) a constant speed of light and (ii) a varying speed of light (VSL), and find that the latter scenario is favored by the data.

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