Effect of a varying gravitational constant on the SN Ia Hubble diagram, AGN luminosity evolution, and X-ray source counts

Tomaschitz, Roman

doi:10.1007/s10509-009-0175-7

Cited by 3 publications

(4 citation statements)

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“…From white dwarf cooling, Garcia-Berro et al (2011) derive an upper bound and Corsico et al (2013) find a white dwarf pulsation limit of . Tomaschitz (2010) considers a gravitational constant scaling linearly with the Hubble parameter, and fits the SNIa Hubble diagram and AGN source counts, concluding that further observational constraints are required.…”

Section: Introductionmentioning

confidence: 99%

Constraining a Possible Variation of G with Type Ia Supernovae

Mould

Uddin

2014

Publ. Astron. Soc. Aust.

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Astrophysical cosmology constrains the variation of Newton's Constant in a manner complementary to laboratory experiments, such as the celebrated lunar laser ranging campaign. Supernova cosmology is an example of the former and has attained campaign status, following planning by a Dark Energy Task Force in 2005. In this paper, we employ the full SNIa data set to the end of 2013 to set a limit on G variation. In our approach, we adopt the standard candle delineation of the redshift distance relation. We set an upper limit on its rate of change |Ġ/G| of 0.1 parts per billion per year over 9 Gyrs. By contrast, lunar laser ranging tests variation of G over the last few decades. Conversely, one may adopt the laboratory result as a prior and constrain the effect of variable G in dark energy equation of state experiments to δw < 0.02. We also examine the parameterisation G ß 1+z. Its short expansion age conflicts with the measured values of the expansion rate and the density in a flat Universe. In conclusion, supernova cosmology complements other experiments in limiting G variation. An important caveat is that it rests on the assumption that the same mass of 56 Ni is burned to create the standard candle regardless of redshift. These two quantities, f and G, where f is the Chandrasekhar mass fraction burned, are degenerate. Constraining f variation alone requires more understanding of the SNIa mechanism.

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Section: Introductionmentioning

confidence: 99%

Constraining a Possible Variation of G with Type Ia Supernovae

Mould

Uddin

2014

Publ. Astron. Soc. Aust.

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“…The precise value of ratio (1.2), the geometric factor 1/(4π), is not really important in this context; if we replace the pion mass by the proton mass, m p /m π ≈ 6.723, or change the adopted value of the Hubble constant, H 0 ≈ 68.02 km s −1 Mpc −1 , this ratio remains moderate. The fact that G 0 cm 3 = 4π 2 H 0 if we choose the pion mass for m and the mentioned value for H 0 , is a remarkable coincidence if one considers which quantities and numbers are involved, but the reasoning in this article or in Tomaschitz (2005Tomaschitz ( , 2010 does not depend on this specific value of the Hubble constant; a variation of H 0 within five percent can readily be accommodated in the fits. By contrast, a deceleration parameter very close to but different from −1 is essential.…”

Section: Resultsmentioning

confidence: 83%

“…6 and 7. By contrast, the SN Ia Hubble diagram in Tomaschitz (2010) only requires a mild luminosity evolution (λ = 1) of nearly perfect standard candles, cf. Stritzinger et al (2006).…”

Section: Resultsmentioning

confidence: 99%

“…We find a pronounced intrinsic luminosity evolution L ∝ G 9 (z) in the distance moduli of the rotators as well as in their surface brightness, reminiscent of the solar luminosity scaling ∝ G 15/2 (Gough 1981). The fits are performed with a special class of cosmic expansion factors capable of explaining the 'early faint Sun paradox' (Sagan and Chyba 1997) in the context of an open Robertson-Walker (RW) cosmology (Tomaschitz 2010).…”

Section: Introductionmentioning

confidence: 94%

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Redshift evolution of angular diameters and surface brightness: how rigid are galactic measuring rods?

Tomaschitz

2010

Astrophys Space Sci

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The effect of a cosmic time variation of Newton's constant on galactic angular diameters, linear size, apparent magnitude, and surface brightness is investigated. The redshift scaling of the gravitational constant is proportional to the Hubble parameter, derived from the constancy of a moderate dimensionless ratio of fundamental constants, and manifested in galactic linear-size evolution. The latter is demonstrated by fitting the angular size-redshift relation to spectroscopically and photometrically selected samples of high-redshift rotators. The intrinsic luminosity evolution of the rotators and their magnitude-redshift and surface brightness-redshift relations are studied. The galactic luminosity scales with a power of the Hubble parameter, and the scaling exponent is inferred from a moderate dimensionless ratio involving the gravitational constant, the Galactic luminosity, and the velocity of the Galaxy in the microwave background. The fits are performed with a cosmic expansion factor derived from paleoplanetary surface temperatures. This expansion factor is tested by comparing the corresponding redshift evolution of the angular-size distance to the distance estimates of two samples of galaxy clusters.Keywords Time variation of the gravitational constant in Robertson-Walker cosmology · Galactic linear-size evolution · Angular diameter-redshift relation · Distance moduli and Hubble diagram of high-redshift rotators · Surface brightness-redshift relation · Galactic luminosity evolution and Tolman test R. Tomaschitz ( )

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Constraining Temporal Oscillations of Cosmological Parameters Using SNe Ia

Brownsberger

Stubbs

Scolnic

2019

ApJ

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The existing set of type Ia supernovae (SNe Ia) is now sufficient to detect oscillatory deviations from the canonical ΛCDM cosmology. We determine that the Fourier spectrum of the Pantheon data set of spectroscopically well-observed SNe Ia is consistent with the predictions of ΛCDM. We also develop and describe two complementary techniques for using SNe Ia to constrain those alternate cosmological models that predict deviations from ΛCDM that are oscillatory in conformal time. The first technique uses the reduced χ 2 statistic to determine the likelihood that the observed data would result from a given model. The second technique uses bootstrap analysis to determine the likelihood that the Fourier spectrum of a proposed model could result from statistical fluctuations around ΛCDM. We constrain three oscillatory alternate cosmological models: one in which the dark energy equation of state parameter oscillates around the canonical value of w Λ = −1, one in which the energy density of dark energy oscillates around its ΛCDM value, and one in which gravity derives from a scalar field evolving under an oscillatory coupling. We further determine that any alternate cosmological model that produces distance modulus residuals with a Fourier amplitude of 36 millimags is strongly ruled out, given the existing data, for frequencies between 0.08 Gyr −1 h 100 and 80 Gyr −1 h 100 .

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Effect of a varying gravitational constant on the SN Ia Hubble diagram, AGN luminosity evolution, and X-ray source counts

Cited by 3 publications

References 58 publications

Constraining a Possible Variation of G with Type Ia Supernovae

Constraining a Possible Variation of G with Type Ia Supernovae

Redshift evolution of angular diameters and surface brightness: how rigid are galactic measuring rods?

Constraining Temporal Oscillations of Cosmological Parameters Using SNe Ia

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