July 29, 2019 to August 2, 2019
Northeastern University
US/Eastern timezone

Constraining Temporal Oscillations of Cosmological Parameters Using Type Ia Supernovae

Jul 30, 2019, 4:00 PM
West Village G 106 (Northeastern University)

West Village G 106

Northeastern University

Oral Presentation Cosmology & Dark Energy Cosmology & Dark Energy


Mr Sasha Brownsberger (Harvard University)


The existing set of type Ia supernovae (SNe Ia) is now sufficient to detect oscillatory deviations from the canonical $\Lambda$CDM cosmology.
We determine that the Fourier spectrum of the Pantheon data set of spectroscopically well-observed SNe Ia is consistent with the predictions of $\Lambda$CDM.
We also develop and describe two complementary techniques for using SNe Ia to constrain those alternate cosmological models that predict deviations from $\Lambda$CDM that are oscillatory in conformal time.
The first technique uses the reduced $\chi^2$ 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 $\Lambda$CDM.
We constrain three oscillatory alternate cosmological models: one in which the dark energy equation of state parameter oscillates around the canonical value of $w_{\Lambda} = -1$, one in which the energy density of dark energy oscillates around its $\Lambda$CDM 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 $\simeq 36$ millimags is strongly ruled out, given the existing data, for frequencies between $\simeq 0.08\ \textrm{Gyr}^ {-1} h_{100}$ and $\simeq 80\ \textrm{Gyr}^ {-1} h_{100}$.

Primary authors

Mr Sasha Brownsberger (Harvard University) Prof. Christopher Stubbs (Harvard University) Prof. Daniel Scolnic (Duke University )

Presentation materials