189 research outputs found
Reconstructing the weak lensing magnification distribution of Type Ia supernovae
Weak lensing of Type Ia supernovae (SNe Ia) is a systematic uncertainty in
the use of SNe Ia as standard candles, as well as an independent cosmological
probe, if the corresponding magnification distribution can be extracted from
data. We study the peak brightness distribution of SNe Ia in the Pantheon
sample, and find that the high sub-sample shows distinct weak lensing
signatures compared to the low subsample: a long tail at the bright end due
to high magnifications and a shift of the peak brightness toward the faint end,
consistent with findings from earlier work. We have developed a technique to
reconstruct the weak lensing magnification distribution of SNe Ia, ,
from the measured SN Ia flux distribution, and applied it to the Pantheon
sample. We find that can be reconstructed at a significance better
than 2 for the subsample of SNe Ia at (124 SNe Ia), and at a
lower significance for the SNe Ia at (49 SNe Ia), due to the small
number of SNe Ia at high redshifts. The large number of SNe Ia from
future surveys will enable the use of reconstructed from SNe Ia as an
independent cosmological probe.Comment: 7 pages, 5 figures, comments welcom
Forecasting cosmological constraints from the weak lensing magnification of type Ia supernovae measured by the Nancy Grace Roman Space Telescope
The weak lensing magnification of type Ia supernovae (SNe Ia) is sensitive to the clustering of matter and provides an independent cosmological probe complementary to SN Ia distance measurements. The Nancy Grace Roman Space Telescope is uniquely sensitive to this measurement as it can discover high redshift SNe Ia and measure them with high precision. We present a methodology for reconstructing the probability distribution of the weak lensing magnification μ of SNe Ia, p(μ), from observational data, and using it to constrain cosmological parameters. We find that the reconstructed p(μ) can be fitted accurately by a stretched Gaussian distribution and used to measure the variance of μ, ξ_μ, which can be compared to theoretical predictions in a likelihood analysis. Applying our methodology to a set of realistically simulated SNe Ia expected from the Roman Space Telescope, we find that using the weak lensing magnification of the SNe Ia constrains a combination of matter density Ω_m and matter clustering amplitude σ₈. SN Ia distances alone lead to a better than 1% measurement of Ω_m. The combination of SN Ia weak lensing magnification and distance measurements result in a ∼10% measurement on σ₈. The SNe Ia from Roman will be powerful in constraining the cosmological model
- …