Speaker
Description
The luminosity distance-redshift ($D_L$-$z$) relation of Type Ia supernovae (SNe Ia) yields evidence for a nonzero cosmological constant, i.e. `dark energy'. SNe Ia analyses typically involve fitting the $D_L$ and $z$ to the functional form derived theoretically from the homogeneous and isotropic Friedmann-Lemaitre-Robertson-Walker (FLRW) metric. However, the metric in the epoch relevant to SNIa measurements deviates appreciably from FLRW due to gravitational clumping of mass into large-scale structures like filaments and voids, whose size distribution spans many orders-of-magnitude. Each line of sight to a SNe Ia passes through a random sequence of structures, so $D_L$ differs stochastically from one line of sight to the next. Such dispersion in $D_L$ may be dominated by a few large voids or many small voids, partly depending on the probability density function of the void size. In this work, we calculate the $D_L$ dispersion in a Lemaitre-Tolman-Bondi Swiss-cheese universe with a power-law hole size distribution, as a function of the lower cut-off and logarithmic slope.
