Color Dispersion and Milky Way Reddening Among Type Ia Supernovae

Understand

Past analyses of Type Ia Supernovae (SNe Ia) have identified an irreducible scatter of 5-10% in distance widely attributed to an intrinsic dispersion in luminosity.

• Another, equally valid, source of this scatter is intrinsic dispersion in color.
• Misidentification of the true source of this scatter can bias both the retrieved color-luminosity relation and cosmological parameter measurements.
• The size of this bias depends on the magnitude of the intrinsic color dispersion relative to the distribution of colors that correlate with distance.