Accurate distance measurements are critical to astronomy. A Type Ia supernova is one of the few objects that we can trust for making distance measurements since they have a fixed peak brightness. But can the brightness of such a supernova change significantly based on the properties of its host galaxy? And what does this mean for our understanding of dark energy?
Measurements of the Hubble constant via different methods over time. Type Ia supernovae are used in conjunction with Cepheid variable stars for the Cepheid method. CMB stands for Cosmic Microwave Background. TRGB stands for “tip of the red giant branch”, which refers to a certain set of stars. The discrepancy between measurements of the Hubble constant has grown with time despite increasing precision. Click to enlarge. [Freedman et al. 2019]
Lighthouses in the Distant Universe
A Type Ia supernovae is what’s known as a “standard candle” — we know what its brightness is at a particular distance, and when we observe these supernovae in distant galaxies, we can extrapolate to determine how far away those galaxies are. Like lighthouses, the fainter a Type Ia supernova is, the further away it is.
Accurate distance measurements form the backbone of astronomy, ...