# Why is there a Phillips relation?

I want to know the explanation of Phillips relation, the relation seen in type Ia supernovae(SN Ia with broader light curve is brighter). More Ni-56 implies a larger luminosity at peak but what about broader light curve?

• There isn't, to my knowledge, an accepted theoretical explanation, but there are several hypotheses. Adam Burrows has these helpful slides on the topic. – pela Oct 10 '18 at 7:47