The Carnegie Supernova Project: Intrinsic Colors of Type Ia Supernovae

BURNS, C. R.; STRITZINGER, MAXIMILIAN D.; PHILLIPS; HSIAO, E. Y.; CONTRERAS; PERSSON; FOLATELLI, GASTÓN; BOLDT; CAMPILLAY; CASTELLON; FREEDMAN; MADORE; MORRELL, N. I.; SALGADO; SUNTZEFF

ASTROPHYSICAL JOURNAL

IOP PUBLISHING LTD

Lugar: Londres; Año: 2014 vol. 789

0004-637X

We present an updated analysis of the intrinsic colors of Type Ia supernova (SNe Ia) using the latest data release of the Carnegie Supernova Project. We introduce a new light-curve parameter very similar to stretch that is better suited for fast-declining events, and find that these peculiar types can be seen as extensions to the population of "normal" SNe Ia. With a larger number of objects, an updated fit to the Lira relation is presented along with evidence for a dependence on the late-time slope of the B - V light-curves with stretch and color. Using the full wavelength range from u to H band, we place constraints on the reddening law for the sample as a whole and also for individual events/hosts based solely on the observed colors. The photometric data continue to favor low values of RV , though with large variations from event to event, indicating an intrinsic distribution. We confirm the findings of other groups that there appears to be a correlation between the derived reddening law, RV , and the color excess, E(B - V), such that larger E(B - V) tends to favor lower RV . The intrinsic u-band colors show a relatively large scatter that cannot be explained by variations in RV or by the Goobar power-law for circumstellar dust, but rather is correlated with spectroscopic features of the supernova and is therefore likely due to metallicity effects.