A New Approach to Investigate the R_V of Dust in Type Ia SNe Host Galaxies

Tuesday, 02 February 2016 2 p.m. — 3 p.m. MST

AURA Lecture Hall

NOIRLab South Colloquia
ALEKSANDAR CIKOTA (PhD student European Southern Observatory and CTIO/LCO Visiting Astronomy Student)

We aim to place limits on the extinction values of Type Ia supernovae to statistically determine the most probable color excess, E(B-V), with galactocentric distance, and to use these statistics to determine the absorption-to-reddening ratio, RV , for dust in the host galaxies.

We determined pixel-based dust mass surface density maps for 59 galaxies from the Key Insight on Nearby Galaxies: a Far-Infrared Survey with Herschel (KINGFISH, Kennicutt et al. (2011)). We use Type Ia supernova spectral templates (Hsiao et al., 2007) to develop a Monte Carlo simulation of color excess E(B-V) with RV =3.1 and investigate the color excess probabilities E(B-V) with projected radial galaxy center distance. Additionally, we tested our model using spectra of SN 1989B, SN 2002bo and SN 2006X, which occurred in three KINGFISH galaxies.

Finally, we determined the most probable reddening for Sa-Sap, Sab-Sbp, Sbc-Scp, Scd-Sdm, S0 and Irregular galaxy classes as a function of R/R25, and found that the largest reddening probability are expected in Sab-Sb and Sbc-Sc galaxies, while S0 and Irregulars are very dust poor. We present a new approach for determining the absorptionto-reddening ratio RV using color excess probability functions, and find for a sample of 21 SNe Ia observed in Sab-Sbp galaxies, and 34 SNe in Sbc-Scp, an RV of 2.71 ± 1.58 and RV = 1.70 ± 0.38 respectively.