Stanishev, V., Rodrigues, M., Mourao, A. and Flores, H. (2012), "Type Ia supernova host galaxies as seen with IFU spectroscopy", ASTRONOMY & ASTROPHYSICS, 545.
Abstract: Context. Type Ia supernovae (SNe Ia) have been widely used in cosmology
as distance indicators. However, to fully exploit their potential in
cosmology, a better control over systematic uncertainties is required.
Some of the uncertainties are related to the unknown nature of the SN Ia
progenitors.
Aims. We aim to test the use of integral field unit (IFU) spectroscopy
for correlating the properties of nearby SNe Ia with the properties of
their host galaxies at the location of the SNe. The results are to be
compared with those obtained from an analysis of the total host
spectrum. The goal is to explore this path of constraining the nature of
the SN Ia progenitors and further improve the use of SNe Ia in
cosmology.
Methods. We used the wide-field IFU spectrograph PMAS/PPAK at the 3.5 m
telescope of Calar Alto Observatory to observe six nearby spiral
galaxies that hosted SNe Ia. Spatially resolved 2D maps of the
properties of the ionized gas and the stellar populations were derived.
Results. Five of the observed galaxies have an ongoing star formation
rate of 1-5 M-circle dot yr(-1) and mean stellar population ages similar
to 5 Gyr. The sixth galaxy shows no star formation and has an about 12
Gyr old stellar population. All galaxies have stellar masses larger than
2 x 10(10) M-circle dot and metallicities above solar. Four galaxies
show negative radial metallicity gradients of the ionized gas up to
-0.058 dex kpc(-1) and one has nearly uniform metallicity with a
possible shallow positive slope. The stellar components show shallower
negative metallicity gradients up to -0.03 dex kpc(-1). We find no clear
correlation between the properties of the galaxy and those of the
supernovae, which may be because of the small ranges spanned by the
galaxy parameters. However, we note that the Hubble residuals are on
average positive while negative Hubble residuals are expected for SNe Ia
in massive hosts such as the galaxies in our sample.
Conclusions. The IFU spectroscopy on 4-m telescopes is a viable
technique for studying host galaxies of nearby SNe Ia. It allows one to
correlate the supernova properties with the properties of their host
galaxies at the projected positions of the supernovae. Our current
sample of six galaxies is too small to draw conclusions about the SN Ia
progenitors or correlations with the galaxy properties, but the ongoing
CALIFA IFU survey will provide a solid basis to exploit this technique
more and improve our understanding of SNe Ia as cosmological standard
candles.