Photometric properties of intermediate redshift Type Ia Supernovae
  observed by SDSS-II Supernova Survey
  We have analyzed multi-band light curves of 328 intermediate redshift (0.05
<= z < 0.24) type Ia supernovae (SNe Ia) observed by the Sloan Digital Sky
Survey-II Supernova Survey (SDSS-II SN Survey). The multi-band light curves
were parameterized by using the Multi-band Stretch Method, which can simply
parameterize light curve shapes and peak brightness without dust extinction
models. We found that most of the SNe Ia which appeared in red host galaxies (u
- r > 2.5) don't have a broad light curve width and the SNe Ia which appeared
in blue host galaxies (u - r < 2.0) have a variety of light curve widths. The
Kolmogorov-Smirnov test shows that the colour distribution of SNe Ia appeared
in red / blue host galaxies is different (significance level of 99.9%). We also
investigate the extinction law of host galaxy dust. As a result, we find the
value of Rv derived from SNe Ia with medium light curve width is consistent
with the standard Galactic value. On the other hand, the value of Rv derived
from SNe Ia that appeared in red host galaxies becomes significantly smaller.
These results indicate that there may be two types of SNe Ia with different
intrinsic colours, and they are obscured by host galaxy dust with two different
properties.
