Constraints on intragroup stellar mass from hostless Type Ia supernova

Understand

We probe the diffuse stellar mass in a sample of 1401 low redshift galaxy groups (10E13 - 10E14 Msun/h) by examining the rate of hostless Type Ia supernova (SNe Ia) within the groups.

• We correlate the sample of confirmed SNe Ia from the SDSS supernova survey with the positions of our galaxy groups, as well as with the resolved galaxies within them.
• We find that 19 of the 59 SNe Ia within the group sample have no detectable host galaxy, with another three ambiguous instances.
• This gives a robust upper limit that a maximum of 2.69% +1.58%/-1.34% of the group's total mass arises from diffuse stars in the intragroup medium.