Intensive Monitoring Survey of Nearby Galaxies (IMSNG)

TL;DR

IMSNG is a high-cadence, multi-telescope survey monitoring nearby galaxies to detect early supernova shock emissions, aiming to understand progenitor sizes and explosion mechanisms.

Contribution

It introduces a novel high-cadence observational strategy targeting nearby galaxies to capture early supernova light curves and shock emissions.

Findings

Detected 18 supernovae in 5 years, confirming the expected SN rate.

Projected detection of 3.4 early SNe per year at R ~ 19.5 mag.

Able to detect shock-heated emission from progenitors as small as 0.1 R_sun.

Abstract

Intensive Monitoring Survey of Nearby Galaxies (IMSNG) is a high cadence observation program monitoring nearby galaxies with high probabilities of hosting supernovae (SNe). IMSNG aims to constrain the SN explosion mechanism by inferring sizes of SN progenitor systems through the detection of the shock-heated emission that lasts less than a few days after the SN explosion. To catch the signal, IMSNG utilizes a network of 0.5-m to 1-m class telescopes around the world and monitors the images of 60 nearby galaxies at distances D < 50 Mpc to a cadence as short as a few hours. The target galaxies are bright in near-ultraviolet (NUV) with M_NUV < -18.4 AB mag and have high probabilities of hosting SNe (0.06 SN/yr per galaxy). With this strategy, we expect to detect the early light curves of 3.4 SNe per year to a depth of R ~ 19.5 mag, enabling us to detect the shock-heated emission from a progenitor star with a radius as small as 0.1 R_sun. The accumulated data will be also useful for studying faint features around the target galaxies and other science projects. So far, 18 SNe have occurred in our target fields (16 in IMSNG galaxies) over 5 years, confirming our SN rate estimate of 0.06 SN/yr per galaxy.