PAndromeda - first results from the high-cadence monitoring of M31 with Pan-STARRS 1

TL;DR

This paper reports initial results from the PAndromeda survey using Pan-STARRS 1, demonstrating the capability to detect microlensing events in M31 with high-cadence, wide-field imaging, and presenting candidate events and variable star light curves.

Contribution

First high-cadence, wide-field monitoring of M31 with Pan-STARRS 1, identifying candidate microlensing events and variable stars, showcasing the survey's potential for astrophysical discoveries.

Findings

Detected 6 candidate microlensing events.

Achieved sufficient PSF quality for event detection.

Presented light curves of variable stars.

Abstract

The Pan-STARRS 1 (PS1) survey of M31 (PAndromeda) is designed to identify gravitational microlensing events, caused by bulge and disk stars (self-lensing) and by compact matter in the halos of M31 and the Milky Way (halo lensing, or lensing by MACHOs). With the 7 deg2 FOV of PS1, the entire disk of M31 can be imaged with one single pointing. Our aim is to monitor M31 with this wide FOV with daily sampling (20 mins/day). In the 2010 season we acquired in total 91 nights towards M31, with 90 nights in the rP1 and 66 nights in the iP1. The total integration time in rP1 and iP1 are 70740s and 36180s, respectively. As a preliminary analysis, we study a 40'\times40' sub-field in the central region of M31, a 20'\times20' sub-field in the disk of M31 and a 20'\times20' sub-field for the investigation of astrometric precision. We demonstrate that the PSF is good enough to detect microlensing events. We present light curves for 6 candidate microlensing events. This is a competitive rate compared to previous M31 microlensing surveys. We finally also present one example light curve for Cepheids, novae and eclipsing binaries in these sub-fields.