M31 Pixel Lensing Event OAB-N2: A Study of the Lens Proper Motion
Abstract
We present an updated analysis of the M31 pixel lensing candidate event OAB-N2 previously reported by Calchi Novati et al. Here we take advantage of new data both astrometrical and photometrical. For astrometry: using archival 4 m KPNO and Hubble Space Telescope/WFPC2 data we perform a detailed analysis of the event source whose result, although not fully conclusive on the source magnitude determination, is confirmed by the following light curve photometry analysis. For photometry: first, unpublished WeCAPP data allow us to confirm OAB-N2, previously reported only as a viable candidate, as a well-constrained pixel lensing event. Second, this photometry enables a detailed analysis in the event parameter space including the effects due to a finite source size. The combined results of these analyses allow us to put a strong lower limit on the lens proper motion. This outcome favors the MACHO lensing hypothesis over self-lensing for this individual event and points the way toward distinguishing between the MACHO and self-lensing hypotheses from larger data sets.
- Publication:
-
The Astrophysical Journal
- Pub Date:
- July 2010
- DOI:
- 10.1088/0004-637X/717/2/987
- arXiv:
- arXiv:1004.3865
- Bibcode:
- 2010ApJ...717..987C
- Keywords:
-
- dark matter;
- galaxies: halos;
- galaxies: individual: M31 NGC 224;
- Galaxy: halo;
- gravitational lensing: micro;
- Astrophysics - Galaxy Astrophysics
- E-Print:
- Accepted for publication in ApJ - minor changes to match the accepted version - Figure 1 updated