M31 PIXEL LENSING EVENT OAB-N2: A STUDY OF THE LENS PROPER MOTION

S. Calchi Novati, M. Dall'Ora, A. Gould, V. Bozza, I. Bruni, F. De Paolis, Martin Dominik, R. Gualandi, G. Ingrosso, Ph. Jetzer, L. Mancini, A. Nucita, G. Scarpetta, M. Sereno, F. Strafella

Research output: Contribution to journalArticlepeer-review

17 Citations (Scopus)

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 For photometry: first, unpublished WeCAPP data allow us to confirm OAB-N2, previously reported only as a viable candidate, as a well-constrained pixel lensing event.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.

Original languageEnglish
Pages (from-to)987-994
Number of pages8
JournalAstrophysical Journal
Volume717
Issue number2
DOIs
Publication statusPublished - 10 Jul 2010

Keywords

  • dark matter
  • galaxies: halos
  • galaxies: individual (M31 NGC 224)
  • Galaxy: halo
  • gravitational lensing: micro
  • LARGE-MAGELLANIC-CLOUD
  • MICROLENSING OPTICAL DEPTH
  • POINT-AGAPE SURVEY
  • ANDROMEDA GALAXY
  • DETECTING PLANETS
  • LOIANO TELESCOPE
  • UNRESOLVED STARS
  • ANGSTROM PROJECT
  • CROWDED FIELDS
  • GALACTIC HALO

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