Fulltext

Measuring polarization in microlensing events

Ingrosso, G. ; Calchi Novati, S. ; De Paolis, F. ; Jetzer, Ph ; Nucita, A. A. ; Strafella, F.

In: Monthly Notices of the Royal Astronomical Society, 2014, vol. 446, no. 1, p. 1090-1097

Add to personal list
    Title
    • Measuring polarization in microlensing events
    Author
    • Ingrosso, G.. Dipartimento di Matematica e Fisica, ‘Ennio De Giorgi', Università del Salento, CP 193, I-73100 Lecce, Italy
    • Calchi Novati, S.. Dipartimento di Fisica ‘E. R. Caianiello', Universitá degli Studi di Salerno, Via Giovanni Paolo II, 132, I-84084 Fisciano (SA) - Italy
    • De Paolis, F.. Dipartimento di Matematica e Fisica, ‘Ennio De Giorgi', Università del Salento, CP 193, I-73100 Lecce, Italy
    • Jetzer, Ph. Physics Department, University of Zürich, Winterthurerstrasse 190, CH-8057 Zürich, Switzerland
    • Nucita, A. A.. Dipartimento di Matematica e Fisica, ‘Ennio De Giorgi', Università del Salento, CP 193, I-73100 Lecce, Italy
    • Strafella, F.. Dipartimento di Matematica e Fisica, ‘Ennio De Giorgi', Università del Salento, CP 193, I-73100 Lecce, Italy
    Document Type
    • Postprint
    Language
    • English
    Published in
    • Monthly Notices of the Royal Astronomical Society, 2014, vol. 446, no. 1, p. 1090-1097. Oxford University Press
    Other Version
    OAI-PMH Identifier
    • oai:doc.rero.ch:299094
    Summary
    We reconsider the polarization of the star light that may arise during microlensing events due to the high gradient of magnification across the atmosphere of the source star, by exploring the full range of microlensing and stellar physical parameters. Since it is already known that only cool evolved giant stars give rise to the highest polarization signals, we follow the model by Simmons etal. to compute the polarization as due to the photon scattering on dust grains in the stellar wind. Motivated by the possibility to perform a polarization measurement during an ongoing microlensing event, we consider the recently reported event catalogue by the Optical Gravitational Lensing Experiment (OGLE) collaboration covering the 2001-2009 campaigns (OGLE-III events), that makes available the largest and more comprehensive set of single-lens microlensing events towards the Galactic bulge. The study of these events, integrated by a Monte Carlo analysis, allows us to estimate the expected polarization profiles and to predict for which source stars and at which time is most convenient to perform a polarization measurement in an ongoing event. We find that about two dozens of OGLE-III events (about 1 per cent of the total) have maximum polarization degree in the range 0.1