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A new analysis of the MEGA M 31 microlensing events


Ingrosso, G; Novati Calchi, S; de Paolis, F; Jetzer, P; Nucita, A A; Scarpetta, G; Strafella, F (2008). A new analysis of the MEGA M 31 microlensing events. Astronomy and Astrophysics, 462(3):895-902.

Abstract

We discuss the results of the MEGA microlensing campaign towards M 31. Our analysis is based on analytically evaluating the microlensing rate, taking the observational efficiency into account as given by the MEGA collaboration. In particular, we studied the spatial and time-duration distributions of the microlensing events for several mass distribution models of the M 31 bulge. We find that only for extreme models of the M 31 luminous components is it possible to reconcile the total observed MEGA events with the expected self-lensing contribution. Nevertheless, the expected spatial distribution of self-lensing events is more concentrated and hardly agrees with the observed distribution. We thus find it difficult to explain all events as due to self-lensing alone. On the other hand, the small number of events does not yet allow firm conclusions to be drawn on the halo dark matter fraction in the form of MACHOs.

Abstract

We discuss the results of the MEGA microlensing campaign towards M 31. Our analysis is based on analytically evaluating the microlensing rate, taking the observational efficiency into account as given by the MEGA collaboration. In particular, we studied the spatial and time-duration distributions of the microlensing events for several mass distribution models of the M 31 bulge. We find that only for extreme models of the M 31 luminous components is it possible to reconcile the total observed MEGA events with the expected self-lensing contribution. Nevertheless, the expected spatial distribution of self-lensing events is more concentrated and hardly agrees with the observed distribution. We thus find it difficult to explain all events as due to self-lensing alone. On the other hand, the small number of events does not yet allow firm conclusions to be drawn on the halo dark matter fraction in the form of MACHOs.

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Additional indexing

Item Type:Journal Article, refereed, original work
Communities & Collections:07 Faculty of Science > Institute for Computational Science
Dewey Decimal Classification:530 Physics
Language:English
Date:2008
Deposited On:06 Mar 2009 15:25
Last Modified:06 Dec 2017 19:08
Publisher:EDP Sciences
ISSN:0004-6361
Publisher DOI:https://doi.org/10.1051/0004-6361:20065851

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