We discuss the results of the MEGA microlensing campaign towards M31. Our analysis is based on analytically evaluating the microlensing rate, taking the observational efficiency into account as given by the MEGA collaboration. We find that only for extreme models of the M31 luminous components it is possible to reconcile the total observed MEGA events with the expected self-lensing contribution. However, the expected spatial distribution of self-lensing events is more concentrated with respect to the distribution of observed events. We thus find difficult to explain all observed events as due to self-lensing alone. On the other hand, the small number of events detected up to date does not yet allow to infer firm conclusions on the halo dark matter fraction in the form of MACHOs.
A New Analysis of the MEGA M31 Microlensing Events
NUCITA, Achille;INGROSSO, Gabriele;DE PAOLIS, Francesco;STRAFELLA, Francesco;
2008-01-01
Abstract
We discuss the results of the MEGA microlensing campaign towards M31. Our analysis is based on analytically evaluating the microlensing rate, taking the observational efficiency into account as given by the MEGA collaboration. We find that only for extreme models of the M31 luminous components it is possible to reconcile the total observed MEGA events with the expected self-lensing contribution. However, the expected spatial distribution of self-lensing events is more concentrated with respect to the distribution of observed events. We thus find difficult to explain all observed events as due to self-lensing alone. On the other hand, the small number of events detected up to date does not yet allow to infer firm conclusions on the halo dark matter fraction in the form of MACHOs.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
