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The Anomaly in the Candidate Microlensing Event PA-99-N2

The lightcurve of PA-99-N2, one of the recently announced microlensing candidates towards M31, shows small deviations from the standard Paczynski form. We explore a number of possible explanations, including correlations with the seeing, the parallax effect and a binary lens. We find that the observ...

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Detalles Bibliográficos
Autores principales: An, J.H., Evans, N.W., Kerins, E., Baillon, P., Calchi-Novati, S., Carr, Bernard J., Creze, M., Giraud-Heraud, Y., Gould, A., Hewett, Paul C., Jetzer, P., Kaplan, J., Paulin-Henriksson, S., Smartt, S.J., Tsapras, Y., Valls-Gabaud, D.
Lenguaje:eng
Publicado: 2003
Materias:
Acceso en línea:https://dx.doi.org/10.1086/380820
http://cds.cern.ch/record/677149
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author An, J.H.
Evans, N.W.
Kerins, E.
Baillon, P.
Calchi-Novati, S.
Carr, Bernard J.
Creze, M.
Giraud-Heraud, Y.
Gould, A.
Hewett, Paul C.
Jetzer, P.
Kaplan, J.
Paulin-Henriksson, S.
Smartt, S.J.
Tsapras, Y.
Valls-Gabaud, D.
author_facet An, J.H.
Evans, N.W.
Kerins, E.
Baillon, P.
Calchi-Novati, S.
Carr, Bernard J.
Creze, M.
Giraud-Heraud, Y.
Gould, A.
Hewett, Paul C.
Jetzer, P.
Kaplan, J.
Paulin-Henriksson, S.
Smartt, S.J.
Tsapras, Y.
Valls-Gabaud, D.
author_sort An, J.H.
collection CERN
description The lightcurve of PA-99-N2, one of the recently announced microlensing candidates towards M31, shows small deviations from the standard Paczynski form. We explore a number of possible explanations, including correlations with the seeing, the parallax effect and a binary lens. We find that the observations are consistent with an unresolved RGB or AGB star in M31 being microlensed by a binary lens. We find that the best fit binary lens mass ratio is about one hundredth, which is one of most extreme values found for a binary lens so far. If both the source and lens lie in the M31 disk, then the standard M31 model predicts the probable mass range of the system to be 0.02-3.6 solar masses (95 % confidence limit). In this scenario, the mass of the secondary component is therefore likely to be below the hydrogen-burning limit. On the other hand, if a compact halo object in M31 is lensing a disk or spheroid source, then the total lens mass is likely to lie between 0.09-32 solar masses, which is consistent with the primary being a stellar remnant and the secondary a low mass star or brown dwarf. The optical depth (or alternatively the differential rate) along the line of sight toward the event indicates that a halo lens is more likely than a stellar lens provided that dark compact objects comprise no less than 15 per cent (or 5 per cent) of haloes.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 2003
record_format invenio
spelling cern-6771492021-09-17T12:49:43Zdoi:10.1086/380820http://cds.cern.ch/record/677149engAn, J.H.Evans, N.W.Kerins, E.Baillon, P.Calchi-Novati, S.Carr, Bernard J.Creze, M.Giraud-Heraud, Y.Gould, A.Hewett, Paul C.Jetzer, P.Kaplan, J.Paulin-Henriksson, S.Smartt, S.J.Tsapras, Y.Valls-Gabaud, D.The Anomaly in the Candidate Microlensing Event PA-99-N2Astrophysics and AstronomyThe lightcurve of PA-99-N2, one of the recently announced microlensing candidates towards M31, shows small deviations from the standard Paczynski form. We explore a number of possible explanations, including correlations with the seeing, the parallax effect and a binary lens. We find that the observations are consistent with an unresolved RGB or AGB star in M31 being microlensed by a binary lens. We find that the best fit binary lens mass ratio is about one hundredth, which is one of most extreme values found for a binary lens so far. If both the source and lens lie in the M31 disk, then the standard M31 model predicts the probable mass range of the system to be 0.02-3.6 solar masses (95 % confidence limit). In this scenario, the mass of the secondary component is therefore likely to be below the hydrogen-burning limit. On the other hand, if a compact halo object in M31 is lensing a disk or spheroid source, then the total lens mass is likely to lie between 0.09-32 solar masses, which is consistent with the primary being a stellar remnant and the secondary a low mass star or brown dwarf. The optical depth (or alternatively the differential rate) along the line of sight toward the event indicates that a halo lens is more likely than a stellar lens provided that dark compact objects comprise no less than 15 per cent (or 5 per cent) of haloes.astro-ph/0310457oai:cds.cern.ch:6771492003-10-16
spellingShingle Astrophysics and Astronomy
An, J.H.
Evans, N.W.
Kerins, E.
Baillon, P.
Calchi-Novati, S.
Carr, Bernard J.
Creze, M.
Giraud-Heraud, Y.
Gould, A.
Hewett, Paul C.
Jetzer, P.
Kaplan, J.
Paulin-Henriksson, S.
Smartt, S.J.
Tsapras, Y.
Valls-Gabaud, D.
The Anomaly in the Candidate Microlensing Event PA-99-N2
title The Anomaly in the Candidate Microlensing Event PA-99-N2
title_full The Anomaly in the Candidate Microlensing Event PA-99-N2
title_fullStr The Anomaly in the Candidate Microlensing Event PA-99-N2
title_full_unstemmed The Anomaly in the Candidate Microlensing Event PA-99-N2
title_short The Anomaly in the Candidate Microlensing Event PA-99-N2
title_sort anomaly in the candidate microlensing event pa-99-n2
topic Astrophysics and Astronomy
url https://dx.doi.org/10.1086/380820
http://cds.cern.ch/record/677149
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