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Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?

Models of our galaxy based on dynamical observations predict a spheroid component much heavier than accounted for by direct measurements of star counts and high velocity stars. If, as first suggested by Caldwell and Ostriker, this discrepancy is due to a large population of faint low-mass stars or d...

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Detalles Bibliográficos
Autores principales: Giudice, G.F., Mollerach, S., Roulet, E.
Lenguaje:eng
Publicado: 1994
Materias:
Acceso en línea:https://dx.doi.org/10.1103/PhysRevD.50.2406
http://cds.cern.ch/record/256625
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author Giudice, G.F.
Mollerach, S.
Roulet, E.
author_facet Giudice, G.F.
Mollerach, S.
Roulet, E.
author_sort Giudice, G.F.
collection CERN
description Models of our galaxy based on dynamical observations predict a spheroid component much heavier than accounted for by direct measurements of star counts and high velocity stars. If, as first suggested by Caldwell and Ostriker, this discrepancy is due to a large population of faint low-mass stars or dark objects in the spheroid, the spheroid could be responsible for microlensing events for sources in the LMC. We show that, although the rate of events is lower than predicted by a galactic halo made of microlensing objects, it is still significant for EROS/MACHO observations. Because of the different matter distributions in the halo and spheroid components, a comparison between microlensing event rates in the LMC, future measurements of microlensing in the galactic bulge and, possibly, in M31 can provide information about the amounts of dark objects in the different galactic components. If the EROS/MACHO collaborations find a deficiency with respect to their halo expectation, when more statistics are available, their detected events could be interpreted as coming from spheroid microlenses, allowing for a galactic halo composed entirely of non-baryonic dark matter.
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institution Organización Europea para la Investigación Nuclear
language eng
publishDate 1994
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spelling cern-2566252023-03-14T17:17:47Zdoi:10.1103/PhysRevD.50.2406http://cds.cern.ch/record/256625engGiudice, G.F.Mollerach, S.Roulet, E.Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?Other Fields of PhysicsModels of our galaxy based on dynamical observations predict a spheroid component much heavier than accounted for by direct measurements of star counts and high velocity stars. If, as first suggested by Caldwell and Ostriker, this discrepancy is due to a large population of faint low-mass stars or dark objects in the spheroid, the spheroid could be responsible for microlensing events for sources in the LMC. We show that, although the rate of events is lower than predicted by a galactic halo made of microlensing objects, it is still significant for EROS/MACHO observations. Because of the different matter distributions in the halo and spheroid components, a comparison between microlensing event rates in the LMC, future measurements of microlensing in the galactic bulge and, possibly, in M31 can provide information about the amounts of dark objects in the different galactic components. If the EROS/MACHO collaborations find a deficiency with respect to their halo expectation, when more statistics are available, their detected events could be interpreted as coming from spheroid microlenses, allowing for a galactic halo composed entirely of non-baryonic dark matter.Models of our galaxy based on dynamical observations predict a spheroid component much heavier than accounted for by direct measurements of star counts and high velocity stars. If, as first suggested by Caldwell and Ostriker, this discrepancy is due to a large population of faint low-mass stars or dark objects in the spheroid, the spheroid could be responsible for microlensing events for sources in the LMC. We show that, although the rate of events is lower than predicted by a galactic halo made of microlensing objects, it is still significant for EROS/MACHO observations. Because of the different matter distributions in the halo and spheroid components, a comparison between microlensing event rates in the LMC, future measurements of microlensing in the galactic bulge and, possibly, in M31 can provide information about the amounts of dark objects in the different galactic components. If the EROS/MACHO collaborations find a deficiency with respect to their halo expectation, when more statistics are available, their detected events could be interpreted as coming from spheroid microlenses, allowing for a galactic halo composed entirely of non-baryonic dark matter.astro-ph/9312047CERN-TH-7127-93CERN-TH-7127-93oai:cds.cern.ch:2566251994
spellingShingle Other Fields of Physics
Giudice, G.F.
Mollerach, S.
Roulet, E.
Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title_full Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title_fullStr Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title_full_unstemmed Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title_short Can EROS/MACHO be detecting the galactic spheroid instead of the galactic halo?
title_sort can eros/macho be detecting the galactic spheroid instead of the galactic halo?
topic Other Fields of Physics
url https://dx.doi.org/10.1103/PhysRevD.50.2406
http://cds.cern.ch/record/256625
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