| Type de publication : |
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Preprint, Working Paper, Document sans référence, etc. |
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| Domaine : |
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Physique/Astrophysique/Cosmologie et astrophysique extra-galactique
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| Titre : |
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Dark halo baryons not in ancient halo white dwarfs |
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| Auteur(s) : |
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M. Crézé ( ) 1, 2, V. Mohan () 3, A.C. Robin () 4, C. Reylé () 4, H. J. Mc Cracken () 5, J.-C. Cuillandre () 6, O. Le Fèvre () 7, Y. Mellier () 5, 8 |
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| Laboratoire : |
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| 1 : |
Physique Corpusculaire et Cosmologie - Collège de France (PCC) |
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CNRS : UMR7553 – IN2P3 – Université Paris VII - Paris Diderot |
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11, place Marcelin Berthelot - 75231 Paris Cedex 05 |
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France |
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| 2 : |
Université de Bretagne Sud (LEMEL) |
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Université de Bretagne Sud |
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Campus de Tohannic , BP573, F-56017 Vannes Cedex |
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France |
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| 3 : |
State Observatory, Naini Tal (State Observatory, Naini Tal) |
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State Observatory, Uttar Anchal |
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Manora Peak, Naini Tal, 263129 India |
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France |
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| 4 : |
Laboratoire d'astrophysique de l'observatoire de Besançon (LAOB) |
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http://www.obs-besancon.fr |
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CNRS : UMR6091 – INSU – Université de Besançon |
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Observatoire des sciences de l'univers de Besançon 41bis, avenue de l'Observatoire BP1615 25010 Besançon |
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France |
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| 5 : |
Institut d'Astrophysique de Paris (IAP) |
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http://www.iap.fr/ |
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CNRS : UMR7095 – INSU – Université Pierre et Marie Curie [UPMC] - Paris VI |
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98bis, bd Arago - 75014 Paris France |
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France |
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| 6 : |
C.F.H.T. (C.F.H.T.) |
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CFHT Corp. |
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P.O. box 1597, Kamuela Hawaii 96783, USA |
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France |
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| 7 : |
Laboratoire d'Astrophysique de Marseille (LAM) |
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http://www.oamp.fr/infoglueDeliverLive/www/LAM |
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CNRS : UMR6110 – INSU – Université de Provence - Aix-Marseille I |
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Pôle de l'Étoile Site de Château-Gombert 38, rue Frédéric Joliot-Curie 13388 Marseille cedex 13 |
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France |
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| 8 : |
Laboratoire d'Etude du Rayonnement et de la Matière en Astrophysique (LERMA) |
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http://lerma.obspm.fr/ |
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CNRS : UMR8112 – INSU – Observatoire de Paris – Université Pierre et Marie Curie [UPMC] - Paris VI – Université de Cergy Pontoise – Ecole normale supérieure de Paris - ENS Paris |
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61, avenue de l'Observatoire - 75014 PARIS |
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France |
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| Résumé : |
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Having ruled out the possibility that stellar objects be the main contributor of the dark matter embedding galaxies, microlensing experiments cannot exclude the hypothesis that a significant fraction of the Milky Way dark halo might be made of MACHOs with masses in the range $0.5-0.8 \msun$. Ancient white dwarfs are generally considered the most plausible candidates for such MACHOs. We report the results of a search for such white dwarfs in a proper motion survey covering a 0.16 sqd field at three epochs at high galactic latitude, and 0.938 sqd at two epochs at intermediate galactic latitude (VIRMOS survey), using the CFH telescope. Both surveys are complete to I = 23, with detection efficiency fading to 0 at I = 24.2. Proper motion data are suitable to separate unambiguously halo white dwarfs identified by belonging to a non rotating system. No candidates were found within the colour-magnitude-proper motion volume where such objects can be safely discriminated from any standard population as well as from possible artefacts. In the same volume, we estimate the maximum white dwarf halo fraction compatible with this observation at different significance levels if the halo is at least 14 gigayears old and under different ad hoc initial mass functions. Our data alone rules out a halo fraction greater than 14% at 95% confidence level. Combined with two previous investigations exploring comparable volumes pushes the limit below 4 % (95% confidence level) or below 1.3% ( 64% confidence), this implies that if baryonic dark matter is present in galaxy halos, it is not, or only marginally in the form of fait white dwarfs. |
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Langue du texte
intégral : |
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Anglais |
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| Mots Clés : |
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dark matter – galaxy halo – white dwarf |
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| Commentaire : |
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soumis à Astronomy and Astrophysics |
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