The contribution of red dwarfs and white dwarfs to the halo dark matter

Abstract

The nature of the several microlensing events observed by the MACHO team towards the LMC still remains controversial. Low-mass substellar objects and stars with masses larger than ~1 M_{sun} have been ruled out as major components of a MACHO galactic halo, while stars of half solar masses are the most probable candidates. In this paper we assess jointly the relative contributions of both red dwarfs and white dwarfs to the mass budget of the galactic halo. In doing so we use a Monte Carlo simulator which incorporates up-to-date evolutionary sequences of both red dwarfs and white dwarfs as well as detailed descriptions of our Galaxy and of the LMC. We explore the complete mass range between 0.08 and 1 M_{sun} as possible microlensing candidates and we compare the synthetic populations obtained with our simulator with the results obtained by the MACHO and EROS experiments. Our results indicate that, despite that the contribution of the red dwarf population increases by a factor of 2 the value of the optical depth obtained when taking into account the white dwarf population alone, it is still insufficient to explain the number of events claimed by the MACHO team. Finally, we find that the contribution to the halo dark matter of the whole population under study is smaller than 10% at the 95% conficence level.

arXiv comment11 pages, 5 figures; accepted for publication in A&A

References in corpus (41)

• A Universal Density Profile from Hierarchical Clustering
• Local stellar kinematics from Hipparcos data
• The MACHO Project: Microlensing Results from 5.7 Years of LMC Observations
• Limits on the Macho Content of the Galactic Halo from the EROS-2 Survey of the Magellanic Clouds
• LCDM-based models for the Milky Way and M31 I: Dynamical Models
• The MACHO Project LMC Microlensing Results from the First Two Years and the Nature of the Galactic Dark Halo
• The Formation Rate, Mass and Luminosity Functions of DA White Dwarfs from the Palomar Green Survey
• A Catalog of Spectroscopically Confirmed White Dwarfs from the Sloan Digital Sky Survey Data Release 4
• The Proper Motion of the Large Magellanic Cloud using HST
• Direct Detection of Galactic Halo Dark Matter
• The SuperCOSMOS Sky Survey. Paper II: Image detection, parameterisation, classification and photometry
• Stars within the Large Magellanic Cloud as Potential Lenses for Observed Microlensing Events
• The ages of very cool hydrogen-rich white dwarfs
• Contribution of brown dwarfs and white dwarfs to recent microlensing observations and to the halo mass budget
• A Survey for Cool White Dwarfs and the age of the Galactic Disc
• The age and colors of massive white dwarf stars
• Implications of White Dwarf Galactic Halos
• Self-Lensing Models of the LMC
• High proper motion white dwarfs and halo dark matter
• Microlensing of tidal debris on the Magellanic great circle
• Faint, moving objects in the Hubble Deep Field: components of the dark halo?
• The halo white dwarf population
• Monte Carlo simulations of the halo white dwarf population
• Lightcurve Classification in Massive Variability Surveys
• Lightcurve Classification in Massive Variability Surveys II: Transients towards the Large Magellanic Cloud
• On high proper motion white dwarfs from photographic surveys
• New UltraCool and Halo White Dwarf Candidates in SDSS Stripe 82
• White dwarfs and Galactic dark matter
• Neural Network identification of halo white dwarfs
• Further constraints on white dwarf galactic halos
• A Proper Motion Survey for White Dwarfs with the Wide Field Planetary Camera 2
• Microlensing towards LMC: a study of the LMC halo contribution
• EROS 2 proper motion survey: Constraints on the halo white dwarfs
• Absolute Proper Motions to B~22.5: IV. Faint, Low Velocity White Dwarfs and the White Dwarf Population Density Law
• Faint Blue Objects in the Hubble Deep Field South Revealed: White Dwarfs, Subdwarfs, and Quasars
• Microlensing Halo Models with Abundant Brown Dwarfs
• MACHOs in dark matter haloes
• Microlensing by the Halo MACHOs with Spatially Varying Mass Function
• The glow of primordial remnants
• The contribution of Oxygen-Neon white dwarfs to the MACHO content of the Galactic Halo
• Galaxy Formation and Dark Matter

Cited by in corpus (6)

• Evolutionary and pulsational properties of white dwarf stars
• The white dwarf luminosity function
• The galactic population of white dwarfs
• A population synthesis fitting of the $Gaia$ resolved white dwarf binary population within 100 pc
• Extremely faint high proper motion objects from SDSS stripe 82 - Optical classification spectroscopy of about 40 new objects
• White dwarfs with hydrogen-deficient atmospheres and the dark matter content of the Galaxy