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Aims. The EROS-2 project was designed to test the hypothesis that massive compact halo objects (the so-called "machos") could be a major component of the dark matter halo of the Milky Way galaxy. To this end, EROS-2 monitored over 6.7 years 33 × 10 6 stars in the Magellanic clouds for microlensing events caused by such objects. Methods. In this work, we use only a subsample of 7 × 10 6 bright stars spread over 84 deg 2 of the LMC and 9 deg 2 of the SMC. The strategy of using only bright stars helps to discriminate against background events due to variable stars and allows a simple determination of the effects of source confusion (blending). The use of a large solid angle makes the survey relatively insensitive to effects that could make the optical depth strongly direction dependent. Results. Using this sample of bright stars, only one candidate event was found, whereas ∼39 events would have been expected if the Halo were entirely populated by objects of mass M ∼ 0.4 M . Combined with the results of EROS-1, this implies that the optical depth toward the Large Magellanic Cloud (LMC) due to such lenses is τ < 0.36 × 10 −7 (95% CL), corresponding to a fraction of the halo mass of less than 8%. This optical depth is considerably less than that measured by the MACHO collaboration in the central region of the LMC. More generally, machos in the mass range 0.6 × 10 −7 M < M < 15 M are ruled out as the primary occupants of the Milky Way Halo.

AstrophysicsChemical evolution of the Galactic bulge as traced by microlensed dwarf and subgiant stars , V. Evidence for a wide age distribution and a complex MDF ABSTRACTBased on high-resolution spectra obtained during gravitational microlensing events we present a detailed elemental abundance analysis of 32 dwarf and subgiant stars in the Galactic bulge. Combined with the sample of 26 stars from the previous papers in this series, we now have 58 microlensed bulge dwarfs and subgiants that have been homogeneously analysed. The main characteristics of the sample and the findings that can be drawn are: (i) the metallicity distribution (MDF) is wide and spans all metallicities between [Fe/H] = −1.9 to +0.6; (ii) the dip in the MDF around solar metallicity that was apparent in our previous analysis of a smaller sample (26 microlensed stars) is no longer evident; instead it has a complex structure and indications of multiple components are starting to emerge. A tentative interpretation is that there could be different stellar populations at interplay, each with a different scale height: the thin disk, the thick disk, and a bar population; (iii) the stars with [Fe/H] −0.1 are old with ages between 10 and 12 Gyr; (iv) the metal-rich stars with [Fe/H] −0.1 show a wide variety of ages, ranging from 2 to 12 Gyr with a distribution that has a dominant peak around 4−5 Gyr and a tail towards higher ages; (v) there are indications in the [α/Fe] − [Fe/H] abundance trends that the "knee" occurs around [Fe/H] = −0.3 to −0.2, which is a slightly higher metallicity as compared to the "knee" for the local thick disk. This suggests that the chemical enrichment of the metal-poor bulge has been somewhat faster than what is observed for the local thick disk. The results from the microlensed bulge dwarf stars in combination with other findings in the literature, in particular the evidence that the bulge has cylindrical rotation, indicate that the Milky Way could be an almost pure disk galaxy. The bulge would then just be a conglomerate of the other Galactic stellar populations (thin disk, thick disk, halo, and ...?), residing together in the central parts of the Galaxy, influenced by the Galactic bar.

The exact formulae for the capture of WIMPS (weakly interacting massive particles) by a massive body are derived. Capture by the earth is found to be significantly enhanced whenever the WIMP mass is roughly equal to the nuclear mass of an element present in the earth in large quantities. For Dirac neutrino WIMPS of mass 10 to 90 GeV, the capture rate is 10 to 300 times that previously believed. Capture rates for the sun are also recalculated and found to be from 1.5 times higher to 3 times lower than previously believed, depending on the mass and type of WIMP. The earth alone, or the earth in combination with the sun is found to give a much stronger annihilation signal from Dirac neutrino WIMPS than the sun alone over a very large mass range. This is particularly important in the neighborhood of mass of iron where previous analyses could not set any significant limits.

We combine V I photometry from OGLE-III with V V V and 2MASS measurements of E(J − K s ) to resolve the longstanding problem of the non-standard optical extinction toward the Galactic bulge. We show that the extinction is wellfit by the relation. The optical and near-IR reddening law toward the inner Galaxy approximately follows an R V ≈ 2.5 extinction curve with a dispersion σ R V ≈ 0.2, consistent with extragalactic investigations of the hosts of type Ia SNe. Differential reddening is shown to be significant on scales as small as as our mean field size of 6 . The intrinsic luminosity parameters of the Galactic bulge red clump (RC) are derived to be (M I,RC , σ I,RC,0 , (V − I) RC,0 , σ (V −I) RC , (J − K s ) RC,0 ) = (−0.12, 0.09, 1.06, 0.121, 0.66). Our measurements of the RC brightness, brightness dispersion and number counts allow us to estimate several Galactic bulge structural parameters. We estimate a distance to the Galactic center of 8.20 kpc. We measure an upper bound on the tilt α ≈ 40 • between the bulge's major axis and the Sun-Galactic center line of sight, though our brightness peaks are consistent with predictions of -2an N-body model oriented at α ≈ 25 • . The number of RC stars suggests a total stellar mass for the Galactic bulge of ∼ 2.3×10 10 M if one assumes a canonical Salpeter IMF, or ∼ 1.6×10 10 M if one assumes a bottom-light Zoccali IMF.We adopt (M I,RC , σ I,RC,0 , (V −I) RC,0 , σ (V −I) RC , (J −K s ) RC,0 ) = (−0.12, 0.09, 1.06, 0.121, 0.66) for the mean absolute magnitude and magnitude dispersion in I, intrinsic (V −I) color,