We use data from the Isaac Newton Telescope Wide Field Camera survey of M31 to determine the surface brightness profile of M31 along the south-east minor axis. We combine surface photometry and faint red giant branch star counts to trace the profile from the innermost regions out to a projected radius of 4 (≈ 55 kpc) where μV ∼ 32 mag arcsec ; this is the first time the M31 minor axis profile h...

With the ultimate aim of distinguishing between various models describing the formation of galaxy halos (e.g. radial or multi-phase collapse, random mergers), we have completed a spectroscopic study of the globular cluster system of M31. We present the results of deep, intermediate-resolution, fibre-optic spectroscopy of several hundred of the M31 globular clusters using the Wide Field Fibre Op...

We first demonstrate that globular cluster G1 could have been formed by tidal interaction between M31 and a nucleated dwarf galaxy (dE,N). Our fully self-consistent numerical simulations show that during tidal interaction between M31 and G1's progenitor dE,N with M B ∼ −15 mag and its nucleus mass of ∼ 10 7 M ⊙ , the dark matter and the outer stellar envelope of the dE,N are nearly completely s...

Aims. We present the first results of a large spectroscopic survey of candidate globular clusters located in the extreme outskirts of the nearby M31 galaxy. The survey is aimed at ascertaining the nature of the selected candidates to increase the sample of confirmed M31 clusters lying more that 2 • away from the center of the galaxy. Methods. We obtained low resolution spectra (λ/∆λ ≃ 800 − 130...

We derive predictions for the Nadir angle (θn) dependence of the ratio Nμ−/Nμ+ of the rates of the μ− and μ+ multi-GeV events, and for the μ−−μ+ event rate asymmetry, Aμ−μ+ = [N(μ −)−N(μ+)]/[N(μ−)+N(μ+)], in iron-magnetized calorimeter detectors (MINOS, INO, etc.) in the case of 3-neutrino oscillations of the atmospheric νμ and ν̄μ, driven by one neutrino mass squared difference, |∆m31| ∼ (2.0−3...

We have used the Westerbork array to carry out an unbiased wide-field survey of H  emission features, achieving an  sensitivity of about 18 mJy/Beam at a velocity resolution of 17 km s−1 over 1800 deg2 and between −1000 < VHel < + 6500 km s−1. The primary data consists of auto-correlation spectra with an effective angular resolution of 49 FWHM. The survey region is centered approximately on...

We demonstrate the presence of an extended and massive circumgalactic medium (CGM) around Messier 31 using archival HST Cosmic Origins Spectrograph ultraviolet spectroscopy of 18 QSOs projected within two virial radii of M31 ( = R 300 vir kpc). We detect absorption from Si III at  v 300 150 LSR km s toward all three sightlines at  R R 0.2 vir, 3 of 4 sightlines at   R R 0.8 1.1 vir , and p...

We combine our compilation of photometry of M31 globular clusters and probable cluster candidates with new near-infrared photometry for 30 objects. Using these data we determine the globular cluster luminosity function (GCLF) in multiple filters for the M31 halo clusters. We find a GCLF peak and dispersion V 0 0 = 16.84 ± 0.11, σt = 0.93± 0.13 (Gaussian σ = 1.20± 0.14), consistent with previous...

This paper is the first in a series which studies interactions between M31 and its satellites, including the origin of the giant southern stream. We construct accurate yet simple analytic models for the potential of the M31 galaxy to provide an easy basis for calculation of orbits in M31’s halo. We use an NFW dark halo, an exponential disk, a Hernquist bulge, and a central black hole point mass...

We present first results from a spectroscopic survey designed to examine the metallicity and kinematics of individual red giant branch stars in the outer halo of the Andromeda spiral galaxy (M31). This study is based on multislit spectroscopy with the Keck II 10-m telescope and Low Resolution Imaging Spectrograph of the Ca ii near-infrared triplet in 99 M31 halo candidates in a field at R = 19 ...