A5029696993- Stellar, planetary, and galactic studies
- Astronomy and Astrophysical Research
- Galaxies: Formation, Evolution, Phenomena
- Astrophysics and Star Formation Studies
- Astronomical Observations and Instrumentation
- Adaptive optics and wavefront sensing
- Gamma-ray bursts and supernovae
- Astro and Planetary Science
- History and Developments in Astronomy
- Astrophysical Phenomena and Observations
- Remote Sensing in Agriculture
- Planetary Science and Exploration
- Calibration and Measurement Techniques
- Advanced Vision and Imaging
- Spectroscopy and Laser Applications
- Dark Matter and Cosmic Phenomena
- Impact of Light on Environment and Health
- Cosmology and Gravitation Theories
- Historical Astronomy and Related Studies
- Spectroscopy and Chemometric Analyses
- Geophysics and Gravity Measurements
- Scientific Research and Discoveries
- Solar and Space Plasma Dynamics
- Scientific Computing and Data Management
- Spacecraft Design and Technology
Herzberg Institute of Astrophysics
2016-2025
University of Victoria
2006-2024
Astrophysique, Instrumentation et Modélisation
2024
Commissariat à l'Énergie Atomique et aux Énergies Alternatives
2024
CEA Paris-Saclay
2024
National Research Council Canada
2009-2022
W.M. Keck Observatory
2019
Australian Astronomical Observatory
2018
Canada–France–Hawaii Telescope
2014-2018
Dominion Astrophysical Observatory
2011-2018
Positional, structural and dynamical parameters for all dwarf galaxies in around the Local Group are presented, various aspects of our observational understanding this volume-limited sample discussed. Over 100 nearby that have distance estimates placing them within 3Mpc Sun identified. This threshold samples dwarfs a large range environments, from satellite systems MW M31, to outer regions Group, numerous isolated found its surroundings. It extends to, but does not include, associated with...
We have obtained Johnson V and Gunn i photometry for a large number of Local Group galaxies using the Isaac Newton Telescope Wide Field Camera (INT WFC). The majority these are members M31 subgroup observations deep enough to study top few magnitudes red giant branch in each system. previously measured location tip (TRGB) Andromeda I, II M33 within systematic uncertainties typically <0.05 mag. As TRGB acts as standard candle old, metal-poor stellar populations, we were able derive distances...
(Abridged). We present a sample of 1716 galaxies with companions within Delta v < 500 km/s, r_p 80 kpc and stellar mass ratio 0.1 M_1/M_2 10 from the Sloan Digital Sky Survey (SDSS) Data Release 4 (DR4). In agreement previous studies, we find an enhancement in star formation rate (SFR) galaxy pairs at projected separations 30--40 kpc. addition, that this is highest (and extends to greatest separations) for approximately equal mass, so-called `major' pairs. However, SFR can still be...
We perform two-dimensional, Point-Spread-Function-convolved, bulge+disk decompositions in the $g$ and $r$ bandpasses on a sample of 1,123,718 galaxies from Legacy area Sloan Digital Sky Survey Data Release Seven. Four different decomposition procedures are investigated which make improvements to sky background determinations object deblending over standard SDSS that lead more robust structural parameters integrated galaxy magnitudes colors, especially crowded environments. use set...
ABSTRACT The Next Generation Virgo Cluster Survey (NGVS) is a program that uses the 1 deg 2 MegaCam instrument on Canada–France–Hawaii Telescope to carry out comprehensive optical imaging survey of cluster, from its core virial radius—covering total area 104 —in u * griz bandpasses. Thanks dedicated data acquisition strategy and processing pipeline, NGVS reaches point-source depth g ≈ 25.9 mag (10σ) surface brightness limit μ ∼ 29 arcsec −2 (2σ above mean sky level), thus superseding all...
We present a deep photometric survey of the Andromeda galaxy, conducted with wide-field cameras CFHT and INT, that covers inner 50 kpc galaxy southern quadrant out to ~150 includes an extension M33 at >200 kpc. This is first systematic panoramic study this very outermost region galaxies. detect multitude large-scale structures low surface brightness, including several streams, two new relatively luminous (MV ∼ − 9) dwarf galaxies: And XV XVI. Significant variations in stellar populations due...
(Abridged) We use N-body simulations to study the evolution of dwarf spheroidal galaxies (dSphs) driven by galactic tides. adopt a cosmologically-motivated model where dSphs are approximated King embedded within an NFW halo. find that these NFW-embedded models extraordinarily resilient tides; stellar density profile still resembles even after losing more than 99% stars. As tides strip galaxy, luminosity, velocity dispersion, central surface brightness, and core radius decrease monotonically....
We present an analysis of the large-scale structure halo Andromeda galaxy, based on Pan-Andromeda Archeological Survey (PAndAS), currently most complete map resolved stellar populations in any galactic halo. Despite presence copious substructures, global follow closely power-law profiles that become steeper with increasing metallicity. divide sample into stream-like and a smooth component (defined as population cannot be spatially distinct substructures PAndAS). Fitting three-dimensional...
We present the Pristine survey, a new narrow-band photometric survey focused on metallicity-sensitive Ca H & K lines and conducted in northern hemisphere with wide-field imager MegaCam Canada-France-Hawaii Telescope (CFHT). This paper reviews our overall strategy discusses data processing metallicity calibration. Additionally we review application of these to main aims which are gather large sample most metal-poor stars Galaxy, further characterise faintest Milky Way satellites, map...
Abstract We present the discovery of Ursa Major III/UNIONS 1, least luminous known satellite Milky Way, which is estimated to have an absolute V -band magnitude <?CDATA $+{2.2}_{-0.3}^{+0.4}$?> <mml:math xmlns:mml="http://www.w3.org/1998/Math/MathML" overflow="scroll"> <mml:mo>+</mml:mo> <mml:msubsup> <mml:mrow> <mml:mn>2.2</mml:mn> </mml:mrow> <mml:mo>−</mml:mo> <mml:mn>0.3</mml:mn> <mml:mn>0.4</mml:mn> </mml:msubsup> </mml:math> mag, equivalent a total stellar mass ${16}_{-5}^{+6}$?>...
(Abridged) We use N-body simulations to study the effects that a divergent (i.e. "cuspy") dark matter (DM) profile introduces on tidal evolution of dwarf spheroidal galaxies (dSphs). Our models assume cosmologically-motivated initial conditions where dSphs are DM-dominated systems eccentric orbits about host galaxy composed halo and baryonic disc. find resilience stripping is extremely sensitive cuspiness; whereas dwarfs with cored can be easily destroyed by disc, those cusps always retain...
We use a sample of 43,690 galaxies selected from the Sloan Digital Sky Survey Data Release 4 to study systematic effects specific star formation rate (SSFR) and galaxy size (as measured by half-light radius, rh) on mass-metallicity relation. find that with high SSFR or large rh for their stellar mass have systematically lower gas-phase metallicities (by up 0.2 dex) than low small rh. discuss possible origins these dependencies, including galactic winds/outflows, abundance gradients,...
The projected structures and integrated properties of the Andromeda I, II, III, V, VI, VII Cetus dwarf spheroidal galaxies are analysed based upon resolved counts red giant branch stars. observations were taken as part Isaac Newton Telescope Wide Field Survey M31 its environs. For each object, we have derived isopleth maps, surface brightness profiles, intensity-weighted centres, position angles, ellipticities, tidal radii, core concentration parameters, exponential scalelengths, Plummer...
We present a homogeneous kinematic analysis of red giant branch stars within 18 the 28 Andromeda dwarf spheroidal (dSph) galaxies, obtained using Keck I LRIS and II DEIMOS spectrographs. Based on their g-i colors (taken with CFHT MegaCam imager), physical positions sky, radial velocities, we assign probabilities dSph membership to each observed star. Using this information, velocity dispersions, central masses densities dark matter halos are calculated for these objects, compared properties...
We use a sample of close galaxy pairs selected from the Sloan Digital Sky Survey Data Release 4 (SDSS DR4) to investigate in what environments mergers occur and how results these depend on differences local density. The galaxies are quantified morphologically using two-dimensional bulge-plus-disk decompositions compared control matched stellar mass, redshift projected Lower density have fractionally more with small separations (r_p) relative velocities (Delta v), but even high contain...
We present the discovery of five new dwarf galaxies, Andromeda XXIII–XXVII, located in outer halo M31. These galaxies were discovered during second year data from Pan-Andromeda Archaeological Survey (PAndAS), a photometric survey M31/M33 subgroup conducted with MegaPrime/MegaCam wide-field camera on Canada–France–Hawaii Telescope. The current PAndAS now provides an almost complete panoramic view M31 out to average projected radius ∼150 kpc. Here we for first time metal-poor stellar density...
In `A Bayesian Approach to Locating the Red Giant Branch Tip Magnitude (PART I),' a new technique was introduced for obtaining distances using TRGB standard candle. Here we describe useful complement with potential further reduce uncertainty in our distance measurements by incorporating matched-filter weighting scheme into model likelihood calculations. this scheme, stars are weighted according their probability of being true object members. We then re-test modified algorithm...
We examine the dynamics of stellar systems embedded within cold dark matter (CDM) halos in order to assess observational constraints on content Local Group dwarf spheroidals (dSphs). Our analysis shows that total mass luminous radius is reasonably well constrained and approximately independent luminosity dwarf, highlighting poor correspondence between halo mass. This result implies average density substantially higher physically small such as Draco Sculptor than larger Fornax. For example,...
A substantial fraction of the lowest metallicity stars show very high enhancements in carbon. It is debated whether these reflect stars' birth composition, or if their atmospheres were subsequently polluted, most likely by accretion from an asymptotic giant branch binary companion. Here we investigate and compare properties three carbon-enhanced subclasses: The metal-poor CEMP-s that are additionally enhanced barium; higher (sg)CH- Ba II also CEMP-no stars, not barium. Through comparison...
The Pan-Andromeda Archaeological Survey is a survey of $>400$ square degrees centered on the Andromeda (M31) and Triangulum (M33) galaxies that has provided most extensive panorama $L_\star$ galaxy group to large projected galactocentric radii. Here, we collate summarise current status our knowledge substructures in stellar halo M31, discuss connections between these features. We estimate 13 distinctive were produced by at least 5 different accretion events, all last 3 or 4 Gyrs. suggest few...
We use a sample of newly-discovered globular clusters from the Pan-Andromeda Archaeological Survey (PAndAS) in combination with previously-catalogued objects to map spatial distribution M31 halo. At projected radii beyond ~30 kpc, where large coherent stellar streams are readily distinguished field, there is striking correlation between these features and positions clusters. Adopting simple Monte Carlo approach, we test significance this association by computing probability that it could be...
We have assembled a large, high-quality catalogue of galaxy colours from the Sloan Digital Sky Survey Data Release 7 and identified 21 347 galaxies in pairs spanning range projected separations (rp < 80 h−170 kpc), relative velocities (Δv 10 000 km s−1, which includes that are essential for quality control) stellar mass ratios (from 1:10 to 10:1). find red fraction is higher than control sample matched redshift, demonstrate this difference likely due fact reside density environments...
The question of whether galaxy mergers are linked to the triggering active galactic nuclei (AGN) continues be a topic considerable debate. issue can broken down into two distinct questions: 1) Can trigger AGN? 2) Are dominant AGN mechanism? A complete picture AGN-merger connection requires that both these questions addressed with same dataset. In previous work, we have shown selected from Sloan Digital Sky Survey (SDSS) show an excess optically-selected, and mid-IR colour-selected AGN,...