Search Publications
The southern stellar stream spectroscopic survey (S5): Overview, target selection, data reduction, validation, and early science
Geha, M.; Bechtol, K.; Allam, S. +30 more
We introduce the southern stellar stream spectroscopy survey (S5), an on-going program to map the kinematics and chemistry of stellar streams in the southern hemisphere. The initial focus of S5 has been spectroscopic observations of recently identified streams within the footprint of the dark energy survey (DES), with the eve…
The first view of δ Scuti and γ Doradus stars with the TESS mission
Reese, D. R.; Niemczura, E.; Handberg, R. +63 more
We present the first asteroseismic results for δ Scuti and γ Doradus stars observed in Sectors 1 and 2 of the TESS mission. We utilize the 2-min cadence TESS data for a sample of 117 stars to classify their behaviour regarding variability and place them in the Hertzsprung-Russell diagram using Gaia DR2 data. Included within our sample are the epon…
The Galactic disc in action space as seen by Gaia DR2
Rix, Hans-Walter; Coronado, Johanna; Trick, Wilma H.
The quality and quantity of 6D stellar position-velocity measurements in the second Gaia data release's radial velocity sample (DR2/RVS) allow us to study small-scale structure in the orbit distribution of the Galactic disc beyond the immediate Solar neighbourhood. We investigate the distribution of orbital actions (JR, Lz, J…
Too big to fail in light of Gaia
Kaplinghat, Manoj; Yu, Hai-Bo; Valli, Mauro
We point out an anticorrelation between the central dark matter (DM) densities of the bright Milky Way dwarf spheroidal galaxies (dSphs) and their orbital pericenter distances inferred from Gaia data. The dSphs that have not come close to the Milky Way centre (like Fornax, Carina and Sextans) are less dense in DM than those that have come closer (…
Massive star cluster formation under the microscope at z = 6
Castellano, M.; Gilli, R.; Grillo, C. +12 more
We report on a superdense star-forming region with an effective radius (Re) smaller than 13 pc identified at z = 6.143 and showing a star formation rate density ΣSFR ∼ 1000 M⊙ yr-1 kpc-2 (or conservatively >300 M⊙ yr-1 kpc-2). Such a dense region is detected…
Is every strong lens model unhappy in its own way? Uniform modelling of a sample of 13 quadruply+ imaged quasars
Smith, M.; Abbott, T. M. C.; Allam, S. +70 more
Strong-gravitational lens systems with quadruply imaged quasars (quads) are unique probes to address several fundamental problems in cosmology and astrophysics. Although they are intrinsically very rare, ongoing and planned wide-field deep-sky surveys are set to discover thousands of such systems in the next decade. It is thus paramount to devise …
The VANDELS survey: the stellar metallicities of star-forming galaxies at 2.5 < z < 5.0
Cimatti, A.; Cullen, F.; McLure, R. J. +24 more
We present the results of a study utilizing ultradeep, rest-frame UV, spectroscopy to quantify the relationship between stellar mass and stellar metallicity for 681 star-forming galaxies at 2.5 < z < 5.0 (<z> = 3.5 ± 0.6) drawn from the VANDELS survey. Via a comparison with high-resolution stellar population synthesis models, we determ…
On the ridges, undulations, and streams in Gaia DR2: linking the topography of phase space to the orbital structure of an N-body bar
White, S. D. M.; Katz, D.; Fragkoudi, F. +7 more
We explore the origin of phase-space substructures revealed by the second Gaia data release in the disc of the Milky Way, such as the ridges in the Vϕ-r plane, the undulations in the Vϕ-r-Vr space and the streams in the Vϕ-Vr plane. We use a collisionless N-body simulation with cospatial thin …
Tracing the formation of the Milky Way through ultra metal-poor stars
Fouesneau, Morgan; Sestito, Federico; Navarro, Julio F. +11 more
We use Gaia DR2 astrometric and photometric data, published radial velocities and MESA models to infer distances, orbits, surface gravities, and effective temperatures for all ultra metal-poor stars ([Fe/H] < -4.0 dex) available in the literature. Assuming that these stars are old (> 11 Gyr) and that they are expected to belong to the Milky …
Intracluster light: a luminous tracer for dark matter in clusters of galaxies
Trujillo, Ignacio; Montes, Mireia
The bulk of stars in galaxy clusters are confined within their constituent galaxies. Those stars do not trace the extended distribution of dark matter well as they are located in the central regions of the cluster's dark matter subhaloes. A small fraction of stars is expected, however, to follow the global dark matter shape of the cluster. These a…