Search Publications
Chasing passive galaxies in the early Universe: a critical analysis in CANDELS GOODS-South
Elbaz, D.; Ciesla, L.; Wang, T. +12 more
We search for passive galaxies at z > 3 in the GOODS-South field, using different techniques based on photometric data, and paying attention to develop methods that are sensitive to objects that have become passive shortly before the epoch of observation. We use CANDELS HST catalogues, ultra-deep Ks data and new IRAC photometry, performing spec…
The Pristine survey IV: approaching the Galactic metallicity floor with the discovery of an ultra-metal-poor star
Fouesneau, Morgan; Sestito, Federico; McConnachie, Alan W. +22 more
The early Universe presented a star formation environment that was almost devoid of heavy elements. The lowest metallicity stars thus provide a unique window into the earliest Galactic stages, but are exceedingly rare and difficult to find. Here, we present the discovery of an ultra-metal-poor star, Pristine_221.8781+9.7844, using narrow-band Ca H…
Not all stars form in clusters - measuring the kinematics of OB associations with Gaia
Kruijssen, J. M. Diederik; Ward, Jacob L.
It is often stated that star clusters are the fundamental units of star formation and that most (if not all) stars form in dense stellar clusters. In this monolithic formation scenario, low-density OB associations are formed from the expansion of gravitationally bound clusters following gas expulsion due to stellar feedback. N-body simulations of …
A 3.5 million Solar masses black hole in the centre of the ultracompact dwarf galaxy fornax UCD3
Romanowsky, Aaron J.; Neumayer, Nadine; Strader, Jay +16 more
The origin of ultracompact dwarfs (UCDs), a class of compact stellar systems discovered two decades ago, still remains a matter of debate. Recent discoveries of central supermassive black holes in UCDs likely inherited from their massive progenitor galaxies provide support for the tidal stripping hypothesis. At the same time, on statistical ground…
Testing gravity with wide binary stars like α Centauri
Banik, Indranil; Zhao, Hongsheng
We consider the feasibility of testing Newtonian gravity at low accelerations using wide binary (WB) stars separated by ≳ 3 kAU. These systems probe the accelerations at which galaxy rotation curves unexpectedly flatline, possibly due to modified Newtonian dynamics (MOND). We conduct Newtonian and MOND simulations of WBs covering a grid of model p…
The search for multiple populations in Magellanic Cloud clusters - IV. Coeval multiple stellar populations in the young star cluster NGC 1978
Martocchia, S.; Dalessandro, E.; Salaris, M. +15 more
We have recently shown that the ∼2 Gyr old Large Magellanic Cloud star cluster NGC 1978 hosts multiple populations in terms of star-to-star abundance variations in [N/Fe]. These can be seen as a splitting or spread in the subgiant and red giant branches (SGB and RGB) when certain photometric filter combinations are used. Because of its relative yo…
The 4:1 outer Lindblad resonance of a long-slow bar as an explanation for the Hercules stream
Bovy, Jo; Hunt, Jason A. S.
There are multiple groups of comoving stars in the Solar neighbourhood, which are possible signatures of one of the fundamental resonances of non-axisymmetric structure such as the Galactic bar or spiral arms. One such stream, Hercules, has been proposed to result from the outer Lindblad resonance of a short-fast rotating bar as shown analytically…
Synthetic Stellar Photometry - II. Testing the bolometric flux scale and tables of bolometric corrections for the Hipparcos/Tycho, Pan-STARRS1, SkyMapper, and JWST systems
Casagrande, L.; VandenBerg, Don A.
We use MARCS model atmosphere fluxes to compute synthetic colours, bolometric corrections and reddening coefficients for the Hipparcos/Tycho, Pan-STARRS1, SkyMapper, and JWST systems. Tables and interpolation subroutines are provided to transform isochrones from the theoretical to various observational planes, to derive bolometric corrections, syn…
The STRong lensing Insights into the Dark Energy Survey (STRIDES) 2016 follow-up campaign - I. Overview and classification of candidates selected by two techniques
Smith, M.; D'Andrea, C. B.; Abbott, T. M. C. +79 more
The primary goals of the STRong lensing Insights into the Dark Energy Survey (STRIDES) collaboration are to measure the dark energy equation of state parameter and the free streaming length of dark matter. To this aim, STRIDES is discovering strongly lensed quasars in the imaging data of the Dark Energy Survey and following them up to measure time…
An application of an optimal statistic for characterizing relative orientations
Martin, P. G.; Poidevin, F.; Hill, Ryley +5 more
We present the projected Rayleigh statistic (PRS), a modification of the classic Rayleigh statistic, as a test for non-uniform relative orientation between two pseudo-vector fields. In the application here, this gives an effective way of investigating whether polarization pseudo-vectors (spin-2 quantities) are preferentially parallel or perpendicu…