Search Publications
Deep generative models for galaxy image simulations
Mandelbaum, Rachel; Lanusse, François; Freeman, Peter +3 more
Image simulations are essential tools for preparing and validating the analysis of current and future wide-field optical surveys. However, the galaxy models used as the basis for these simulations are typically limited to simple parametric light profiles, or use a fairly limited amount of available space-based data. In this work, we propose a meth…
White dwarf-main-sequence binaries from Gaia EDR3: the unresolved 100 pc volume-limited sample
Althaus, L. G.; Solano, E.; Rebassa-Mansergas, A. +6 more
We use the data provided by the Gaia Early Data Release 3 to search for a highly complete volume-limited sample of unresolved binaries consisting of a white dwarf and a main-sequence companion (i.e. WDMS binaries) within 100 pc. We select 112 objects based on their location within the Hertzsprung-Russell diagram, of which 97 are new identification…
ML-MOC: Machine Learning (kNN and GMM) based Membership determination for Open Clusters
Vaidya, Kaushar; Rao, Khushboo K.; Agarwal, Manan +1 more
The existing open-cluster membership determination algorithms are either prior dependent on some known parameters of clusters or are not automatable to large samples of clusters. In this paper, we present ML-MOC, a new machine-learning-based approach to identify likely members of open clusters using the Gaia DR2 data and no a priori information ab…
Ultraviolet spectra of extreme nearby star-forming regions: Evidence for an overabundance of very massive stars
Charlot, Stéphane; Chevallard, Jacopo; Stark, Daniel P. +3 more
As deep spectroscopic campaigns extend to higher redshifts and lower stellar masses, the interpretation of galaxy spectra depends increasingly upon models for very young stellar populations. Here we present new HST/COS ultraviolet spectroscopy of seven nearby (<120 Mpc) star-forming regions hosting very young stellar populations (~4-20 Myr) wit…
The COS Absorption Survey of Baryon Harbors: unveiling the physical conditions of circumgalactic gas through multiphase Bayesian ionization modelling
Tripp, Todd M.; Prochaska, J. Xavier; Burchett, Joseph N. +4 more
Quasar absorption systems encode a wealth of information about the abundances, ionization structure, and physical conditions in intergalactic and circumgalactic media. Simple (often single-phase) photoionization models are frequently used to decode such data. Using five discrete absorbers from the COS Absorption Survey of Baryon Harbors (CASBaH) t…
On the radial abundance gradients of nitrogen and oxygen in the inner Galactic disc
Méndez-Delgado, J. E.; Arellano-Córdova, K. Z.; García-Rojas, J. +1 more
We present optical spectra of nine Galactic H II regions observed with the 10.4 m Gran Telescopio Canarias telescope and located at Galactocentric distances (RG) from 4 to 8 kpc. The distances of the objects have been revised using Gaia DR2 parallaxes. We determine the electron temperature for all the nebulae, which allows a precise com…
XMM-Newton campaign on the ultraluminous X-ray source NGC 247 ULX-1: outflows
Fabian, A. C.; Pinto, C.; D'Aì, A. +13 more
Most ultraluminous X-ray sources (ULXs) are believed to be powered by super-Eddington accreting neutron stars and, perhaps, black holes. Above the Eddington rate the disc is expected to thicken and to launch powerful winds through radiation pressure. Winds have been recently discovered in several ULXs. However, it is yet unclear whether the thicke…
The contribution of N-rich stars to the Galactic stellar halo using APOGEE red giants
Bovy, Jo; Cunha, Katia; Majewski, Steven R. +13 more
The contribution of dissolved globular clusters (GCs) to the stellar content of the Galactic halo is a key constraint on models for GC formation and destruction, and the mass assembly history of the Milky Way. Earlier results from APOGEE pointed to a large contribution of destroyed GCs to the stellar content of the inner halo, by as much as 25 ${{…
A scaling relationship for non-thermal radio emission from ordered magnetospheres: from the top of the main sequence to planets
Umana, G.; Fossati, L.; Loru, S. +20 more
In this paper, we present the analysis of incoherent non-thermal radio emission from a sample of hot magnetic stars, ranging from early-B to early-A spectral type. Spanning a wide range of stellar parameters and wind properties, these stars display a commonality in their radio emission which presents new challenges to the wind scenario as original…
Year 1 of the ZTF high-cadence Galactic plane survey: strategy, goals, and early results on new single-mode hot subdwarf B-star pulsators
Hermes, J. J.; Duev, Dmitry A.; Riddle, Reed +18 more
We present the goals, strategy, and first results of the high-cadence Galactic plane survey using the Zwicky Transient Facility (ZTF). The goal of the survey is to unveil the Galactic population of short-period variable stars, including short-period binaries, and stellar pulsators with periods less than a few hours. Between 2018 June and 2019 Janu…