Search Publications
Testing the cosmic curvature at high redshifts: the combination of LSST strong lensing systems and quasars as new standard candles
Zhang, Jia; Liu, Yuting; Cao, Shuo +3 more
The cosmic curvature, a fundamental parameter for cosmology could hold deep clues to inflation and cosmic origins. We propose an improved model-independent method to constrain the cosmic curvature by combining the constructed Hubble diagram of high-redshift quasars with galactic-scale strong lensing systems expected to be seen by the forthcoming L…
Asteroseismology of luminous red giants with Kepler I: long-period variables with radial and non-radial modes
Huber, Daniel; Bedding, Timothy R.; Stello, Dennis +4 more
While long-period variables (LPVs) have been extensively investigated, especially with MACHO and OGLE data for the Magellanic Clouds, there still exist open questions in their pulsations regarding the excitation mechanisms, radial order, and angular degree assignment. Here, we perform asteroseismic analyses on LPVs observed by the 4-year Kepler mi…
The little things matter: relating the abundance of ultrafaint satellites to the hosts' assembly history
Belokurov, Vasily; Deason, Alis J.; Bose, Sownak +1 more
Ultrafaint dwarf galaxies ( $M_\star \le 10^{5}\, {\rm M}_\odot$ ) are relics of an early phase of galaxy formation. They contain some of the oldest and most metal-poor stars in the Universe which likely formed before the epoch of hydrogen reionization. These galaxies are so faint that they can only be detected as satellites of the Milky Way. They…
The tale of the tail - disentangling the high transverse velocity stars in Gaia DR2
Amarante, João A. S.; Smith, Martin C.; Boeche, Corrado
Although the stellar halo accounts for just ∼1 per cent of the total stellar mass of the Milky Way, the kinematics of halo stars encode valuable information about the origins and evolution of our Galaxy. It has been shown that the high transverse velocity stars in Gaia DR2 reveal a double sequence in the Hertzsprung-Russell (HR) diagram, indicatin…
Constraining churning and blurring in the Milky Way using large spectroscopic surveys - an exploratory study
Bowers, J. Bradley; Feltzing, Sofia; Agertz, Oscar
We have investigated the possibilities to quantify how much stars move in the Milky Way disc due to diffuse processes (blurring) and due to influences from spiral arms and the bar (churning). We assume that the formation radius of a star can be inferred if we know its elemental abundances and age and the metallicity profile of the interstellar med…
Seeing above the clouds with high-resolution spectroscopy
Gandhi, Siddharth; Brogi, Matteo; Webb, Rebecca K.
In the last decade, ground-based high-resolution Doppler spectroscopy (HRS) has detected numerous species in transiting and non-transiting hot Jupiters, and is ideally placed for atmospheric characterization of warm Neptunes and super Earths. Many of these cooler and smaller exoplanets have shown cloudy atmospheres from low-resolution near-infrare…
Mapping the Galactic disc with the LAMOST and Gaia red clump sample: II. 3D asymmetrical kinematics of mono-age populations in the disc between 6-14 kpc
Wang, H. -F.; López-Corredoira, M.; Huang, Y. +11 more
We perform analysis of the 3D kinematics of Milky Way disc stars in mono-age populations. We focus on stars between Galactocentric distances of R = 6 and 14 kpc, selected from the combined LAMOST Data Release 4 (DR4) red clump giant stars and Gaia DR2 proper motion catalogue. We confirm the 3D asymmetrical motions of recent works and provide time …
Eccentricity distribution of wide low-mass binaries
Tokovinin, Andrei
Distribution of eccentricities of very wide (up to 10 kau) low-mass binaries in the solar neighbourhood is studied using the catalogue of El-Badry and Rix (2018) based on Gaia. Direction and speed of relative motions in wide pairs contain statistical information on the eccentricity distribution, otherwise inaccessible owing to very long orbital pe…
Self-gravitating filament formation from shocked flows: velocity gradients across filaments
Ostriker, Eve C.; Chen, Che-Yu; Mundy, Lee G. +2 more
In typical environments of star-forming clouds, converging supersonic turbulence generates shock-compressed regions, and can create strongly magnetized sheet-like layers. Numerical magnetohydrodynamic simulations show that within these post-shock layers, dense filaments and embedded self-gravitating cores form via gathering material along the magn…
Detecting outliers in astronomical images with deep generative networks
Huertas-Company, Marc; Dubois, Yohan; Storey-Fisher, Kate +5 more
With the advent of future big-data surveys, automated tools for unsupervised discovery are becoming ever more necessary. In this work, we explore the ability of deep generative networks for detecting outliers in astronomical imaging data sets. The main advantage of such generative models is that they are able to learn complex representations direc…