Search Publications
Evidence for rapid disc formation and reprocessing in the X-ray bright tidal disruption event candidate AT 2018fyk
Gromadzki, M.; Hodgkin, S. T.; Kostrzewa-Rutkowska, Z. +15 more
We present optical spectroscopic and Swift UVOT/XRT observations of the X-ray and UV/optical bright tidal disruption event (TDE) candidate AT 2018fyk/ASASSN-18ul discovered by ASAS-SN. The Swift light curve is atypical for a TDE, entering a plateau after ∼40 d of decline from peak. After 80 d the UV/optical light curve breaks again to decline furt…
Constraining the Metallicities, Ages, Star Formation Histories, and Ionizing Continua of Extragalactic Massive Star Populations
Dahle, H.; Rigby, J. R.; Sharon, K. +4 more
We infer the properties of massive star populations using the far-ultraviolet stellar continua of 61 star-forming galaxies: 42 at low redshift observed with the Hubble Space Telescope and 19 at z ∼ 2 from the MEGaSaURA sample. We fit each stellar continuum with a linear combination of up to 50 single-age and single-metallicity STARBURST99 models. …
Ubiquitous cold and massive filaments in cool core clusters
Godard, B.; Fabian, A. C.; Combes, F. +19 more
Multi-phase filamentary structures around brightest cluster galaxies (BCG) are likely a key step of AGN-feedback. We observed molecular gas in three cool cluster cores, namely Centaurus, Abell S1101, and RXJ1539.5, and gathered ALMA (Atacama Large Millimeter/submillimeter Array) and MUSE (Multi Unit Spectroscopic Explorer) data for 12 other cluste…
NIHAO XV: the environmental impact of the host galaxy on galactic satellite and field dwarf galaxies
Buck, Tobias; Dutton, Aaron A.; Macciò, Andrea V. +2 more
We study the impact of the host on dwarf galaxy properties using four new Milky Way (MW)-like, ultra-high-resolution simulations (Npart > 107) from the NIHAO project. We split our sample into satellite (R < R200), nearby (1 < R/R200 < 2.5), and field (R > 2.5R200) galaxies. Simu…
Rotation Curve of the Milky Way from Classical Cepheids
Udalski, Andrzej; Mróz, Przemek; Szymański, Michał K. +7 more
Flat rotation curves of spiral galaxies are considered as an evidence for dark matter, but the rotation curve of the Milky Way is difficult to measure. Various objects were used to track the rotation curve in the outer parts of the Galaxy, but most studies rely on incomplete kinematical information and inaccurate distances. Here, we use a sample o…
The total stellar halo mass of the Milky Way
Belokurov, Vasily; Sanders, Jason L.; Deason, Alis J.
We measure the total stellar halo luminosity using red giant branch (RGB) stars selected from Gaia data release 2. Using slices in magnitude, colour, and location on the sky, we decompose RGB stars belonging to the disc and halo by fitting two-dimensional Gaussians to the Galactic proper motion distributions. The number counts of RGB stars are con…
The strong gravitational lens finding challenge
Kneib, J. -P.; Bertin, E.; Jullo, E. +34 more
Large-scale imaging surveys will increase the number of galaxy-scale strong lensing candidates by maybe three orders of magnitudes beyond the number known today. Finding these rare objects will require picking them out of at least tens of millions of images, and deriving scientific results from them will require quantifying the efficiency and bias…
A comprehensive three-dimensional radiative magnetohydrodynamic simulation of a solar flare
Cheung, M. C. M.; De Pontieu, B.; Sainz Dalda, A. +11 more
Solar and stellar flares are the most intense emitters of X-rays and extreme ultraviolet radiation in planetary systems1,2. On the Sun, strong flares are usually found in newly emerging sunspot regions3. The emergence of these magnetic sunspot groups leads to the accumulation of magnetic energy in the corona. When the magneti…
Late-time UV Observations of Tidal Disruption Flares Reveal Unobscured, Compact Accretion Disks
Brown, Thomas M.; Fruchter, Andrew S.; Stone, Nicholas C. +3 more
The origin of thermal optical and UV emission from stellar tidal disruption flares (TDFs) remains an open question. We present Hubble Space Telescope far-UV (FUV) observations of eight optical/UV-selected TDFs 5-10 yr post-peak. Six sources are cleanly detected, showing point-like FUV emission ({10}41.5{--42.5} {erg} {{{s}}}-1
Abundance to age ratios in the HARPS-GTO sample with Gaia DR2. Chemical clocks for a range of [Fe/H]
Chaplin, W. J.; Moya, A.; Davies, G. R. +8 more
Aims: The purpose of this work is to evaluate how several elements produced by different nucleosynthesis processes behave with stellar age and provide empirical relations to derive stellar ages from chemical abundances.
Methods: We derived different sets of ages using Padova and Yonsei-Yale isochrones and HIPPARCOS and Gaia parallaxes fo…