Search Publications
The soft X-ray excess: NLS1s versus BLS1s
Gliozzi, Mario; Williams, James K.
The soft X-ray excess - the excess of X-rays below 2 keV with respect to the extrapolation of the hard X-ray spectral continuum model - is a very common feature among type 1 active galactic nuclei (AGNs); yet the nature of the soft X-ray excess is still poorly understood and hotly debated. To shed some light on this issue, we have measured in a mo…
Revealing the tidal scars of the Small Magellanic Cloud
Erkal, Denis; Gallart, Carme; De Leo, Michele +3 more
Due to their close proximity, the Large and Small Magellanic Clouds (LMC/SMC) provide natural laboratories for understanding how galaxies form and evolve. With the goal of determining the structure and dynamical state of the SMC, we present new spectroscopic data for ∼3000 SMC red giant branch stars observed using the AAOmega spectrograph at the A…
The 2020 April-June super-outburst of OJ 287 and its long-term multiwavelength light curve with Swift: binary supermassive black hole and jet activity
Komossa, S.; Grupe, D.; Parker, M. L. +4 more
We report detection of a very bright X-ray-UV-optical outburst of OJ 287 in 2020 April-June, the second brightest since the beginning of our Swift multiyear monitoring in late 2015. It is shown that the outburst is predominantly powered by jet emission. Optical-UV-X-rays are closely correlated, and the low-energy part of the XMM-Newton spectrum di…
Weak lensing reveals a tight connection between dark matter halo mass and the distribution of stellar mass in massive galaxies
Sifón, Cristóbal; Leauthaud, Alexie; Behroozi, Peter +9 more
Using deep images from the Hyper Suprime-Cam (HSC) survey and taking advantage of its unprecedented weak lensing capabilities, we reveal a remarkably tight connection between the stellar mass distribution of massive central galaxies and their host dark matter halo mass. Massive galaxies with more extended stellar mass distributions tend to live in…
The Young Suns Exoplanet Survey: Detection of a wide-orbit planetary-mass companion to a solar-type Sco-Cen member
Todorov, K. O.; Ginski, C.; Manara, C. F. +9 more
The Young Suns Exoplanet Survey consists of a homogeneous sample of 70 young, solar-mass stars located in the Lower Centaurus-Crux subgroup of the Scorpius-Centaurus association with an average age of 15 ± 3 Myr. We report the detection of a co-moving companion around the K3IV star TYC 8998-760-1 (2MASSJ13251211-6456207) that is located at a dista…
On testing CDM and geometry-driven Milky Way rotation curve models with Gaia DR2
Lattanzi, Mario G.; Crosta, Mariateresa; Giammaria, Marco +1 more
Flat rotation curves (RCs) in disc galaxies provide the main observational support to the hypothesis of surrounding dark matter (DM). Despite of the difficulty in identifying the DM contribution to the total mass density in our Galaxy, stellar kinematics, as tracer of gravitational potential, is the most reliable observable for gauging different m…
First Gaia dynamical model of the Milky Way disc with six phase space coordinates: a test for galaxy dynamics
Neumayer, Nadine; Cappellari, Michele; Nitschai, Maria Selina
We construct the first comprehensive dynamical model for the high-quality subset of stellar kinematics of the Milky Way disc, with full 6D phase-space coordinates, provided by the Gaia Data Release 2. We adopt an axisymmetric approximation and use an updated Jeans Anisotropic Modelling (JAM) method, which allows for a generic shape and radial orie…
NGTS clusters survey - I. Rotation in the young benchmark open cluster Blanco 1
Jackman, James A. G.; Wheatley, Peter J.; Foreman-Mackey, Daniel +18 more
We determine rotation periods for 127 stars in the ∼115-Myr-old Blanco 1 open cluster using ∼200 d of photometric monitoring with the Next Generation Transit Survey. These stars span F5-M3 spectral types (1.2 M⊙ ≳ M ≳ 0.3 M⊙) and increase the number of known rotation periods in Blanco 1 by a factor of four. We determine rotat…
From hydrogen to helium: the spectral evolution of white dwarfs as evidence for convective mixing
Hollands, Mark; Gentile Fusillo, Nicola Pietro; Tremblay, Pier-Emmanuel +2 more
We present a study of the hypothesis that white dwarfs undergo a spectral change from hydrogen- to helium-dominated atmospheres using a volume-limited photometric sample drawn from the Gaia-DR2 catalogue, the Sloan Digital Sky Survey (SDSS), and the Galaxy Evolution Explorer (GALEX). We exploit the strength of the Balmer jump in hydrogen-atmospher…
How stellar rotation shapes the colour-magnitude diagram of the massive intermediate-age star cluster NGC 1846
Martocchia, S.; Salaris, M.; Cabrera-Ziri, I. +19 more
We present a detailed study of stellar rotation in the massive 1.5 Gyr old cluster NGC 1846 in the Large Magellanic Cloud. Similar to other clusters at this age, NGC 1846 shows an extended main-sequence turn-off (eMSTO), and previous photometric studies have suggested it could be bimodal. In this study, we use MUSE integral-field spectroscopy to m…