Search Publications
Linking the rotation of a cluster to the spins of its stars: the kinematics of NGC 6791 and NGC 6819 in 3D
Balbinot, E.; Hénault-Brunet, V.; Gieles, M. +2 more
The physics governing the formation of star clusters is still not entirely understood. One open question concerns the amount of angular momentum that newly formed clusters possess after emerging from their parent gas clouds. Recent results suggest an alignment of stellar spins and binary orbital spins in star clusters, which support a scenario in …
Secularly powered outflows from AGNs: the dominance of non-merger driven supermassive black hole growth
Simmons, B. D.; Smethurst, R. J.; Lintott, C. J. +1 more
Recent observations and simulations have revealed the dominance of secular processes over mergers in driving the growth of both supermassive black holes (SMBHs) and galaxy evolution. Here, we obtain narrow-band imaging of AGN powered outflows in a sample of 12 galaxies with disc-dominated morphologies, whose history is assumed to be merger-free. W…
A low-flux state in IRAS 00521-7054 seen with NuSTAR and XMM-Newton: relativistic reflection and an ultrafast outflow
Harrison, F. A.; Stern, D.; Fabian, A. C. +8 more
We present results from a deep, coordinated XMM-Newton + NuSTAR observation of the Seyfert 2 galaxy IRAS 00521-7054. The NuSTAR data provide the first detection of this source in high-energy X-rays (E > 10 keV), and the broad-band data show this to be a highly complex source which exhibits relativistic reflection from the inner accretion disc, …
Clocking the assembly of double-barred galaxies with the MUSE TIMER project
Leaman, Ryan; Fragkoudi, Francesca; van de Ven, Glenn +11 more
The formation of two stellar bars within a galaxy has proved challenging for numerical studies. It is not yet clear whether the inner bar is born via a star formation process promoted by gas inflow along the outer bar or whether it is dynamically assembled from instabilities in a small-scale stellar disc. Observational constraints to these scenari…
Search for extra-tidal RR Lyrae stars in Milky Way globular clusters from Gaia DR2
Minniti, Dante; Singh, Harinder P.; Kundu, Richa
We used extra-tidal RR Lyrae stars to study the dynamics of Galactic globular clusters and know how effects like dynamical friction and tidal disruption affect these clusters. The Gaia DR2 catalogue for RR Lyrae stars (Clementini et al. 2018) is used along with the proper motions and tidal radii data for the globular clusters compiled from literat…
Dynamical evolution of star-forming regions: III. Unbound stars and predictions for Gaia
Parker, Richard J.; Schoettler, Christina; Wright, Nicholas J. +3 more
We use N-body simulations to probe the early phases of the dynamical evolution of star-forming regions and focus on mass and velocity distributions of unbound stars. In this parameter space study, we vary the initial virial ratio and degree of spatial and kinematic substructure and analyse the fraction of stars that become unbound in two different…
On measuring the Galactic dark matter halo with hypervelocity stars
Rossi, E. M.; Marchetti, T.; Contigiani, O.
Hypervelocity stars (HVSs) travel from the Galactic Centre across the dark matter halo of the Milky Way, where they are observed with velocities in excess of the Galactic escape speed. Because of their quasi-radial trajectories, they represent a unique probe of the still poorly constrained dark matter component of the Galactic potential. In this p…
A relativistic disc reflection model for 1H0419-577: Multi-epoch spectral analysis with XMM-Newton and NuSTAR
Fabian, Andrew C.; Walton, Dominic J.; Jiang, Jiachen +1 more
We present a detailed analysis of the spectral properties of the Seyfert 1 galaxy 1H0419-577, based on the archival XMM-Newton, NuSTAR, and simultaneous Swift observations taken between 2002 and 2015. All the observations show a broad emission line feature at the iron band. We demonstrate that the broad-band spectral variability at different level…
The first spectroscopic dust reverberation programme on active galactic nuclei: the torus in NGC 5548
Starkey, D. A.; Pott, J. -U.; Peterson, B. M. +16 more
We have recently initiated the first spectroscopic dust reverberation programme on active galactic nuclei in the near-infrared. Spectroscopy enables measurement of dust properties, such as flux, temperature, and covering factor, with higher precision than photometry. In particular, it enables measurement of both luminosity-based dust radii and dus…
Analysis of colour and polarimetric variability of RW Aur A in 2010-2018
Grankin, K.; Shenavrin, V.; Safonov, B. +6 more
The results of UBVRIJHKLM photometry and VRI polarimetry of a young star RW Aur A observed during unprecedented long and deep (up to ΔV ≈ 5 mag) dimming events in 2010-11 and 2014-18 are presented. The polarization degree p of RW Aur A at this period has reached 30 per cent in the I band. As in the case of UX Ori-type stars (UXORs), the so-called …