Search Publications
Spatially offset black holes in the Horizon-AGN simulation and comparison to observations
Ferreira, Pedro G.; Devriendt, Julien; Slyz, Adrianne +2 more
We study the displacements between the centres of galaxies and their supermassive black holes (BHs) in the cosmological hydrodynamical simulation Horizon-AGN, and in a variety of observations from the literature. The BHs in Horizon-AGN feel a subgrid dynamical friction force, sourced by the surrounding gas, which prevents recoiling BHs being eject…
Bayesian calibration of the mixing length parameter αML and of the helium-to-metal enrichment ratio ΔY/ΔZ with open clusters: the Hyades test-bed
Valle, G.; Dell'Omodarme, M.; Prada Moroni, P. G. +2 more
We tested the capability of a Bayesian procedure to calibrate both the helium abundance and the mixing length parameter (αML), using precise photometric data for main-sequence (MS) stars in a cluster with negligible reddening and well-determined distance. The method has been applied first to a mock data set generated to mimic Hyades MS …
The intermediate polar cataclysmic variable GK Persei 120 years after the nova explosion: a first dynamical mass study
Sabo, R.; Torres, M. A. P.; Hakala, P. +15 more
We present a dynamical study of the intermediate polar and dwarf nova cataclysmic variable GK Persei (Nova Persei 1901) based on a multisite optical spectroscopy and R-band photometry campaign. The radial velocity curve of the evolved donor star has a semi-amplitude $K_2=126.4 \pm 0.9 \, \mathrm{km}\, \mathrm{s}^{-1}$ and an orbital period $P=1.99…
The Sun's distance from the Galactic Centre and mid-plane, and the Galactic old bulge's morphology: 715 VVV Type II Cepheids
Pietrukowicz, Pawel; Gedalin, Michael; Jiang, Ing-Guey +2 more
A statistical method is employed in tandem with new VISTA Variables in the Via Lactea (VVV) near-infrared observations to determine the Sun's distance from the Galactic Centre (r0, GC), the Sun's height from the local mid-plane (z0), and to likewise infer the shape of the Galactic ∼10 Gyr old bulge. Specifically, the conclusi…
A microlensing search of 700 million VVV light curves
McGill, Peter; Smith, Leigh C.; Evans, N. Wyn +1 more
The VISTA Variables in the Via Lactea (VVV) survey and its extension have been monitoring about 560 deg2 of sky centred on the Galactic bulge and inner disc for nearly a decade. The photometric catalogue contains of order 10$^9$ sources monitored in the $K_s$ band down to 18 mag over hundreds of epochs from 2010 to 2019. Using these dat…
Measuring the total infrared light from galaxy clusters at z = 0.5-1.6: connecting stellar populations to dusty star formation
Weiner, Benjamin J.; Dey, Arjun; Alberts, Stacey +13 more
Massive galaxy clusters undergo strong evolution from z ~ 1.6 to z ~ 0.5, with overdense environments at high-z characterized by abundant dust-obscured star formation and stellar mass growth which rapidly give way to widespread quenching. Data spanning the near- to far-infrared (IR) can directly trace this transformation; however, such studies hav…
A hyperluminous obscured quasar at a redshift of z ≈ 4.3
Burgarella, Denis; Oliver, Seb; Małek, Katarzyna +9 more
In this work we report the discovery of the hyperluminous galaxy HELP_J100156.75 + 022344.7 at a photometric redshift of $z$ ≈ 4.3. The galaxy was discovered in the Cosmological Evolution Survey (COSMOS) field, one of the fields studied by the Herschel Extragalactic Legacy Project (HELP). We present the spectral energy distribution (SED) of the ga…
The chemical composition of the accretion disc and donor star in ultra-compact X-ray binaries: A comprehensive X-ray analysis
Vasilopoulos, Georgios; Webb, Natalie; Koliopanos, Filippos +1 more
We have analysed the X-ray spectra of all known Ultra-Compact X-ray Binaries (UCXBs), with the purpose of constraining the chemical composition of their accretion disc and donor star. Our investigation was focused on the presence (or absence) of the Fe Kα emission line, which was used as the probe of chemical composition of the disc, based on prev…
High-resolution spectroscopy of the hot Am star HR 3383
Nielsen, K. E.; Leckrone, D. S.; Wahlgren, G. M.
We present the spectrum analysis of the hot Am star HR 3383 (A1 Vm). Hubble Space Telescope STIS and Nordic Optical Telescope SOFIN data are modelled with synthetic spectra, and abundances are investigated for 78 elements. Most light elements up through oxygen show deficiencies, compared to solar abundances, followed by the general trend of increa…
Probing within the Bondi radius of the ultramassive black hole in NGC 1600
Walker, S. A.; Runge, J.
We present deep (250 ks) Chandra observations of the nearby galaxy group NGC 1600, which has at its centre an ultramassive black hole (17 ± 1.5 billion M⊙). The exceptionally large mass of the black hole coupled with its low redshift makes it one of only a handful of black holes for which spatially resolved temperature and density profi…