Search Publications
A parsec-scale radio jet launched by the central intermediate-mass black hole in the dwarf galaxy SDSS J090613.77+561015.2
Paragi, Zsolt; Frey, Sándor; Yang, Jun +4 more
The population of intermediate-mass black holes (IMBHs) in nearby dwarf galaxies plays an important 'ground truth' role in exploring black hole formation and growth in the early Universe. In the dwarf elliptical galaxy SDSS J090613.77+561015.2 (z = 0.0465), an accreting IMBH has been revealed by optical and X-ray observations. Aiming to search for…
Discovery of a soft X-ray lag in the ultraluminous X-ray source NGC 1313 X-1
Fabian, A. C.; Pinto, C.; Bachetti, M. +14 more
Ultraluminous X-ray sources (ULXs) provide a unique opportunity to probe the geometry and energetics of super-Eddington accretion. The radiative processes involved in super-Eddington accretion are not well understood, and so studying correlated variability between different energy bands can provide insights into the causal connection between diffe…
Cosmological insights into the assembly of the radial and compact stellar halo of the Milky Way
Hernquist, Lars; Helmi, Amina; Sales, Laura V. +1 more
Recent studies using Gaia DR2 have identified a massive merger in the early history of the Milky Way (MW) whose debris is dominated by radial and counterrotating orbits. This event, dubbed the Gaia-Enceladus/Gaia-Sausage (GE/GS), is also hypothesized to have built the majority of the inner stellar halo. We use the cosmological hydrodynamic simulat…
Local RR Lyrae stars: native and alien
Chen, X.; Zinn, R.; Layden, A. C. +1 more
Measurements of [Fe/H] and radial velocity are presented for 89 RR Lyrae (RRL) candidates within 6 kpc of the Sun. After the removal of two suspected non-RRLs, these stars were added to an existing data base, which yielded 464 RRLs with [Fe/H] on a homogeneous scale. Using data from the Gaia satellite (Data Release 2), we calculated the positions …
A search for the lenses in the Herschel Bright Sources (HerBS) sample
Eales, Stephen; Bakx, Tom J. L. C.; Amvrosiadis, Aristeidis
Verifying that sub-mm galaxies are gravitationally lensed requires time-expensive observations with oversubscribed high-resolution observatories. Here, we aim to strengthen the evidence of gravitational lensing within the Herschel Bright Sources (HerBS) by cross-comparing their positions to optical (SDSS) and near-infrared (VIKING) surveys, in ord…
Kinematics of RR Lyrae stars in the Galactic bulge with OGLE-IV and Gaia DR2
Mao, Shude; Pietrukowicz, Pawel; Shen, Juntai +2 more
We analyse the kinematics and spatial distribution of 15 599 fundamental-mode RR Lyrae (RRL) stars in the Milky Way bulge by combining OGLE-IV photometric data and Gaia DR2 proper motions. We show that the longitudinal proper motions and the line-of-sight velocities can give similar results for the rotation in the Galactic central regions. The ang…
Three discoveries of γ Cas analogues from dedicated XMM-Newton observations of Be stars
Smith, Myron A.; Nazé, Yaël; Torrejón, José M. +5 more
In the last years, a peculiarity of some Be stars - their association with unusually hard and intense X-ray emission - was shown to extend beyond a mere few cases. In this paper, we continue our search for new cases by performing a limited survey of 18 Be stars using XMM-Newton. The targets were selected either on the basis of a previous X-ray det…
Single magnetic white dwarfs with Balmer emission lines: a small class with consistent physical characteristics as possible signposts for close-in planetary companions
Gänsicke, Boris T.; Pala, Anna F.; Rodríguez-Gil, Pablo +4 more
We report the identification of SDSS J121929.45+471522.8 as the third apparently isolated magnetic (B ≃ 18.5 ± 1.0 MG) white dwarf exhibiting Zeeman-split Balmer emission lines. The star shows coherent variability at optical wavelengths with an amplitude of ≃0.03 mag and a period of 15.26 h, which we interpret as the spin period of the white dwarf…
Systematic versus statistical uncertainties in masses and magnifications of the Hubble Frontier Fields
Keeton, Charles R.; Raney, Catie A.; Brennan, Sean +1 more
The Hubble Frontier Fields data, along with multiple data sets obtained by other telescopes, have provided some of the most extensive constraints on cluster lenses to date. Multiple lens modelling teams analyzed the fields and made public a number of deliverables. By comparing these results, we can then undertake a unique and vital test of the sta…
Panchromatic properties of the extreme Fe II emitter PHL 1092
Marziani, Paola; Rodríguez-Ardila, Alberto; Marinello, Murilo +2 more
We present near-infrared spectroscopy of the NLS1 galaxy PHL 1092 (z = 0.394), the strongest Fe II emitter ever reported, combined with optical and UV data. We modelled the continuum and the broad emission lines using a power-law plus a blackbody function and Lorentzian functions, respectively. The strength of the Fe II emission was estimated usin…