Search Publications
A variable ULX and possible IMBH candidate in M51a
Done, Chris; Middleton, Matthew J.; Sutton, Andrew D. +7 more
Ultraluminous X-ray source (ULX)-7, in the northern spiral arm of M51, demonstrates unusual behaviour for an ULX, with a hard X-ray spectrum but very high short-term variability. This suggests that it is not in a typical ultraluminous state. We analyse the source using archival data from XMM-Newton, Chandra and NuSTAR, and by examining optical and…
The binary populations of eight globular clusters in the outer halo of the Milky Way
Milone, A. P.; Marino, A. F.; Bedin, L. R. +6 more
We analyse colour-magnitude diagrams of eight globular clusters (GCs) in the outer Galactic halo. Images were taken with the Wide Field Channel of the Advanced Camera for Survey and the Ultraviolet and Visual Channel of the Wide Field Camera 3 on board of the Hubble Space Telescope. We have determined the fraction of binary stars along the main se…
Acceleration of cometary dust near the nucleus: application to 67P/Churyumov-Gerasimenko
Hartogh, Paul; Skorov, Yuri; Reshetnyk, Volodymyr +2 more
We present a model of cometary dust capable of simulating the dynamics within the first few tens of km of the comet surface. Recent measurements by the Grain Impact Analyser and Dust Accumulator and Cometary Secondary Ion Mass Analyser instruments on Rosetta show that the nucleus emits fluffy dust particles with porosities above 50 per cent and si…
The multiplicity of 250-µm Herschel sources in the COSMOS field
Griffin, Matt; Oliver, Seb; Wang, Lingyu +5 more
We investigate the multiplicity of extragalactic sources detected by the Herschel Space Observatory in the COSMOS field. Using 3.6- and 24-µm catalogues, in conjunction with 250-µm data from Herschel, we seek to determine if a significant fraction of Herschel sources are composed of multiple components emitting at 250 µm. We use …
Upholding the unified model for active galactic nuclei: VLT/FORS2 spectropolarimetry of Seyfert 2 galaxies
Hönig, S. F.; Tadhunter, C. N.; Acosta-Pulido, J. A. +5 more
The origin of the unification model for active galactic nuclei (AGN) was the detection of broad hydrogen recombination lines in the optical polarized spectrum of the Seyfert 2 galaxy (Sy2) NGC 1068. Since then, a search for the hidden broad-line region (HBLR) of nearby Sy2s started, but polarized broad lines have only been detected in ∼30-40 per c…
Hubble Space Telescope observations of the host galaxies and environments of calcium-rich supernovae
Lyman, J. D.; Angus, C. R.; Davies, M. B. +4 more
Calcium-rich supernovae (SNe) represent a significant challenge for our understanding of the fates of stellar systems. They are less luminous than other SN types and they evolve more rapidly to reveal nebular spectra dominated by strong calcium lines with weak or absent signatures of other intermediate- and iron-group elements, which are seen in o…
The missing satellite problem in 3D
Treu, T.; Torrey, Paul; Lu, Y. +3 more
It is widely believed that the large discrepancy between the observed number of satellite galaxies and the predicted number of dark subhaloes can be resolved via a variety of baryonic effects which suppress star formation in low-mass haloes. Supporting this hypothesis, numerous high-resolution simulations with star formation and associated feedbac…
Massive stars dying alone: the extremely remote environment of SN 2009ip
Smith, Nathan; Andrews, Jennifer E.; Mauerhan, Jon C.
We present late-time Hubble Space Telescope (HST) images of the site of supernova (SN) 2009ip taken almost 3 yr after its bright 2012 luminosity peak. SN 2009ip is now slightly fainter in broad filters than the progenitor candidate detected by HST in 1999. The current source continues to be dominated by ongoing late-time circumstellar material int…
The MUSE view of QSO PG 1307+085: an elliptical galaxy on the MBH-σ* relation interacting with its group environment
Scharwächter, J.; Husemann, B.; Bennert, V. N. +2 more
We report deep optical integral-field spectroscopy with the Multi-Unit Spectroscopic Explorer (MUSE) at the Very Large Telescope of the luminous radio-quiet quasi-stellar object (QSO) PG 1307+085 obtained during commissioning. Given the high sensitivity and spatial resolution delivered by MUSE, we are able to resolve the compact (re ∼ 1…
Imprints of a high-velocity wind on the soft X-ray spectrum of PG1211+143
Vaughan, S.; Reeves, J. N.; Pounds, K. A. +2 more
An extended XMM-Newton observation of the luminous narrow-line Seyfert galaxy PG1211+143 in 2014 has revealed a more complex high-velocity wind, with components distinguished in velocity, ionization level, and column density. Here we report soft X-ray emission and absorption features from the ionized outflow, finding counterparts of both high-velo…