Search Publications
The detection and X-ray view of the changing look AGN HE 1136-2304
Harrison, F. A.; Schartel, N.; Rodríguez-Pascual, P. M. +9 more
We report the detection of high-amplitude X-ray flaring of the AGN HE 1136-2304, which is accompanied by a strong increase in the flux of the broad Balmer lines, changing its Seyfert type from almost type 2 in 1993 down to 1.5 in 2014. HE 1136-2304 was detected by the XMM-Newton slew survey at >10 times the flux it had in the ROSAT all-sky surv…
ZFOURGE catalogue of AGN candidates: an enhancement of 160-µm-derived star formation rates in active galaxies to z = 3.2
Papovich, Casey; van Dokkum, Pieter G.; Allen, Rebecca J. +15 more
We investigate active galactic nuclei (AGN) candidates within the FourStar Galaxy Evolution Survey (ZFOURGE) to determine the impact they have on star formation in their host galaxies. We first identify a population of radio, X-ray, and infrared-selected AGN by cross-matching the deep Ks-band imaging of ZFOURGE with overlapping multiwav…
Star formation rates in luminous quasars at 2 < z < 3
Clements, David L.; Chapman, Scott; Vieira, Joaquin +22 more
We investigate the relation between star formation rates (dot{{M}}_s) and AGN properties in optically selected type 1 quasars at 2 < z < 3 using data from Herschel and the SDSS. We find that dot{{M}}_s remains approximately constant with redshift, at 300 ± 100 M⊙ yr-1. Conversely, dot{{M}}_s increases with AGN luminosit…
Quantifying the (X/peanut)-shaped structure in edge-on disc galaxies: length, strength, and nested peanuts
Ciambur, Bogdan C.; Graham, Alister W.
X-shaped or peanut-shaped (X/P) bulges are observed in more than 40 per cent of (nearly) edge-on disc galaxies, though to date a robust method to quantify them is lacking. Using Fourier harmonics to describe the deviation of galaxy isophotes from ellipses, we demonstrate with a sample of 11 such galaxies (including NGC 128) that the sixth Fourier …
Beyond spheroids and discs: classifications of CANDELS galaxy structure at 1.4 < z < 2 via principal component analysis
Papovich, Casey; Barro, Guillermo; Grogin, Norman A. +15 more
Important but rare and subtle processes driving galaxy morphology and star formation may be missed by traditional spiral, elliptical, irregular or Sérsic bulge/disc classifications. To overcome this limitation, we use a principal component analysis (PCA) of non-parametric morphological indicators (concentration, asymmetry, Gini coefficient, M…
Low-ionization structures in planetary nebulae - I. Physical, kinematic and excitation properties
Gonçalves, Denise R.; Akras, Stavros
Though the low-ionization small-scale structures (LISs) such as knots, filaments and jets of planetary nebulae (PNe) are known for ∼30 yr, some of their observational properties are not well established. In consequence, our ability to include them in the wider context of the formation and evolution of PNe is directly affected. Why most structures …
Carbon to oxygen ratios in extrasolar planetesimals
Gänsicke, Boris T.; Koester, Detlev; Farihi, Jay +1 more
Observations of small extrasolar planets with a wide range of densities imply a variety of planetary compositions and structures. Currently, the only technique to measure the bulk composition of extrasolar planetary systems is the analysis of planetary debris accreting on to white dwarfs, analogous to abundance studies of meteorites. We present me…
SN 2015U: a rapidly evolving and luminous Type Ibn supernova
Van Dyk, Schuyler D.; Filippenko, Alexei V.; Kelly, Patrick L. +7 more
Supernova (SN) 2015U (also known as PSN J07285387+3349106) was discovered in NGC 2388 on 2015 Feb. 11. A rapidly evolving and luminous event, it showed effectively hydrogen-free spectra dominated by relatively narrow helium P-Cygni spectral features and it was classified as an SN Ibn. In this paper, we present photometric, spectroscopic, and spect…
The white dwarf binary pathways survey - I. A sample of FGK stars with white dwarf companions
Gänsicke, B. T.; Rebassa-Mansergas, A.; Parsons, S. G. +3 more
The number of spatially unresolved white dwarf plus main-sequence star binaries has increased rapidly in the last decade, jumping from only ∼30 in 2003 to over 3000. However, in the majority of known systems the companion to the white dwarf is a low-mass M dwarf, since these are relatively easy to identify from optical colours and spectra. White d…
Strong gravitational lensing and the stellar IMF of early-type galaxies
Charlot, Stéphane; Saha, Prasenjit; Bruzual, Gustavo +3 more
Systematic variations of the initial mass function (IMF) in early-type galaxies, and their connection with possible drivers such as velocity dispersion or metallicity, have been much debated in recent years. Strong lensing over galaxy scales combined with photometric and spectroscopic data provides a powerful method to constrain the stellar mass-t…