Search Publications
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…
Formation and X-ray emission from hot bubbles in planetary nebulae - II. Hot bubble X-ray emission
Toalá, J. A.; Arthur, S. J.
We present a study of the X-ray emission from numerical simulations of hot bubbles in planetary nebulae (PNe). High-resolution, two-dimensional, radiation-hydrodynamical simulations of the formation and evolution of hot bubbles in PNe, with and without thermal conduction, are used to calculate the X-ray emission and study its time-dependence and r…
A search for X-ray reprocessing echoes in the power spectral density functions of AGN
Papadakis, I. E.; Emmanoulopoulos, D.; Dovčiak, M. +3 more
We present the results of a detailed study of the X-ray power spectral density (PSD) functions of 12 X-ray bright AGN, using almost all the archival XMM-Newton data. The total net exposure of the EPIC-pn light curves is larger than 350 ks in all cases (and exceeds 1 Ms in the case of 1H 0707-497). In a physical scenario in which X-ray reflection o…
A GMRT study of Seyfert galaxies NGC 4235 and NGC 4594: evidence of episodic activity?
Singh, V.; Ishwara-Chandra, C. H.; Kharb, P. +3 more
Low-frequency observations at 325 and 610 MHz have been carried out for two `radio-loud' Seyfert galaxies, NGC 4235 and NGC 4594 (Sombrero galaxy), using the Giant Meterwave Radio Telescope (GMRT). The 610 MHz total intensity and 325-610 MHz spectral index images of NGC 4235 tentatively suggest the presence of a `relic' radio lobe, most likely fro…
The evolution of the Sun's birth cluster and the search for the solar siblings with Gaia
Brown, A. G. A.; Antoja, T.; Portegies Zwart, S. +3 more
We use self-consistent numerical simulations of the evolution and disruption of the Sun's birth cluster in the Milky Way potential to investigate the present-day phase-space distribution of the Sun's siblings. The simulations include the gravitational N-body forces within the cluster and the effects of stellar evolution on the cluster population. …