Search Publications
Investigating the sensitivity of observed spectral energy distributions to clumpy torus properties in Seyfert galaxies
Packham, C.; González-Martín, O.; Levenson, N. A. +5 more
We present nuclear spectral energy distributions (SEDs) from 1 to 18 µm of a small sample of nearby, nearly face-on and undisturbed Seyfert galaxies without prominent nuclear dust lanes. These nuclear SEDs probe the central ∼35 pc of the galaxies, on average, and include photometric and spectroscopic infrared (IR) data. We use these SEDs, th…
X-ray time delays in the narrow line Seyfert 1 galaxy PG 1244+026
Done, C.; Vaughan, S.; Alston, W. N.
We analyse the X-ray time-lags in the narrow line Seyfert 1 (NLS1) galaxy PG 1244+026 (MBH ∼ 107 M⊙, L/LEdd ∼ 1). The time delay between the soft (0.3-0.7 keV) and harder (1.2-4.0 keV) variations shows the well-established switch from hard lags at low frequencies to soft lags at high frequencies. The low…
Progenitor constraints on the Type-Ia supernova SN2011fe from pre-explosion Hubble Space Telescope HeII narrow-band observations.
Maoz, D.; Graur, O.; Shara, M. M.
We present Hubble Space Telescope (HST) imaging observations of the site of the Type-Ia supernova SN2011fe in the nearby galaxy M101, obtained about 1 yr prior to the event, in a narrow band centred on the He II λ4686 Å emission line. In a `single-degenerate' progenitor scenario, the hard photon flux from an accreting white dwarf (WD), burning hyd…
The central parsecs of active galactic nuclei: challenges to the torus
Prieto, M. A.; Fernández-Ontiveros, J. A.; Mezcua, M. +1 more
Type 2 active galactic nuclei (AGN) are by definition nuclei in which the broad-line region and continuum light are hidden at optical/UV wavelengths by dust. Via accurate registration of infrared (IR) Very Large Telescope adaptive optics images with optical Hubble Space Telescope images we unambiguously identify the precise location of the nucleus…
Evidence for dust destruction from the early-time colour change of GRB 120119A
Filippenko, Alexei V.; Cenko, S. Bradley; Li, Weidong +16 more
We present broad-band observations and analysis of Swift gamma-ray burst (GRB) 120119A. Our early-time afterglow detections began under 15 s after the burst in the host frame (redshift z = 1.73), and they yield constraints on the burst energetics and local environment. Late-time afterglow observations of the burst show evidence for a moderate colu…
A measurement of the millimetre emission and the Sunyaev-Zel'dovich effect associated with low-frequency radio sources
Ivison, R. J.; Hilton, Matt; Sifón, Cristóbal +38 more
We present a statistical analysis of the millimetre-wavelength properties of 1.4 GHz-selected sources and a detection of the Sunyaev-Zel'dovich (SZ) effect associated with the haloes that host them. We stack data at 148, 218 and 277 GHz from the Atacama Cosmology Telescope at the positions of a large sample of radio AGN selected at 1.4 GHz. The th…
Lensed Type Ia supernovae as probes of cluster mass models
Kneib, J. -P.; Huang, X.; Lidman, C. +20 more
Using three magnified Type Ia supernovae (SNe Ia) detected behind CLASH (Cluster Lensing and Supernovae with Hubble) clusters, we perform a first pilot study to see whether standardizable candles can be used to calibrate cluster mass maps created from strong lensing observations. Such calibrations will be crucial when next-generation Hubble Space …
The planetary nebula Abell 48 and its [WN] nucleus
Frew, David J.; Stupar, M.; Parker, Q. A. +6 more
We have conducted a detailed multi-wavelength study of the peculiar nebula Abell 48 and its central star. We classify the nucleus as a helium-rich, hydrogen-deficient star of type [WN4-5]. The evidence for either a massive WN or a low-mass [WN] interpretation is critically examined, and we firmly conclude that Abell 48 is a planetary nebula (PN) a…
The violent youth of bright and massive cluster galaxies and their maturation over 7 billion years
Kocevski, D. D.; Lemaux, B. C.; Ascaso, B. +4 more
In this study, we investigate the formation and evolution mechanisms of the brightest cluster galaxies (BCGs) over cosmic time. At high redshift (z ∼ 0.9), we selected BCGs and most massive cluster galaxies (MMCGs) from the Cl1604 supercluster and compared them to low-redshift (z ∼ 0.1) counterparts drawn from the MCXC meta-catalogue, supplemented…
Improved Hubble Space Telescope proper motions for Tycho-G and other stars in the remnant of Tycho's Supernova 1572
Filippenko, A. V.; Ruiz-Lapuente, P.; Bedin, L. R. +3 more
With archival and new Hubble Space Telescope observations, we have refined the space-velocity measurements of the stars in the central region of the remnant of Tycho's supernova (SN) 1572, one of the historical Galactic Type Ia supernova remnants (SNRs). We derived a proper motion for Tycho-G of (µαcos δ; µδ)…