Publications (29)
Long Term Reverberation Mapping of Iron Coronal Lines in MKN 110
Charles Yin, Andy Lawrence, Martin Ward +2
We present flux measurements of the coronal lines [Fe VII] and [Fe X] spanning three decades, in the highly variable Active Galactic Nucleus (AGN) MKN 110. These coronal lines are…
A Submillimetre Survey of the Hubble Deep Field: Unveiling Dust-Enshrouded Star Formation in the Early Universe
David H. Hughes, James Dunlop, Michael Rowan-Robinson +11
The advent of sensitive sub-mm array cameras now allows a proper census of dust-enshrouded massive star-formation in very distant galaxies, previously hidden activity to which even…
Unveiling Dust-enshrouded Star Formation in the Early Universe: a Sub-mm Survey of the Hubble Deep Field
David Hughes, Steve Serjeant, James Dunlop +12
The advent of sensitive sub-mm array cameras now allows a proper census of dust-enshrouded massive star-formation in very distant galaxies, previously hidden activity to which even…
A spectroscopic study of IRAS F10214+4724
Stephen Serjeant, Steve Rawlings, Mark Lacy +4
The z=2.286 IRAS galaxy F10214+4724 remains one of the most luminous galaxies in the Universe, despite its gravitational lens magnification. We present optical and near-infrared sp…
AGN accretion disks as spatially resolved by polarimetry
Makoto Kishimoto, Robert Antonucci, Omer Blaes +4
A crucial difficulty in understanding the nature of the putative accretion disk in AGNs is that some of its key intrinsic spectral signatures cannot be observed directly. The stron…
The AGN/Normal Galaxy Connection : Summary
Andy Lawrence
The connection between normal and active galaxies is reviewed, by summarizing our progress on answering nine key questions. (1) Do all galaxies contain massive dark objects (MDOs)?…
Behaviour of the MgII 2798AA Line Over the Full Range of AGN Variability
David Homan, Chelsea L. Macleod, Andy Lawrence +2
We investigate the responsiveness of the 2798AA Mg II broad emission line in AGN on timescales of several years. Our study is based on a sample of extremely variable AGN as well as…
The 'Big Dipper': The nature of the extreme variability of the AGN SDSS J2232-0806
Daniel Kynoch, Martin J. Ward, Andy Lawrence +3
SDSS J2232-0806 (the 'Big Dipper') has been identified as a 'slow-blue nuclear hypervariable': a galaxy with no previously known active nucleus, blue colours and large-amplitude br…
Systematic light curve modelling of TDEs: statistical differences between the spectroscopic classes
Matt Nicholl, Daniel Lanning, Paige Ramsden +4
With the sample of observed tidal disruption events (TDEs) now reaching several tens, distinct spectroscopic classes have emerged: TDEs with only hydrogen lines (TDE-H), only heliu…
A luminous quasar at a redshift of z = 7.085
Daniel J. Mortlock, Stephen J. Warren, Bram P. Venemans +14
The intergalactic medium was not completely reionized until approximately a billion years after the Big Bang, as revealed by observations of quasars with redshifts of less than 6.5…
Quasar Viscosity Crisis
Andy Lawrence
Recent observations of extreme variability in Active Galactic Nuclei have pushed standard viscous accretion disc models over an edge. "Extreme reprocessing" where an erratically va…
The SuperCOSMOS Sky Survey. Paper I: Introduction and Description
Nigel Hambly, Harvey MacGillivray, Mike Read +11
In this, the first in a series of three papers concerning the SuperCOSMOS Sky Survey (SSS), we give an introduction and user guide to the survey programme. We briefly describe othe…
Hot-Dust-Poor Quasars in Mid-Infrared and Optically Selected Samples
Heng Hao, Martin Elvis, Francesca Civano +1
We show that the Hot-Dust-Poor (HDP) quasars, originally found in the X-ray selected XMM-COSMOS type 1 AGN sample, are just as common in two samples selected at optical/infrared wa…
Clues to the Structure of AGN through massive variability surveys
Andy Lawrence
Variability studies hold information on otherwise unresolvable regions in Active Galactic Nuclei (AGN). Population studies of large samples likewise have been very productive for o…
The UV peak in Active Galactic Nuclei : a false continuum from blurred reflection ?
Andy Lawrence
I summarise and analyse key problems with observations of the UV bump in Active Galactic Nuclei (AGN), and especially the accretion disc interpretation - the temperature problem, t…
The Distribution of AGN Covering Factors
Andy Lawrence, Isaac Roseboom, Jack Mayo +4
We review our knowledge of the most basic properties of the AGN obscuring region - its location, scale, symmetry, and mean covering factor - and discuss new evidence on the distrib…
First Discoveries of z>6 Quasars with the DECam Legacy Survey and UKIRT Hemisphere Survey
Feige Wang, Xiaohui Fan, Jinyi Yang +19
We present the first discoveries from a survey of quasars using imaging data from the DECam Legacy Survey (DECaLS) in the optical, the UKIRT Deep Infrared Sky Survey (U…
The broad band SEDs of four 'hypervariable' AGN
James S. Collinson, Martin J. Ward, Andy Lawrence +6
We present an optical to X-ray spectral analysis of four 'hypervariable' AGN (HVAs) discovered by comparing Pan-STARRS data to that from SDSS over a 10 year baseline (Lawrence et a…
Enabling Science from the Rubin Alert Stream with Lasair
Roy D. Williams, Gareth P. Francis, Andy Lawrence +4
Lasair is the UK Community Broker for transient alerts from the Legacy Survey of Space and Time (LSST) from the Vera C. Rubin Observatory. We explain the system's capabilities, how…
Discovery of 16 New z ~ 5.5 Quasars : Filling in the Redshift Gap of Quasar Color Selection
Jinyi Yang, Xiaohui Fan, Xue-Bing Wu +13
We present initial results from the first systematic survey of luminous quasars. Quasars at 5.5, the post-reionization epoch, are crucial tools to explore the…
Euro-VO - Coordination of Virtual Observatory activities in Europe
Francoise Genova, Mark G. Allen, Christophe Arviset +4
The European Virtual Observatory Euro-VO has been coordinating European VO activities through a series of projects co-funded by the European Commission over the last 15 years. The…
On the progenitor of the Type IIP SN 2013ej in M74
Morgan Fraser, Justyn R. Maund, Stephen J. Smartt +10
We use natural seeing imaging of SN 2013ej in M74 to identify a progenitor candidate in archival {\it Hubble Space Telescope} + ACS images. We find a source coincident with the SN…
The characteristic blue spectra of accretion disks in quasars as uncovered in the infrared
Makoto Kishimoto, Robert Antonucci, Omer Blaes +4
Quasars are thought to be powered by supermassive black holes accreting surrounding gas. Central to this picture is a putative accretion disk which is believed to be the source of…
A Systematic Search for Changing-Look Quasars in SDSS
Chelsea L. MacLeod, Nicholas P. Ross, Andy Lawrence +10
We present a systematic search for changing-look quasars based on repeat photometry from SDSS and Pan-STARRS1, along with repeat spectra from SDSS and SDSS-III BOSS. Objects with l…
The Second and Third Data Releases from the UKIRT Hemisphere Survey
Adam C. Schneider, Frederick J. Vrba, Justice Bruursema +16
This paper describes the second and third data releases (DR2 and DR3, respectively) from the ongoing United Kingdom Infrared Telescope (UKIRT) Hemisphere Survey (UHS). DR2 is prima…
The Herschel-SPIRE Legacy Survey (HSLS): the scientific goals of a shallow and wide submillimeter imaging survey with SPIRE
Asantha Cooray, Steve Eales, Scott Chapman +247
A large sub-mm survey with Herschel will enable many exciting science opportunities, especially in an era of wide-field optical and radio surveys and high resolution cosmic microwa…
The Effect of Partial Obscuration on the Luminosity Dependence of the Obscured Fraction in Active Galactic Nuclei
Jack H. Mayo, Andy Lawrence
Surveys of Active Galactic Nuclei (AGN) in different observational regimes seem to give different answers for the behaviour of the obscured fraction with luminosity. Based on the c…
Astronomy, Doughnuts, and Carrying Capacity
Andy Lawrence
I examine the applicability of ecological concepts in discussing issues related to space environmentalism. Terms such as "ecosystem"", "carrying capacity"", and "tipping point" are…
Changing-Look Quasar Candidates: First Results from Follow-up Spectroscopy of Highly Optically Variable Quasars
Chelsea L. MacLeod, Paul J. Green, Scott F. Anderson +15
Active galactic nuclei (AGN) that show strong rest-frame optical/UV variability in their blue continuum and broad line emission are classified as "changing-look" AGN, or at higher…