Search Publications
A long XMM-Newton observation of an extreme narrow-line Seyfert 1: PG 1244+026
Done, Chris; Ward, Martin; Jin, Chichuan +1 more
We explore the origin of the strong soft X-ray excess in narrow-line Seyfert 1 galaxies using spectral-timing information from a 120 ks XMM-Newton observation of PG 1244+026. Spectral fitting alone cannot distinguish between a true additional soft X-ray continuum component and strongly relativistically smeared reflection, but both models also requ…
Spatially resolved images of dust belt(s) around the planet-hosting subgiant κ CrB
Crepp, Justin R.; Wyatt, Mark C.; Johnson, John A. +4 more
We present Herschel spatially resolved images of the debris disc orbiting the subgiant κ Coronae Borealis (κ CrB). Not only are these the first resolved images of a debris disc orbiting a subgiant, but κ CrB is a rare example of an intermediate mass star where a detailed study of the structure of the planetary system can be made, including both pl…
The X-ray spectral properties of very-faint persistent neutron star X-ray binaries
Degenaar, N.; Wijnands, R.; Armas Padilla, M.
AX J1754.2-2754, 1RXS J171824.2-402934 and 1RXH J173523.7-354013 are three persistent neutron star low-mass X-ray binaries that display a 2-10 keV accretion luminosity LX of only (1-10) × 1034 erg s-1 (i.e. only ≃0.005-0.05 per cent of the Eddington limit). The phenomenology of accreting neutron stars which accrete…
Supernova 2012ec: identification of the progenitor and early monitoring with PESSTO.
Sollerman, J.; Gal-Yam, A.; Inserra, C. +13 more
We present the identification of the progenitor of the Type IIP SN 2012ec in archival pre-explosion Hubble Space Telescope Wide Field Planetary Camera 2 (WFPC2) and Advanced Camera for Surveys Wide Field Channel F814W images. The properties of the progenitor are further constrained by non-detections in pre-explosion WFPC2 F450W and F606W images. W…
A new dynamo pattern revealed by the tilt angle of bipolar sunspot groups
Tlatov, A.; Illarionov, E.; Sokoloff, D. +1 more
We obtain the latitude-time distribution of the averaged tilt angle of solar bipoles. For large bipoles, which are mainly bipolar sunspot groups, the spatially averaged tilt angle is positive in the Northern solar hemisphere and negative in the Southern, with modest variations during the course of the solar cycle. We consider the averaged tilt ang…
Helioseismic calibration of the equation of state and chemical composition in the solar convective envelope
Vorontsov, S. V.; Baturin, V. A.; Ayukov, S. V. +1 more
Accurate and precise measurements of solar p-mode frequencies allow sensitive diagnostics of the adiabatic exponent Γ1 = (∂ln p/∂ln ρ)S as a function of depth in the adiabatically stratified part of the solar convective envelope. The profile of the adiabatic exponent contains information about the chemical composition of the …
Rehabilitating C IV-based black hole mass estimates in quasars
Shang, Zhaohui; Brotherton, M. S.; Runnoe, Jessie C. +1 more
Currently, the ability to produce black hole mass estimates using the C IV λ1549 line that are consistent with Hβ mass estimates is uncertain, due in large part to disagreement between velocity line width measurements for the two lines. This discrepancy between Hβ and C IV arises from the fact that both line profiles are treated the same way in si…
Weak lensing analysis of RXC J2248.7-4431
Zenteno, A.; Gruen, D.; Young, J. +8 more
We present a weak lensing analysis of the cluster of galaxies RXC J2248.7-4431, a massive system at z = 0.3475 with prominent strong lensing features covered by the Cluster Lensing And Supernova survey with Hubble (CLASH). Based on UBVRIZ imaging from the Wide-Field Imager camera at the MPG/ESO 2.2-m telescope, we measure photometric redshifts and…
Newborn spheroids at high redshift: when and how did the dominant, old stars in today's massive galaxies form?
Ryan, R. E.; O'Connell, R. W.; Dekel, A. +10 more
We study ∼330 massive (M* > 109.5 M⊙), newborn spheroidal galaxies (SGs) around the epoch of peak star formation (1 < z < 3) to explore the high-redshift origin of SGs and gain insight into when and how the old stellar populations that dominate today's Universe formed. The sample is drawn from the Hubble S…
The flux-dependent X-ray time lags in NGC 4051
Vaughan, S.; Uttley, P.; Alston, W. N.
We present an analysis of the X-ray time lags for the highly variable Seyfert 1 galaxy NGC 4051, based on a series of XMM-Newton observations taken in 2009. We investigate the Fourier frequency dependent time lags in the light curves between the 0.3-1.0 keV and 2.0-5.0 keV energy bands as a function of source flux, including simultaneous modelling…