Search Publications
Tomographic reflection modelling of quasi-periodic oscillations in the black hole binary H 1743-322
Ingram, Adam; Middleton, Matthew; Altamirano, Diego +2 more
Accreting stellar mass black holes (BHs) routinely exhibit Type-C quasi-periodic oscillations (QPOs). These are often interpreted as Lense-Thirring precession of the inner accretion flow, a relativistic effect whereby the spin of the BH distorts the surrounding space-time, inducing nodal precession. The best evidence for the precession model is th…
The Progenitor and Early Evolution of the Type IIb SN 2016gkg
Lundqvist, P.; Gal-Yam, A.; Smith, M. +24 more
We report initial observations and analysis on the Type IIb SN 2016gkg in the nearby galaxy NGC 613. SN 2016gkg exhibited a clear double-peaked light curve during its early evolution, as evidenced by our intensive photometric follow-up campaign. SN 2016gkg shows strong similarities with other Type IIb SNe, in particular, with respect to the He I e…
Two-dimensional Radiative Magnetohydrodynamic Simulations of Partial Ionization in the Chromosphere. II. Dynamics and Energetics of the Low Solar Atmosphere
Martínez-Sykora, Juan; De Pontieu, Bart; Nóbrega-Siverio, Daniel +3 more
We investigate the effects of interactions between ions and neutrals on the chromosphere and overlying corona using 2.5D radiative MHD simulations with the Bifrost code. We have extended the code capabilities implementing ion-neutral interaction effects using the generalized Ohm’s law, I.e., we include the Hall term and the ambipolar diffusion (Pe…
A study of the sensitivity of shape measurements to the input parameters of weak-lensing image simulations
Hoekstra, Henk; Viola, Massimo; Herbonnet, Ricardo
Improvements in the accuracy of shape measurements are essential to exploit the statistical power of planned imaging surveys that aim to constrain cosmological parameters using weak lensing by large-scale structure. Although a range of tests can be performed using the measurements, the performance of the algorithm can only be quantified using simu…
AGN Populations in Large-volume X-Ray Surveys: Photometric Redshifts and Population Types Found in the Stripe 82X Survey
Kirkpatrick, Allison; Nandra, Kirpal; Marchesi, Stefano +16 more
Multiwavelength surveys covering large sky volumes are necessary to obtain an accurate census of rare objects such as high-luminosity and/or high-redshift active galactic nuclei (AGNs). Stripe 82X is a 31.3 X-ray survey with Chandra and XMM-Newton observations overlapping the legacy Sloan Digital Sky Survey Stripe 82 field, which has a rich invest…
The GOODS-N Jansky VLA 10 GHz Pilot Survey: Sizes of Star-forming µJY Radio Sources
Dickinson, Mark; Weiner, Benjamin J.; Inami, Hanae +5 more
Our sensitive ({σ }{{n}}≈ 572 {nJy} {{beam}}-1), high-resolution (FWHM {θ }1/2=0\buildrel{\prime\prime}\over{.} 22≈ 2 {kpc} {at} z≳ 1), 10 GHz image covering a single Karl G. Jansky Very Large Array (VLA) primary beam (FWHM {{{\Theta }}}1/2≈ 4\buildrel{ \prime}\over{.} 25) in the GOODS-N field contains 3…
Improved measurements of turbulence in the hot gaseous atmospheres of nearby giant elliptical galaxies
Kaastra, J. S.; de Plaa, J.; Fabian, A. C. +7 more
We present significantly improved measurements of turbulent velocities in the hot gaseous haloes of nearby giant elliptical galaxies. Using deep XMM-Newton Reflection Grating Spectrometer (RGS) observations and a combination of resonance scattering and direct line broadening methods, we obtain well bounded constraints for 13 galaxies. Assuming tha…
Change of outgassing pattern of 67P/Churyumov-Gerasimenko during the March 2016 equinox as seen by ROSINA
Mall, Urs; De Keyser, Johan; Berthelier, Jean-Jacques +18 more
As the spin axis of comet 67P/Churyumov-Gerasimenko (67P) is not normal to the orbital plane, 67P has strong seasonal changes in the illumination conditions on the nucleus' surface, with a short and intense summer in the Southern hemisphere. We have been monitoring these seasonal variations in the gas coma with the Rosetta Orbiter Spectrometer for…
The Carnegie-Chicago Hubble Program. II. The Distance to IC 1613: The Tip of the Red Giant Branch and RR Lyrae Period-luminosity Relations
Madore, Barry F.; Freedman, Wendy L.; Beaton, Rachael L. +8 more
IC 1613 is an isolated dwarf galaxy within the Local Group. Low foreground and internal extinction, low metallicity, and low crowding make it an invaluable testbed for the calibration of the local distance ladder. We present new, high-fidelity distance estimates to IC 1613 via its Tip of the Red Giant Branch (TRGB) and its RR Lyrae (RRL) variables…
D2O and HDS in the coma of 67P/Churyumov-Gerasimenko
Altwegg, K.; Balsiger, H.; Berthelier, J. J. +12 more
The European Rosetta mission has been following comet 67P/Churyumov-Gerasimenko for 2 years, studying the nucleus and coma in great detail. For most of these 2 years the Rosetta Orbiter Sensor for Ion and Neutral Analysis (ROSINA) has analysed the volatile part of the coma. With its high mass resolution and sensitivity it was able to not only dete…