Search Publications
A year in the life of GW 170817: the rise and fall of a structured jet from a binary neutron star merger
Troja, E.; Piro, L.; van Eerten, H. +6 more
We present the results of our year-long afterglow monitoring of GW 170817, the first binary neutron star merger detected by Advanced Laser Interferometer Gravitational-Wave Observatory (LIGO) and Advanced Virgo. New observations with the Australian Telescope Compact Array and the Chandra X-ray Telescope were used to constrain its late-time behavio…
The afterglow and kilonova of the short GRB 160821B
Troja, E.; Cenko, S. B.; Sakamoto, T. +24 more
GRB 160821B is a short duration gamma-ray burst (GRB) detected and localized by the Neil Gehrels Swift Observatory in the outskirts of a spiral galaxy at z = 0.1613, at a projected physical offset of 16 kpc from the galaxy's center. We present X-ray, optical/nIR, and radio observations of its counterpart and model them with two distinct components…
A long-lived neutron star merger remnant in GW170817: constraints and clues from X-ray observations
Troja, E.; Piro, L.; van Eerten, H. +12 more
Multimessenger observations of GW170817 have not conclusively established whether the merger remnant is a black hole (BH) or a neutron star (NS). We show that a long-lived magnetized NS with a poloidal field B ≈ 1012 G is fully consistent with the electromagnetic dataset, when spin-down losses are dominated by gravitational wave (GW) em…
The discovery of weak coherent pulsations in the ultraluminous X-ray source NGC 1313 X-2
Fabian, A. C.; Pinto, C.; Bachetti, M. +8 more
We report the detection of weak pulsations from the archetypal ultraluminous X-ray source (ULX) NGC 1313 X-2. Acceleration searches reveal sinusoidal pulsations in segments of two out of six new deep observations of this object, with a period of ∼1.5 s and a pulsed fraction of ∼ 5 per cent. We use Monte Carlo simulations to demonstrate that the in…
High Density Reflection Spectroscopy - II. The density of the inner black hole accretion disc in AGN
Fabian, Andrew C.; Reynolds, Christopher S.; Walton, Dominic J. +7 more
We present a high density disc reflection spectral analysis of a sample of 17 Seyfert 1 galaxies to study the inner disc densities at different black hole mass scales and accretion rates. All the available XMM-Newton observations in the archive are used. OM observations in the optical/UV band are used to estimate their accretion rates. We find tha…
Black hole masses of tidal disruption event host galaxies II
Jonker, Peter G.; Stone, Nicholas C.; Auchettl, Katie +8 more
We present new medium resolution, optical long-slit spectra of a sample of six ultraviolet (UV)/optical and 17 X-ray-selected tidal disruption event candidate host galaxies. We measure emission line ratios from the optical spectra, finding that the large majority of hosts are quiescent galaxies, while those displaying emission lines are generally …
A public relativistic transfer function model for X-ray reverberation mapping of accreting black holes
Ingram, Adam; García, Javier A.; Mastroserio, Guglielmo +3 more
We present the publicly available model RELTRANS that calculates the light-crossing delays and energy shifts experienced by X-ray photons originally emitted close to the black hole when they reflect from the accretion disc and are scattered into our line of sight, accounting for all general relativistic effects. Our model is fast and flexible enou…
GRRMHD simulations of tidal disruption event accretion discs around supermassive black holes: jet formation, spectra, and detectability
Narayan, Ramesh; Curd, Brandon
We report results from general relativistic radiation magnetohydrodynamics (GRRMHD) simulations of a super-Eddington black hole (BH) accretion disc formed as a result of a tidal disruption event (TDE). We consider the fiducial case of a solar mass star on a mildly penetrating orbit disrupted by a supermassive BH of mass 10^6 M_⊙, and consider the …
Dark Energy Surveyed Year 1 results: calibration of cluster mis-centring in the redMaPPer catalogues
Bechtol, K.; Smith, M.; Allam, S. +84 more
The centre determination of a galaxy cluster from an optical cluster finding algorithm can be offset from theoretical prescriptions or N-body definitions of its host halo centre. These offsets impact the recovered cluster statistics, affecting both richness measurements and the weak lensing shear profile around the clusters. This paper models the …
The remarkable X-ray variability of IRAS 13224-3809 - I. The variability process
Young, A. J.; Fabian, A. C.; Reynolds, C. S. +17 more
We present a detailed X-ray timing analysis of the highly variable narrow-line Seyfert 1 (NLS1) galaxy IRAS 13224-3809. The source was recently monitored for 1.5 Ms with XMM-Newton, which, combined with 500 ks archival data, makes this the best-studied NLS1 galaxy in X-rays to date. We apply standard time- and Fourier-domain techniques in order to…