Search Publications
SKA weak lensing - I. Cosmological forecasts and the power of radio-optical cross-correlations
Zuntz, Joe; Camera, Stefano; Brown, Michael L. +1 more
We construct forecasts for cosmological parameter constraints from weak gravitational lensing surveys involving the Square Kilometre Array (SKA). Considering matter content, dark energy and modified gravity parameters, we show that the first phase of the SKA (SKA1) can be competitive with other Stage III experiments such as the Dark Energy Survey …
First identification of direct collapse black hole candidates in the early Universe in CANDELS/GOODS-S
Grazian, Andrea; Ferrara, Andrea; Fiore, Fabrizio +3 more
The first black hole seeds, formed when the Universe was younger than ∼500 Myr, are recognized to play an important role for the growth of early (z ∼ 7) supermassive black holes. While progresses have been made in understanding their formation and growth, their observational signatures remain largely unexplored. As a result, no detection of such s…
A comprehensive analysis of the hard X-ray spectra of bright Seyfert galaxies
Papadakis, I. E.; Paltani, S.; Walter, R. +7 more
Hard X-ray spectra of 28 bright Seyfert galaxies observed with INTEGRAL were analysed together with the X-ray spectra from XMM-Newton, Suzaku and RXTE. These broad-band data were fitted with a model assuming a thermal Comptonization as a primary continuum component. We tested several model options through a fitting of the Comptonized continuum acc…
Non-linearity and environmental dependence of the star-forming galaxies main sequence
Finoguenov, A.; Berta, S.; Magnelli, B. +30 more
Using data from four deep fields (COSMOS, AEGIS, ECDFS, and CDFN), we study the correlation between the position of galaxies in the star formation rate (SFR) versus stellar mass plane and local environment at z < 1.1. To accurately estimate the galaxy SFR, we use the deepest available Spitzer/MIPS 24 and Herschel/PACS data sets. We distinguish …
Unexpected and significant findings in comet 67P/Churyumov-Gerasimenko: an interdisciplinary view
Fulchignoni, M.; Grün, E.; Altobelli, N. +5 more
ESA's Rosetta Mission has followed Comet 67P/Churyumov-Gerasimenko from 3.6 au inbound to 3.6 au outbound. Many results are largely unexpected, as compared to previous models based on in situ and ground-based observations of Jupiter-family comets. The main topics discussed in this review are (1) the importance of the large concavities characterizi…
Detection of the first infra-red quasi-periodic oscillation in a black hole X-ray binary
van der Klis, M.; Casella, P.; Maccarone, T. +5 more
We present the analysis of fast variability of Very Large Telescope/ISAAC (Infrared Spectrometer And Array Camera) (infra-red), XMM-Newton/OM (optical) and EPIC-pn (X-ray), and RXTE/PCA (X-ray) observations of the black hole X-ray binary GX 339-4 in a rising hard state of its outburst in 2010. We report the first detection of a quasi-periodic osci…
Testing quasar unification: radiative transfer in clumpy winds
Knigge, C.; Long, K. S.; Sim, S. A. +3 more
Various unification schemes interpret the complex phenomenology of quasars and luminous active galactic nuclei (AGN) in terms of a simple picture involving a central black hole, an accretion disc and an associated outflow. Here, we continue our tests of this paradigm by comparing quasar spectra to synthetic spectra of biconical disc wind models, p…
SPIDERS: the spectroscopic follow-up of X-ray selected clusters of galaxies in SDSS-IV
Zhang, Y. -Y.; Finoguenov, A.; Kneib, J. -P. +17 more
SPIDERS (The SPectroscopic IDentification of eROSITA Sources) is a programme dedicated to the homogeneous and complete spectroscopic follow-up of X-ray active galactic nuclei and galaxy clusters over a large area (∼7500 deg2) of the extragalactic sky. SPIDERS is part of the Sloan Digital Sky Survey (SDSS)-IV project, together with the E…
Short-term X-ray spectral variability of the quasar PDS 456 observed in a low-flux state
Tombesi, F.; Reeves, J. N.; Braito, V. +4 more
We present a detailed analysis of a recent, 2013 Suzaku campaign on the nearby (z = 0.184) luminous (Lbol ∼ 1047 erg s-1) quasar PDS 456. This consisted of three observations, covering a total duration of ∼1 Ms and a net exposure of 455 ks. During these observations, the X-ray flux was unusually low, suppressed by …
SHARP - II. Mass structure in strong lenses is not necessarily dark matter substructure: a flux ratio anomaly from an edge-on disc in B1555+375
Vegetti, S.; McKean, J. P.; Auger, M. W. +5 more
Gravitational lens flux-ratio anomalies provide a powerful technique for measuring dark matter substructure in distant galaxies. However, before using these flux-ratio anomalies to test galaxy formation models, it is imperative to ascertain that the given anomalies are indeed due to the presence of dark matter substructure and not due to some othe…