Search Publications
RE J1034+396: the origin of the soft X-ray excess and quasi-periodic oscillation
Done, Chris; Ward, Martin; Gierliński, Marek +2 more
The X-ray quasi-periodic oscillation (QPO) seen in RE J1034+396 is so far unique amongst active galactic nuclei (AGN). Here, we look at another unique feature of RE J1034+396, namely its huge soft X-ray excess, to see if this is related in any way to the detection of the QPO. We show that all potential models considered for the soft energy excess …
The population of early-type galaxies at 1 < z < 2 - new clues on their formation and evolution
Andreon, S.; Longhetti, M.; Saracco, P.
We present the morphological analysis based on Hubble Space Telescope HST-NICMOS (Near-Infrared Camera and Multi-Object Spectrometer) observations in the F160W filter (λ ~= 1.6µm) of a sample of 32 early-type galaxies (ETGs) at 1 < z < 2 with spectroscopic confirmation of their redshift and spectral type. The 32 ETGs at <z> ~ 1.5…
AGN-starburst connection in NGC7582: Gemini near-infrared spectrograph integral field unit observations
Storchi-Bergmann, Thaisa; Riffel, Rogemar A.; Winge, Cláudia +1 more
We analyse two-dimensional near-infrared K-band spectra from the inner 660 × 315pc2 of the Seyfert galaxy NGC7582 obtained with the Gemini near-infrared spectrograph integral field unit at a spatial resolution of ~50pc and spectral resolving power R ~ 5900. The nucleus harbours an unresolved source well reproduced by a blackbody of temp…
The C+N+O abundances and the splitting of the subgiant branch in the globular cluster NGC 1851
D'Antona, F.; Ventura, P.; Caloi, V. +3 more
Among the newly discovered features of multiple stellar populations in globular clusters (GCs), the cluster NGC 1851 harbours a double subgiant branch (SGB), that can be explained in terms of two stellar generations, only slightly differing in age, the younger one having an increased total C+N+O abundance. Thanks to this difference in the chemistr…
Quantifying the fast outflow in the luminous Seyfert galaxy PG1211+143
Reeves, J. N.; Pounds, K. A.
We report two new XMM-Newton observations of PG1211+143 in 2007 December, again finding evidence for the fast outflow of highly ionized gas first detected in 2001. Stacking the new spectra with those from two earlier XMM-Newton observations reveals strong and broad emission lines of FeXXV and OVIII, indicating the fast outflow to be persistent and…
The SAURON Project - XIV. No escape from Vesc: a global and local parameter in early-type galaxy evolution
Krajnović, Davor; Emsellem, Eric; van de Ven, Glenn +13 more
We present the results of an investigation of the local escape velocity (Vesc) - line strength index relationship for 48 early-type galaxies from the SAURON sample, the first such study based on a large sample of galaxies with both detailed integral field observations and extensive dynamical modelling. Values of Vesc are comp…
The XMM -Newton view of AGN with intermediate-mass black holes
Ponti, G.; Iwasawa, K.; Fabian, A. C. +3 more
We have observed with XMM-Newton four radiatively efficient active type 1 galaxies with black hole masses <106Msolar, selected optically from the Sloan Digital Sky Survey and previously detected in the ROSAT All Sky Survey. Their X-ray spectra closely resemble those of more luminous Seyferts and quasars, powered by accreti…
On the HI content, dust-to-gas ratio and nature of MgII absorbers
Ménard, Brice; Chelouche, Doron
We estimate the mean dust-to-gas ratio of MgII absorbers as a function of rest equivalent width W0 and redshift over the range 0.5 < z < 1.4. Using the expanded Sloan Digital Sky Survey/Hubble Space Telescope sample of low-redshift Lyman-α absorbers, we first show the existence of a 8σ correlation between the mean hydrogen column …
A relativistically smeared spectrum in the neutron star X-ray binary 4U 1705-44: looking at the inner accretion disc with X-ray spectroscopy
Santangelo, A.; Robba, N. R.; Papitto, A. +9 more
Iron emission lines at 6.4-6.97 keV, identified with fluorescent Kα transitions, are among the strongest discrete features in the X-ray band. These are therefore one of the most powerful probes to infer the properties of the plasma in the innermost part of the accretion disc around a compact object. In this paper, we present a recent XMM-Newton ob…
Determination of masses of the central black holes in NGC 524 and 2549 using laser guide star adaptive optics
Krajnović, Davor; Cappellari, Michele; Davies, Roger L. +1 more
We present observations of early-type galaxies NGC 524 and 2549 with laser guide star adaptive optics (LGS AO) obtained at GEMINI North telescope using the Near-infrared Integral Field Spectrograph (NIFS) integral field unit (IFU) in the K band. The purpose of these observations is to determine high spatial resolution stellar kinematics within the…