Search Publications
The supermassive black hole of FornaxA
Saglia, R. P.; Nowak, N.; Davies, R. I. +3 more
The radio galaxy FornaxA (NGC 1316) is a prominent merger remnant in the outskirts of the Fornax cluster. Its giant radio lobes suggest the presence of a powerful active galactic nuclei (AGN) and thus a central supermassive black hole (SMBH). FornaxA now seems to be in a transition state between active black hole growth and quiescence, as indicate…
On the geometry of broad emission region in quasars
Falomo, R.; Treves, A.; Decarli, R. +1 more
We study the geometry of the Hβ broad emission region by comparing the MBH values derived from Hβ through the virial relation with those obtained from the host galaxy luminosity in a sample of 36 low-redshift (z ~ 0.3) quasars. This comparison lets us infer the geometrical factor f needed to deproject the line-of-sight velocity componen…
The dark matter environment of the Abell 901/902 supercluster: a weak lensing analysis of the HST STAGES survey
Bell, Eric F.; Wisotzki, Lutz; Wolf, Christian +21 more
We present a high-resolution dark matter reconstruction of the z = 0.165 Abell 901/902 supercluster from a weak lensing analysis of the Hubble Space Telescope STAGES survey. We detect the four main structures of the supercluster at high significance, resolving substructure within and between the clusters. We find that the distribution of dark matt…
The history of mass assembly of faint red galaxies in 28 galaxy clusters since z = 1.3
Andreon, S.
We measure the relative evolution of the number of bright and faint (as faint as 0.05L*) red galaxies in a sample of 28 clusters, out of which 16 are at 0.50 <= z <= 1.27, all observed through a pair of filters bracketing the 4000-Å break rest frame. The abundance of red galaxies, relative to bright ones, is constant over all the studied red…
Detection of the 2175 Å extinction feature and 21-cm absorption in two MgII systems at z ~ 1.3
Petitjean, P.; Saikia, D. J.; Srianand, R. +2 more
We have discovered two dusty intervening MgII absorption systems at z ~ 1.3 in the Sloan Digital Sky Survey (SDSS) data base. The overall spectra of both quasi-stellar objects (QSOs) are red (u - K > 4.5mag) and are well modelled by the composite QSO spectrum reddened by the extinction curve from the Large Magellanic Cloud (LMC2) Supershell red…
Mapping dusty star formation in and around a cluster at z = 0.81 by wide-field imaging with AKARI
Oyabu, Shinki; Shimasaku, Kazuhiro; Koyama, Yusei +8 more
We present environmental dependence of dusty star-forming activity in and around the cluster RXJ1716.4+6708 at z = 0.81 based on wide-field and multiwavelength observations with the Prime Focus Camera on the Subaru Telescope (Suprime-Cam) and the Infrared Camera onboard the AKARI satellite. Our optical data show that the optical colour distributio…
Mass and gas profiles in A1689: joint X-ray and lensing analysis
Lemze, Doron; Rephaeli, Yoel; Barkana, Rennan +1 more
We carry out a comprehensive joint analysis of high-quality HST/ACS and Chandra measurements of A1689, from which we derive mass, temperature, X-ray emission and abundance profiles. The X-ray emission is smooth and symmetric, and the lensing mass is centrally concentrated indicating a relaxed cluster. Assuming hydrostatic equilibrium we deduce a 3…
The hydrogen-deficient knot of the `born-again' planetary nebula Abell 58 (V605 Aql)
Barlow, M. J.; Liu, X. -W.; De Marco, O. +3 more
We have analysed deep optical spectra of the `born-again' planetary nebula Abell 58 and its hydrogen-deficient knot, surrounding V605 Aql, which underwent a nova-like eruption in 1919. Our analysis shows that the extinction towards the central knot is much higher than previously thought, with c(Hβ) = 2.0. The outer nebula is less reddened, with c(…
The connection between globular cluster systems and their host galaxy and environment: a case study of the isolated elliptical NGC 821
Spitler, Lee R.; Forbes, Duncan A.; Brodie, Jean P. +2 more
In an effort to probe the globular cluster (GC) system of an isolated elliptical galaxy, a comprehensive analysis of the NGC 821 GC system was performed. New imaging from the WIYN Mini-Mosaic imager, supplemented with Hubble Space Telescope (HST) WFPC2 images reveals a GC system similar to those found in counterpart ellipticals located in high-den…
A study of X-ray flares - I. Active late-type dwarfs
Pandey, J. C.; Singh, K. P.
We present temporal and spectral characteristics of X-ray flares observed from six late-type G-K active dwarfs (V368Cep, XIBoo, IMVir, V471Tau, CCEri and EPEri) using data from observations with the XMM-Newton observatory. All the stars were found to be flaring frequently and altogether a total of 17 flares were detected above the `quiescent' stat…