Search Publications
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…
Unveiling dark haloes in lensing galaxies
Saha, Prasenjit; Ferreras, Ignacio; Burles, Scott
We present a spatially resolved comparison of the stellar mass and total mass surface distributions of nine early-type galaxies. The galaxies are a subset of the Sloan Lens ACS Survey. The total mass distributions are obtained by exploring pixelated mass models that reproduce the lensed images. The stellar mass distributions are derived from popul…
Photometric properties of the Local Volume dwarf galaxies
Dolphin, A. E.; Tully, R. Brent; Sharina, M. E. +9 more
We present surface photometry and metallicity measurements for 104 nearby dwarf galaxies imaged with the Advanced Camera for Surveys and Wide Field and Planetary Camera 2 aboard the Hubble Space Telescope. In addition, we carried out photometry for 26 galaxies of the sample and for Sextans B on images of the Sloan Digital Sky Survey. Our sample co…
Unresolved emission and ionized gas in the bulge of M31
Bogdán, Á.; Gilfanov, M.
We study the origin of unresolved X-ray emission from the bulge of M31 based on archival Chandra and XMM-Newton observations. We demonstrate that three different components are present. (i) Broad-band emission from a large number of faint sources - mainly accreting white dwarfs and active binaries, associated with the old stellar population, simil…