Search Publications
Stellar population properties for a sample of hard X-ray AGNs
Minniti, D.; Masetti, N.; Parisi, P. +5 more
Aims: The aim of this paper is to study the stellar population of galaxies hosting an active galactic nucleus (AGN). We studied a subsample of hard X-ray emitting AGNs from the INTEGRAL and Swift catalogs, which were previously identified and characterized through optical spectroscopy. Our analysis provides complementary information, namely a…
Spatial variation of energy conversion at the Earth's magnetopause: Statistics from Cluster observations
Dandouras, I.; Lucek, E.; Palmroth, M. +2 more
We investigate magnetopause energy conversion in a large statistical data set utilizing Cluster spacecraft observations. We have compiled a database of about 4000 magnetopause crossings from Cluster spacecraft 1 measurements during years 2001-2008. We have estimated the local energy conversion across the magnetopause for these crossings using Gene…
Validation of methodology to derive elemental abundances from X-ray observations on Chandrayaan-1
Babu, B. R. S.; Narendranath, S.; Sreekumar, P. +2 more
The Chandrayaan-1 X-ray Spectrometer (C1XS) observed characteristic X-ray fluorescence (XRF) lines of major rock forming elements from the lunar surface during different solar flare conditions. As the Sun was undergoing an unusually low activity cycle during the observing period of C1XS (28th Nov. 2008-29th Aug. 2009), most observations were made …
Under Pressure: Star Clusters and the Neutral Hydrogen Medium of Tidal Tails
Bastian, N.; Konstantopoulos, I. S.; English, J. +9 more
Using archival data from ATCA, WHISP, and the Very Large Array, we have analyzed the H I emission of 22 tidal tail regions of the Mullan et al. sample of pairwise interacting galaxies. We have measured the column densities, line-of-sight velocity dispersions, and kinetic energy densities on ~kpc scales. We also constructed a tracer of the line-of-…
X-ray emission around the z = 4.1 radio galaxy TN J1338-1942 and the potential role of far-infrared photons in AGN feedback
Smail, Ian; Blundell, Katherine M.
We report the discovery in an 80-ks observation of spatially extended X-ray emission around the high-redshift radio galaxy TN J1388-1942 (z = 4.11) with the Chandra X-ray Observatory. The X-ray emission extends over a ∼30-kpc diameter region and although it is less extended than the GHz-radio lobes, it is roughly aligned with them. We suggest that…
SoFAST: Automated Flare Detection with the PROBA2/SWAP EUV Imager
Berghmans, D.; Poedts, S.; De Groof, A. +2 more
The Sun Watcher with Active Pixels and Image Processing (SWAP) EUV imager onboard PROBA2 provides a non-stop stream of coronal extreme-ultraviolet (EUV) images at a cadence of typically 130 seconds. These images show the solar drivers of space-weather, such as flares and erupting filaments. We have developed a software tool that automatically proc…
Three active galactic nuclei close to the effective Eddington limit for dusty gas
Fabian, A. C.; Mushotzky, R. F.; Trippe, M. L. +3 more
The effective Eddington limit for dusty gas surrounding active galactic nucleus (AGN) is lower than the canonical Eddington limit for hydrogen gas. Previous results from the Swift/Burst Alert Telescope 9-month catalogue suggested that in the overwhelming majority of local AGN, the dusty absorbing gas is below this effective Eddington limit, implyi…
Comparative analysis of airglow emissions in terrestrial planets, observed with VIRTIS-M instruments on board Rosetta and Venus Express
Piccioni, G.; Capaccioni, F.; Gérard, J. -C. +3 more
Airglow emissions are optimal processes to investigate the chemistry and dynamics in planetary atmospheres. In this study, we focus on the O2 and OH airglow emissions in Venus, Earth, and Mars atmospheres, which are controlled by chemical reactions common to the three planets. By studying these phenomena on Venus, Earth, and Mars using …
The three-dimensional geometry and merger history of the massive galaxy cluster MACS J0358.8-2955
Richard, Johan; Ebeling, Harald; Hsu, Li-Yen
We present results of a combined X-ray/optical analysis of the dynamics of the massive cluster MACS J0358.8-2955 (z = 0.428) based on observations with the Chandra X-ray Observatory, the Hubble Space Telescope and the Keck-I telescope on Mauna Kea. MACS J0358.8-2955 is found to be one of the most X-ray luminous clusters known at z > 0.3, featur…
Estimates of fluvial erosion on Titan from sinuosity of lake shorelines
Perron, J. Taylor; Tewelde, Yodit; Ford, Peter +2 more
Titan has few impact craters, suggesting that its surface is geologically young. Titan's surface also has abundant landforms interpreted to be fluvial networks. Here we evaluate whether fluvial erosion has caused significant resurfacing by estimating the cumulative erosion around the margins of polar lakes. A scarcity of detailed topographic data …