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Nonthermal Spectral Line Broadening and the Nanoflare Model
Klimchuk, J. A.; Patsourakos, S.
A number of theoretical and observational considerations suggest that coronal loops are bundles of unresolved, impulsively heated strands. This ``nanoflare'' model, as it is sometimes called, predicts high-speed evaporative upflows, which might be revealed as nonthermal broadening of spectral line profiles. We have therefore generated synthetic li…
Parametric strong gravitational lensing analysis of Abell 1689
Pannella, M.; Seitz, S.; Halkola, A.
We have derived the mass distribution of galaxy cluster Abell 1689 within 0.3h-170Mpc of the cluster centre using its strong lensing (SL) effect on 32 background galaxies, which are mapped in altogether 107 multiple images. The multiple images are based on some from the literature with modifications to both include new and ex…
Investigating the nature of narrow-line Seyfert 1 galaxies with high-energy spectral complexity
Gallo, L. C.
With the commissioning of XMM-Newton came the discovery of 2.5-10keV spectral complexity in some narrow-line Seyfert 1 galaxies (NLS1). This high-energy complexity can be manifested as sharp, spectral drops or gradual curvature in the spectrum. Models which are normally considered are ionized reflection and partial covering. In this work, we defin…
Elemental abundances in the atmosphere of clump giants
Soubiran, C.; Korotin, S. A.; Bienaymé, O. +4 more
Aims.The aim of this paper is to provide the fundamental parameters and abundances for a large sample of local clump giants with a high accuracy. This study is a part of a big project, in which the vertical distribution of the stars in the Galactic disc and the chemical and dynamical evolution of the Galaxy are being investigated.
Methods: .Th…
A Search for Binary Systems among the Nearest L Dwarfs
Burgasser, Adam J.; Reid, I. Neill; Cruz, Kelle L. +2 more
We have used the Near-Infrared Camera and Multi-Object Spectrometer NIC1 camera on the Hubble Space Telescope to obtain high angular resolution images of 52 ultracool dwarfs in the immediate solar neighborhood. Nine systems are resolved as binary, with component separations from 1.5 to 15 AU. Based on current theoretical models and empirical bolom…
Gamma-Ray Imaging of the 2003 October/November Solar Flares
Krucker, S.; Lin, R. P.; Smith, D. M. +3 more
We present RHESSI imaging of three flares (2003 October 28 and 29 and November 2) in the 2.223 MeV neutron-capture gamma-ray line with angular resolution as high as 35". Comparisons of imaged and spatially integrated fluences show that in all cases most, if not all, of the emission was confined to compact sources with size scales of tens of arcsec…
A Chandra Survey of Early-Type Galaxies. I. Metal Enrichment in the Interstellar Medium
Humphrey, Philip J.; Buote, David A.
We present a Chandra study of the emission-weighted metal abundances in 28 early-type galaxies, spanning ~3 orders of magnitude in X-ray luminosity (LX). We report constraints for Fe, O, Ne, Mg, Si, S, and Ni. We find no evidence of the very subsolar Fe abundance (ZFe) historically reported, confirming a trend in recent obser…
The Stellar Masses and Star Formation Histories of Galaxies at z ~ 6: Constraints from Spitzer Observations in the Great Observatories Origins Deep Survey
Dickinson, Mark; Ferguson, Henry C.; Giavalisco, Mauro +3 more
Using the deep Spitzer Infrared Array Camera (IRAC) observations of the Great Observatories Origins Deep Survey (GOODS), we study the stellar masses and star formation histories of galaxies at z~6 based on the i775-band dropout sample selected from the GOODS fields. In total, we derive stellar masses for 53 i775-band dropouts…
The XMM-Newton/Chandra monitoring campaign of the Galactic center region. Description of the program and preliminary results
Wijnands, R.; Homan, J.; van der Klis, M. +10 more
We present the first results of our X-ray monitoring campaign on a 1.7 square degree region centered on Sgr A* using the satellites XMM-Newton and Chandra. The purpose of this campaign is to monitor the behavior (below 10 keV) of X-ray sources (both persistent and transient) which are too faint to be detected by monitoring instruments aboard other…
The Chandra view of the 3C/FR I sample of low luminosity radio-galaxies
Capetti, A.; Grandi, P.; Balmaverde, B.
We present results from Chandra observations of the 3C/FR I sample of low luminosity radio-galaxies. We detected a power-law nuclear component in 12 objects out of the 18 with available data. In 4 galaxies we detected nuclear X-ray absorption at a level of NH ∼ (0.2{-}6) × 1022 cm-2. X-ray absorbed sources are asso…