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The early-type galaxies NGC 1407 and NGC 1400 - I. Spatially resolved radial kinematics and surface photometry
Forbes, Duncan A.; Proctor, Robert N.; Brough, Sarah +2 more
This is the first paper of a series focused on investigating the star formation and evolutionary history of the two early-type galaxies NGC 1407 and NGC 1400. They are the two brightest galaxies of the NGC 1407 (or Eridanus-A) group, one of the 60 groups studied as part of the Group Evolution Multi-wavelength Study.
Here, we present new high …On the detection of the progenitor of the type Ia supernova 2007on
Bassa, Cees; Nelemans, Gijs; Voss, Rasmus +1 more
We present new Chandra X-ray observations and detailed astrometry of the field of the type Ia supernova 2007on, for which the detection of a likely progenitor in archival Chandra data was recently reported.
No source is detected in the new Chandra images, taken six weeks after optical maximum. We calculate a 90-99 per cent probability that an…Galaxy populations in the Antlia cluster - II. Compact elliptical galaxy candidates
Richtler, Tom; Faifer, Favio R.; Smith Castelli, Analía V. +1 more
Continuing our study of galaxy populations in the Antlia cluster, we present a photometric analysis of four galaxies classified as compact elliptical (cE) galaxies in the 1990 Antlia Group catalogue of Ferguson and Sandage. Until now, there have been only six known members of this rare type of galaxy. Using data from various photometric systems (W…
Gamma-ray bursts from the early Universe: predictions for present-day and future instruments
Covino, S.; Campana, S.; Tagliaferri, G. +2 more
Long gamma-ray bursts (GRBs) are important for the study of the Universe near and beyond the epoch of reionization. In this paper, we describe the characteristics of an `ideal' instrument that can be used to search for GRBs at z >= 6-10. We find that the detection of these objects requires soft-band detectors with high sensitivity and a moderat…
The molecular polar disc in NGC 2768
Bureau, Martin; Crocker, Alison F.; Young, Lisa M. +1 more
We present CO(1-0) and CO(2-1) maps of the molecular polar disc in the elliptical galaxy NGC 2768 obtained at the Institute de Radioastronomie Millimétrique (IRAM) Plateau de Bure Interferometer. The maps have a resolution of and for the CO(1-0) and CO(2-1) lines, respectively. The CO maps complete the unique picture of the interstellar medium (IS…
Non-parametric strong lens inversion of Cl 0024+1654: illustrating the monopole degeneracy
de Rijcke, S.; Dejonghe, H.; Liesenborgs, J. +1 more
The cluster lens Cl 0024+1654 is undoubtedly one of the most beautiful examples of strong gravitational lensing, providing five large images of a single source with well-resolved substructure. Using the information contained in the positions and the shapes of the images, combined with the null space information, a non-parametric technique is used …
The nature of the ghost cavity in the NGC 741 group
Babul, Arif; Raychaudhury, Somak; Ponman, Trevor J. +4 more
We discuss the effects of energy injection into the intragroup medium of the group of galaxies associated with NGC 741. The X-ray emission reveals a large bubble, which in the absence of a currently bright central radio source may have been inflated by a previous cycle of nuclear activity. If the bubble is filled with a light, relativistic fluid, …
IGRJ16479-4514: the first eclipsing supergiant fast X-ray transient?
Campana, S.; Israel, G.; Stella, L. +2 more
Supergiant fast X-ray transients (SFXTs) are a new class of high-mass X-ray binaries recently discovered with INTEGRAL. Hours-long outbursts from these sources have been observed on numerous occasions at luminosities of ~1036-1037ergs-1, whereas their low-level activity at ~1032-1034ergs-…
A search for the most massive galaxies - II. Structure, environment and formation
Nichol, R. C.; Fritz, A.; Gebhardt, K. +3 more
We study a sample of 43 early-type galaxies, selected from the Sloan Digital Sky Survey (SDSS) because they appeared to have velocity dispersions of σ >= 350 km s-1. High-resolution photometry in the SDSS i passband using the High-Resolution Channel of the Advanced Camera for Surveys on board the Hubble Space Telescope shows that jus…
Earth X-ray albedo for cosmic X-ray background radiation in the 1-1000 keV band
Sunyaev, R.; Revnivtsev, M.; Sazonov, S. +1 more
We present calculations of the reflection of the cosmic X-ray background (CXB) by the Earth's atmosphere in the 1-1000 keV energy range. The calculations include Compton scattering and X-ray fluorescent emission and are based on a realistic chemical composition of the atmosphere. Such calculations are relevant for CXB studies using the Earth as an…