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AWM 4 - an isothermal cluster observed with XMM-Newton
O'Sullivan, E.; Vrtilek, J. M.; David, L. P. +2 more
We present an analysis of an XMM-Newton observation of the poor cluster AWM 4. The cluster is relaxed and its X-ray halo is regular with no apparent substructure. Azimuthally averaged radial spectral profiles suggest that the cluster is isothermal to a radius of at least 160 kpc, with no evidence of a central cooling region. Spectral mapping shows…
Rotation periods for stars of the TW Hydrae association: the evidence for two spatially and rotationally distinct pre-main-sequence populations
Lawson, Warrick A.; Crause, Lisa A.
We have conducted a photometric study of late-type members of the TW Hydrae association (TWA) and measured the rotation periods for 16 stars in 12 systems. For TWA stars listed by Webb et al. and Sterzik et al. (TWA 1-13 led by TW Hya = TWA 1) we find a median period of 4.7 d. However, for stars that we measured in the TWA 14-19 group identified b…
A Chandra X-ray survey of nearby dwarf starburst galaxies - I. Data reduction and results
Ott, Jürgen; Walter, Fabian; Brinks, Elias
We present an analysis of Chandra X-ray observations of a sample of eight dwarf starburst galaxies (IZw18, VIIZw403, NGC1569, NGC3077, NGC4214, NGC4449, NGC5253 and He2-10). Extended, diffuse X-ray emission is detected in all but two of the objects. Unresolved sources were found within all dwarf galaxies (total: 55 sources). These point sources ar…
The evolution of actively star-forming galaxies in the mid-infrared
Panuzzo, P.; Bressan, A.; Chavez, M. +3 more
In this paper we analyze the evolution of actively star-forming galaxies in the mid-infrared (MIR). This spectral region, characterized by continuum emission by hot dust and by the presence of strong emission features generally ascribed to polycyclic aromatic hydrocarbon (PAH) molecules, is the most strongly affected by the heating processes assoc…
The continuum and narrow-line region of the narrow-line Seyfert 1 galaxy Mrk 766
Contini, M.; Rodríguez-Ardila, A.; Viegas, S. M.
We present the first spectroscopic observations in the interval 0.8-4.0 µm, complemented with existing Hubble Space Telescope ultraviolet (UV) and optical spectroscopy, of the narrow-line Seyfert 1 galaxy Mrk 766. The near-infrared spectrum is characterized by numerous permitted lines of HI, HeI, HeII and FeII, and forbidden lines of [SII], …
Batch discovery of nine z~ 1 clusters using X-ray and K or R, z' images
Altieri, B.; Valtchanov, I.; Pierre, M. +5 more
We present the results of an initial search for clusters of galaxies at z~ 1 and above, using data from 2.9 square degrees of XMM-Newton images. By selecting weak potentially extended X-ray sources with faint or no identifications in deep, ground-based optical imaging, we have constructed a starting sample of 19 high-redshift cluster candidates. N…
Star-forming accretion flows and the low-luminosity nuclei of giant elliptical galaxies
Tan, Jonathan C.; Blackman, Eric G.
The luminosities of the centres of nearby elliptical galaxies are very low compared to models of thin disc accretion on to their black holes at the Bondi rate, typically a few hundredths to a few tenths of a solar mass per year. This has motivated models of inefficiently radiated accretion that invoke weak electron-ion thermal coupling, and/or inh…
Mid-infrared imaging of NGC 1068 with VISIR at the Very Large Telescope
Pantin, E.; Alloin, D.; Galliano, E. +1 more
High-resolution mid-infrared (MIR) images of the central region of NGC 1068 have been obtained with VISIR, the multi-mode MIR instrument recently installed at the European Southern Observatory Very Large Telescope on Paranal. A map of the emission at 12.8 µm with increased sensitivity over the central 8 × 8 arcsec2 area is discuss…
On the evolutionary status of early-type galaxies in clusters at z~ 0.2 - I. The Fundamental Plane
Smail, Ian; Davies, Roger L.; Bower, Richard G. +2 more
We investigate a spectroscopic sample of 48 early-type galaxies in the rich cluster Abell 2390 at z= 0.23 and 48 early-type galaxies from a previously published survey of Abell 2218 at z= 0.18. The spectroscopic data of A2390 are based on multi-object spectroscopy using the multi-object spectrograph for Calar Alto at the 3.5-m telescope on Calar A…
A study of two post-common envelope binary systems
Maxted, P. F. L.; Exter, K. M.; Napiwotzki, R. +2 more
We present intermediate-resolution, phase-resolved spectra of the close-binary systems EC 11575-1845 and V664 Cas, the central star of the planetary nebula HFG 1. Both systems have a very rich emission-line spectrum originating from the face of the cool star, which is irradiated by the hot subdwarf star. The HI emission lines are wide, consistent …