Search Publications
An optical/NIR survey of globular clusters in early-type galaxies. II. Ages of globular cluster systems and the relation to galaxy morphology
Larsen, S. S.; Kuntschner, H.; Anders, P. +5 more
Context. Some photometric studies of extragalactic globular cluster (GC) systems using the optical and near-infrared colour combination have suggested the presence of a large fraction of intermediate-age (2-8 Gyr) GCs.
Aims: We investigate the age distributions of GC systems in 14 E/S0 galaxies.
Methods: We carried out a differential com…
On the relationship of shock waves to flares and coronal mass ejections
Hillaris, A.; Preka-Papadema, P.; Nindos, A. +1 more
Context. Metric type II bursts are the most direct diagnostic of shock waves in the solar corona.
Aims: There are two main competing views about the origin of coronal shocks: that they originate in either blast waves ignited by the pressure pulse of a flare or piston-driven shocks due to coronal mass ejections (CMEs). We studied three well-ob…
Multistate observations of the Galactic black hole XTE J1752-223: evidence for an intermediate black hole spin
Wijnands, R.; Fabian, A. C.; Miller, J. M. +6 more
The Galactic black hole candidate XTE J1752-223 was observed during the decay of its 2009 outburst with the Suzaku and XMM-Newton observatories. The observed spectra are consistent with the source being in the ‘intermediate’ and ‘low-hard’ states, respectively. The presence of a strong, relativistic iron emission line is clearly detected in both o…
VLT-VIMOS integral field spectroscopy of luminous and ultraluminous infrared galaxies. III. The atlas of the stellar and ionized gas distribution
Colina, L.; Monreal-Ibero, A.; Arribas, S. +3 more
Context. Luminous and ultraluminous infrared galaxies (LIRGs and ULIRGs) are much more numerous at higher redshifts than locally, dominating the star-formation rate density at redshifts ~1-2. Therefore, they are important objects in order to understand how galaxies form and evolve through cosmic time. Local samples provide a unique opportunity to …
The hard X-ray emission of Centaurus A
Terrier, R.; Jean, P.; Beckmann, V. +2 more
Context. The radio galaxy Cen A has been detected all the way up to the TeV energy range. This raises the question about the dominant emission mechanisms in the high-energy domain.
Aims: Spectral analysis allows us to put constraints on the possible emission processes. Here we study the hard X-ray emission, in order to distinguish between a t…
Witnessing the magnetospheric boundary at work in Vela X-1
Santangelo, A.; Doroshenko, V.; Suleimanov, V.
We present an analysis of the Vela X-1 "off-states" based on Suzaku observations taken in June 2008. Defined as states in which the flux suddenly decreases below the instrumental sensitivity, these "off-states" have been interpreted by several authors as the onset of the "propeller regime". For the first time ever, however, we find that the source…
The Gas-Galaxy Connection at z abs = 0.35: O VI and H I Absorption toward J 0943+0531
Sembach, K. R.; Prochaska, J. X.; Tripp, T. M. +4 more
We present observations of H I and O VI absorption systems proximate to a galaxy at z gal = 0.3529. The absorption was detected serendipitously in Cosmic Origins Spectrograph observations of the low-z QSO J 0943 + 0531 (z qso = 0.564). The data show two separate clouds along the sightline at an impact parameter of 95 kpc from…
Luminous Satellites of Early-type Galaxies. I. Spatial Distribution
Treu, T.; Auger, M. W.; Fassnacht, C. D. +2 more
We study the spatial distribution of faint satellites of intermediate redshift (0.1 < z < 0.8), early-type galaxies, selected from the GOODS fields. We combine high-resolution Hubble Space Telescope images and state-of-the-art host subtraction techniques to detect satellites of unprecedented faintness and proximity to intermediate redshift h…
Asymmetries of the Stokes V profiles observed by HINODE SOT/SP in the quiet Sun
Sánchez Almeida, J.; Viticchié, B.
Aims: A recent analysis of polarization measurements of HINODE SOT/SP in the quiet Sun pointed out very complex shapes of Stokes V profiles. Here we present the first classification of the SOT/SP circular polarization measurements with the aim of highlighting exhaustively the whole variety of Stokes V shapes emerging from the quiet Sun.
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The Structure of the Accretion Disk in the Lensed Quasar SBS 0909+532
Kochanek, C. S.; Arribas, S.; Acosta-Pulido, J. +7 more
We derive the size and temperature profile of the accretion disk of the lensed quasar SBS 0909+532 by measuring the wavelength dependence (chromaticity) of the microlensing magnification produced by the stars in the lens galaxy. After correcting for extinction using the flux ratios of 14 emission lines, we observe a marked change in the B-A flux r…