Search Publications
Far-infrared metallicity diagnostics: application to local ultraluminous infrared galaxies
Farrah, D.; Rigopoulou, D.; Lebouteiller, V. +2 more
The abundance of metals in galaxies is a key parameter that permits to distinguish between different galaxy formation and evolution models. Most of the metallicity determinations are based on optical line ratios. However, the optical spectral range is subject to dust extinction and, for high-z objects (z > 3), some of the lines used in optical …
Deep LOFAR observations of the merging galaxy cluster CIZA J2242.8+5301
Brunetti, G.; White, G. J.; Shimwell, T. W. +20 more
Previous studies have shown that CIZA J2242.8+5301 (the 'Sausage' cluster, z = 0.192) is a massive merging galaxy cluster that hosts a radio halo and multiple relics. In this paper, we present deep, high-fidelity, low-frequency images made with the LOw-Frequency Array (LOFAR) between 115.5 and 179 MHz. These images, with a noise of 140 µJy b…
The structural and dynamical properties of compact elliptical galaxies
Gebhardt, Karl; van de Ven, Glenn; Husemann, Bernd +5 more
Dedicated photometric and spectroscopic surveys have provided unambiguous evidence for a strong stellar mass-size evolution of galaxies within the last 10 Gyr. The likely progenitors of today's most massive galaxies are remarkably small, discy, passive and have already assembled much of their stellar mass at redshift z = 2. An in-depth analysis of…
An investigation of the rotational properties of magnetic chemically peculiar stars
Paunzen, Ernst; Hümmerich, Stefan; Bernhard, Klaus +1 more
The magnetic chemically peculiar (mCP) stars of the upper main sequence exhibit strong, globally organized magnetic fields that are inclined to the rotational axis and facilitate the development of surface abundance inhomogeneities resulting in photometric and spectroscopic variability. Therefore, mCP stars are perfectly suited for a direct measur…
Cosmology from large-scale galaxy clustering and galaxy-galaxy lensing with Dark Energy Survey Science Verification data
Benoit-Lévy, A.; Nichol, R. C.; D'Andrea, C. B. +81 more
We present cosmological constraints from the Dark Energy Survey (DES) using a combined analysis of angular clustering of red galaxies and their cross-correlation with weak gravitational lensing of background galaxies. We use a 139 deg2 contiguous patch of DES data from the Science Verification (SV) period of observations. Using large-sc…
Analysis of NuSTAR and Suzaku observations of Cyg X-1 in the hard state: evidence for a truncated disc geometry
Parker, Michael; Zdziarski, Andrzej A.; Basak, Rupal +1 more
The geometry of the accretion flow in black hole X-ray binaries in the hard state, in particular the position of the disc inner edge, has been a subject of intense debate in recent years. We address this issue by performing a spectral study of simultaneous observations of Cyg X-1 in the hard state by NuSTAR and Suzaku. The same data were analysed …
On the metallicity dependence of the [Y/Mg]-age relation for solar-type stars
McMillan, Paul J.; Feltzing, Sofia; Howes, Louise M. +1 more
Several recent studies of solar twins in the solar neighbourhood have shown a tight correlation between various elemental abundances and age, in particular [Y/Mg]. If this relation is real and valid for other types of stars as well as elsewhere in the Galaxy, it would provide a very powerful tool to derive ages of stars without the need to resort …
Red clump stars and Gaia: calibration of the standard candle using a hierarchical probabilistic model
Bovy, Jo; Leistedt, Boris; Hogg, David W. +1 more
Distances to individual stars in our own Galaxy are critical in order to piece together the nature of its velocity and spatial structure. Core helium burning red clump (RC) stars have similar luminosities, are abundant throughout the Galaxy and thus constitute good standard candles. We build a hierarchical probabilistic model to quantify the quali…
Updating the (supermassive black hole mass)-(spiral arm pitch angle) relation: a strong correlation for galaxies with pseudobulges
Graham, Alister W.; Davis, Benjamin L.; Seigar, Marc S.
We have conducted an image analysis of the (current) full sample of 44 spiral galaxies with directly measured supermassive black hole (SMBH) masses, MBH, to determine each galaxy's logarithmic spiral arm pitch angle, ϕ. For predicting black hole masses, we have derived the relation: log (MBH/M⊙) = (7.01 ± 0.07) - (…
Fractal dust constrains the collisional history of comets
Blum, J.; Fulle, M.
The fractal dust particles observed by Rosetta cannot form in the physical conditions observed today in comet 67P/Churyumov-Gerasimenko (67P hereinafter), being instead consistent with models of the pristine dust aggregates coagulated in the solar nebula. Since bouncing collisions in the protoplanetary disc restructure fractals into compact aggreg…