Search Publications
Constraining dark matter properties with SPI
Boyarsky, Alexey; Ruchayskiy, Oleg; Malyshev, Denys +1 more
Using the high-resolution spectrometer SPI on board the International Gamma-Ray Astrophysics Laboratory (INTEGRAL), we search for a spectral line produced by a dark matter (DM) particle with a mass in the range 40keV < MDM < 14MeV, decaying in the DM halo of the Milky Way. To distinguish the DM decay line from numerous instrumenta…
The evolution of the brightest cluster galaxies since z ~ 1 from the ESO Distant Cluster Survey (EDisCS)
Milvang-Jensen, B.; Noll, S.; Poggianti, B. M. +13 more
We present K-band data for the brightest cluster galaxies (BCGs) from the ESO Distant Cluster Survey (EDisCS). These data are combined with the photometry published by Aragón-Salamanca, Baugh & Kauffmann and a low-redshift comparison sample built from the BCG catalogue of von der Linden et al. BCG luminosities are measured inside a metric circ…
X-ray spectra from magnetar candidates - I. Monte Carlo simulations in the non-relativistic regime
Zane, S.; Nobili, L.; Turolla, R.
The anomalous X-ray pulsars (AXPs) and soft γ-repeaters (SGRs) are peculiar high-energy sources believed to host a magnetar, an ultramagnetized neutron star with surface magnetic field in the petagauss range. Their persistent, soft X-ray emission exhibits a two component spectrum, usually modelled by the superposition of a blackbody and a power-la…
The UV colours of high-redshift early-type galaxies: evidence for recent star formation and stellar mass assembly over the last 8 billion years
van Dokkum, P. G.; Gawiser, E.; Urry, C. M. +7 more
We combine deep optical and NIR (UBVRIzJK) photometry from the Multiwavelength Survey by Yale-Chile (MUSYC) with redshifts from the COMBO-17 survey to perform a large-scale study of the rest-frame ultraviolet (UV) properties of 674 high-redshift (0.5 < z < 1) early-type galaxies, drawn from the Extended Chandra Deep Field-South (E-CDFS). Gal…
Multidimensional modelling of X-ray spectra for AGN accretion disc outflows
Turner, T. J.; Long, K. S.; Sim, S. A. +1 more
We use a multidimensional Monte Carlo code to compute X-ray spectra for a variety of active galactic nucleus (AGN) disc-wind outflow geometries. We focus on the formation of blueshifted absorption features in the Fe K band and show that line features similar to those which have been reported in observations are often produced for lines of sight th…
Large Einstein radii: a problem for ΛCDM
Barkana, Rennan; Broadhurst, Tom J.
The Einstein radius of a cluster provides a relatively model-independent measure of the mass density of a cluster within a projected radius of ~150kpc, large enough to be relatively unaffected by gas physics. We show that the observed Einstein radii of four well-studied massive clusters, for which reliable virial masses are measured, lie well beyo…
The role of AGN in the colour transformation of galaxies at redshifts z ~ 1
Barmby, P.; Cooper, M. C.; Georgakakis, A. +10 more
We explore the role of active galactic nuclei (AGN) in establishing and/or maintaining the bimodal colour distribution of galaxies by quenching their star formation and hence, causing their transition from the blue to the red cloud. Important tests for this scenario include (i) the X-ray properties of galaxies in the transition zone between the tw…
The shape of the dark matter halo in the early-type galaxy NGC 2974
Krajnović, Davor; van de Ven, Glenn; Morganti, Raffaella +3 more
We present HI observations of the elliptical galaxy NGC 2974, obtained with the Very Large Array. These observations reveal that the previously detected HI disc in this galaxy is in fact a ring. By studying the harmonic expansion of the velocity field along the ring, we constrain the elongation of the halo and find that the underlying gravitationa…
Galaxy evolution in Hickson compact groups: the role of ram-pressure stripping and strangulation
Yun, Min S.; Ponman, Trevor J.; Verdes-Montenegro, Lourdes +2 more
Galaxies in compact groups tend to be deficient in neutral hydrogen compared to isolated galaxies of similar optical properties. In order to investigate the role played by a hot intragroup medium (IGM) for the removal and destruction of HI in these systems, we have performed a Chandra and XMM-Newton study of eight of the most HI deficient Hickson …
The weak magnetic field of the O9.7 supergiant ζOrionisA
Bouret, J. -C.; Martins, F.; Donati, J. -F. +4 more
We report here the detection of a weak magnetic field of 50-100G on the O9.7 supergiant ζOrionisA (ζOriA), using spectropolarimetric observations obtained with NARVAL at the 2-m Télescope Bernard Lyot atop Pic du Midi (France). ζOriA is the third O star known to host a magnetic field (along with θ1OriC and HD191612), and the first detec…