Search Publications
Detecting gravitationally lensed Population III galaxies with the Hubble Space Telescope and the James Webb Space Telescope
Broadhurst, Tom; Schaerer, Daniel; Östlin, Göran +6 more
Small galaxies consisting entirely of Population III (pop III) stars may form at high redshifts, and could constitute one of the best probes of such stars. Here, we explore the prospects of detecting gravitationally lensed pop III galaxies behind the galaxy cluster J0717.5+3745 (J0717) with both the Hubble Space Telescope (HST) and the upcoming Ja…
On the metallicity dependence of crystalline silicates in oxygen-rich asymptotic giant branch stars and red supergiants
Zijlstra, A. A.; Boyer, M. L.; Gielen, C. +10 more
We investigate the occurrence of crystalline silicates in oxygen-rich evolved stars across a range of metallicities and mass-loss rates. It has been suggested that the crystalline silicate feature strength increases with increasing mass-loss rate, implying a correlation between lattice structure and wind density. To test this, we analyse Spitzer I…
A broad iron line in LMC X-1
Steiner, James F.; Reis, Rubens C.; Fabian, Andrew C. +6 more
We present results from a deep Suzaku observation of the black hole in LMC X-1, supplemented by coincident monitoring with the Rossi X-ray Timing Explorer (RXTE). We identify broad relativistic reflection features in a soft disc-dominated spectrum. A strong and variable power-law component of emission is present which we use to demonstrate that en…
Investigating the spectroscopic, magnetic and circumstellar variability of the O9 subgiant star HD 57682
Kaper, L.; Rivinius, Th.; Ribeiro, J. +12 more
The O9IV star HD 57682, discovered to be magnetic within the context of the Magnetism in Massive Stars (MiMeS) survey in 2009, is one of only eight convincingly detected magnetic O-type stars. Among this select group, it stands out due to its sharp-lined photospheric spectrum. Since its discovery, the MiMeS Collaboration has continued to obtain sp…
Galaxy cluster outskirts: a universal entropy profile for relaxed clusters?
Fabian, A. C.; Sanders, J. S.; Walker, S. A. +1 more
We fit a functional form for a universal intracluster medium entropy profile to the scaled entropy profiles of a catalogue of X-ray galaxy cluster outskirts results, which are all relaxed cool core clusters at redshift below 0.25. We also investigate the functional form suggested by Lapi et al. and Cavaliere et al. for the behaviour of the entropy…
VLA imaging of 12CO J = 1-0 and free-free emission in lensed submillimetre galaxies
Thomson, A. P.; Kneib, J. -P.; Ivison, R. J. +7 more
We present a study using the Karl G. Jansky Very Large Array (VLA) of 12CO J = 1-0 emission in three strongly lensed submillimetre-selected galaxies (SMM J16359, SMM J14009 and SMM J02399) at z = 2.5-2.9. These galaxies span LIR = 1011-1013 L⊙, offering an opportunity to compare the interstell…
Accreting magnetars: a new type of high-mass X-ray binaries?
Reig, P.; Torrejón, J. M.; Blay, P.
The discovery of very slow pulsations (Pspin =5560 s) has solved the long-standing question of the nature of the compact object in the high-mass X-ray binary 4U 2206+54 but has posed new ones. According to spin evolutionary models in close binary systems, such slow pulsations require a neutron star magnetic field strength larger than th…
Clustering of submillimetre galaxies in a self-regulated baryon collapse model
Danese, L.; Negrello, M.; Lapi, A. +3 more
We investigate anisotropies in the cosmic infrared background (CIB) using a combination of the physical evolutionary model for proto-spheroid galaxies of Granato et al. and an independent halo occupation distribution analysis. After having re-calibrated the cumulative flux function dS/dz at ?m using the available determinations of the shot-noise a…
NGC 454: unveiling a new 'changing look' active galactic nucleus
Braito, V.; Caccianiga, A.; Severgnini, P. +2 more
We present a detailed analysis of the X-ray spectrum of the Seyfert 2 galaxy NGC 454E, belonging to the interacting system NGC 454. Observations performed with Suzaku, XMM-Newton and Swift allowed us to detect a dramatic change in the curvature of the 2-10 keV spectrum, revealing a significant variation of the absorbing column density along the li…
Simultaneous X-ray and optical observations of true type 2 Seyfert galaxies
Wolter, Anna; Bianchi, Stefano; La Franca, Fabio +9 more
We present the results of a campaign of simultaneous X-ray and optical observations of 'true' type 2 Seyfert galaxies candidates, i.e. active galactic nuclei without a broad-line region (BLR). Out of the initial sample composed of eight sources, one object, IC 1631, was found to be a misclassified starburst galaxy, another, Q2130-431, does show br…