Search Publications
A population of faint low surface brightness galaxies in the Perseus cluster core
Wittmann, Carolin; Kotulla, Ralf; Lisker, Thorsten +7 more
We present the detection of 89 low surface brightness (LSB), and thus low stellar density galaxy candidates in the Perseus cluster core, of the kind named 'ultra-diffuse galaxies', with mean effective V-band surface brightnesses 24.8-27.1 mag arcsec-2, total V-band magnitudes -11.8 to -15.5 mag, and half-light radii 0.7-4.1 kpc. The can…
The Gaia ultracool dwarf sample - I. Known L and T dwarfs and the first Gaia data release
Caballero, J. A.; Sarro, L. M.; Marocco, F. +5 more
We identify and investigate known ultracool stars and brown dwarfs that are being observed or indirectly constrained by the Gaia mission. These objects will be the core of the Gaia ultracool dwarf sample composed of all dwarfs later than M7 that Gaia will provide direct or indirect information on. We match known L and T dwarfs to the Gaia first da…
Eclipsing binary stars with a δ Scuti component
Smalley, B.; Kahraman Aliçavuş, F.; Kubát, J. +1 more
Eclipsing binaries with a δ Sct component are powerful tools to derive the fundamental parameters and probe the internal structure of stars. In this study, spectral analysis of six primary δ Sct components in eclipsing binaries has been performed. Values of Teff, v sin I, and metallicity for the stars have been derived from medium-resol…
The most distant, luminous, dusty star-forming galaxies: redshifts from NOEMA and ALMA spectral scans
Pérez-Fournon, I.; Ivison, R. J.; Omont, A. +23 more
We present 1.3- and/or 3-mm continuum images and 3-mm spectral scans, obtained using Northern Extended Millimeter Array (NOEMA) and Atacama Large Millimeter Array (ALMA), of 21 distant, dusty, star-forming galaxies. Our sample is a subset of the galaxies selected by Ivison et al. on the basis of their extremely red far-infrared (far-IR) colours an…
A high fraction of Be stars in young massive clusters: evidence for a large population of near-critically rotating stars
Cabrera-Ziri, I.; Usher, C.; Bastian, N. +6 more
Recent photometric analyses of the colour-magnitude diagrams of young massive clusters (YMCs) have found evidence for splitting in the main sequence and extended main-sequence turn-offs, both of which have been suggested to be caused by stellar rotation. Comparison of the observed main-sequence splitting with models has led various authors to sugg…
The statistical properties of neutral gas at z < 1.65 from UV measurements of Damped Lyman Alpha systems
Turnshek, David A.; Rao, Sandhya M.; Monier, Eric M. +1 more
We derive the statistical properties of neutral gas at redshifts 0.11 < z < 1.65 from ultraviolet (UV) measurements of quasar Ly α absorption lines corresponding to 369 Mg II systems with W^{λ 2796}0 ≥ 0.3 Å. In addition to the 41 damped Lyman alpha (DLA) systems presented in Rao et al. (2006), the current DLA sample includes 29 n…
Intergalactic Lyman continuum photon budget in the past 5 billion years
Khaire, Vikram; Srianand, Raghunathan; Choudhury, Tirthankar Roy +1 more
We constrain the H I photoionization rate (Γ _{H I}) at z ≲ 0.45 by comparing the flux probability distribution function and power spectrum of the Lyα forest data along 82 Quasi-Stellar Object (QSO) sightlines obtained using Cosmic Origins Spectrograph with models generated from smoothed particle hydrodynamic simulations. We have developed a modul…
Swift observations of V404 Cyg during the 2015 outburst: X-ray outflows from super-Eddington accretion
Altamirano, D.; Sanna, A.; Knigge, C. +11 more
The black hole (BH) binary V404 Cyg entered the outburst phase in 2015 June after 26 yr of X-ray quiescence, and with its behaviour broke the outburst evolution pattern typical of most BH binaries. We observed the entire outburst with the Swift satellite and performed time-resolved spectroscopy of its most active phase, obtaining over a thousand s…
Interpreting the star formation efficiency of nearby molecular clouds with ionizing radiation
Hennebelle, Patrick; Soler, Juan D.; Geen, Sam
We investigate the origin of observed local star formation relations using radiative magnetohydrodynamic simulations with self-consistent star formation and ionizing radiation. We compare these clouds to the density distributions of local star-forming clouds and find that the most diffuse simulated clouds match the observed clouds relatively well.…
Close entrainment of massive molecular gas flows by radio bubbles in the central galaxy of Abell 1795
Fabian, A. C.; Combes, F.; McDonald, M. +8 more
We present new ALMA observations tracing the morphology and velocity structure of the molecular gas in the central galaxy of the cluster Abell 1795. The molecular gas lies in two filaments that extend 5-7 kpc to the N and S from the nucleus and project exclusively around the outer edges of two inner radio bubbles. Radio jets launched by the centra…