Search Publications
Spatially resolved integral field spectroscopy of the ionized gas in IZw18
Kunth, D.; Durret, F.; Brinchmann, J. +6 more
We present a detailed 2D study of the ionized ionized interstellar medium (ISM) of IZw18 using new Potsdam Multi-Aperture Spectrophotometer-integral field unit (PMAS-IFU) optical observations. IZw18 is a high-ionization galaxy which is among the most metal-poor starbursts in the local Universe. This makes IZw18 a local benchmark for understanding …
The selective effect of environment on the atomic and molecular gas-to-dust ratio of nearby galaxies in the Herschel Reference Survey
Ciesla, L.; Boquien, M.; Baes, M. +10 more
We combine dust, atomic (H I) and molecular (H2) hydrogen mass measurements for 176 galaxies in the Herschel Reference Survey to investigate the effect of environment on the gas-to-dust mass (Mgas/Mdust) ratio of nearby galaxies. We find that, at fixed stellar mass, the average Mgas/Mdust rati…
The near-to-mid infrared spectrum of quasars
Alonso-Herrero, Almudena; Hatziminaoglou, Evanthia; Hernán-Caballero, Antonio +1 more
We analyse a sample of 85 luminous (log (νLν(3 µm)/erg s-1) > 45.5) quasars with rest frame ∼2-11 µm spectroscopy from AKARI and Spitzer. Their high luminosity allows a direct determination of the near-infrared quasar spectrum free from host galaxy emission. A semi-empirical model consisting of a single templat…
An enhanced merger fraction within the galaxy population of the SSA22 protocluster at z = 3.1
Lehmer, B. D.; Alexander, D. M.; Matsuda, Y. +3 more
The overdense environments of protoclusters of galaxies in the early Universe (z > 2) are expected to accelerate the evolution of galaxies, with an increased rate of stellar mass assembly and black hole accretion compared to co-eval galaxies in the average density `field'. These galaxies are destined to form the passive population of massive ga…
The X-ray spectral evolution of the ultraluminous X-ray source Holmberg IX X-1
Done, Chris; Roberts, Timothy P.; Luangtip, Wasutep
We present a new analysis of X-ray spectra of the archetypal ultraluminous X-ray source (ULX) Holmberg IX X-1 obtained by the Swift, XMM-Newton and NuSTAR observatories. This ULX is a persistent source, with a typical luminosity of ∼1040 erg s-1, that varied by a factor of 4-5 over eight years. We find that its spectra tend t…
Statistical analysis of suprathermal electron drivers at 67P/Churyumov-Gerasimenko
Frahm, R. A.; Eriksson, A.; Henri, P. +16 more
We use observations from the Ion and Electron Sensor (IES) on board the Rosetta spacecraft to study the relationship between the cometary suprathermal electrons and the drivers that affect their density and temperature. We fit the IES electron observations with the summation of two kappa distributions, which we characterize as a dense and warm pop…
Testing deviations from ΛCDM with growth rate measurements from six large-scale structure surveys at z = 0.06-1
Ho, Shirley; Silvestri, Alessandra; Alam, Shadab
We use measurements from the Planck satellite mission and galaxy redshift surveys over the last decade to test three of the basic assumptions of the standard model of cosmology, ΛCDM (Λ cold dark matter): the spatial curvature of the universe, the nature of dark energy and the laws of gravity on large scales. We obtain improved constraints on seve…
Quantifying tensions between CMB and distance data sets in models with free curvature or lensing amplitude
Mohr, J. J.; Saro, A.; Dietrich, J. P. +2 more
Recent measurements of the cosmic microwave background (CMB) by the Planck Collaboration have produced arguably the most powerful observational evidence in support of the standard model of cosmology, I.e. the spatially flat ΛCDM paradigm. In this work, we perform model selection tests to examine whether the base CMB temperature and large scale pol…
Relativistic X-ray reverberation modelling of the combined time-averaged and lag-energy spectra in AGN
Chainakun, P.; Young, A. J.; Kara, E.
General relativistic ray tracing simulations of the time-averaged spectrum and energy-dependent time delays in active galactic nuclei (AGN) are presented. We model the lamp-post geometry in which the accreting gas is illuminated by an X-ray source located on the rotation axis of the black hole. The spectroscopic features imprinted in the reflectio…
Subaru Telescope adaptive optics observations of gravitationally lensed quasars in the Sloan Digital Sky Survey
Terada, Hiroshi; Pyo, Tae-Soo; Oguri, Masamune +12 more
We present the results of an imaging observation campaign conducted with the Subaru Telescope adaptive optics system (IRCS+AO188) on 28 gravitationally lensed quasars and candidates (23 doubles, 1 quad, 1 possible triple, and 3 candidates) from the SDSS Quasar Lens Search. We develop a novel modelling technique that fits analytical and hybrid poin…