Search Publications
Relativistic jet activity from the tidal disruption of a star by a massive black hole
Troja, E.; Im, M.; Sakamoto, T. +55 more
Supermassive black holes have powerful gravitational fields with strong gradients that can destroy stars that get too close, producing a bright flare in ultraviolet and X-ray spectral regions from stellar debris that forms an accretion disk around the black hole. The aftermath of this process may have been seen several times over the past two deca…
Planck early results. VIII. The all-sky early Sunyaev-Zeldovich cluster sample
Kneissl, R.; Dahle, H.; Miville-Deschênes, M. -A. +235 more
We present the first all-sky sample of galaxy clusters detected blindly by the Planck satellite through the Sunyaev-Zeldovich (SZ) effect from its six highest frequencies. This early SZ (ESZ) sample is comprised of 189 candidates, which have a high signal-to-noise ratio ranging from 6 to 29. Its high reliability (purity above 95%) is further ensur…
Estimation of the XUV radiation onto close planets and their evaporation
Eiroa, C.; Ribas, I.; Solano, E. +5 more
Context. The current distribution of planet mass vs. incident stellar X-ray flux supports the idea that photoevaporation of the atmosphere may take place in close-in planets. Integrated effects have to be accounted for. A proper calculation of the mass loss rate through photoevaporation requires the estimation of the total irradiation from the who…
An Extremely Luminous Panchromatic Outburst from the Nucleus of a Distant Galaxy
Cenko, S. B.; Sánchez-Ramírez, R.; Cooper, M. C. +60 more
Variable x-ray and γ-ray emission is characteristic of the most extreme physical processes in the universe. We present multiwavelength observations of a unique γ-ray-selected transient detected by the Swift satellite, accompanied by bright emission across the electromagnetic spectrum, and whose properties are unlike any previously observed source.…
An XMM-Newton spectral survey of 12 µm selected galaxies - I. X-ray data
Nandra, Kirpal; Brightman, Murray
We present an X-ray spectral analysis of 126 galaxies of the 12 µm galaxy sample. By studying this sample at X-ray wavelengths, we aim to determine the intrinsic power, continuum shape and obscuration level in these sources. We improve upon previous works by the use of superior data in the form of higher signal-to-noise ratio spectra, finer …
Three-year Swift-BAT Survey of Active Galactic Nuclei: Reconciling Theory and Observations?
Greiner, J.; Merloni, A.; Comastri, A. +3 more
It is well accepted that unabsorbed as well as absorbed active galactic nuclei (AGNs) are needed to explain the nature and shape of the Cosmic X-ray background (CXB), even if the fraction of highly absorbed objects (dubbed Compton-thick sources) still substantially escapes detection. We derive and analyze the absorption distribution using a comple…
Dissecting Photometric Redshift for Active Galactic Nucleus Using XMM- and Chandra-COSMOS Samples
Kneib, J. -P.; Aussel, H.; Le Floc'h, E. +62 more
In this paper, we release accurate photometric redshifts for 1692 counterparts to Chandra sources in the central square degree of the Cosmic Evolution Survey (COSMOS) field. The availability of a large training set of spectroscopic redshifts that extends to faint magnitudes enabled photometric redshifts comparable to the highest quality results pr…
Evidence for Ultra-fast Outflows in Radio-quiet Active Galactic Nuclei. II. Detailed Photoionization Modeling of Fe K-shell Absorption Lines
Cappi, M.; Dadina, M.; Tombesi, F. +3 more
X-ray absorption line spectroscopy has recently shown evidence for previously unknown Ultra-fast Outflows (UFOs) in radio-quiet active galactic nuclei (AGNs). These have been detected essentially through blueshifted Fe XXV/XXVI K-shell transitions. In the previous paper of this series we defined UFOs as those highly ionized absorbers with an outfl…
Planck early results. XI. Calibration of the local galaxy cluster Sunyaev-Zeldovich scaling relations
Kneissl, R.; Dahle, H.; Miville-Deschênes, M. -A. +207 more
We present precise Sunyaev-Zeldovich (SZ) effect measurements in the direction of 62 nearby galaxy clusters (z < 0.5) detected at high signal-to-noise in the first Planck all-sky data set. The sample spans approximately a decade in total mass, 2 × 1014 M⊙ < M500 < 2 × 1015 M⊙, where M…
The cool-core bias in X-ray galaxy cluster samples. I. Method and application to HIFLUGCS
Paltani, S.; Molendi, S.; Eckert, D.
Aims: When selecting flux-limited cluster samples, the detection efficiency of X-ray instruments is not the same for centrally-peaked and flat objects, which introduces a bias in flux-limited cluster samples. We quantify this effect in the case of a well-known cluster sample, HIFLUGCS.
Methods: We simulate a population of X-ray clusters …