Search Publications
HIFLUGCS: Galaxy cluster scaling relations between X-ray luminosity, gas mass, cluster radius, and velocity dispersion
Zhang, Y. -Y.; Böhringer, H.; Girardi, M. +5 more
We present relations between X-ray luminosity and velocity dispersion (L - σ), X-ray luminosity and gas mass (L - Mgas), and cluster radius and velocity dispersion (r500 - σ) for 62 galaxy clusters in the HIFLUGCS, an X-ray flux-limited sample minimizing bias toward any cluster morphology. Our analysis in total is based on ~ …
Intermittent heating in the solar corona employing a 3D MHD model
Peter, H.; Bingert, S.
Aims: We investigate the spatial and temporal evolution of the heating of the corona of a cool star such as our Sun in a three-dimensional magneto-hydrodynamic (3D MHD) model.
Methods: We solve the 3D MHD problem numerically in a box representing part of the (solar) corona. The energy balance includes Spitzer heat conduction along the ma…
Planck early results. XII. Cluster Sunyaev-Zeldovich optical scaling relations
Kneissl, R.; Dahle, H.; Miville-Deschênes, M. -A. +202 more
We present the Sunyaev-Zeldovich (SZ) signal-to-richness scaling relation (Y500 - N200) for the MaxBCG cluster catalogue. Employing a multi-frequency matched filter on the Planck sky maps, we measure the SZ signal for each cluster by adapting the filter according to weak-lensing calibrated mass-richness relations (N200
Reflection in Seyfert galaxies and the unified model of AGN
Paltani, S.; Walter, R.; Ricci, C. +1 more
We present a deep study of the average hard X-ray spectra of Seyfert galaxies. We aim to test the unified model of active galactic nuclei, and constrain differences and similarities between different classes of objects. We analyzed all public INTEGRAL IBIS/ISGRI data available on all the 165 Seyfert galaxies detected at z < 0.2. Our final sampl…
Cross-calibration of the X-ray instruments onboard the Chandra, INTEGRAL, RXTE, Suzaku, Swift, and XMM-Newton observatories using G21.5-0.9
Read, A. M.; Guainazzi, M.; Tsujimoto, M. +7 more
Context. For many years, X-ray astronomy missions have used the Crab nebula as a celestial calibration source for the X-ray flux and spectral shape. However, the object is often too bright for current and future missions equipped with instruments with improved sensitivity.
Aims: We use G21.5-0.9, a pulsar-wind nebula with a time-constant powe…
Planck early results. XIII. Statistical properties of extragalactic radio sources in the Planck Early Release Compact Source Catalogue
Kneissl, R.; Miville-Deschênes, M. -A.; Bernard, J. -P. +201 more
The data reported in Planck's Early Release Compact Source Catalogue (ERCSC) are exploited to measure the number counts (dN/dS) of extragalactic radio sources at 30, 44, 70, 100, 143 and 217 GHz. Due to the full-sky nature of the catalogue, this measurement extends to the rarest and brightest sources in the sky. At lower frequencies (30, 44, and 7…
Sulfur depletion in dense clouds and circumstellar regions. I. H2S ice abundance and UV-photochemical reactions in the H2O-matrix
Muñoz Caro, G. M.; Jiménez-Escobar, A.
Aims: This work aims to study the unexplained sulfur depletion observed toward dense clouds and protostars.
Methods: We made simulation experiments of the UV-photoprocessing and sublimation of H2S and H2S:H2O ice in dense clouds and circumstellar regions, using the InterStellar Astrochemistry Chamber (ISA…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. IX. Time delays, lens dynamics and baryonic fraction in HE 0435-1223
Magain, P.; Koleva, M.; Faure, C. +13 more
We present accurate time delays for the quadruply imaged quasar HE 0435-1223. The delays were measured from 575 independent photometric points obtained in the R-band between January 2004 and March 2010. With seven years of data, we clearly show that quasar image A is affected by strong microlensing variations and that the time delays are best expr…
Planck early results. XV. Spectral energy distributions and radio continuum spectra of northern extragalactic radio sources
Kneissl, R.; Miville-Deschênes, M. -A.; Bernard, J. -P. +246 more
Spectral energy distributions (SEDs) and radio continuum spectra are presented for a northern sample of 104 extragalactic radio sources, based on the Planck Early Release Compact Source Catalogue (ERCSC) and simultaneous multifrequency data. The nine Planck frequencies, from 30 to 857 GHz, are complemented by a set of simultaneous observations ran…
Quantitative evidence of an intrinsic luminosity spread in the Orion nebula cluster
Robberto, M.; Da Rio, N.; Ricci, L. +3 more
Aims: We study the distribution of stellar ages in the Orion nebula cluster (ONC) using accurate HST photometry taken from HST Treasury Program observations of the ONC utilizing the cluster distance estimated by Menten and collaborators. We investigate whether there is an intrinsic age spread in the region and whether the age depends on the s…