Search Publications
Unveiling the nature of six HMXBs through IR spectroscopy
Mennickent, R. E.; Fabregat, J.; Nespoli, E.
Context: The International Gamma-Ray Astrophyiscs Laboratory (INTEGRAL) is discovering a large number of new hard X-ray sources, many of them being HMXBs. The identification and spectral characterization of their optical/infrared counterparts is a necessary step to undertake detailed study of these systems. In particular, the determination of the …
Exploring a SNR/molecular cloud association within HESS J1745-303
Santangelo, A.; Ripken, J.; Carrigan, S. +139 more
Aims: HESS J1745-303 is an extended, unidentified VHE (very high energy) gamma-ray source discovered using HESS in the Galactic Plane Survey. Since no obvious counterpart has previously been found in longer-wavelength data, the processes that power the VHE emission are not well understood.
Methods: Combining the latest VHE data with recent XMM…
Direct evidence of a sub-stellar companion around CT Chamaeleontis
Neuhäuser, R.; Schmidt, T. O. B.; Hauschildt, P. H. +5 more
Aims: In our ongoing search for close and faint companions around T Tauri stars in the Chamaeleon star-forming region, we here present observations of a new common proper motion companion to the young T-Tauri star and Chamaeleon member CT Cha and discuss its properties in comparison to other young, low-mass objects and to synthetic model spectra f…
Testing the inverse-Compton catastrophe scenario in the intra-day variable blazar S5 0716+71. III. Rapid and correlated flux density variability from radio to sub-mm bands
Grewing, M.; Britzen, S.; Wagner, S. J. +22 more
Aims: The BL Lac object S5 0716+71 was observed in a global multi-frequency campaign to search for rapid and correlated flux density variability and signatures of an inverse-Compton (IC) catastrophe during the states of extreme apparent brightness temperatures.
Methods: The observing campaign involved simultaneous ground-based monitoring at ra…
Spectroscopy of clusters in the ESO distant cluster survey (EDisCS). II.. Redshifts, velocity dispersions, and substructure for clusters in the last 15 fields
Moustakas, J.; Pelló, R.; White, S. D. M. +17 more
Aims: We present spectroscopic observations of galaxies in 15 survey fields as part of the ESO Distant Cluster Survey (EDisCS). We determine the redshifts and velocity dispersions of the galaxy clusters located in these fields, and we test for possible substructure in the clusters.
Methods: We obtained multi-object mask spectroscopy using the …
Tracing a disk wind in NGC 3516
Turner, T. J.; Kraemer, S. B.; Reeves, J. N. +1 more
Context: X-ray spectra of AGN often contain signatures indicative of absorption in multiple layers of gas whose ionization-state and covering fraction may vary with time. It has been unclear to date how much of the observed X-ray spectral and timing behavior in AGN can be attributed to variations in absorption, versus variations in the strengths o…
Multiwavelength observations of a giant flare on CN Leonis. I. The chromosphere as seen in the optical spectra
Liefke, C.; Schmitt, J. H. M. M.; Reiners, A. +1 more
Aims: Flares on dM stars contain plasmas at very different temperatures and thus affect a wide wavelength range in the electromagnetic spectrum. While the coronal properties of flares are studied best in X-rays, the chromosphere of the star is observed best in the optical and ultraviolet ranges. Therefore, multiwavelength observations are essentia…
Temperature structure of the intergalactic medium within seven nearby and bright clusters of galaxies observed with XMM-Newton
Bourdin, H.; Mazzotta, P.
Aims:Using a newly developed algorithm, we map, to the highest angular resolution allowed by the data, the temperature structure of the intra-cluster medium (ICM) within a nearly complete X-ray flux limited sample of galaxy clusters in the redshift range between {z}=0.045 and {z}=0.096. Our sample contains seven bright clusters of galaxies observe…
GMASS ultradeep spectroscopy of galaxies at z ∼2. III. The emergence of the color bimodality at z ∼2
Berta, S.; Cimatti, A.; Daddi, E. +12 more
Aims: The aim of this work is to study the evolution of the rest-frame color distribution of galaxies with the redshift, in particular in the critical interval 1.4<z<3.
Methods: We combined ultradeep spectroscopy from the GMASS project (Galaxy Mass Assembly ultradeep Spectroscopic Survey) with GOODS multi-band photometry (from optical to…
COSMOGRAIL: the COSmological MOnitoring of GRAvItational Lenses. VII. Time delays and the Hubble constant from WFI J2033-4723
Magain, P.; Kochanek, C. S.; Meylan, G. +10 more
Gravitationally lensed quasars can be used to map the mass distribution in lensing galaxies and to estimate the Hubble constant H0 by measuring the time delays between the quasar images. Here we report the measurement of two independent time delays in the quadruply imaged quasar WFI J2033-4723 (z = 1.66). Our data consist of R-band imag…