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Counting papers with at most 25 authors, so collaboration author lists do not stand in for the people here.
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29 papers · 1 filter
Detection of a Lyman-alpha Emission-Line Companion to the z=4.69 QSO BR1202-0725
Esther M. Hu, Richard G. McMahon, Eiichi Egami
We report the detection of a nearby emission-line companion to the z=4.695 quasar BR1202-0725. Deep narrow-band exposures on this field from the UH 2.2 m show a Ly alpha flux of 1.…
Radio observations of the -ray blazar 0528+134
M. Pohl, W. Reich, T. P. Krichbaum +10
We report multifrequency observations of the -ray blazar 0528+134 with the Effelsberg 100-m telescope, the IRAM 30-m telescope, and the NRL Green Bank Interferometer. 0528+134 u…
Disk galaxies at Z=0 and at High Redshift: an explanation of the observed evolution of damped Ly-alpha systems
Guinevere Kauffmann
The analysis of disk formation is based on the White & Rees (1978) picture, in which disk galaxies form by continuous cooling and accretion of gas within a merging hierarchy of dar…
X-ray evolution in the ROSAT Brightest Cluster Sample
H. Ebeling, S. W. Allen, C. S. Crawford +5
We present the X-ray luminosity function (XLF) of the ROSAT Brightest Cluster Sample (BCS), an X-ray selected, flux limited sample of 172 clusters of galaxies at compil…
New Parametrizations of Non-Gaussian Line-of-sight Velocity Distribution
HongSheng Zhao, Francisco Prada
A five-parameter fitting formula for the line-of-sight stellar velocity distributions of steady state systems is proposed. It can faithfully reproduce velocity distributions of the…
Ultrasoft transient X-ray emission from AGN
K. Mannheim, D. Grupe, K. Beuermann +2
We report some remarkable and unexpected results of optical/UV/X-ray follow-up observations of bright soft X-ray selected AGN from the ROSAT All-Sky-Survey. The majority of these A…
Interaction in the Bimodal Galaxy Cluster A3528
S. Schindler
X-ray and radio continuum observations of the bimodal cluster A3528 in the Shapley Supercluster are presented. From a ROSAT PSPC pointed observation we find a marginal tendency of…
Ca depletion and the presence of dust in large scale nebulosities in radiogalaxies (I)
M. Villar-Martin, L. Binette
We show that the study of the Calcium depletion is a valid an highly sensitive method for investigating the chemical and physical history of the very extended ionized nebulae seen…
ROSAT Results on Groups and Clusters of Galaxies
S. Schindler
We present a selection of ROSAT results on the morphology, the evolution, and the masses of galaxy clusters and groups. ROSAT provides the first complete X-ray view on the Virgo cl…
The variable OVIII Warm Absorber in MCG-6-30-15
C. Otani, T. Kii, C. S. Reynolds +8
We present the results of a 4 day ASCA observation of the Seyfert galaxy MCG-6-30-15, focussing on the nature of the X-ray absorption by the warm absorber, characterizd by the K-ed…
The large scale structure of the soft X-ray background. I: Clusters of galaxies
Andrzej M. Soltan, Guenther Hasinger, Roland Egger +2
Large-scale fluctuations of the X-ray background are investigated using the ROSAT All-Sky Survey. The autocorrelation function of the extragalactic background at 1 keV is determine…
Is the X-ray spectrum of the Seyfert 2 galaxy NGC5252 intrinsically flat?
M. cappi, T. Mihara, M. Matsuoka +3
The first X-ray observation of the Seyfert 2 galaxy NGC5252 is reported. ASCA collected photons/detector enough to perform an accurate spectral analysis of this source.…
Evolution of a Magnetic Flux Tube in a Sunspot Penumbra
K. Jahn, R. Schlichenmaier, H. U. Schmidt
The motion of an individual magnetic flux tube inside the penumbra of a sunspot is studied numerically. Here, we present preliminary results. The thin flux tube approximation toget…
The Deficit of Distant Galaxy Clusters in the RIXOS X-ray Survey
F. J. Castander, R. G. Bower, R. S. Ellis +8
Clusters of galaxies are the largest gravitationally bound systems and therefore provide an important way of studying the formation and evolution of the large scale structure of th…
A test for partial correlation with censored astronomical data
M. G. Akritas, J. Siebert
A new procedure is presented, which allows, based on Kendall's , to test for partial correlation in the presence of censored data. Further, a significance level can be assigned…
On broad iron K-alpha lines in Seyfert 1 galaxies
A. C. Fabian, K. Nandra, C. S. Reynolds +5
The X-ray spectrum obtained by Tanaka et al from a long observation of the active galaxy MCG shows a broad iron K line skewed to low energies. The simplest interpretat…
Discovery of a Large Gravitational Arc in the X-ray Cluster A2280
I. M. Gioia, J. P. Henry, G. A. Luppino +6
This Letter presents the serendipitous discovery of a large arc in an X-ray selected cluster detected in the Rosat North Ecliptic Pole (NEP) survey. The cluster, associated with Ab…
ROSAT observations of radio-selected BL Lac objects
Andrea Comastri, Silvano Molendi, Gabriele Ghisellini
ROSAT observations of a homogeneous sample of radio--selected BL Lac objects are presented. Results of a detailed spectral analysis in the soft 0.1-2.0 keV energy range are discuss…
ASCA observations of high redshift quasars
J. Siebert, M. Matsuoka, W. Brinkmann +3
ASCA observations of 4 high redshift radio--loud quasars with 1.44z3.21 are presented. The spectral analysis for three of them (PKS 0332-403, PKS 0537-286, PKS 2149-306) reve…
Search for GRB counterparts
J. Greiner
A state-of-the-art review is given on the search for counterparts of -ray bursts. Particular emphasis is put on the search for flaring counterparts, i.e. emission during or shor…
GEMINGA'S SOFT X-RAY EMISSION AND THE STRUCTURE OF ITS SURFACE
Dany Page, Yu. A. Shibanov, V. E. Zavlin
We present a model to explain the decrease in the amplitude of the pulse profile with increasing energy observed in Geminga's soft X-ray surface thermal emission. We assume the pre…
Subcluster merging in clusters of galaxies and the cosmological density parameter
F. E. Nakamura, M. Hattori, S. Mineshige
Recent X-ray observations have established that collisions between subclusters of galaxies are rather common phenomena. Prompted by such observations, we have performed N-body simu…
Soft X-ray properties of "narrow-line" Seyfert 1 galaxies
Th. Boller, W. N. Brandt, H. Fink
We report on AGN with extremely soft X-ray spectra observed with ROSAT. From their optical emission lines these objects are classified as narrow-line Seyfert 1 galaxies (NLS1), alm…
Cooling flows, central galaxy--cluster alignments, X-ray absorption and dust
S. W. Allen, A. C. Fabian, A. C. Edge +2
We present the analysis of pointed ROSAT PSPC observations of five of the most luminous, intermediate redshift () clusters of galaxies detected in the ROSAT All-Sky…