On the Influence of X-Ray Galaxy Clusters in the Fluctuations of the Cosmic Microwave Background

The negative evolution found in X--ray clusters of galaxies limits the amount of available hot gas for the inverse Compton scattering of the Cosmic Microwave Background (the Sunyaev--Zel'dovich effect). Using a parametrisation of the X-ray luminosity function and its evolution in terms of a coalescence model (as presented in the analysis of a flux limited X-ray cluster sample by Edge et al. 1990), as well as a simple virialised structure for the clusters (which requires a gas to total mass fraction \approxgt 0.1 in order to reproduce observed properties of nearby clusters) we show that the Compton distortion $y$ parameter is about two orders of magnitude below the current FIRAS upper limits. Concerning the anisotropies imprinted on arcmin scales they are dominated by the hottest undetected objects. We show that they are negligible ({\Delta T\over T}\approxlt 10^{-7}) at wavelengths \lambda\approxgt 1~mm. At shorter wavelengths they become more important (${\Delta T\over T}\sim 10^{-6}$ at $\lambda\sim 0.3$~mm), but in fact most clusters will produce an isolated and detectable feature in sky maps. After removal of these signals, the fluctuations imprinted by the remaining clusters on the residual radiation are still much smaller. The conclusion is that X-ray clusters can be ignored as sources of Cosmic Microwave Background fluctuations.Comment: 20 pages Plain Tex, 7 figures available upon request,UCAST-94-0

X-ray sources as tracers of the large-scale structure in the Universe

We review the current status of studies of large-scale structure in the X-ray Universe. After motivating the use X-rays for cosmological purposes, we discuss the various approaches used on different angular scales including X-ray background multipoles, cross-correlations of the X-ray background with galaxy catalogues, clustering of X-ray selected sources and small-scale fluctuations and anisotropies in the X-ray background. We discuss the implications of the above studies for the bias parameter of X-ray sources, which is likely to be moderate for X-ray selected AGN and the X-ray background (~1-2). We finally outline how all-sky X-ray maps at hard X-rays and medium surveys with large sky coverage could provide important tests for the cosmological models.Comment: Invited review presented at the Workshop X-ray Astronomy'99: Stellar endpoints, AGN and the diffuse X-ray background (Astrophys Lett and Comm

H1320+551: A Seyfert 1.8/1.9 galaxy with an unabsorbed X-ray spectrum

We present new optical spectroscopic and XMM-Newton X-ray observations of the Active Galactic Nucleus H1320+551. The optical data (consistent with but of better quality than a previously published spectrum) show this source to be a Seyfert 1.8/1.9 galaxy at z=0.0653. The narrow line region is significantly reddened, with a Balmer decrement Ha/Hb~6 and the broad line region, with a barely detectable Hb broad component, shows a much pronnounced Balmer decrement (Ha/Hb>27). In spite of this, the EPIC-pn X-ray spectrum exhibits a power-law continuum with a soft excess that is well fitted by a black body, with no photoelectric absorption above the Galactic value. A Fe K emission line is also seen at a rest-frame energy ~6.5 keV with an equivalent width of ~400 eV, far too weak for the source being Compton-thick. Reconciling the optical and X-ray data requires the narrow line region being internally reddened but with small covering factor over the nuclear emission and the Balmer decrement of the broad line region being an intrinsic property rather than caused by reddening/absorption. The H1320+551 Seyfert 1.8/1.9 galaxy is not consistent with being an obscured Seyfert 1 nucleus, i.e., it does not match the basic AGN unified scheme hypothesis.Comment: 9 pages, 9 eps figures, to appear in MNRA

On the origin of the X-ray emission from a narrow-line radioquasar at z>1

We present new XMM-Newton X-ray observations of the z=1.246 narrow-line radioquasar RX J1011.2+5545 serendipitously discovered by ROSAT. The flat X-ray spectrum previously measured by ROSAT and ASCA is shown to be the result of a steep Gamma~1.8 power law spectrum seen through a moderate intrinsic absorbing column NH~4E21 cm^-2. The position of the X-ray source is entirely coincident with the nucleus of the radio source that we have resolved in new sensitive VLA observations at 3.6 and 6 cm, implying that scattering in the radio lobes is not responsible for the bulk of X-ray emission. In the EPIC pn image, a faint patch of X-ray emission is apparent 14'' to the NE of the main X-ray source. The former is positionally coincident with an apparently extended optical object with R~21.9, but there is no associated radio emission, thus ruling out the possibility that this represents a hotspot in a jet emanating from the primary X-ray source. No reflection features are detected in the X-ray spectrum of the narrow-line radioquasar, although an Fe line with equivalent width of up to 600 eV cannot be ruled out.Comment: 7 pages, 6 figures, MNRAS in the pres

The Damping Tail of CMB Anisotropies

By decomposing the damping tail of CMB anisotropies into a series of transfer functions representing individual physical effects, we provide ingredients that will aid in the reconstruction of the cosmological model from small-scale CMB anisotropy data. We accurately calibrate the model-independent effects of diffusion and reionization damping which provide potentially the most robust information on the background cosmology. Removing these effects, we uncover model-dependent processes such as the acoustic peak modulation and gravitational enhancement that can help distinguish between alternate models of structure formation and provide windows into the evolution of fluctuations at various stages in their growth.Comment: 24pgs, aaspp4, 10 figs. included; supporting material (e.g. color figures) at http://www.sns.ias.edu/~whu/pub.htm

Zygomycosis in Two Hematologic Cases

Zygomycosis are invasive mould infections, rarely diagnosed in hematologic patients. Most of the cases published are in patients with prolonged neutropenia, along with other risk factors such as the use of prior broad-spectrum antibiotics (including new antifungal agents, such as voriconazole), diabetes mellitus (with or without ketoacidosis), malnutrition, iron overload (with or without the use of deferoxamine). These infections have poor prognosis due to the involvement of vital anatomic structures and late diagnosis. Until recent years, the treatment was based on high doses of amphotericin B plus surgical debridement. Here we present two patients with hematologic diseases (one with leukemia, the second with aplastic anemia) with an impaired immune system and the diagnosis of zygomycosis. The survival of one of them was mainly due to early diagnosis and surgical debridement; unfortunately the second was misdiagnosed as an extensive ecchymosis due to thrombocytopenia and died with CNS involvement