Do the low PN velocity dispersions around elliptical galaxies imply that these lack dark matter?

While kinematical modelling of the low PN velocity dispersions observed in the outer regions of elliptical galaxies suggest a lack of dark matter around these galaxies, we report on an analysis of a suite of $N$-body simulations (with gas) of major mergers of spiral galaxies embedded in dark matter halos, and find that the outer velocity dispersions are as low as observed for the PNe. The inconsistency between our dynamical modelling and previous kinematical modelling is caused by very radial stellar orbits and projection effects when viewing face-on oblate ellipticals. Our simulations (weakly) suggest the youth of PNe around ellipticals, and we propose that the universality of the PN luminosity function may be explained if the bright PNe in ellipticals are formed after the regular accretion of very low mass gas-rich galaxies.Comment: Contributed talk at meeting, "Planetary Nebulae as astronomical tools", Gdansk, Poland, June-July 2005, ed. R. Szczerba, G. Stasi\'nska, and S. K. G\'orny, AIP Conference Proceedings, Melville, New York, 2005. 4 or 5 pages, 6 figure

Lost and found dark matter in elliptical galaxies

The kinematical properties of elliptical galaxies formed during the mergers of equal mass, stars+gas+dark matter spiral galaxies are compared to the observed low velocity dispersions found for planetary nebulae on the outskirts of ellipticals, which have been interpreted as pointing to a lack of dark matter in ellipticals (which poses a problem for the standard model of galaxy formation). We find that the velocity dispersion profiles of the stars in the simulated ellipticals match well the observed ones. The low outer stellar velocity dispersions are mainly caused by the radial orbits of the outermost stars, which, for a given binding energy must have low angular momentum to reach their large radial distances, usually driven out along tidal tails.Comment: Talk presented at 21st IAP meeting, Mass Profiles andShapes of Cosmological Structures. Ed. G. A. Mamon, F. Combes, C. Deffayet & B. Fort (Paris: EDP), 4 pages, 3 figures (4 plots

The Hubble Legacy Archive NICMOS Grism Data

The Hubble Legacy Archive (HLA) aims to create calibrated science data from the Hubble Space Telescope archive and make them accessible via user-friendly and Virtual Observatory (VO) compatible interfaces. It is a collaboration between the Space Telescope Science Institute (STScI), the Canadian Astronomy Data Centre (CADC) and the Space Telescope - European Coordinating Facility (ST-ECF). Data produced by the Hubble Space Telescope (HST) instruments with slitless spectroscopy modes are among the most difficult to extract and exploit. As part of the HLA project, the ST-ECF aims to provide calibrated spectra for objects observed with these HST slitless modes. In this paper, we present the HLA NICMOS G141 grism spectra. We describe in detail the calibration, data reduction and spectrum extraction methods used to produce the extracted spectra. The quality of the extracted spectra and associated direct images is demonstrated through comparison with near-IR imaging catalogues and existing near-IR spectroscopy. The output data products and their associated metadata are publicly available through a web form at http://hla.stecf.org and via VO interfaces. In total, 2470 spectra of 1923 unique targets are included in the current release.Comment: 18 pages, 21 figures, accepted for publication in Astronomy & Astrophysic

Bacillary angiomatosis in HIV-infected patients - An epidemiological and clinical study

Background: No data were available on the epidemiological and clinical characteristics of bacillary angiomatosis (BA) in Germany. Objective:To determine epidemiological and clinical data on HIV-associated BA. Methods: A chart review of all BA cases between 1990 and 1998 was performed in 23 German AIDS treatment units. Results: A total of 21 cases of BA was diagnosed. During th is period, the participating HIV centers treated about 17,000 HIV-infected patients. As a result, a BA prevalence of 1.2 cases/1,000 patients can be assumed. 19 BA were localized in the skin; in 5 cases bones and in 4 cases the liver were involved. Out of 20 patients who received antibiotic therapy, 13 had complete remission. The median time of duration up to complete remission was 32 days (9-82), During the follow-up of the 20 patients, 7 relapses were observed, Conclusion: BA is a rare HIV-associated disease with a prevalence of 1,2 cases/1,000 patients in the presented study. Copyright (C) 2000 S. Karger AG, Basel

Kinematic deprojection and mass inversion of spherical systems of known velocity anisotropy

Traditionally, the mass / velocity anisotropy degeneracy (MAD) inherent in the spherical, stationary, non-streaming Jeans equation has been handled by assuming a mass profile and fitting models to the observed kinematical data. Here, the opposite approach is considered: the equation of anisotropic kinematic projection is inverted for known arbitrary anisotropy to yield the space radial velocity dispersion profile in terms of an integral involving the radial profiles of anisotropy and isotropic dynamical pressure. Then, through the Jeans equation, the mass profile is derived in terms of double integrals of observable quantities. Single integral formulas for both deprojection and mass inversion are provided for several simple anisotropy models (isotropic, radial, circular, general constant, Osipkov-Merritt, Mamon-Lokas and Diemand-Moore-Stadel). Tests of the mass inversion on NFW models with these anisotropy models yield accurate results in the case of perfect observational data, and typically better than 70% (in 4 cases out of 5) accurate mass profiles for the sampling errors expected from current observational data on clusters of galaxies. For the NFW model with mildly increasing radial anisotropy, the mass is found to be insensitive to the adopted anisotropy profile at 7 scale radii and to the adopted anisotropy radius at 3 scale radii. This anisotropic mass inversion method is a useful complementary tool to analyze the mass and anisotropy profiles of spherical systems. It provides the practical means to lift the MAD in quasi-spherical systems such as globular clusters, round dwarf spheroidal and elliptical galaxies, as well as groups and clusters of galaxies, when the anisotropy of the tracer is expected to be linearly related to the slope of its density.Comment: Accepted in MNRAS. 19 pages. Minor changes from previous version: Table 1 of nomenclature, some math simplifications, paragraph in Discussion on alternative deprojection method by deconvolution. 19 pages. 6 figure

The effect of minihaloes on cosmic reionization

One of the most debated issues in the theoretical modeling of cosmic reionization is the impact of small-mass gravitationally-bound structures. We carry out the first numerical investigation of the role of such sterile `minihaloes', which serve as self-shielding screens of ionizing photons. Minihaloes are too small to be properly resolved in current large-scale cosmological simulations, and thus we estimate their effects using a sub-grid model, considering two cases that bracket their effect within this framework. In the `extreme suppression' case in which minihalo formation ceases once a region is partially ionized, their effect on cosmic reionization is modest, reducing the volume-averaged ionization fraction by an overall factor of less than 15%. In the other extreme, in which minihalo formation is never suppressed, they delay complete reionization as much as Delta z~2, in rough agreement with the results from a previous semi-analytical study by the authors. Thus, depending on the details of the minihalo formation process, their effect on the overall progress of reionization can range from modest to significant, but the minihalo photon consumption is by itself insufficient to force an extended reionization epoch.Comment: 9 pages, 2 figures, accepted for pubblication in MNRA

The Hubble Legacy Archive ACS Grism Data

A public release of slitless spectra, obtained with ACS/WFC and the G800L grism, is presented. Spectra were automatically extracted in a uniform way from 153 archival fields (or "associations") distributed across the two Galactic caps, covering all observations to 2008. The ACS G800L grism provides a wavelength range of 0.55-1.00 \mu$m, with a dispersion of$40 \ \AA / pixel$and a resolution of$\sim 80\ \AA$for point-like sources. The ACS G800L images and matched direct images were reduced with an automatic pipeline that handles all steps from archive retrieval, alignment and astrometric calibration, direct image combination, catalogue generation, spectral extraction and collection of metadata. The large number of extracted spectra (73,581) demanded automatic methods for quality control and an automated classification algorithm was trained on the visual inspection of several thousand spectra. The final sample of quality controlled spectra includes 47,919 datasets (65of extracted spectra) for$32,149$unique objects, with a median$i_{\rm AB}$-band magnitude of 23.7, reaching 26.5 AB for the faintest objects. Each released dataset contains science-ready 1D and 2D spectra, as well as multi-band image cutouts of corresponding sources and a useful preview page summarising the direct and slitless data, astrometric and photometric parameters. In order to characterize the slitless spectra, emission-line flux and equivalent width sensitivity of the ACS data were compared with public ground-based spectra in the GOODS-South field. An example list of emission line galaxies with two or more identified lines is also included, covering the redshift range$0.2-4.6$.Comment: Accepted for publication in Astronomy and Astrophysics; 29 pages, 16 Figures, 4 Tables in text and 3Tables in Appendi

Fibroblast growth factor receptor (FGFR) alterations in squamous differentiated bladder cancer: a putative therapeutic target for a small subgroup.

Although drugable fibroblast growth factor receptor (FGFR) alterations in squamous cell carcinomas (SCC) of various entities are well known, little is known about FGFR modifications in squamous differentiated bladder cancer. Therefore, our study evaluated FGFR1-3 alterations as a putative therapeutic target in this subgroup. We analyzed 73 squamous differentiated bladder cancers (n = 10 pT2, n = 55 pT3, n = 8 pT4) for FGFR1-3 protein expression, FGFR1-3 copy number variations, FGFR3 chromosomal rearrangements (fluorescence in situ hybridization (FISH)) and FGFR3 mutations (SNapShot analysis). Only single cases displayed enhanced protein expression, most frequently FGFR3 overexpression (9.4% (6/64)). FISH showed no amplifications of FGFR1, 2 or 3. Break apart events were only slightly above the cut off in 12.1% (8/66) of cases and no FGFR3-TACC3 rearrangements could be proven by qPCR. FGFR3 mutations (p.S249C) were found in 8.5% (6/71) of tumors and were significantly associated with FGFR3 protein overexpression (p < 0.001), and unfavourable clinical outcome (p = 0.001). Our findings are consistent with the results of the TCGA data set for the "squamous-like" subtype of bladder cancer (n = 85), which revealed reduced overall expression of FGFR1 and FGFR2 in tumors compared to normal tissue, while expression of FGFR3 remained high. In the TCGA "squamous-like" subtype FGFR3 mutations were found in 4.9% and correlated with high FGFR3 RNA expression. Mutations of FGFR1 and FGFR2 were less frequent (2.4% and 1.2%). Hence, our comprehensive study provides novel insights into a subgroup of squamous differentiated bladder tumors that hold clues for novel therapeutic regimens and may benefit from FGFR3-targeted therapies