Palomar 13: a velocity dispersion inflated by binaries ?

Recently, combining radial velocities from Keck/HIRES echelle spectra with published proper motion membership probabilities, Cote et al (2002) observed a sample of 21 stars, probable members of Palomar 13, a globular cluster in the Galactic halo. Their projected velocity dispersion sigma_p = 2.2 +/-0.4 km/s gives a mass-to-light ratio M/L_V = 40 +24/-17, about one order of magnitude larger than the usual estimate for globular clusters. We present here radial velocities measured from three different CCD frames of commissioning observations obtained with the new ESO/VLT instrument FLAMES (Fibre Large Array Multi Element Spectrograph). From these data, now publicly available, we measure the homogeneous radial velocities of eight probable members of this globular cluster. A new projected velocity dispersion sigma_p = 0.6-0.9 +/-0.3 km/s implies Palomar 13 mass-to-light ratio M/L_V = 3-7, similar to the usual value for globular clusters. We discuss briefly the two most obvious reasons for the previous unusual mass-to-light ratio finding: binaries, now clearly detected, and more homogeneous data from the multi-fibre FLAMES spectrograph.Comment: 9 pages, 2 Postscript figure

Growing supermassive black holes in the late stages of galaxy mergers are heavily obscured

Mergers of galaxies are thought to cause significant gas inflows to the inner parsecs, which can activate rapid accretion onto supermassive black holes (SMBHs), giving rise to Active Galactic Nuclei (AGN). During a significant fraction of this process, SMBHs are predicted to be enshrouded by gas and dust. Studying 52 galactic nuclei in infrared-selected local Luminous and Ultra-luminous infrared galaxies in different merger stages in the hard X-ray band, where radiation is less affected by absorption, we find that the amount of material around SMBHs increases during the last phases of the merger. We find that the fraction of Compton-thick (CT, $N_{\rm\,H}\geq 10^{24}\rm\,cm^{-2}$) AGN in late merger galaxies is higher ($f_{\rm\,CT}=65^{+12}_{-13}\%$) than in local hard X-ray selected AGN ($f_{\rm\,CT}=27\pm 4\%$), and that obscuration reaches its maximum when the nuclei of the two merging galaxies are at a projected distance of $D_{12}\simeq0.4-10.8$ kiloparsecs ($f_{\rm\,CT}=77_{-17}^{+13}\%$). We also find that all AGN of our sample in late merger galaxies have $N_{\rm\,H}> 10^{23}\rm\,cm^{-2}$, which implies that the obscuring material covers $95^{+4}_{-8}\%$ of the X-ray source. These observations show that the material is most effectively funnelled from the galactic scale to the inner tens of parsecs during the late stages of galaxy mergers, and that the close environment of SMBHs in advanced mergers is richer in gas and dust with respect to that of SMBHs in isolated galaxies, and cannot be explained by the classical AGN unification model in which the torus is responsible for the obscuration.Comment: Final version matching the article published in MNRAS - 30 pages, 16 figure

Effect of replacing dried skim milk with soy products on function and morphology of the small intestine in nursery pigs

Sixty-six pigs (averaging 21 d of age and 11.8 lb) were used in a 7-d experiment to evaluate the effects of specially processed soy products on function and morphology of the small intestine. Treatments were: 1) corn-milk products control; 2, 3, 4, and 5) simple corn-based diets with either soybean meal, soy isolate2, soy concentrate3, or modified soy flour4 as the major protein source; 6) a high nutrient density diet (HNDD) containing 20% dried skim milk and 20% dried whey; 7, 8, and 9) the HNDD with soy isolate, soy concentrate, or modified soy flour plus lactose replacing 100% of the dried skim milk. Xylose absorption was determined from plasma collected on d 6 post-weaning. On d 7 post-weaning, serum was collected for determination of antisoy titers, and four pigs/trt were sacrificed for collection of tissues to determine villus height and crypt depth. The milk diet was more digestible than the other treatments, and the complex diets were more digestible than the simple diets. Nitrogen from soy isolate and concentrate was more digestible than N from soy flour in the simple diets. Pigs fed diets with the specially processed soy products had lower antisoy titers than pigs fed diets with soybean meal. However, diets with the specially processed soy products resulted in lower xylose absorptions than the diet with soybean meal. Pigs fed the corn-milk products control tended to have longer villi and lower crypt depths than pigs fed the other treatments. In conclusion, it appears that the specially processed soy products were better utilized than soybean meal but of lower nutritional value than milk products. Of the specially processed soy products, soy protein isolate had the greatest nutritional value in simple diets, but the soy products were of similar nutritional value in the complex diets.; Swine Day, Manhattan, KS, November 15, 199

Two distinct ancient components in the Sculptor Dwarf Spheroidal Galaxy: First Results from DART

We have found evidence for the presence of two distinct ancient stellar components (both geq 10 Gyr old) in the Sculptor dwarf spheroidal galaxy. We used the ESO Wide Field Imager (WFI) in conjunction with the VLT/FLAMES spectrograph to study the properties of the resolved stellar population of Sculptor out to and beyond the tidal radius. We find that two components are discernible in the spatial distribution of Horizontal Branch stars in our imaging, and in the [Fe/H] and v_hel distributions for our large sample of spectroscopic measurements. They can be generally described as a ``metal-poor'' component ([Fe/H] -1.7). The metal-poor stars are more spatially extended than the metal-rich stars, and they also appear to be kinematically distinct. These results provide an important insight into the formation processes of small systems in the early universe and the conditions found there. Even this simplest of galaxies appears to have had a surprisingly complex early evolution.Comment: accepted for publication in ApJL 12 pages, 4 figure

30 years of multi-wavelength observations of 3C 273

We present a wide multi-wavelength database of most observations of the quasar 3C 273 obtained during the last 30 years. This database is the most complete set of observations available for an active galactic nucleus (AGN). It contains nearly 20'000 observations grouped together into 70 light curves covering 16 orders of magnitude in frequency from the radio to the gamma-ray domain. The database is constituted of many previously unpublished observations and of most publicly available data gathered in the literature and on the World Wide Web (WWW). It is complete to the best of our knowledge, except in the optical (UBV) domain where we chose not to add all observations from the literature. In addition to the photometric data, we present the spectra of 3C 273 obtained by the International Ultraviolet Explorer (IUE) satellite. In the X-ray domain, we used the spectral fit parameters from the literature to construct the light curves. Apart from describing the data, we show the most representative light curves and the average spectrum of 3C 273. The database is available on the WWW in a homogeneous and clear form and we wish to update it regularly by adding new observations.Comment: 12 pages, 6 figures, to be published in A&AS, data available at: http://obswww.unige.ch/3c273

Cloning Hubble Deep Fields I: A Model-Independent Measurement of Galaxy Evolution

We present a model-independent method of quantifying galaxy evolution in high-resolution images, which we apply to the Hubble Deep Field (HDF). Our procedure is to k-correct all pixels belonging to the images of a complete set of bright galaxies and then to replicate each galaxy image to higher redshift by the product of its space density, 1/V_{max}, and the cosmological volume. The set of bright galaxies is itself selected from the HDF, because presently the HDF provides the highest quality UV images of a redshift-complete sample of galaxies (31 galaxies with I<21.9, \bar{z}=0.5, and for which V/V_{max} is spread fairly). These galaxies are bright enough to permit accurate pixel-by-pixel k-corrections into the restframe UV (\sim 2000 A). We match the shot noise, spatial sampling and PSF smoothing of the HDF data, resulting in entirely empirical and parameter-free ``no-evolution'' deep fields of galaxies for direct comparison with the HDF. In addition, the overcounting rate and the level of incompleteness can be accurately quantified by this procedure. We obtain the following results. Faint HDF galaxies (I>24) are much smaller, more numerous, and less regular than our ``no-evolution'' extrapolation, for any interesting geometry. A higher proportion of HDF galaxies ``dropout'' in both U and B, indicating that some galaxies were brighter at higher redshifts than our ``cloned'' z\sim0.5 population.Comment: 51 pages, 23 figures, replacement includes figures not previously include

Cattle tick infestation in Brangus cattle raised with Nellore in central Brazil.

The present study evaluated the behavior of Rhipicephalus microplus naturally infesting Brangus cattle raised with Nellore animals in the municipality of Água Clara, state of Mato Grosso do Sul, Central Brazil. For the field experiment composed of a group with 15 Brangus animals and 15 Nellore animals and a control group with 30 Brangus cattle, all at the post-weaning stage. The 2 groups were kept for 6 months in 2 adjacent paddocks, naturally infested with ticks, at a stocking rate of approximately 0.6 of an animal unit per hectare (AU/ha). Every 18 days, the animals were weighed, and ticks on both sides of each bovine were counted. Every 36 days, blood was collected for hematocrit measurement and molecular diagnosis of the 3 pathogens that cause tick fever. The Brangus animals had 6.8 times more ticks than the Nellore cattle. No significant difference was observed in the weight gain of the Brangus and Nellore animals, and no correlation between the number of ticks and weight was observed in either group. During the 6 months of the study, all animals presented normal hematocrit, were positive for Babesia bigemina and Anaplasma marginale, and were negative for Babesia bovis. Animals in Group 1 produced 27% fewer ticks than the animals in Group 2. The production rate of engorged female ticks in Nellore and Brangus cattle was 0.83% and 2.01%, respectively. Considering the infestation pattern required to produce 10 engorged females/day/animal, the Nellore and Brangus animals required 1,204 and 497 larvae/day, respectively. Our estimates showed that Brangus cattle need only 11.3% of the larvae in the pastures with Nellore cattle to maintain the infestation level observed in the present study. Brangus animals raised with Nellore cattle do not have a lower parasitic load and continue to suffer from tick infestation. Finally, Nellore cattle raised with Brangus cattle do not act as a cleaner because this grouping does not contribute to a reduced infestation in the Brangus animals. Key words: Bovine. Cattle tick. Control. Infestation.Título em português: Infestação de carrapatos em bovinos Brangus criados com Nelore no Brasil central