5,415 research outputs found
Mid-Infrared line diagnostics of Active Galaxies -- A spectroscopic AGN survey with ISO-SWS
We present medium resolution (R approx. 1500) ISO-SWS 2.4--45 micron spectra
of a sample of 29 galaxies with active nuclei. This data set is rich in fine
structure emission lines tracing the narrow line regions and (circum-)nuclear
star formation regions, and it provides a coherent spectroscopic reference for
future extragalactic studies in the mid-infrared. We use the data set to
briefly discuss the physical conditions in the narrow line regions (density,
temperature, excitation, line profiles) and to test for possible differences
between AGN sub-types. Our main focus is on new tools for determining the
propertibes of dusty galaxies and on the AGN-starburst connection. We present
mid-IR line ratio diagrams which can be used to identify composite (starburst +
AGN) sources and to distinguish between emission excited by active nuclei and
emission from (circum-nuclear) star forming regions. For instance, line ratios
of high to low excitation lines like [O IV]25.9um/[Ne II]12.8um, that have been
used to probe for AGNs in dusty objects, can be examined in more detail and
with better statistics now. In addition, we present two-dimensional diagnostic
diagrams that are fully analogous to classical optical diagnostic diagrams, but
better suited for objects with high extinction. Finally, we discuss
correlations of mid-infrared line fluxes to the mid- and far-infrared
continuum. We compare these relations to similar relations in starburst
galaxies in order to examine the contribution of AGNs to the bolometric
luminosities of their host galaxies. The spectra are available in electronic
form from the authors.Comment: 24 pages, 23 figures, 5 tables. Accepted for A&
Metallicity of Red Giants in the Galactic Bulge from Near-Infrared Spectroscopy
We present K-band spectra of more than 110 M giants in Galactic bulge fields
interior to -4 degrees and as close as 0.2 degrees of the Galactic Center. From
the equivalent widths of three features in these spectra, EW(Na),EW(Ca), and
EW(CO) we calculate [Fe/H] for the stars with a calibration derived from
globular clusters Stephens et al (2000). The mean [Fe/H] for each field is in
good agreement with the results from Frogel et al. (1999) based on the slope of
the giant branch method. We find no evidence for a metallicity gradient along
the minor or major axes of the inner bulge (R < 0.6 kpc). A metallicity
gradient along the minor axis, found earlier, arises when fields located at
larger galactic radius are included. However, these more distant fields are
located outside of the infrared bulge defined by the COBE/DIRBE observations.
We compute the [Fe/H] distribution for the inner bulge and find a mean value of
-0.21 dex with a full width dispersion of 0.30 dex, close to the values found
for Baade's Window (BW) by Sadler et al. (1996) and to a theoretical prediction
for a bulge formed by dissipative collapse Molla et al (2000).Comment: 32 pages, 10 figures, AJ submitte
A new cubic theory of gravity in five dimensions: Black hole, Birkhoff's theorem and C-function
We present a new cubic theory of gravity in five dimensions which has second
order traced field equations, analogous to BHT new massive gravity in three
dimensions. Moreover, for static spherically symmetric spacetimes all the field
equations are of second order, and the theory admits a new asymptotically
locally flat black hole. Furthermore, we prove the uniqueness of this solution,
study its thermodynamical properties, and show the existence of a C-function
for the theory following the arguments of Anber and Kastor (arXiv:0802.1290
[hep-th]) in pure Lovelock theories. Finally, we include the
Einstein-Gauss-Bonnet and cosmological terms and we find new asymptotically AdS
black holes at the point where the three maximally symmetric solutions of the
theory coincide. These black holes may also possess a Cauchy horizon.Comment: 21 pages, no figures, V2: two appendices and some references added,
V3: New section on the generalization to arbitrary higher order. Analogy with
BHT new massive gravity Lagrangian made more precise, V4: Typos corrected. To
appear in CQ
A new formulation of oral viscous budesonide in treating of paediatric eosinophilic oesophagitis: a pilot study
OBJECTIVES:
Oral viscous budesonide is a recent therapeutic option for eosinophilic oesophagitis (EoE) compared with dietary restriction and inhaled steroids. This single-centre, open-label, not blinded study aims to evaluate the efficacy and safety of a new, preprepared oral viscous budesonide suspension (PVB) in children and adolescents with EoE.
METHODS:
We treated 36 children with PVB (29 boys; median age 12 years) with EoE diagnosed according to European Society for Paediatric Gastroenterology Hepatology and Nutrition guidelines. Patients <150 and >150 cm height received 2 and 4 mg PVB daily, respectively, for 12 weeks. Upper gastrointestinal endoscopy was performed at baseline, after 12 weeks of therapy and 24 weeks after the end of therapy. Baseline and post-treatment scores were calculated for symptoms, endoscopy, and histology. Serum cortisol was performed at baseline, 12, and 36 weeks.
RESULTS:
At the end of PVB trial, endoscopy showed macroscopic remission in 32 patients (88.9%), whereas at histology median pre- and post-treatment peak eosinophil count/high power field (HPF) markedly decreased from 42.2 (range: 15-100) to 2.9 (range: 0-30); moreover, mean symptom and histology scores impressively improved compared with baseline (P < 0.01). At 24 weeks after the end of PVB therapy, endoscopy showed oesophageal relapse in 21 patients (58.3%), whereas 15 (41.7%) were still in remission. Seven children (19.4%) with positive multichannel intraluminal impedance-pH were treated also with proton pump inhibitors. No significant difference between pre-/post-treatment morning cortisol levels occurred.
CONCLUSIONS:
The new PVB suspension presented in the present study is effective and safe for treating children with proven EoE. Larger placebo-controlled clinical trials would provide more information about dosing, efficacy, and long-term safety of this formulation, specifically designed for the oesophagus
Contrastación de diferentes criterios numéricos para la resolución de flujos potenciales mediante el empleo de coordenadas curvilíneas. Parte II: Potencial de velocidad
En este trabajo se analizan y contrastan diferentes criterios numéricos para la resolución de flujos potenciales subsónicos compresibles mediante el empleo de la función potencial de velocidad. La discretización del dominio se realiza en base a la generación de sistemas de coordenadas curvilíneas adaptables a los contornos; los criterios numéricos empleados son análogos a los utilizados para la función de corriente en la primera parte de este trabajoa, si bien se hace especial énfasis en el análisis de las condiciones de contorno por ser esencialmente de Neuman. Las diferencias entre los distintos esquemas numéricos y la influencia de ciertos parámetros son puestas de manifiesto para dos casos concretos de flujos confinados.Peer Reviewe
Spectrophotometric Redshifts. A New Approach to the Reduction of Noisy Spectra and its Application to GRB090423
We have developed a new method, close in philosophy to the photometric
redshift technique, which can be applied to spectral data of very low
signal-to-noise ratio. Using it we intend to measure redshifts while minimising
the dangers posed by the usual extraction techniques. GRB afterglows have
generally very simple optical spectra over which the separate effects of
absorption and reddening in the GRB host, the intergalactic medium, and our own
Galaxy are superimposed. We model all these effects over a series of template
afterglow spectra to produce a set of clean spectra that reproduce what would
reach our telescope. We also model carefully the effects of the
telescope-spectrograph combination and the properties of noise in the data,
which are then applied on the template spectra. The final templates are
compared to the two-dimensional spectral data, and the basic parameters
(redshift, spectral index, Hydrogen absorption column) are estimated using
statistical tools. We show how our method works by applying it to our data of
the NIR afterglow of GRB090423. At z ~ 8.2, this was the most distant object
ever observed. We use the spectrum taken by our team with the Telescopio
Nazionale Galileo to derive the GRB redshift and its intrinsic neutral Hydrogen
column density. Our best fit yields z=8.4^+0.05/-0.03 and N(HI)<5x10^20 cm^-2,
but with a highly non-Gaussian uncertainty including the redshift range z [6.7,
8.5] at the 2-sigma confidence level. Our method will be useful to maximise the
recovered information from low-quality spectra, particularly when the set of
possible spectra is limited or easily parameterisable while at the same time
ensuring an adequate confidence analysis.Comment: 6 pages, 6 figures. Accepted for publication in Astronomy and
Astrophysic
Contrastación de diferentes criterios numéricos para la resolución de flujos potenciales mediante el empleo de coordenadas curvilíneas. Parte II: Potencial de velocidad
En este trabajo se analizan y contrastan diferentes criterios numéricos para la resolución de flujos potenciales subsónicos compresibles mediante el empleo de la función potencial de velocidad. La discretización del dominio se realiza en base a la generación de sistemas de coordenadas curvilíneas adaptables a los contornos; los criterios numéricos empleados son análogos a los utilizados para la función de corriente en la primera parte de este trabajoa, si bien se hace especial énfasis en el análisis de las condiciones de contorno por ser esencialmente de Neuman. Las diferencias entre los distintos esquemas numéricos y la influencia de ciertos parámetros son puestas de manifiesto para dos casos concretos de flujos confinados.Peer Reviewe
[Fe II] and H2 filaments in the Supernova Remnant G11.2-0.3: Supernova Ejecta and Presupernova Circumstellar Wind
We present the results of near-infrared imaging and spectroscopic
observations of the young, core-collapse supernova remnant (SNR) G11.2-0.3. In
the [Fe II] 1.644 um image, we first discover long, clumpy [Fe II] filaments
within the radio shell of the SNR, together with some faint, knotty features in
the interior of the remnant. We have detected several [Fe II] lines and HI Br-G
line toward the peak position of the bright southeastern [Fe II] filament. The
derived extinction is large (Av=13 mag) and it is the brightest [Fe II]
filament detected toward SNRs to date. By analyzing two [Fe II] 1.644 um images
obtained in 2.2 yrs apart, we detect a proper motion corresponding to an
expansion rate of 0.''035 (0.''013) /yr [or 830 (310) km/s]. We also discover
two small H2 filaments. One is bright and along the SE boundary of the radio
shell, while the other is faint and just outside of its NE boundary. We have
detected H2 (2-1) S(3) line toward the former filament and derive an excitation
temperature of 2,100 K. We suggest that the H2 filaments are dense clumps in a
presupernova circumstellar wind swept up by the SNR shock while the [Fe II]
filaments are probably composed of both shocked wind material and shocked
supernova (SN) ejecta. The distribution of [Fe II] filaments may indicate that
the SN explosion in G11.2-0.3 was asymmetric as in Cassiopeia A. Our results
support the suggestion that G11.2-0.3 is a remnant of a SN IIL/b interacting
with a dense red supergiant wind.Comment: 30 pages with 10 figures, To appear in the Astrophysical Journa
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