Structural properties of disk galaxies I. The intrinsic ellipticity of bulges

(Abridged) A variety of formation scenarios was proposed to explain the diversity of properties observed in bulges. Studying their intrinsic shape can help in constraining the dominant mechanism at the epochs of their assembly. The structural parameters of a magnitude-limited sample of 148 unbarred S0--Sb galaxies were derived in order to study the correlations between bulges and disks as well as the probability distribution function (PDF) of the intrinsic equatorial ellipticity of bulges. It is presented a new fitting algorithm (GASP2D) to perform the two-dimensional photometric decomposition of galaxy surface-brightness distribution. This was assumed to be the sum of the contribution of a bulge and disk component characterized by elliptical and concentric isophotes with constant (but possibly different) ellipticity and position angles. Bulge and disk parameters of the sample galaxies were derived from the J-band images which were available in the Two Micron All Sky Survey. The PDF of the equatorial ellipticity of the bulges was derived from the distribution of the observed ellipticities of bulges and misalignments between bulges and disks. Strong correlations between the bulge and disk parameters were found. About 80% of bulges in unbarred lenticular and early-to-intermediate spiral galaxies are not oblate but triaxial ellipsoids. Their mean axial ratio in the equatorial plane is = 0.85. There is not significant dependence of their PDF on morphology, light concentration, and luminosity. The interplay between bulge and disk parameters favors scenarios in which bulges assembled from mergers and/or grew over long times through disk secular evolution. But all these mechanisms have to be tested against the derived distribution of bulge intrinsic ellipticities.Comment: 24 pages, 13 figures, accepted for publication in A&A, corrected proof

Inversion of stellar statistics equation for the Galactic Bulge

A method based on Lucy (1974, AJ 79, 745) iterative algorithm is developed to invert the equation of stellar statistics for the Galactic bulge and is then applied to the K-band star counts from the Two-Micron Galactic Survey in a number of off-plane regions (10 deg.>|b|>2 deg., |l|<15 deg.). The top end of the K-band luminosity function is derived and the morphology of the stellar density function is fitted to triaxial ellipsoids, assuming a non-variable luminosity function within the bulge. The results, which have already been outlined by Lopez-Corredoira et al.(1997, MNRAS 292, L15), are shown in this paper with a full explanation of the steps of the inversion: the luminosity function shows a sharp decrease brighter than M_K=-8.0 mag when compared with the disc population; the bulge fits triaxial ellipsoids with the major axis in the Galactic plane at an angle with the line of sight to the Galactic centre of 12 deg. in the first quadrant; the axial ratios are 1:0.54:0.33, and the distance of the Sun from the centre of the triaxial ellipsoid is 7860 pc. The major-minor axial ratio of the ellipsoids is found not to be constant. However, the interpretation of this is controversial. An eccentricity of the true density-ellipsoid gradient and a population gradient are two possible explanations. The best fit for the stellar density, for 1300 pc<t<3000 pc, are calculated for both cases, assuming an ellipsoidal distribution with constant axial ratios, and when K_z is allowed to vary. From these, the total number of bulge stars is ~ 3 10^{10} or ~ 4 10^{10}, respectively.Comment: 19 pages, 23 figures, accepted in MNRA

Astrophysical inputs on the SUSY dark matter annihilation detectability

If dark matter (DM), which is considered to constitute most of the mass of galaxies, is made of supersymmetric (SUSY) particles, the centers of galaxies should emit gamma-rays produced by their self-annihilation. We present accurate estimates of continuum gamma-ray fluxes due to neutralino annihilation in the central regions of the Milky Way. We use detailed models of our Galaxy, which satisfy available observational data, and include some important physical processes, which were previously neglected. Our models predict that spatially extended annihilation signal should be detected at high confidence levels by incoming experiments assuming that neutralinos make up most of the DM in the Universe and that they annihilate according to current SUSY models.Comment: 4 pages, submitted to Physical Review Letter

Determining the Physical Properties of the B Stars I. Methodology and First Results

We describe a new approach to fitting the UV-to-optical spectra of B stars to model atmospheres and present initial results. Using a sample of lightly reddened stars, we demonstrate that the Kurucz model atmospheres can produce excellent fits to either combined low dispersion IUE and optical photometry or HST FOS spectrophotometry, as long as the following conditions are fulfilled: 1) an extended grid of Kurucz models is employed, 2) the IUE NEWSIPS data are placed on the FOS absolute flux system using the Massa & Fitzpatrick (1999) transformation, and 3) all of the model parameters and the effects of interstellar extinction are solved for simultaneously. When these steps are taken, the temperatures, gravities, abundances and microturbulence velocities of lightly reddened B0-A0 V stars are determined to high precision. We also demonstrate that the same procedure can be used to fit the energy distributions of stars which are reddened by any UV extinction curve which can be expressed by the Fitzpatrick & Massa (1990) parameterization scheme. We present an initial set of results and verify our approach through comparisons with angular diameter measurements and the parameters derived for an eclipsing B star binary. We demonstrate that the metallicity derived from the ATLAS 9 fits to main sequence B stars is essentially the Fe abundance. We find that a near zero microturbulence velocity provides the best-fit to all but the hottest or most luminous stars (where it may become a surrogate for atmospheric expansion), and that the use of white dwarfs to calibrate UV spectrophotometry is valid.Comment: 17 pages, including 2 pages of Tables and 6 pages of Figures. Astrophysical Jounral, in pres

Tadalafil for the Treatment of Pulmonary Arterial Hypertension A Double-Blind 52-Week Uncontrolled Extension Study

ObjectivesThe aim of this study was to evaluate the long-term safety and durability of efficacy of tadalafil for pulmonary arterial hypertension.BackgroundTadalafil is an oral phosphodiesterase-5 inhibitor approved for PAH treatment. In the multicenter, placebo-controlled, randomized, 16-week PHIRST (Pulmonary Arterial Hypertension and Response to Tadalafil) study, tadalafil 40 mg improved exercise capacity and delayed clinical worsening.MethodsEligible patients from PHIRST received once-daily tadalafil 20 mg (T20 mg) or 40 mg (T40 mg) (n = 357) in the double-blind, 52-week, uncontrolled extension study (PHIRST-2); 293 patients completed PHIRST-2. Durability of efficacy was explored using the 6-min walk distance (6MWD) test. Clinical worsening and changes in World Health Organization functional class were evaluated.ResultsThe safety profile of tadalafil in PHIRST-2 was similar to that in PHIRST, with typical phosphodiesterase-5 inhibitor adverse events. The 6MWDs achieved in PHIRST for the subset of patients receiving T20 mg and T40 mg in both PHIRST and PHIRST-2 (406 ± 67 m [n = 52] and 413 ± 81 m [n = 59] at PHIRST-2 enrollment, respectively) were maintained at PHIRST-2 completion (415 ± 80 m [n = 51] and 410 ± 78 m [n = 59], respectively). Numerically fewer patients who were on T40 mg in PHIRST and PHIRST-2 experienced World Health Organization functional class deterioration (6% [n = 5]) compared with those randomized to T20 mg (9% [n = 7]) across both studies. Post hoc analyses showed that background bosentan use and higher 6MWD at PHIRST baseline were associated with fewer clinical worsening events.ConclusionsLong-term treatment with tadalafil was well tolerated in patients with pulmonary arterial hypertension. In patients receiving either T20 mg or T40 mg, the improvements in 6MWD demonstrated in the 16-week PHIRST study appeared sustained for up to 52 additional weeks of treatment in PHIRST-2. (Pulmonary Arterial Hypertension and Response to Tadalafil Study; NCT00549302

Long-term results from the EARLY study of bosentan in WHO functional class II pulmonary arterial hypertension patients.

Abstract BACKGROUND: The double-blind phase of the EARLY study of bosentan remains the only randomized controlled trial of a PAH-targeted therapy in World Health Organization functional class (FC) II patients. We report on the efficacy, safety, disease worsening, survival and prognostic factors in mildly symptomatic pulmonary arterial hypertension (PAH) patients treated with bosentan in the open-label extension phase of the EARLY study. METHODS: Exploratory efficacy outcomes included 6-minute walk distance (6 MWD) and WHO FC. Adverse events were recorded. Kaplan-Meier analysis was used to estimate time to first PAH worsening event (death, initiation of intravenous or subcutaneous prostanoids, atrial septostomy or lung transplantation) and survival. Cox regression analysis determined factors prognostic of survival. RESULTS: Median exposure to bosentan (n=173) was 51 months. At the end of the bosentan-treatment assessment period, 77.8% of patients were in WHO FC I/II. Adverse events led to discontinuation of bosentan in 20.2% of patients. Aminotransferase elevations>3× upper limit of normal occurred in 16.8%. Four-year PAH-event-free survival and survival were 79.5% (95% confidence intervals [95% CI] 73.4, 85.6) and 84.8% [95% CI 79.4, 90.2], respectively. Low 6 MWD, low mixed venous oxygenation, high N-terminal pro hormone of brain natriuretic peptide levels and PAH associated with connective tissue disease were associated with a higher risk of death. CONCLUSIONS: The majority of patients exposed to long-term bosentan maintained or improved their functional class. Approximately 20% of the patients discontinued treatment because of adverse events, which were most commonly PAH worsening and elevated liver enzymes

Structural properties of disk galaxies. II. Intrinsic shape of bulges

(Abridged) The structural parameters of a magnitude-limited sample of 148 unbarred S0-Sb galaxies were analyzed to derive the intrinsic shape of their bulges. We developed a new method to derive the intrinsic shape of bulges based on the geometrical relationships between the apparent and intrinsic shapes of bulges and disks. The equatorial ellipticity and intrinsic flattening of bulges were obtained from the length of the apparent major and minor semi-axes of the bulge, twist angle between the apparent major axis of the bulge and the galaxy line of nodes, and galaxy inclination. We found that the intrinsic shape is well constrained for a subsample of 115 bulges with favorable viewing angles. A large fraction of them is characterized by an elliptical section (B/A<0.9). This fraction is 33%, 55%, and 43% if using their maximum, mean, or median equatorial ellipticity, respectively. Most are flattened along their polar axis (C<(A+B)/2). The distribution of triaxiality is strongly bimodal. This bimodality is driven by bulges with Sersic index n>2, or equivalently, by the bulges of galaxies with a bulge-to-total ratio B/T>0.3. In particular, bulges with n\leq2 and with B/T\leq0.3 show a larger fraction of oblate axisymmetric (or nearly axisymmetric) bulges, a smaller fraction of triaxial bulges, and fewer prolate axisymmetric (or nearly axisymmetric) bulges with respect to bulges with n>2 and with B/T>0.3, respectively. According to predictions of the numerical simulations of bulge formation, bulges with n\leq2, which show a high fraction of oblate axisymmetric (or nearly axisymmetric) shapes and have B/T\leq0.3, could be the result of dissipational minor mergers. Both major dissipational and dissipationless mergers seem to be required to explain the variety of shapes found for bulges with n>2 and B/T>0.3.Comment: 16 pages, 12 figures; accepted for publication in A&

Long-term safety and efficacy of imatinib in pulmonary arterial hypertension

Abstract BACKGROUND: Imatinib is an oral inhibitor of several protein kinases implicated in the pathophysiology of pulmonary hypertension. Treatment with imatinib resulted in improved hemodynamics and exercise capacity in a controlled trial (Imatinib [QTI571] in Pulmonary Arterial Hypertension, a Randomized Efficacy Study [IMPRES]), among pulmonary arterial hypertension (PAH) patients inadequately responsive to 2 to 3 PAH-specific therapies. METHODS: The long-term (up to 204 weeks) safety and efficacy of imatinib in this open-label extension study were reviewed until early study termination on April 16, 2014. Of 202 IMPRES-enrolled patients, 66 imatinib and 78 placebo recipients entered the extension. RESULTS: Overall, 93.8% (135 of 144) of patients discontinued the extension study; administrative issues (i.e., sponsor termination; 32.6%) and adverse events (31.3%) were the primary reasons for discontinuation. Nine patients completed the extension study before it was terminated. Serious and unexpected adverse events were frequent. These included 6 subdural hematomas in the extension study and 17 deaths during or within 30 days of study end. Although the patients who tolerated imatinib and remained in the extension for a longer duration did experience an improvement in functional class and walk distance, most discontinued the drug and the study. CONCLUSIONS: Severe adverse events, significant side effects, and a high discontinuation rate limit the utility of imatinib in the treatment of PAH. These risks outweigh any possible improvements in hemodynamics and walk distance seen in those patients able to remain on drug. The off-label use of this compound in PAH is discouraged