Study of time lags in HETE-2 Gamma-Ray Bursts with redshift: search for astrophysical effects and Quantum Gravity signature

The study of time lags between spikes in Gamma-Ray Bursts light curves in different energy bands as a function of redshift may lead to the detection of effects due to Quantum Gravity. We present an analysis of 15 Gamma-Ray Bursts with measured redshift, detected by the HETE-2 mission between 2001 and 2006 in order to measure time lags related to astrophysical effects and search for Quantum Gravity signature in the framework of an extra-dimension string model. The use of photon-tagged data allows us to consider various energy ranges. Systematic effects due to selection and cuts are evaluated. No significant Quantum Gravity effect is detected from the study of the maxima of the light curves and a lower limit at 95% Confidence Level on the Quantum Gravity scale parameter of 3.2x10**15 GeV is set.Comment: 4 pages, 5 figures. v3: Error corrected in Eq. 1. Results updated. Proceedings of the 30th ICRC, Merida, Mexico (2007

Broad band X-ray spectral properties of Gamma-ray bursts with BeppoSAX

In about one year, five gamma-ray bursts were simultaneously observed with the Wide Field Cameras and Gamma Ray Burst Monitor aboard the BeppoSAX satellite. From some of them X-ray afterglow emission has been clearly detected with the same satellite. In order to understand how GRB emission is related to the X-ray afterglow, we are performing a systematic study of the spectral properties of these events. We report here preliminary results of this study.Comment: 5 pages, 3 figures. To appear in the Proceedings of the 4th Huntsville Gamma-ray Burst Symposiu

Detection of a fast, intense and unusual gamma ray transient

An unusual transient pulse of approximately 50 keV was detected by the gamma-ray burst sensor network using nine space probes and satellites. Its characteristics are unlike those of the known variety of gamma-ray bursts and therefore suggest that it was formed either by a completely different origin species or in a very different manner. It is identified with the LMC supernova remnant N49

Comparing the effects of two inhaled glucocorticoids on allergen-induced bronchoconstriction and markers of systemic effects, a randomised cross-over double-blind study

<p>Abstract</p> <p>Background</p> <p>Inhaled glucocorticoids are efficient in protecting against asthma exacerbations, but methods to compare their efficacy vs systemic effects have only been attempted in larger multi-centre studies. The aim of the current study was therefore to directly compare the effects of two separate inhaled glucocorticoids, mometasone and budesonide, to compare the effects on the early and late asthmatic responses to inhaled allergen in patients with mild allergic asthma, and sputum eosinophils, and to relate the clinical positive effects to any systemic effects observed.</p> <p>Methods</p> <p>Twelve patients with documented early and late asthmatic responses (EAR and LAR) to inhaled allergen at a screening visit were randomized in a double-blind fashion to treatment with mometasone (200 μg × 2 or 400 μg × 2), budesonide (400 μg × 2) or placebo in a double-blind crossover fashion for a period of seven days. Challenge with the total allergen dose causing both an EAR and LAR was given on the last day of treatment taken in the morning. Lung function was assessed using FEV1, and systemic glucocorticoid activity was quantified using 24 h urinary cortisol.</p> <p>Results</p> <p>Mometasone and budesonide attenuate both EAR and LAR to allergen to a similar degree. No significant dose-related effects on the lung function parameters were observed. Both treatments reduced the relative amount of sputum eosinophils (%) after allergen. At the dose of 800 μg daily, mometasone reduced 24 h urinary cortisol by approximately 35%. Both drugs were well tolerated.</p> <p>Conclusions</p> <p>Mometasone and budesonide are equieffective in reducing early and late asthmatic responses induced by inhaled allergen challenge. Mometasone 800 μg given for seven days partially affects the HPA axis.</p

Gamma-Ray Burst 980329 and its X-Ray Afterglow

GRB 980329 is the brightest gamma-ray burst detected so far with the Wide Field Cameras aboard BeppoSAX, both in gamma-rays and X-rays. With respect to its fluence (2.6 X 10**-5 erg/s/cm**2 in 50 to 300 keV) it would be in the top 4% of gamma-ray bursts in the 4B catalog (Meegan et al. 1998). The time-averaged burst spectrum from 2 to 20 and 70 to 650 keV can be well described by the empirical model of Band et al. (1993). The resulting photon index above the break energy is exceptionally hard at -1.32 +/- 0.03. An X-ray afterglow was detected with the narrow-field instruments aboard BeppoSAX 7 h after the event within the error box as determined with the Wide Field Cameras. Its peak flux is (1.4 +/- 0.2) X 10**-12 erg/s/cm**2 (2 to 10 keV). The afterglow decayed according to a power law function with an index of -1.35 +/- 0.03. GRB 980329 is characterized by being bright and hard, and lacking strong spectral evolution.Comment: 13 pages with 3 figures. Accepted for publication in ApJ Let

Time-resolved X-ray spectral modeling of an intermediate burst from SGR1900+14 observed by HETE-2/FREGATE and WXM

We present a detailed analysis of a 3.5 s long burst from SGR 1900+14 that occurred on 2001 July 2. The 2-150 keV time-integrated energy spectrum is well described by the sum of two blackbodies whose temperatures are approximately 4.3 and 9.8 keV. The time-resolved energy spectra are similarly well fitted by the sum of two blackbodies. The higher temperature blackbody evolves with time in a manner consistent with a shrinking emitting surface. The interpretation of these results in the context of the magnetar model suggests that the two-blackbody fit is an approximation of an absorbed, multitemperature spectrum expected on theoretical grounds rather than a physical description of the emission. If this is indeed the case, our data provide further evidence for a strong magnetic field and indicate that the entire neutron star was radiating during most of the burst duration

The INTEGRAL view of the Soft Gamma-ray Repeater SGR 1806-20

We present the results obtained by INTEGRAL on the Soft-Gamma Ray Repeater SGR 1806-20. In particular we report on the temporal and spectral properties of the bursts detected during a moderately active period of the source in September and October 2003 and on the search for quiescent emission.Comment: To appear in the proceedings (ESA-SP) of the 5th INTEGRAL Workshop, "The INTEGRAL UNIVERSE", Munich, 16-20 February 200