New observations with the gamma ray imager SIGMA

Results from the use of the gamma ray telescope SIGMA are given. An identification and an extensive study was done of sources contributing to the emission of the Galactic center region above 30 keV. A strong line was observed at 480 keV from Nova Muscae, which may be interpreted as an annihilation line with a redshift due to the presence of a compact object. The soft x-ray tails observed by SIGMA in some transient sources already identified as soft x-ray transients might be a common characteristic of these objects and has to be explained. The unusual spectrum of NGC4151 with a break around 50 keV can characterize a particular state of this kind of object. If it is the case, it has interesting implications for the origin of the Cosmic Diffuse Background

The Pulse Scale Conjecture and the Case of BATSE Trigger 2193

The pulses that compose gamma-ray bursts (GRBs) are hypothesized to have the same shape at all energies, differing only by scale factors in time and amplitude. This "Pulse Scale Conjecture" is confirmed here between energy channels of the dominant pulse in GRB 930214c (BATSE trigger 2193), the single most fluent single-pulsed GRB that occurred before May 1998. Furthermore, pulses are hypothesized to start at the same time independent of energy. This "Pulse Start Conjecture" is also confirmed in GRB 930214c. Analysis of GRB 930214c also shows that, in general, higher energy channels show shorter temporal scale factors. Over the energy range 100 KeV - 1 MeV, it is found that the temporal scale factors between a pulse measured at different energies are related to that energy by a power law, possibly indicating a simple relativistic mechanism is at work. To test robustness, the Pulse Start and Pulse Scale Conjectures were also tested on the four next most fluent single-pulse GRBs. Three of the four clearly passed, with a second smaller pulse possibly confounding the discrepant test. Models where the pulse rise and decay are created by different phenomena do not typically predict pulses that satisfy both the Pulse Start Conjecture and the Pulse Scale Conjecture, unless both processes are seen to undergo common time dilation.Comment: 19 pages, 9 figures, analysis revised and extended, accepted to Ap

Ex-situ Tunnel Junction Process Technique Characterized by Coulomb Blockade Thermometry

We investigate a wafer scale tunnel junction fabrication method, where a plasma etched via through a dielectric layer covering bottom Al electrode defines the tunnel junction area. The ex-situ tunnel barrier is formed by oxidation of the bottom electrode in the junction area. Room temperature resistance mapping over a 150 mm wafer give local deviation values of the tunnel junction resistance that fall below 7.5 % with an average of 1.3 %. The deviation is further investigated by sub-1 K measurements of a device, which has one tunnel junction connected to four arrays consisting of N junctions (N = 41, junction diameter 700 nm). The differential conductance is measured in single-junction and array Coulomb blockade thermometer operation modes. By fitting the experimental data to the theoretical models we found an upper limit for the local tunnel junction resistance deviation of ~5 % for the array of 2N+1 junctions. This value is of the same order as the minimum detectable deviation defined by the accuracy of our experimental setup

An improved time of flight gamma-ray telescope to monitor diffuse gamma-ray in the energy range 5 MeV - 50 MeV

A time of flight measuring device is the basic triggering system of most of medium and high energy gamma-ray telescopes. A simple gamma-ray telescope has been built in order to check in flight conditions the functioning of an advanced time of flight system. The technical ratings of the system are described. This telescope has been flown twice with stratospheric balloons, its axis being oriented at various Zenital directions. Flight results are presented for diffuse gamma-rays, atmospheric secondaries, and various causes of noise in the 5 MeV-50 MeV energy range

INTEGRAL and Swift/XRT observations of IGR~J16460+0849

IGR J16460+0849 is reported in the 3rd IBIS catalog with the shortest exposure of about 10 ks among all the detected sources, which makes it the most interesting target to be investigated with a deeper exposure. We analyze all available observations carried out by the International Gamma-Ray Astrophysics Laboratory (INTEGRAL) on the unidentified source IGR J16460+0849. The data were processed by using the latest version OSA 7.0. In addition we analyze also all the available Swift/XRT data on this source. We find that IGR J16460+0849 has a detection significance of ~ 4.4 sigma in the 20-100 keV band during the observational period between March 2003 and September 2004, when it was exposed by ~ 19 ks. Thereafter the source was not detected anymore, despite an additional exposure of ~ 271 ks. This suggests a flux variability on a timescale of years. The spectral analysis shows that the IBIS/ISGRI data are well presented by a power-law shape, with a photon index obtained as 1.45+-0.86. So far, the source has been detected consistently by IBIS/ISGRI in the subsequent observations and in the adjacent energy bands. We have analyzed the Swift/XRT observations on IGR J16460+0849 as well, and found no source inside the IBIS/ISGRI error circle. The non-detection during the Swift/XRT observation is consistent with the source having a variable nature.Comment: published in A&

A second catalog of gamma ray bursts: 1978 - 1980 localizations from the interplanetary network

Eighty-two gamma ray bursts were detected between 1978 September 14 and 1980 February 13 by the experiments of the interplanetary network (Prognoz 7, Venera 11 and 12 SIGNE experiments, Pioneer Venus Orbiter, International Sun-Earth Explorer 3, Helios 2, and Vela). Sixty-five of these events have been localized to annuli or error boxes by the method of arrival time analysis. The distribution of sources is consistent with isotropy, and there is no statistically convincing evidence for the detection of more than one burst from any source position. The localizations are compared with those of two previous catalogs

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

Early SPI/INTEGRAL contraints on the morphology of the 511 keV line emission in the 4th galactic quadrant

We provide first constraints on the morphology of the 511 keV line emission from the galactic centre region on basis of data taken with the spectrometer SPI on the INTEGRAL gamma-ray observatory. The data suggest an azimuthally symmetric galactic bulge component with FWHM of ~9 deg with a 2 sigma uncertainty range covering 6-18 deg. The 511 keV line flux in the bulge component amounts to (9.9+4.7-2.1) 10e-4 ph cm-2 s-1. No evidence for a galactic disk component has been found so far; upper 2 sigma flux limits in the range (1.4-3.4) 10e-3 ph cm-2 s-1 have been obtained that depend on the assumed disk morphology. These limits correspond to lower limits on the bulge-to-disk ratio of 0.3-0.6.Comment: 5 pages, 3 figures, accepted for publication in A&