SuperAGILE Research Articles

TEMPORAL PROPERTIES OF GX 301−2 OVER A YEAR-LONG OBSERVATION WITH SuperAGILE

ABSTRACT We present the long-term monitoring of the high-mass X-ray binary GX 301−2 performed with the SuperAGILE (SA) instrument on-board the Astro-rivelatore Gamma ad Immagini LEggero (AGILE) mission. The source was monitored in the 20–60 keV energy band during the first year of the mission from 2007 July 17 to 2008 August 31, covering about one whole orbital period and three more pre-periastron (PP) passages for a total net observation time of about 3.7 Ms. The SA data set represents one of the most continuous and complete monitoring at hard X-ray energies of the 41.5 days long binary period available to date. The source behavior was characterized at all orbital phases in terms of hard X-ray flux, spectral hardness, spin-period history, pulsed fraction, and pulse shape profile. We also complemented the SA observations with the soft X-ray data of the Rossi X-Ray Timing Explorer/All-Sky Monitor. Our analysis shows a clear orbital modulation of the spectral hardness, with peaks in correspondence with the PP flare and near phase 0.25. The hardness peaks, we found, could be related with the wind-plus-stream accretion model proposed in order to explain the orbital light-curve modulation of GX 301−2. Timing analysis of the pulsar spin period shows that the secular trend of the ∼680 s pulse period is consistent with the previous observations, although there is evidence of a slight decrease in the spin-down rate. The analysis of the hard X-ray-pulsed emission also showed a variable pulse shape profile as a function of the orbital phase, with substructures detected near the passage at the periastron, and a clear modulation of the pulsed fraction, which appears in turn strongly anticorrelated with the source intensity.

Diving to the Deep: Uncovering the Mysteries of Mid-Ocean Ridges

AbstractLong Beach City College (LBCC) returns to the 2008 MATE Remotely Operated Vehicle (ROV) Competition with the Viking Super Agile Benthic Exploration ROV (SABER) ready for work. The purpose of this ROV is to explore the depths of the mid-oceanic ridges while taking temperature readings of black smokers, recovering samples and safely returning them to the surface. The ROV was designed with a frame made from buoyant PVC. The design made in SolidWorks greatly increases water flow, allowing it to glide through the water to a depth of about 30 m due to tether length. The length, width, and height of the ROV are 76 cm, 50 cm, and 28 cm, respectively. With a surprising 16 kg of weight, an average person could lift it easily, using the handles that are part of the frame design. LBCC’s ROV carries four cameras: a dual camera stereovision system, which creates a distance-measuring viewing system; a single high-resolution, low-light color camera with multi-directional movement; and an unfixed camera, which can be mounted anywhere for extra viewing. The five thrusters provide 2.9 kg of thrust each, enabling it to be quick and powerful. In order to complete the assigned tasks, a multi-function gripper was designed and built. This gripper has a built-in hook to grab the ocean bottom seismometer and help return it to the surface. The gripper has a channel cut into the middle of it to allow water flow, so the temperature sensor can be deployed properly and it can also easily pick up the lava samples.

Design and construction of the Mini-Calorimeter of the AGILE satellite

AGILE is a small space mission of the Italian Space Agency (ASI) devoted to gamma-ray and hard-X astrophysics, successfully launched on April 23, 2007. The AGILE Payload is composed of three instruments: a gamma-ray imager based on a tungsten-silicon tracker (ST), for observations in the gamma ray energy range 30 MeV–50 GeV, a Silicon based X-ray detector, SuperAGILE (SA), for imaging in the range 18–60 keV and a CsI(Tl) Mini-Calorimeter (MCAL) that detects gamma rays or charged particles energy loss in the range 300 keV–100 MeV. MCAL is composed of 30 CsI(Tl) scintillator bars with photodiode readout at both ends, arranged in two orthogonal layers. MCAL can work both as a slave of the ST and as an independent gamma-ray detector for transients and gamma-ray bursts detection. In this paper a detailed description of MCAL is presented together with its performance.

Search of GRB with AGILE Minicalorimeter

AGILE, the small scientific mission of the Italian Space Agency devoted to Hard-X and Gamma-ray astrophysics, was successfully launched on April 23, 2007. The AGILE payload is composed of a tungsten-silicon tracker (ST), operating in the gamma-ray energy range 30MeV–50GeV; Super-AGILE, an X-ray imager operating in the energy range 15–45keV; the Minicalorimeter (MCAL) and an Anticoincidence shield. MCAL is a detector of about 1400cm2 sensitive in the range 0.3–200MeV, that can be used both as a slave of the ST to contribute to the AGILE Gamma Ray imaging Detector (GRID operative mode) and autonomously for detection of transient events (BURST operative mode). MCAL is made of 30 CsI(Tl) bar-shaped scintillation detectors with photodiode readout at both ends, arranged in two orthogonal layers. Energy and position of interaction can be derived from a proper composition of the signals readout at the bar's ends, absolute time tagging can be achieved with a μs resolution. The Burst logic deals with various rate-meters on different time scales, energy bands, and MCAL spatial zones. Different algorithms can be chosen for Burst triggering considering also the contribution of other detectors like Super AGILE. In this paper the various trigger logic will be reviewed as well as their on-ground test performed with a dedicated experimental setup.

The AGILE contribution to GRBs studies

AGILE is a gamma-ray mission planned to be operating as an Observatory during the period 2002-2005. Its baseline instrument is designed to detect gamma rays in the band. AGILE's good sensitivity, very large field of view ( of the whole sky), and excellent timing capability ( ms deadtime) are ideal to study gamma-ray bursts (GRBs). AGILE is expected to detect ~10 GRBs per year at energies above 100 MeV. The Super–AGILE option might be able to localize GRBs within a few arcminutes and provide additional information in the hard X-ray band. A rapid alert program is an essential part of the scientific goals of the AGILE Observatory.