Compton Large Area Silicon Timing Tracker for Cosmic Vision M3

Proposed in response to the ESA call for the third Medium size mission (M3), CAPSiTT is a small mission designed for a 3-year survey of the non-thermal high energy sky from an equatorial LEO orbit. With a large effective area and a very wide field of view, its single instrument, a silicon tracker, provides good imaging, spectroscopic and polarimetric capabilities with a sensitivity 10-100 times better than COMPTEL. Nucleosynthesis and particle acceleration mechanisms in various sites are the main scientific topics addressed by CAPSiTT.

GRIPS and the perspective of next-generation gamma-ray surveys

GRIPS is one example of next generation telescopes proposed for astronomy the energy range between hard X-ray mirror instruments such as NuStar and the Fermi telescope. The Compton telescope principle is an advantageous concept in view of background suppression, imaging sensitivity within a large field of view and energy range, and capability to measure polarization. The diversity of astrophysical sources at high energies (diffuse emission from cosmic-ray interactions, nuclear lines from point-like and diffuse sources, accreting binaries, cosmic-ray acceleration sites, novae and supernovae, GRBs) presents a challenge, and in particular emphasizes the need for large fields of view and surveys. We discuss the astrophysical challenges which are expected to remain after the extended INTEGRAL mission, and how such a next-generation survey at low-energy gamma-rays would impact on these. We argue that qualitatively new and more direct insights could be obtained on cosmic high-energy phenomena and their underlying physical processes.

Temporal properties of Swift GRBs with known redshifts

The Swift Gamma Ray Burst (GRB) mission has enabled the rapid detection of GRBs and the determination of the redshift of a greater proportion of source counterparts than previous missions. The mean redshift of the Swift GRBs is significantly higher than that of earlier missions. We present the results of a temporal analysis performed on 134 Swift long GRBs with known redshift. ‡ The GRBs were denoised using wavelets and subjected to an automatic pulse selection algorithm with the objective of identifying pulses. The rise times, fall times, full-width at half-maxima (FWHM), pulse amplitudes and pulse areas were measured and the frequency distributions of some of them are presented here. The results provide a comprehensive description of the pulse profiles in Swift GRBs with known redshift, determining that the temporal properties are consistent with lognormal distributions and that correcting for the known redshift of the source does not have a significant impact on the distributions. Lognormal distributions arise from random multiplicative processes and abound in a variety of natural phenomena.

Unveiling Physical Processes in Type Ia Supernovae With a Laue Lens Telescope

We present in this paper a focusing gamma-ray telescope that has only one goal: addressing the true nature of Type Ia Supernovae (SNe Ia). This telescope is based on a Laue lens focusing a 100-keV wide energy band centered on 847 keV, which correspond to a bright line emitted by the decay chain of 56Ni, a radioactive element massively produced during SNe Ia events. Spectroscopy and light curve measurements of this gamma-ray line allow direct measurement of the underlying explosion physics and dynamics, and thus discriminate among the competing models. However reaching this goal the observation of several events with high detection significance, meaning more powerful telescopes. The telescope concept we present in this paper is composed of a Laue lens held 30 m apart from the focal instrument (a compact Compton telescope) by an extensible mast. With a 3-sigma sensitivity of 1.8\times10-6 ph/s/cm2 in the 3%-broadened line at 847 keV (in 1Ms observation time), dozens of SNe Ia could be detected per year out to \sim40 Mpc, enough to perform detailed time-evolved spectroscopy on several events each year. This study took place in the framework of the DUAL mission proposal which was recently submitted to ESA for the third medium class mission of the Cosmic Vision program.

Recent Results from the Fermi Gamma-ray Space Telescope

The Fermi Gamma-ray Space Telescope, formerly named GLAST, is a mission in low-Earth orbit to observe gamma rays from the cosmos in the broad energy range from 20 MeV to >300 GeV, with supporting observations of gamma-ray bursts from 8 keV to 30 MeV. The telescope far surpasses previous generations in its ability to detect and localize faint gamma-ray sources, as well as its ability to see 20% of the sky at any instant and scan the entire sky on a timescale of a few hours. With its launch on 11 June 2008, Fermi opened a new and exciting window on a wide variety of exotic astrophysical objects and is enabling new research on such topics as the origin and circulation of cosmic rays and searches for hypothetical new phenomena such as annihilation of dark matter. In addition to introducing the mission and the instruments, this talk will present the latest results on dark matter searches, diffuse gamma-ray production, galactic sources such as pulsars and micro-quasars, and extragalactic sources such as active galaxies and gamma-ray bursts.

Status of the TUS space experiment preparation

The TUS space project for investigation of Ultra High Energy Cosmic Rays (UHECR) by the measurement of Extensive Atmospheric Shower fluorescent radiation is in the construction stage. The main goal of the TUS mission is to search for cosmic ray particles beyond the GZK energy limit. The observation of the full sky for primary particle arrival directions is an advantage of the TUS project in comparison to the ground based experiments. The TUS experience of UHECR study from the space will be of importance for future space detectors like the JEM-EUSO mission. The TUS detector operation could be considered as a ”pathfinder” for the JEM-EUSO mission including the JEM-EUSO UV sensor test. The technological TUS prototype is produced and their tests are in progress. The flight detector has to be produced in 2010-2011. The mission is planned for operation at the end of 2011 at the dedicated “Mikhail Lomonosov” satellite.

The AXTAR mission

All-sky Monitoring of Variable Sources with Fermi GBM

Using the Gamma ray Burst Monitor (GBM) on Fermi, we monitor the transient hard X-ray/soft gamma ray sky. The twelve GBM NaI detectors span 8 keV to 1 MeV, while the two BGO detectors span 150 keV to 40 MeV. We use the Earth occultation technique to monitor a number of sources, including X-ray binaries, AGN, and solar flaring activity. Our monitoring reveals predictable and unpredictable phenomena such as transient outbursts and state changes. With GBM we also track the pulsed flux and spin frequency of accretion powered pulsars using epoch-folding techniques. Searches for quasi-periodic oscillations and X-ray bursts are also possible with GBM all-sky monitoring. Highlights from the Earth Occultation and Pulsar projects will be presented including our recent surprising discovery of variations in the total flux from the Crab. Inclusion of an all-sky monitor is crucial for a successful future X-ray timing mission.

Preliminary concept of modern X-ray timing mission

We present the concept of new X-ray timing mission proposed for Russian astrophysical program. The preliminary study includes the main scientific tasks for the X-ray timing mission, requirements for scientific payload and spacecraft. The mission will concentrate on study X-ray variability of bright accreting black holes and neutron stars. These objects can give unique information for both strong gravity and nuclear physics. The study of accretion flows variability mechanism is essential to successful interpretation of X-ray data and unambiguous determination of fundamental parameters of compact objects. The main instrument of the observatory is large area X-ray timing spectrometer.

Charge-starved jets and rapid variability in blazars

Very rapid variations of the gamma-ray flux from blazars sugg est that there is a mechanism at work which modulates blazar emission on timescales much sma ller than the light-crossing time of the black hole’s event horizon. We propose a scenario in wh ich blazar photons are modulated at the frequencyω of a large-amplitude wave that is launched in the polar regio n of the central, rotating black hole, and propagates in a charge-starved jet . Using a two-fluid ( e±) description, we find the outflow exhibits a delayed acceleration phase that st arts when the inertia associated with the wave currents becomes important. The modulation of the e mission from the accelerating jet is preserved for the observer provided that the density of pa irs, produced in an electromagnetic cascade, is sufficiently low.