INTEGRAL Status Report - May 2006
The 6th INTEGRAL workshop, 2-8 July 2006, cannot take place in St Petersburg due to the G8 summit meeting but will be held at IKI Moscow instead. Approximately 180 abstracts have been received.
Operations and Archiving
The 7th SPI annealing was successfully performed between 9 and 24 January 2006 recovering the energy resolutions of the detectors to close to their pre-launch values. Immediately following this, INTEGRAL performed four observations of the Earth as an occulting device to study the cosmic diffuse high-energy background.
As we are approaching solar minimum, a slow increase in the instrumental background counting rates is being observed. Work is in progress to re-allocate telemetry between the different instruments and observing modes in order to preserve the core scientific capabilities.
The ISDC continues to routinely dispatch data products to observers within 6-8 weeks of their observation. As of 2006 March, the on-line ISDC public archive includes nearly all public observations made until 2005 January. In collaboration with the ISDC, the ISOC Science Data Archive (ISDA) at ESAC has been updated with the latest data and products. These include products from the 2nd IBIS/ISGRI soft gamma-ray catalog containing >200 sources and published in the Astrophysical Journal.
Science Highlights
As of the end of 2006 February, there have been 153 refereed and 335 non-refereed papers containing results from INTEGRAL. Of the refereed ones, 68 were published in 2005 and 16 to date in 2006. Kuiper et al. (ApJ in press) have studied four Anomalous X-ray Pulsars (AXPs) by combining data form INTEGRAL and R-XTE. These objects are extremely rare and only 7 are known to exist. Originally it was thought that they were binary systems and that their high-energy emission was produced by accretion onto a compact neutron star. An alternative theory is that they are single neutron stars with the energy needed to produce the high-energy emission coming from the decay of a super-intense magnetic field. The new results support this idea as the authors find exceptionally hard total emission and hard pulsed emission above 10 keV. The energy of this emission exceeds the spin-down power by a few orders of magnitude, and supports the idea that the decay of the magnetic field is responsible for the emission. However, the physics of how this happens is unclear and requires a new mechanism for particle acceleration in the magnetospheres of neutron stars.