{mosimage}IGR J22517+2218 was yet another unidentified object discovered by INTEGRAL/IBIS, but this time the quest for its identification turned out to be particularly rewarding. Follow up Swift/XRT observations identified its optical counterpart in MG3 J225155+2217, a quasar at z=3.668, the farthest object so far detected by INTEGRAL.

The image shows the detection of this new source by the ISGRI camera on IBIS in the 20-100 keV band, while the zoom refers to a Swift/XRT observation covering the entire INTEGRAL error box: the brightest object detected in the 2-10 keV band is indeed the high redshift quasar. Superimposed on the image is the combined IBIS/XRT spectrum over the 0.4-100 keV band (or 2-500 keV in the source rest frame).

{mosimage}Three researchers of IASF-BO played a leading role in this outstanding research: {cb_profile=bassani}Loredana Bassani{/cb_profile}, {cb_profile=landi}Raffaella Landi{/cb_profile} and {cb_profile=malizia}Angela Malizia{/cb_profile}. Details of this observations are described in Bassani et al. 2007, astro-ph (0709.3023), ApJ Lett. in press.

You may also want to read some articles from local and national newspapers: L’unità, Il Domani, Il Mattino (with a long interview to Bassani), Leggo,
and Avvenire.