Adriana Mancini Pires, Christian Motch, Roberto Turolla, Axel Schwope, Maura Pilia, Aldo Treves, Sergei B. Popov, Eduardo Janot-Pacheco
While fewer in number relative to the dominant rotation-powered radio pulsar population, peculiar classes of isolated neutron stars (INSs) -- which include magnetars, the ROSAT-discovered "Magnificent Seven" (M7), rotating radio transients (RRATs) and central compact objects in supernova remnants (CCOs) -- represent a key element to understand the neutron star phenomenology. We report here on the results of an observational campaign aiming at studying the properties of the source 2XMM J104608.7-594306. Its evolutionary state is investigated by means of deep dedicated observations obtained with XMM-Newton, the ESO Very Large Telescope as well as on publicly available gamma-ray data from the Fermi and AGILE missions. The observations confirm previous expectations and further reveal a unique object. The source, likely within the Carina Nebula, shows a soft spectrum with absorption features and no magnetospheric emission. The optical counterpart is fainter than V=27 and no gamma-ray emission is significantly detected. Very interestingly, while these characteristics are remarkably similar to those of the M7 or of the only RRAT so far detected in X-rays, all with spin periods of a few seconds, we found intriguing evidence for a very fast rotation, P=18.6 ms. We interpret the new results in the light of the observed properties of the currently known neutron star population, in particular those of standard rotation-powered pulsars, recycled objects and CCOs. We find that none of these scenarios can satisfactorily explain the collective properties of 2XMM J104608.7-594306, although a relation with the still poorly known class of Galactic anti-magnetars may be more favoured. New XMM-Newton data, granted for the next cycle of observations (AO11), will much improve the current observational picture on the source, given the oportunity to significantly constrain the pulsar spin down.
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http://arxiv.org/abs/1205.0427
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