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Thanks to the huge amount of gamma-ray pulsar photons collected by the Fermi Large Area Telescope since June 2008, it is now possible to constrain gamma-ray geometrical models by comparing simulated and observed light-curve morphological characteristics. We assumed vacuum-retarded dipole pulsar magnetic field and tested simulated and observed morphological light-curve characteristics in the framework of two pole emission geometries, Polar Cap (PC), radio, and Slot Gap (SG), and Outer Gap (OG)/One Pole Caustic (OPC) emission geometries. We compared simulated and observed/estimated light-curve morphological parameters as a function of observable and non-observable pulsar parameters. The PC model gives the poorest description of the LAT pulsar light-curve morphology. The OPC best explains both the observed gamma-ray peak multiplicity and shape classes. The OPC and SG models describe the observed gamma-ray peak-separation distribution for low- and high-peak separations, respectively. This suggests that the OPC geometry best explains the single-peak structure but does not manage to describe the widely separated peaks predicted in the framework of the SG model as the emission from the two magnetic hemispheres. The OPC radio-lag distribution shows higher agreement with observations suggesting that assuming polar radio emission, the gamma-ray emission regions are likely to be located in the outer magnetosphere. The larger agreement between simulated and LAT estimations in the framework of the OPC suggests that the OPC model best predicts the observed variety of profile shapes. The larger agreement between observations and the OPC model jointly with the need to explain the abundant 0.5 separated peaks with two-pole emission geometries, calls for thin OPC gaps to explain the single-peak geometry but highlights the need of two-pole caustic emission geometry to explain widely separated peaks.
We used the 10.4m Gran Telescopio Canarias to search for the optical counterparts to four isolated $gamma$-ray pulsars, all detected in the X-rays by either xmm or chan but not yet in the optical. Three of them are middle-aged pulsars -- PSR, J1846+0
We present precise phase-connected pulse timing solutions for 16 gamma-ray-selected pulsars recently discovered using the Large Area Telescope (LAT) on the Fermi Gamma-ray Space Telescope plus one very faint radio pulsar (PSR J1124-5916) that is more
In a search with the Parkes radio telescope of 56 unidentified Fermi-LAT gamma-ray sources, we have detected 11 millisecond pulsars (MSPs), 10 of them discoveries, of which five were reported in Kerr et al. (2012). We did not detect radio pulsations
We present the results of 2.5 years of AGILE observations of PSR B1509-58 and of the same interval of Fermi observations. The modulation significance of AGILE light curve above 30 MeV is at a 5 sigma confidence level and the light curve shows a broad
The evolutionary stage of a powerful radio source originated by an AGN is related to its linear size. In this context, compact symmetric objects (CSOs), which are powerful and intrinsically small objects, should represent the young stage in the indiv