Latest results on gamma-ray pulsars with Fermi

The Fermi Large Area Telescope (LAT) has been scanning the gamma-ray sky since 2008. The number of pulsars detected by the LAT now exceeds 200, making them by far the largest class of Galactic gamma-ray emitters. I discuss some of the latest pulsar discoveries made by the LAT, in particular those made since the release of the Pass 8 data.Comment: 5 pages, to appear in Il Nuovo Cimento

Fermi-LAT searches for gamma-ray pulsars

The Large Area Telescope (LAT) on the Fermi satellite is the first gamma-ray instrument to discover pulsars directly via their gamma-ray emission. Roughly one third of the 117 gamma-ray pulsars detected by the LAT in its first three years were discovered in blind searches of gamma-ray data and most of these are undetectable with current radio telescopes. I review some of the key LAT results and highlight the specific challenges faced in gamma-ray (compared to radio) searches, most of which stem from the long, sparse data sets and the broad, energy-dependent point-spread function (PSF) of the LAT. I discuss some ongoing LAT searches for gamma-ray millisecond pulsars (MSPs) and gamma-ray pulsars around the Galactic Center. Finally, I outline the prospects for future gamma-ray pulsar discoveries as the LAT enters its extended mission phase, including advantages of a possible modification of the LAT observing profile.Comment: Proceedings of the IAU Symposium 291, IAU XXVIII General Assembly, Beijing, China, August 2012: "Neutron Stars and Pulsars: Challenges and Opportunities after 80 years", Editor: Joeri van Leeuwen. To be published by Cambridge University Press. 6 page

Quintessence reconstructed: new constraints and tracker viability

We update and extend our previous work reconstructing the potential of a quintessence field from current observational data. We extend the cosmological data set to include new supernova data, plus information from the cosmic microwave background and from baryon acoustic oscillations. We extend the modeling by considering Padé approximant expansions as well as Taylor series, and by using observations to assess the viability of the tracker hypothesis. We find that parameter constraints have improved by a factor of 2, with a strengthening of the preference of the cosmological constant over evolving quintessence models. Present data show some signs, though inconclusive, of favoring tracker models over nontracker models under our assumptions

Sensitivity of a climatologically-driven sea ice model to the ocean heat flux

Ocean heat flux sensitivity was studied on a numerical model of sea ice covering the Weddell Sea region of the southern ocean. The model is driven by mean monthly climatological atmospheric variables. For each model run, the ocean heat flux is uniform in both space and time. Ocean heat fluxes below 20 W m to the minus 2 power do not provide sufficient energy to allow the ice to melt to its summertime thicknesses and concentrations by the end of the 14 month simulation, whereas ocean heat fluxes of 30 W m to the minus 2 power and above result in too much ice melt, producing the almost total disappearance of ice in the Weddell Sea by the end of the 14 months. These results are dependent on the atmospheric forcing fields