Le 7 juillet 2017
De 10h30 à 12h00
George Younes
George Washington University
Magnetars represent the most extreme manifestation of the neutron star population. Their seconds-long rotational periods and large spindown rates imply surface dipole magnetic fields up to 7.0E14 G, the strongest ever measured in the Universe (million-billion times that of Earth), and young ages (thousands of years). They are detected mainly in our own Galaxy as bright X-ray emitters with luminosities exceeding their rotational energy losses. Magnetars are the most variable sources in the neutron star zoo on time-scales ranging from milliseconds to years. On milliseconds to seconds time-scale, they show a unique and peculiar bursting behavior of hard X-ray/soft gamma-ray radiation with luminosities reaching upward of 1.0E47 erg/s/cm2. Following these bursting episodes, magnetars enter a period of enhanced high energy radiation where their X-ray luminosities increase by as many as 3 orders of magnitude compared to their quiescent persistent emission. During this time, their rotational properties can show drastic changes either in the form of timing noise or glitches. They recover back to their usual self within months to years. In this talk, I will give an overview of the magnetar field through recent exciting discoveries such as the unexpected magnetar-like behavior of a rotation powered pulsar, the discovery of the first wind nebula around a magnetar, a property normally associated to rotation powered pulsars, and the status of the strongest, most burst prolific of magnetars, SGR 1806-20, 13 and a half years after it emitted the brightest flash ever detected on Earth. Finally, I will conclude by looking at what the future holds for this rapidly growing field of research.