BEGIN:VCALENDAR
VERSION:2.0
PRODID:-//Talks.cam//talks.cam.ac.uk//
X-WR-CALNAME:Talks.cam
BEGIN:VEVENT
SUMMARY:Modelling the magnetars quiescent spectra - Dr Silvia Zane\, MSSL-
 UCL
DTSTART:20090916T151500Z
DTEND:20090916T153000Z
UID:TALK19878@talks.cam.ac.uk
CONTACT:Alexander Blustin
DESCRIPTION:Soft gamma-ray repeaters (SGRs) and anomalous X-ray pulsars (A
 XPs) are peculiar X-ray sources which are believed to be magnetars: ultra-
 magnetized neutron stars with surface field in excess of 1E14 G\, i.e. wel
 l above the QED threshold. Spectral analysis is an important tool in magne
 tar astrophysics since it can provide key information on the emission mech
 anisms. The first attempts at modelling the persistent (i.e. outside burst
 s) soft X-ray (<10 keV) spectra of AXPs proved that a model consisting of 
 a blackbody (kT ~ 0.3-0.6 keV) plus a power-law (photon index ~ 2-4) could
  successfully reproduce the observed emission. Moreover\, recent INTEGRAL 
 observations have shown that\, while in quiescence\, magnetars emit substa
 ntial persistent radiation also at higher energies\, up to a few hundreds 
 of keV. Their high energy spectra are tipically modelled by a further powe
 r law which in some cases has been proved to exhibit a strong dependence o
 n the spin phase. However\, a convincing physical interpretation of the va
 rious spectral components is still missing and our knowledge of the broadb
 and emission is severely hampered by the impossibility\, so far\, to carry
  out simultaneous observations in the whole energy range. In this talk I w
 ill focus on the interpretation of magnetar spectral properties during qui
 escence. I will summarise the present status of the art and our first atte
 mpts to model the broadband persistent emission of magnetars within a self
  consistent\, physical scenario. I will then present the predictions of a 
 synthetic model that we calculated with a new magnetic montecarlo 3D radia
 tive code. Our code accounts for resonant cyclotron upscattering of soft t
 hermal photons (emitted by the star surface)\, by a population of relativi
 stic electrons threated in the magnetosphere. Polarization and QED effects
  are consistently accounted for\, as well different configurations for the
  magnetosphere. I will discuss the predicted spectral and polarization pro
 perties in the 0.1-100 keV range\, and the application to existing magneta
 rs data. 
LOCATION:Sackler Lecture Theatre\, IoA
END:VEVENT
END:VCALENDAR