Magnetar Twists: Fermi / GBM Detecon of SGR 1550‐5418 · Magnetar Twists: Fermi / GBM Detecon of...
14
Magnetar Twists: Fermi / GBM Detec5on of SGR 1550‐5418 Ersin Göğüş Sabancı University, Istanbul Yuki Kaneko C. Kouveliotou, E. Ramirez‐Ruiz, J. Granot, A. van der Horst, A. WaYs, A. von Kienlin, et al. Fermi Symposium, Washington, D.C. November 4, 2009
Transcript of Magnetar Twists: Fermi / GBM Detecon of SGR 1550‐5418 · Magnetar Twists: Fermi / GBM Detecon of...
MagnetarTwists:Fermi/GBMDetec5onof
SGR1550‐5418
ErsinGöğüşSabancıUniversity,Istanbul
YukiKaneko
C.Kouveliotou,E.Ramirez‐Ruiz,J.Granot,A.vanderHorst,A.WaYs,A.vonKienlin,etal.
FermiSymposium,Washington,D.C. November4,2009
SGR1550‐5418=1E1547.0‐5408
GBMTrigger090122037
• Triggerat00:53:52UTonJanuary22,2009
• 1stof41GBMTriggers
• Triggerdatafor600s
• 58untriggeredburstsiden5fiedwithin600s
EnhancedPersistentEmission
Pulsa5onDetec5on
12-27 keV
27-50 keV
50-102 keV
102-293 keV
TimingAnalysis
PulseProfiles
• DoublepeakatlowE• SinglepeakathighE• Nopulsa5on>110keV
(a) 10 － 14 keV (b) 14 － 22 keV (c) 22 － 33 keV (d) 33 － 50 keV (e) 50 － 74 keV (f) 74 － 110 keV
RMSPulsedFrac5onSpectrum
• Correlateswithenergy
• Peaksin50–74keV
• Notsignificant>110keV
• Indica5onofa“dip”
SpectralAnalysisTimeIntegratedSpectrum[T0+72–248s]
8–909keVBurstFree
PowerLaw
Addi5onalBlackbody(kT=18keV):ΔCstat=13.5(for2DOF)
TotalEnergy4.3 × 1040 ergs
TimeResolvedSpectra(ν Fν)[T0+72–117,122–169,173–223s]
122–169s 173–223s
PowerLaw
BlackbodyBlackbody
PowerLaw
74–117sPowerLawonly(Blackbodyisnotneeded)
FBB/FTOTAL=26% 25%
TemporalProper+es• Pulsa5onsmostsignificant
in120–210s
• Pulsefrac5onpeaksin50–74keV
• Pulsa5onsnotseenabove110keV
SpectralProper+es• Blackbodyrequiredin
122–223s
• BlackbodykT~17keV(Wienpeak~50keV)
• FBB25%
FPWRL75%
Assumingahotspotofradius RHSontheneutronstarsurface
For D =5kpc,kT=17keV:
AHS≈ 0.044(D/5kpc)2km2
RHS≈120m
Hot Spot
Corona on Magnetars by Beloborodov & Thompson (2006)
Dissipation rate: Ld ~ Ι ΦE Net current: Ι ∝ Β, Δψ, a2
Lobs = 2.8 × 1038 erg s-1 >> Ld
inconsistent with observation
e± plasmas & photons confined by closed B field region
Trapped energy: EB(a) = 1/6 a3B2 > Eiso,BB
For a = 120 m & Eiso,BB= 5.6 × 1040 erg: B > 1.4 × 1014 G
consistent with B = 2.2 x 1014 G from PP
Energy dissipated in the corona is radiated in two forms:
non-thermal, high energy radiation produced by collisionless dissipation of the coronal beam
blackbody radiation by thermalization: as the remaining energy dissipated in the corona enters the dense atmosphere, the crust is thermalized by two-body collisions and e-/e+ pair formation
Both components are expected to have comparable luminosities.
Assumingahotspotofradius RHSontheneutronstarsurface
For D =5kpc,kT=17keV:
AHS≈ 0.044(D/5kpc)2km2
RHS≈120m
whichisthesizeofthemagne+cally‐confinedhotplasmaandis<<1%oftheNSsurfacearea
Hot Spot
