granada may2008 2 - cosmos.esa.int · nanda rea- university of amsterdam introduction: magnetars...
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XMM-Newton reveals magnetars’ magnetospheric densities
Nanda ReaUniversity of Amsterdam
Astronomical Institute “Anton Pannekoek”NWO Veni Fellow
In collaboration with :Silvia Zane
Roberto TurollaMaxim Lyutikov
Diego GotzLuciano Nobili
Nanda Rea- University of Amsterdam
Introduction: Magnetars
• bright X-ray pulsars Lx ~ 1033-1036 erg/s
• rotating with periods of 2-12s
• large period derivatives
• glitches
• bursts on many timescales (ms to 100s)
• transient outbursts
• radio pulsars only during outbursts
(review: Woods & Thompson 2006, Cambridge Press; Mereghetti 2008, A&AR)
Nanda Rea- University of Amsterdam
Introduction: Magnetars
Radio
IR and optical
soft X-rays Hard X-rays
Gamma-rays
(Rea et al. 2005, MNRAS; Gotthelf et al. 2004, ApJ)
Nanda Rea- University of Amsterdam
RXS J1708-4009
Introduction: Magnetars
XTE 1810-197
Resonant Cyclotron Scattering in Magnetars
Nanda Rea- University of Amsterdam
Twisted magnetospheres are filled with plasma which may modify radiation properties.
Main point: closed field lines in NS magnetospheres are not dead.Populated by hot, highly over-dense plasma, n >> nGJ
(e.g. Thompson, Lyutikov & Kulkarni 2002; Liutykov & Gavriil 2006)
!
"RCS~
RL
re
#
$ %
&
' ( "T
~ 105"
Tat 1 keV
!
RL~ 8R
NS
BNS
Bcrit
"
# $
%
& '
1/ 3
1keV
h(B
"
# $
%
& '
1/ 3
with
Resonant Cyclotron Scattering in Magnetars
Nanda Rea- University of Amsterdam
ω0=ωB
Δr ~r βT /3 <<r
ω0
n-
n+
How does a warm plasma in the magnetosphere modify the emergent spectra?
!
"RCS
= #RCSn$edz
.
Nanda Rea- University of Amsterdam
Resonant Cyclotron Scattering in Magnetars
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
3 free parameters, same as for theempirical blackbody+powerlaw model:
same statistical significance
Optical depth
!
"T
Electron thermal velocity
Surface Temperature (keV)
!
kT
Flu
x
0.1 - Energy (keV) - 10
F
lux
1 - Energy (keV) - 10
(1-10)
(0.1-0.5)
(0.1-1.3)
2000.38 / 2.03.98.0in SMCCXO J0100-72~ transient5.3 - 2500.63 / 2.93.96.41E 1048-5937
transient/radio2.6 - 1700.52 / 2.92.22.01E 1547-5408
hard X80-1900.44 / 2.44.711RXS J1708-4009
~ transient/hard X17 - 1590.41 / 3.80.67.0CTB 1091E 2259+586
4 - 100260
320 - 540200 - 350
5 - 1201-130
5 - 260
110
72
L (1033 erg/s)(0.2-10keV)
transient0.68/2.01.510.6in Wes1CXO 1647-4552
G337.0-0.1? in LMC
OBOB
G29.6+0.1
Kes 73
Hosts
GF/hardX0.43 / 2.05.75.2SGR 1900+14GF/hardX/outburst0.6 / 1.47.87.5SGR 1806-20
GF/?0.53 / 3.17.48.0SGR 0526-66outburst/ 2.9-6.4 ?SGR 1627-41
commentskT(keV)/ Γ
B(1014G)
P(s)
transient/ 4.6-7.0AX J1845-0258
transient/radio0.67 / 3.72.95.5XTE 1810-197
hard X0.44 / 2.07.111.81E 1841-045
hard X0.46 / 3.41.38.74U 0142+61
The Magnetar Sample
Nanda Rea- University of Amsterdam
Nanda Rea- University of Amsterdam
Resonant Cyclotron Scattering in Magnetars
AXPs with hard X-ray emission
4U 0142+61
RXS J1708-4009 RXS J1708-4009
1E 1841-045 1E 1841-045
BB+PL+PL
BB+PL
RCS+PL
RCS+PL
RCS+PL
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
4U 0142+61
BB+PL+PL
Flu
x
1 - Energy (keV) - 200
Resonant Cyclotron Scattering in Magnetars
Nanda Rea- University of Amsterdam
Transient AXPs
BB+PL
RCS
1E 1547-5408
RCSBB+PL
CXO 1647-4552
RCS
BB+PL
XTE 1810-197
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
BB+PL
RCS
1E 1048-5937
Flu
x
1 - Energy (keV) - 10
Nanda Rea- University of Amsterdam
Resonant Cyclotron Scattering in Magnetars
SGRs with hard X-ray emission
BB+PL
RCS+PL
SGR 1900+14
SGR 1806-20
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
SGR 1900+14
BB+PL
Flu
x
1 - Energy (keV) - 200
RCS+PL
SGR 1806-20
F
lux
1 - Energy (keV) - 10
Nanda Rea- University of Amsterdam
Resonant Cyclotron Scattering in Magnetars
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
L1-10keV (1034 erg/s)
kT (k
eV)
Nanda Rea- University of Amsterdam
Resonant Cyclotron Scattering in Magnetars
Magnetospheric e- density of n~1.5x1013 cm-3 = 103 nGJ
Rea, Zane, Turolla, Lyutikov & Gotz 2008, ApJ submitted, arXiv:0802.192v2
τ res
L1-10keV (1034 erg/s)
3D Monte Carlo RCS: applications (preliminary)
RCS3D
1E 1048-5937
1E 1547-5408
RCS3D
+PL
1E 1841-045
RCS3D
(Nobili, Turolla & Zane 2008, MNRAS; Rea et al. 2008, in prep; Albano et al. 2008, in prep)
Magnetospheric e- densityconsistent with the simplified 1D
model, hence being ~ 103 nGJ
kT ~ 0.2-0.6 keVβbulk ~ 0.2-0.4 Δφ ~ 1 -1.8
• Resonant cyclotron scattering reproduces all magnetar spectra–This model has a clear physical motivation, unlike BB+PL models
Conclusions
• Absorption values now matches what has been derived from single edge fitting – The BB+PL model overestimates the NH
• We could derive for the first time the magnetospheric density of magnetars–Much larger than for normal pulsars, as indeed predicted by the theory
• We built an analytical model to threat resonant cyclotron scattering– Implementing it in XSPEC for real data fitting
• More advanced 3D Monte-Carlo models for magnetar magnetospheres– Full 3-D magnetosphere (Fernandez & Thompson 2007; Nobili, Turolla & Zane 2008)– Application to the data (Rea et al. in prep; Albano et al. in prep)
in progress…
…done
Nanda Rea- University of Amsterdam
http://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/models/rcs.html