granada may2008 2 - cosmos.esa.int · Nanda Rea- University of Amsterdam Introduction: Magnetars • bright X-ray pulsars Lx ~ 1033-1036 erg/s • rotating with periods of 2-12s •

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)



Radio

IR and optical

soft X-rays Hard X-rays

Gamma-rays

(Rea et al. 2005, MNRAS; Gotthelf et al. 2004, ApJ)


RXS J1708-4009


XTE 1810-197

Resonant Cyclotron Scattering in Magnetars


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



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

.



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




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


4U 0142+61

BB+PL+PL

Flu

x




Transient AXPs

BB+PL

RCS

1E 1547-5408

RCSBB+PL

CXO 1647-4552

RCS

BB+PL

XTE 1810-197


BB+PL

RCS

1E 1048-5937

Flu

x




SGRs with hard X-ray emission

BB+PL

RCS+PL

SGR 1900+14

SGR 1806-20


SGR 1900+14

BB+PL

Flu

x


RCS+PL

SGR 1806-20

F

lux





L1-10keV (1034 erg/s)

kT (k

eV)



Magnetospheric e- density of n~1.5x1013 cm-3 = 103 nGJ


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


http://heasarc.gsfc.nasa.gov/docs/xanadu/xspec/models/rcs.html

Documents

granada may2008 2 - cosmos.esa.int · Nanda Rea- University of Amsterdam Introduction: Magnetars • bright X-ray pulsars Lx ~ 1033-1036 erg/s • rotating with periods of 2-12s •